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Laser controlled flame stabilization
Early, James W.; Thomas, Matthew E.
A method and apparatus is provided for initiating and stabilizing fuel combustion in applications such as gas turbine electrical power generating engines and jet turbine engines where it is desired to burn lean fuel/air mixtures which produce lower amounts of NO.sub.x. A laser induced spark is propagated at a distance from the fuel nozzle with the laser ignitor being remotely located from the high temperature environment of the combustion chamber. A laser initiating spark generated by focusing high peak power laser light to a sufficiently tight laser spot within the fuel to cause the ionization of air and fuel into a plasma is unobtrusive to the flow dynamics of the combustion chamber of a fuel injector, thereby facilitating whatever advantage can be taken of flow dynamics in the design of the fuel injector.
Flame stabilizer for stagnation flow reactor
Hahn, David W.; Edwards, Christopher F.
A method of stabilizing a strained flame in a stagnation flow reactor. By causing a highly strained flame to be divided into a large number of equal size segments it is possible to stablize a highly strained flame that is on the verge of extinction, thereby providing for higher film growth rates. The flame stabilizer is an annular ring mounted coaxially and coplanar with the substrate upon which the film is growing and having a number of vertical pillars mounted on the top surface, thereby increasing the number of azimuthal nodes into which the flame is divided and preserving an axisymmetric structure necessary for stability.
The stability and visualized flame and flow structures of a combusting jet in cross flow
Huang, R.F.; Chang, J.M. . Dept. of Mechanical Engineering)
The blowoff stability and flame behavior of a combusting propane gas jet issuing from a well-contoured burner perpendicularly to a cross air stream in a wind tunnel test section is studied experimentally. A category of never-lift flames was found to have different stability characteristics and behavior from the conventionally reported liftable flames. The stability domain of the never-lift flames covers higher cross-flow velocities and lower fuel jet velocities compared with the liftable flames. The flame configurations in the stability domain are identified by characteristic modes: down-washed flame, flashing flame, developing flame, dual-flame, flickering flame, and pre-blowoff flame. The schlieren photographs are presented in order to discuss the effects of the flow structures on the general behavior of the flames in each characteristic mode and on the flame stability characteristics. The bisector of the eddy travelling avenue reasonably depicts the trajectory of the combusting jet in cross flow. Correlations for the trajectories of cold and combusting jets in cross flow are obtained.
An experimental investigation of thermoacoustic instabilities in a premixed swirl-stabilized flame
Fritsche, D.; Fueri, M.; Boulouchos, K.
Modern gas turbines use lean premixed combustion to achieve the best compromise between pollutant emissions and efficiency. This type of combustion increases the flame receptivity to external perturbations, thereby promoting the onset of large-amplitude pressure oscillations called thermoacoustic instabilities (often referred to as combustion noise). To improve our understanding of stability properties in such complex systems, encountered in many industrial applications, the flame structure of an atmospheric swirl-stabilized burner of 30 to 75 kW was systematically investigated for various inlet temperatures and air-fuel ratios. This investigation revealed the existence of two stable flame types (one lean and one rich) separated by a region of unstable flames characterized by very distinct flame shapes, flame pressure drops, and dynamic pressure oscillations. The lean transition from stable to unstable flames has been associated with a critical flame temperature at the edge of two different flame-stabilizing mechanisms, while the rich transition from unstable to stable flames has been attributed to a critical ratio of hydrodynamic to combustion times in terms of Damkoehler number. In this noise island, the mechanism for instability is due to the nonmonotonic behavior of flame pressure drop as the air-fuel ratio is changed, the maximum pressure drop across the flame coinciding with the maximum dynamic pressure. Finally, the frequency analysis of the dynamic pressure revealed the coupling with the acoustic eigenmodes of the combustion chamber for the dominant mode and with the plenum for secondary ones the frequency of which did not change with flame temperature. (author)
Energy Science and Technology Software Center (OSTI)
FLAME is data processing software explicitly written to support the ACAP software of DSP Technologies, Inc., of Fremont, CA. ACAP acquires and processes in-cylinder pressure data for reciprocating engines. However, it also has the capability to acquire data for two Sandia-developed technologies, ionization-probe instrumented head gaskets and fiber-optic instrumented spark plugs. FLAME post processes measurements of flame arrival from data files aquired with ACAP. Flame arrival time is determined from analog ionization-probe or visible-emission signals.more » The resulting data files are integrated with the standard ACAP files, providing a common data base for engine development.« less
Effect of fuel composition and differential diffusion on flame stabilization in reacting syngas jets in turbulent cross-flow
Minamoto, Yuki; Kolla, Hemanth; Grout, Ray W.; Gruber, Andrea; Chen, Jacqueline H.
Here, three-dimensional direct numerical simulation results of a transverse syngas fuel jet in turbulent cross-flow of air are analyzed to study the influence of varying volume fractions of CO relative to H2 in the fuel composition on the near field flame stabilization. The mean flame stabilizes at a similar location for CO-lean and CO-rich cases despite the trend suggested by their laminar flame speed, which is higher for the CO-lean condition. To identify local mixtures having favorable mixture conditions for flame stabilization, explosive zones are defined using a chemical explosive mode timescale. The explosive zones related to flame stabilization aremore » located in relatively low velocity regions. The explosive zones are characterized by excess hydrogen transported solely by differential diffusion, in the absence of intense turbulent mixing or scalar dissipation rate. The conditional averages show that differential diffusion is negatively correlated with turbulent mixing. Moreover, the local turbulent Reynolds number is insufficient to estimate the magnitude of the differential diffusion effect. Alternatively, the Karlovitz number provides a better indicator of the importance of differential diffusion. A comparison of the variations of differential diffusion, turbulent mixing, heat release rate and probability of encountering explosive zones demonstrates that differential diffusion predominantly plays an important role for mixture preparation and initiation of chemical reactions, closely followed by intense chemical reactions sustained by sufficient downstream turbulent mixing. The mechanism by which differential diffusion contributes to mixture preparation is investigated using the Takeno Flame Index. The mean Flame Index, based on the combined fuel species, shows that the overall extent of premixing is not intense in the upstream regions. However, the Flame Index computed based on individual contribution of H2 or CO species reveals that hydrogen
Effect of fuel composition and differential diffusion on flame stabilization in reacting syngas jets in turbulent cross-flow
Minamoto, Yuki; Kolla, Hemanth; Grout, Ray W.; Gruber, Andrea; Chen, Jacqueline H.
Here, three-dimensional direct numerical simulation results of a transverse syngas fuel jet in turbulent cross-flow of air are analyzed to study the influence of varying volume fractions of CO relative to H2 in the fuel composition on the near field flame stabilization. The mean flame stabilizes at a similar location for CO-lean and CO-rich cases despite the trend suggested by their laminar flame speed, which is higher for the CO-lean condition. To identify local mixtures having favorable mixture conditions for flame stabilization, explosive zones are defined using a chemical explosive mode timescale. The explosive zones related to flame stabilization are located in relatively low velocity regions. The explosive zones are characterized by excess hydrogen transported solely by differential diffusion, in the absence of intense turbulent mixing or scalar dissipation rate. The conditional averages show that differential diffusion is negatively correlated with turbulent mixing. Moreover, the local turbulent Reynolds number is insufficient to estimate the magnitude of the differential diffusion effect. Alternatively, the Karlovitz number provides a better indicator of the importance of differential diffusion. A comparison of the variations of differential diffusion, turbulent mixing, heat release rate and probability of encountering explosive zones demonstrates that differential diffusion predominantly plays an important role for mixture preparation and initiation of chemical reactions, closely followed by intense chemical reactions sustained by sufficient downstream turbulent mixing. The mechanism by which differential diffusion contributes to mixture preparation is investigated using the Takeno Flame Index. The mean Flame Index, based on the combined fuel species, shows that the overall extent of premixing is not intense in the upstream regions. However, the Flame Index computed based on individual contribution of H2 or CO species reveals that
Effect of virtual mass on the characteristics and the numerical stability in two-phase flows
No, H.C.; Kazimi, M.S.
It is known that the typical six equation two-fluid model of the two-phase flow possesses complex characteristics, exhibits unbounded instabilities in the short-wavelength limit and constitutes an ill-posed initial value problem. Among the suggestions to overcome these difficulties, one model for the virtual mass force terms were studied here, because the virtual mass represents real physical effects to accomplish the dissipation for numerical stability. It was found that the virtual mass has a profound effect upon the mathematical characteristic and numerical stability. Here a quantitative bound on the coefficient of the virtual mass terms was suggested for mathematical hyperbolicity and numerical stability. It was concluded that the finite difference scheme with the virtual mass model is restricted only by the convective stability conditions with the above suggested value.
Investigation of nitrogen dilution effects on the laminar burning velocity and flame stability of syngas fuel at atmospheric condition
Prathap, C.; Ray, Anjan; Ravi, M.R. [Department of Mechanical Engineering, Indian Institute of Technology, Delhi, New Delhi 110016 (India)
The objective of this investigation was to study the effect of dilution with nitrogen on the laminar burning velocity and flame stability of syngas fuel (50% H{sub 2}-50% CO by volume)-air (21% O{sub 2}-79% N{sub 2} by volume) mixtures. The syngas fuel composition considered in this work comprised x% N{sub 2} by volume and (100-x)% an equimolar mixture of CO and H{sub 2}. The proportion x (i.e., %N{sub 2}) was varied from 0 to 60% while the H{sub 2}/CO ratio was always kept as unity. Spherically expanding flames were generated by centrally igniting homogeneous fuel-air gas mixtures in a 40-L cylindrical combustion chamber fitted with optical windows. Shadowgraphy technique with a high-speed imaging camera was used to record the propagating spherical flames. Unstretched burning velocity was calculated following the Karlovitz theory for weakly stretched flames. Also, Markstein length was calculated to investigate the flame stability conditions for the fuel-air mixtures under consideration. Experiments were conducted for syngas fuel with different nitrogen proportions (0-60%) at 0.1 MPa (absolute), 302{+-}3K, and equivalence ratios ranging from 0.6 to 3.5. All the measurements were compared with the numerical predictions obtained using RUN-1DL and PREMIX with a contemporary chemical kinetic scheme. Dilution with nitrogen in different proportions in syngas resulted in (a) decrease in laminar burning velocity due to reduction in heat release and increase in heat capacity of unburned gas mixture and hence the flame temperature, (b) shift in occurrence of peak laminar burning velocity from {phi}=2.0 for 0% N{sub 2} dilution to {phi}=1.4 for 60% N{sub 2} dilution, (c) augmentation of the coupled effect of flame stretch and preferential diffusion on laminar burning velocity, and (d) shift in the equivalence ratio for transition from stable to unstable flames from {phi}=0.6 for 0% N{sub 2} dilution to {phi}=1.0 for 60% N{sub 2} dilution. The present work also indicated that
Regularities of flame propagation in a tube under weightless conditions: stability investigation
Samsonov, V.P.; Abrukov, S.A.; Kidin, N.I.
In research devoted to the theoretical investigation of laminar flames during propagation in channels, one of the mandatory assumptions is the assumption about no gravity forces but until now the verification of the results of such work has been impossible because of the lack of experimental data on flame propagation under weightless conditions. This paper reports on experiments conducted to verify existing deductions and to do so the flame structure and certain regularities of its propagation in a half-open square tube under weightless conditions were investigated using a Schlieren method. Further, the evolution of the displacement of single perturbations on the flame surface to the wall was investigated by the method of a stroboscopic survey.
Dynamics and structure of stretched flames
Law, C.K.
This program aims to gain fundamental understanding on the structure, geometry, and dynamics of laminar premixed flames, and relate these understanding to the practical issues of flame extinction and stabilization. The underlying fundamental interest here is the recent recognition that the response of premixed flames can be profoundly affected by flame stretch, as manifested by flow nonuniformity, flame curvature, and flame/flow unsteadiness. As such, many of the existing understanding on the behavior of premixed flames need to be qualitatively revised. The research program consists of three major thrusts: (1) detailed experimental and computational mapping of the structure of aerodynamically-strained planar flames, with emphasis on the effects of heat loss, nonequidiffusion, and finite residence time on the flame thickness, extent of incomplete reaction, and the state of extinction. (2) Analytical study of the geometry and dynamics of stretch-affected wrinkled flame sheets in simple configurations, as exemplified by the Bunsen flame and the spatially-periodic flame, with emphasis on the effects of nonlinear stretch, the phenomena of flame cusping, smoothing, and tip opening, and their implications on the structure and burning rate of turbulent flames. (3) Stabilization and blowoff of two-dimensional inverted premixed and stabilization and determining the criteria governing flame blowoff. The research is synergistically conducted through the use of laser-based diagnostics, computational simulation of the flame structure with detailed chemistry and transport, and mathematical analysis of the flame dynamics.
Large Eddy Simulation Modeling of Flashback and Flame Stabilization in Hydrogen-Rich Gas Turbines Using a Hierarchical Validation Approach
Clemens, Noel
This project was a combined computational and experimental effort to improve predictive capability for boundary layer flashback of premixed swirl flames relevant to gas-turbine power plants operating with high-hydrogen-content fuels. During the course of this project, significant progress in modeling was made on four major fronts: 1) use of direct numerical simulation of turbulent flames to understand the coupling between the flame and the turbulent boundary layer; 2) improved modeling capability for flame propagation in stratified pre-mixtures; 3) improved portability of computer codes using the OpenFOAM platform to facilitate transfer to industry and other researchers; and 4) application of LES to flashback in swirl combustors, and a detailed assessment of its capabilities and limitations for predictive purposes. A major component of the project was an experimental program that focused on developing a rich experimental database of boundary layer flashback in swirl flames. Both methane and high-hydrogen fuels, including effects of elevated pressure (1 to 5 atm), were explored. For this project, a new model swirl combustor was developed. Kilohertz-rate stereoscopic PIV and chemiluminescence imaging were used to investigate the flame propagation dynamics. In addition to the planar measurements, a technique capable of detecting the instantaneous, time-resolved 3D flame front topography was developed and applied successfully to investigate the flow-flame interaction. The UT measurements and legacy data were used in a hierarchical validation approach where flows with increasingly complex physics were used for validation. First component models were validated with DNS and literature data in simplified configurations, and this was followed by validation with the UT 1-atm flashback cases, and then the UT high-pressure flashback cases. The new models and portable code represent a major improvement over what was available before this project was initiated.
CNEEC - Flame Synthesis Tutorial by Xiaolin Zheng
U.S. Department of Energy (DOE) all webpages (Extended Search)
Flame Synthesis of Nanomaterials
Flame Chemistry and Diagnostics
U.S. Department of Energy (DOE) all webpages (Extended Search)
Flame Conditions Flame Chemistry Insights (n-butanol flame) Experiment vs. ... Molecular beam sampling "freezes" chemistry Time-of-flight mass spectrometry ...
The interaction of high-speed turbulence with flames: Global properties and internal flame structure
Poludnenko, A.Y.; Oran, E.S. [Laboratory for Computational Physics and Fluid Dynamics, Naval Research Laboratory, Washington, DC 20375 (United States)
We study the dynamics and properties of a turbulent flame, formed in the presence of subsonic, high-speed, homogeneous, isotropic Kolmogorov-type turbulence in an unconfined system. Direct numerical simulations are performed with Athena-RFX, a massively parallel, fully compressible, high-order, dimensionally unsplit, reactive flow code. A simplified reaction-diffusion model represents a stoichiometric H{sub 2}-air mixture. The system being modeled represents turbulent combustion with the Damkoehler number Da=0.05 and with the turbulent velocity at the energy injection scale 30 times larger than the laminar flame speed. The simulations show that flame interaction with high-speed turbulence forms a steadily propagating turbulent flame with a flame brush width approximately twice the energy injection scale and a speed four times the laminar flame speed. A method for reconstructing the internal flame structure is described and used to show that the turbulent flame consists of tightly folded flamelets. The reaction zone structure of these is virtually identical to that of the planar laminar flame, while the preheat zone is broadened by approximately a factor of two. Consequently, the system evolution represents turbulent combustion in the thin reaction zone regime. The turbulent cascade fails to penetrate the internal flame structure, and thus the action of small-scale turbulence is suppressed throughout most of the flame. Finally, our results suggest that for stoichiometric H{sub 2}-air mixtures, any substantial flame broadening by the action of turbulence cannot be expected in all subsonic regimes. (author)
Investigations of swirl flames in a gas turbine model combustor
Meier, W.; Duan, X.R.; Weigand, P.
The thermochemical states of three swirling CH{sub 4}/air diffusion flames, stabilized in a gas turbine model combustor, were investigated using laser Raman scattering. The flames were operated at different thermal powers and air/fuel ratios and exhibited different flame behavior with respect to flame instabilities. They had previously been characterized with respect to their flame structures, velocity fields, and mean values of temperature, major species concentrations, and mixture fraction. The single-pulse multispecies measurements presented in this article revealed very rapid mixing of fuel and air, accompanied by strong effects of turbulence-chemistry interactions in the form of local flame extinction and ignition delay. Flame stabilization is accomplished mainly by hot and relatively fuel-rich combustion products, which are transported back to the flame root within an inner recirculation zone. The flames are not attached to the fuel nozzle, and are stabilized approximately 10 mm above the fuel nozzle, where fuel and air are partially premixed before ignition. The mixing and reaction progress in this area are discussed in detail. The flames are short (<50 mm), especially that exhibiting thermoacoustic oscillations, and reach a thermochemical state close to adiabatic equilibrium at the flame tip. The main goals of this article are to outline results that yield deeper insight into the combustion of gas turbine flames and to establish an experimental database for the validation of numerical models.
Method of growing films by flame synthesis using a stagnation-flow reactor
Hahn, David W.; Edwards, Christopher F.
A method of stabilizing a strained flame in a stagnation flow reactor. By causing a highly strained flame to be divided into a large number of equal size segments it is possible to stablize a highly strained flame that is on the verge of extinction, thereby providing for higher film growth rates. The flame stabilizer is an annular ring mounted coaxially and coplanar with the substrate upon which the film is growing and having a number of vertical pillars mounted on the top surface, thereby increasing the number of azimuthal nodes into which the flame is divided and preserving an axisymmetric structure necessary for stability.
Method of growing films by flame synthesis using a stagnation-flow reactor
Hahn, D.W.; Edwards, C.F.
A method is described for stabilizing a strained flame in a stagnation flow reactor. By causing a highly strained flame to be divided into a large number of equal size segments it is possible to stablize a highly strained flame that is on the verge of extinction, thereby providing for higher film growth rates. The flame stabilizer is an annular ring mounted coaxially and coplanar with the substrate upon which the film is growing and having a number of vertical pillars mounted on the top surface, thereby increasing the number of azimuthal nodes into which the flame is divided and preserving an axisymmetric structure necessary for stability. 5 figs.
A New Type of Steady and Stable, Laminar, Premixed Flame in Ultra-Lean, Hydrogen-Air Combustion
Grcar, Joseph F; Grcar, Joseph F
Ultra-lean, hydrogen-air mixtures are found to support another kind of laminar flame that is steady and stable beside flat flames and flame balls. Direct numerical simulations are performed of flames that develop into steadily and stably propagating cells. These cells were the original meaning of the word"flamelet'' when they were observed in lean flammability studies conducted early in the development of combustion science. Several aspects of these two-dimensional flame cells are identified and are contrasted with the properties of one-dimensional flame balls and flat flames. Although lean hydrogen-air flames are subject to thermo-diffusive effects, in this case the result is to stabilize the flame rather than to render it unstable. The flame cells may be useful as basic components of engineering models for premixed combustion when the other types of idealized flames are inapplicable.
NO concentration imaging in turbulent nonpremixed flames
Schefer, R.W.
The importance of NO as a pollutant species is well known. An understanding of the formation characteristics of NO in turbulent hydrocarbon flames is important to both the desired reduction of pollutant emissions and the validation of proposed models for turbulent reacting flows. Of particular interest is the relationship between NO formation and the local flame zone, in which the fuel is oxidized and primary heat release occurs. Planar imaging of NO provides the multipoint statistics needed to relate NO formation to the both the flame zone and the local turbulence characteristics. Planar imaging of NO has been demonstrated in turbulent flames where NO was seeded into the flow at high concentrations (2000 ppm) to determine the gas temperature distribution. The NO concentrations in these experiments were significantly higher than those expected in typical hydrocarbon-air flames, which require a much lower detectability limit for NO measurements. An imaging technique based on laser-induced fluorescence with sufficient sensitivity to study the NO formation mechanism in the stabilization region of turbulent lifted-jet methane flames.
Can we characterize turbulence in premixed flames?
Lipatnikov, A.N. [Department of Applied Mechanics, Chalmers University of Technology, Gothenburg, 412 96 (Sweden)
Modeling of premixed turbulent combustion involves averaging reaction rates in turbulent flows. The focus of most approaches to resolving this problem has been placed on determining the dependence of the mean rate w of product creation on the laminar flame speed S{sub L}, the rms turbulence velocity u', etc. The goal of the present work is to draw attention to another issue: May the input quantity u{sup '} for a model of w= w(u'/S{sub L},..) be considered to be known? The point is that heat release substantially affects turbulence and, hence, turbulence characteristics in premixed flames should be modeled. However, standard moment methods for numerically simulating turbulent flows do not allow us to evaluate the true turbulence characteristics in a flame. For instance, the Reynolds stresses in premixed flames are affected not only by turbulence itself, but also by velocity jump across flamelets. A common way to resolving this problem consists of considering the Reynolds stresses conditioned on unburned (or burned) mixture to be the true turbulence characteristics. In the present paper, this widely accepted but never proved hypothesis is put into question, first, by considering simple model constant-density problems (flame motion in an oscillating one-dimensional laminar flow; flame stabilized in a periodic shear, one-dimensional, laminar flow; turbulent mixing). In all the cases, the magnitude of velocity fluctuations, calculated using the conditioned Reynolds stresses, is affected by the intermittency of reactants and products and, hence, is not the true rms velocity. Second, the above claim is further supported by comparing balance equations for the mean and conditioned Reynolds stresses. The conditioned Reynolds stresses do not characterize the true turbulence in flames, because conditional averaging cuts off flow regions characterized by either high or low velocities. (author)
Extremely weak hydrogen flames
Lecoustre, V.R.; Sunderland, P.B. [Department of Fire Protection Engineering, University of Maryland, College Park, MD 20742 (United States); Chao, B.H. [Department of Mechanical Engineering, University of Hawaii, Honolulu, HI 96822 (United States); Axelbaum, R.L. [Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130 (United States)
Hydrogen jet diffusion flames were observed near their quenching limits. These involved downward laminar flow of hydrogen from a stainless steel hypodermic tube with an inside diameter of 0.15 mm. Near their quenching limits these flames had hydrogen flow rates of 3.9 and 2.1 {mu}g/s in air and oxygen, respectively. Assuming complete combustion, the associated heat release rates are 0.46 and 0.25 W. To the authors' knowledge, these are the weakest self-sustaining steady flames ever observed. (author)
Structure of hydrogen triple flames and premixed flames compared
Owston, Rebecca; Abraham, John
Triple flames consisting of lean, stoichiometric, and rich reaction zones may be produced in stratified mixtures undergoing combustion. Such flames have unique characteristics that differ from premixed flames. The present work offers a direct comparison of the structure and propagation behavior between hydrogen/air triple and premixed flames through a numerical study. Important similarities and differences are highlighted. Premixed flames are generated by spark-igniting initially quiescent homogeneous mixtures of hydrogen and air in a two-dimensional domain. Triple flame results are also generated in a two-dimensional domain by spark-igniting initially quiescent hydrogen/air stratified layers. Detailed flame structure and chemical reactivity information is collected along isocontours of equivalence ratio 0.5, 1.0, and 3.0 in the triple flame for comparison with premixed flames at the same equivalence ratios. Full chemistry and effective binary diffusion coefficients are employed for all computations. (author)
The effect of fuel composition on flame dynamics
Hendricks, Adam G.; Vandsburger, Uri
As fuel sources diversify, the gas turbine industry is under increasing pressure to develop fuel-flexible plants, able to use fuels with a variety of compositions from a large range of sources. However, the dynamic characteristics vary considerably with composition, in many cases altering the thermoacoustic stability of the combustor. We compare the flame dynamics, or the response in heat release rate of the flame to acoustic perturbations, of the three major constituents of natural gas: methane, ethane, and propane. The heat release rate is quantified using OH* chemiluminescence and product gas temperature. Gas temperature is measured by tracking the absorption of two high-temperature water lines, via Tunable Diode Laser Absorption Spectroscopy. The flame dynamics of the three fuels differ significantly. The changes in flame dynamics due to variations in fuel composition have the potential to have a large effect on the thermoacoustic stability of the combustor. (author)
Extinction and structure of counterflow premixed flames. Master's thesis
Crump, J.K.
A theoretical and experimental investigation of the extinction of a counterflow premixed flame was performed using methane as the fuel. The extinction limits were measured for a premixed flame stabilized between a premixed, fuel lean stream of methane, air and nitrogen and a stream of hot combustion product. The composition of the reactant mixture as a function of the strain rate was measured at extinction over a wide range of conditions. The results are interpreted using previously developed theories to derive overall chemical kinetic rate parameters. Temperature and composition profiles were obtained for several premixed flames near extinction.
DNS of a turbulent lifted DME jet flame
Minamoto, Yuki; Chen, Jacqueline H.
A three-dimensional direct numerical simulation (DNS) of a turbulent lifted dimethyl ether (DME) slot jet flame was performed at elevated pressure to study interactions between chemical reactions with low-temperature heat release (LTHR), negative temperature coefficient (NTC) reactions and shear generated turbulence in a jet in a heated coflow. By conditioning on mixture fraction, local reaction zones and local heat release rate, the turbulent flame is revealed to exhibit a "pentabrachial" structure that was observed for a laminar DME lifted flame [Krisman et al., (2015)]. The propagation characteristics of the stabilization and triple points are also investigated. Potential stabilization points, spatialmore » locations characterized by preferred temperature and mixture fraction conditions, exhibit autoignition characteristics with large reaction rate and negligible molecular diffusion. The actual stabilization point which coincides with the most upstream samples from the pool of potential stabilization points fovr each spanwise location shows passive flame structure with large diffusion. The propagation speed along the stoichiometric surface near the triple point is compared with the asymptotic value obtained from theory [Ruetsch et al., (1995)]. At stoichiometric conditions, the asymptotic and averaged DNS values of flame displacement speed deviate by a factor of 1.7. However, accounting for the effect of low-temperature species on the local flame speed increase, these two values become comparable. In conclusion, this suggests that the two-stage ignition influences the triple point propagation speed through enhancement of the laminar flame speed in a configuration where abundant low-temperature products from the first stage, low-temperature ignition are transported to the lifted flame by the high-velocity jet.« less
Autoignited laminar lifted flames of methane, ethylene, ethane, and n-butane jets in coflow air with elevated temperature
Choi, B.C.; Chung, S.H.
The autoignition characteristics of laminar lifted flames of methane, ethylene, ethane, and n-butane fuels have been investigated experimentally in coflow air with elevated temperature over 800 K. The lifted flames were categorized into three regimes depending on the initial temperature and fuel mole fraction: (1) non-autoignited lifted flame, (2) autoignited lifted flame with tribrachial (or triple) edge, and (3) autoignited lifted flame with mild combustion. For the non-autoignited lifted flames at relatively low temperature, the existence of lifted flame depended on the Schmidt number of fuel, such that only the fuels with Sc > 1 exhibited stationary lifted flames. The balance mechanism between the propagation speed of tribrachial flame and local flow velocity stabilized the lifted flames. At relatively high initial temperatures, either autoignited lifted flames having tribrachial edge or autoignited lifted flames with mild combustion existed regardless of the Schmidt number of fuel. The adiabatic ignition delay time played a crucial role for the stabilization of autoignited flames. Especially, heat loss during the ignition process should be accounted for, such that the characteristic convection time, defined by the autoignition height divided by jet velocity was correlated well with the square of the adiabatic ignition delay time for the critical autoignition conditions. The liftoff height was also correlated well with the square of the adiabatic ignition delay time. (author)
TU-F-18A-09: CT Number Stability Across Patient Sizes Using Virtual-Monoenergetic Dual-Energy CT
Michalak, G; Grimes, J; Fletcher, J; McCollough, C; Halaweish, A
Purpose: Virtual-monoenergetic imaging uses dual-energy CT data to synthesize images corresponding to a single photon energy, thereby reducing beam-hardening artifacts. This work evaluated the ability of a commercial virtual-monoenergetic algorithm to achieve stable CT numbers across patient sizes. Methods: Test objects containing a range of iodine and calcium hydroxyapatite concentrations were placed inside 8 torso-shaped water phantoms, ranging in lateral width from 15 to 50 cm, and scanned on a dual-source CT system (Siemens Somatom Force). Single-energy scans were acquired from 70-150 kV in 10 kV increments; dual-energy scans were acquired using 4 energy pairs (low energy: 70, 80, 90, and 100 kV; high energy: 150 kV + 0.6 mm Sn). CTDIvol was matched for all single- and dual-energy scans for a given phantom size. All scans used 128×0.6 mm collimation and were reconstructed with 1-mm thickness at 0.8-mm increment and a medium smooth body kernel. Monoenergetic images were generated using commercial software (syngo Via Dual Energy, VA30). Iodine contrast was calculated as the difference in mean iodine and water CT numbers from respective regions-of-interest in 10 consecutive images. Results: CT numbers remained stable as phantom width varied from 15 to 50 cm for all dual-energy data sets (except for at 50 cm using 70/150Sn due to photon starvation effects). Relative to the 15 cm phantom, iodine contrast was within 5.2% of the 70 keV value for phantom sizes up to 45 cm. At 90/150Sn, photon starvation did not occur at 50 cm, and iodine contrast in the 50-cm phantom was within 1.4% of the 15-cm phantom. Conclusion: Monoenergetic imaging, as implemented in the evaluated commercial system, eliminated the variation in CT numbers due to patient size, and may provide more accurate data for quantitative tasks, including radiation therapy treatment planning. Siemens Healthcare.
Strained flamelets for turbulent premixed flames II: Laboratory flame results
Kolla, H.; Swaminathan, N. [Department of Engineering, Cambridge University, Cambridge CB2 1PZ (United Kingdom)
The predictive ability of strained flamelets model for turbulent premixed flames is assessed using Reynolds Averaged Navier Stokes (RANS) calculations of laboratory flames covering a wide range of conditions. Reactant-to-product (RtP) opposed flow laminar flames parametrised using the scalar dissipation rate of reaction progress variable are used as strained flamelets. Two turbulent flames: a rod stabilised V-flame studied by Robin et al. [Combust. Flame 153 (2008) 288-315] and a set of pilot stabilised Bunsen flames studied by Chen et al. [Combust. Flame 107 (1996) 223-244] are calculated using a single set of model parameters. The V-flame corresponds to the corrugated flamelets regime. The strained flamelet model and an unstrained flamelet model yield similar predictions which are in good agreement with experimental measurements for this flame. On the other hand, for the Bunsen flames which are in the thin reaction zones regime, the unstrained flamelet model predicts a smaller flame brush compared to experiment. The predictions of the strained flamelets model allowing for fluid-dynamics stretch induced attenuation of the chemical reaction are in good agreement with the experimental data. This model predictions of major and minor species are also in good agreement with experimental data. The results demonstrate that the strained flamelets model using the scalar dissipation rate can be used across the combustion regimes. (author)
Spatially distributed flame transfer functions for predicting combustion dynamics in lean premixed gas turbine combustors
Kim, K.T.; Lee, J.G.; Quay, B.D.; Santavicca, D.A.
The present paper describes a methodology to improve the accuracy of prediction of the eigenfrequencies and growth rates of self-induced instabilities and demonstrates its application to a laboratory-scale, swirl-stabilized, lean-premixed, gas turbine combustor. The influence of the spatial heat release distribution is accounted for using local flame transfer function (FTF) measurements. The two-microphone technique and CH{sup *} chemiluminescence intensity measurements are used to determine the input (inlet velocity perturbation) and the output functions (heat release oscillation), respectively, for the local flame transfer functions. The experimentally determined local flame transfer functions are superposed using the flame transfer function superposition principle, and the result is incorporated into an analytic thermoacoustic model, in order to predict the linear stability characteristics of a given system. Results show that when the flame length is not acoustically compact the model prediction calculated using the local flame transfer functions is better than the prediction made using the global flame transfer function. In the case of a flame in the compact flame regime, accurate predictions of eigenfrequencies and growth rates can be obtained using the global flame transfer function. It was also found that the general response characteristics of the local FTF (gain and phase) are qualitatively the same as those of the global FTF. (author)
During the DFI process, high velocity flame jets impinge upon the material being heated, creating a high heat transfer rate. As a result, refractory walls and exhaust gases are cooler, which increases thermal efficiency and lowers NOx emissions. Because the jet nozzles are located a few inches from the load, furnace size can be reduced significantly.
Stabilization of piloted turbulent flames with inhomogeneous...
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Additional Journal Information: Journal Volume: 35; Journal Issue: 2; Related Information: CHORUS Timestamp: 2016-05-06 21:27:30; Journal ID: ISSN 1540-7489 Publisher: Elsevier ...
Lean Flame Stabilization Ring - Energy Innovation Portal
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Applications and Industries Small-to-medium water heater and forced-air furnace retrofits Reduction of air pollution Patents and Patent Applications ID Number Title and Abstract ...
Effect of thermal gravitational convection on flame propagation over a fuel surface
Samsonov, V.P.
The effect of thermal gravitational convection on flame propagation velocity and stability was determined by comparison of experimental results obtained by changing gravitational conditions while maintaining other external conditions constant. The fuel materials used were series BF glues. Interferograms were produced to study the alcohol vapor concentration field above the drying glue surface. Under conditions of normal gravity, flame behavior changes markedly. The flame loses stability and its structure becomes complex and strictly periodically repetitive. Experiments under conditions of weightlessness revealed that in the absence of gravity, relaxation combustion is impossible.
Investigation on Flame Characteristics and Burner Operability Issues of Oxy-Fuel Combustion
Choudhuri, Ahsan
Oxy-fuel combustion has been used previously in a wide range of industrial applications. Oxy- combustion is carried out by burning a hydrocarbon fuel with oxygen instead of air. Flames burning in this configuration achieve higher flame temperatures which present opportunities for significant efficiency improvements and direct capture of CO2 from the exhaust stream. In an effort to better understand and characterize the fundamental flame characteristics of oxy-fuel combustion this research presents the experimental measurements of flame stability of various oxyfuel flames. Effects of H2 concentration, fuel composition, exhaust gas recirculation ratio, firing inputs, and burner diameters on the flame stability of these fuels are discussed. Effects of exhaust gas recirculation i.e. CO2 and H2O (steam) acting as diluents on burner operability are also presented. The roles of firing input on flame stability are then analyzed. For this study it was observed that many oxy-flames did not stabilize without exhaust gas recirculation due to their higher burning velocities. In addition, the stability regime of all compositions was observed to decrease as the burner diameter increased. A flashback model is also presented, using the critical velocity gradient gF) values for CH4-O2-CO2 flames. The second part of the study focuses on the experimental measurements of the flow field characteristics of premixed CH4/21%O2/79%N2 and CH4/38%O2/72%CO2 mixtures at constant firing input of 7.5 kW, constant, equivalence ratio of 0.8, constant swirl number of 0.92 and constant Reynolds Numbers. These measurements were taken in a swirl stabilized combustor at atmospheric pressure. The flow field visualization using Particle Imaging Velocimetry (PIV) technique is implemented to make a better understanding of the turbulence characteristics of
Spatially resolved heat release rate measurements in turbulent premixed flames
Ayoola, B.O.; Kaminski, C.F.; Balachandran, R.; Mastorakos, E.; Frank, J.H.
Heat release rate is a fundamental property of great importance for the theoretical and experimental elucidation of unsteady flame behaviors such as combustion noise, combustion instabilities, and pulsed combustion. Investigations of such thermoacoustic interactions require a reliable indicator of heat release rate capable of resolving spatial structures in turbulent flames. Traditionally, heat release rate has been estimated via OH or CH radical chemiluminescence; however, chemiluminescence suffers from being a line-of-sight technique with limited capability for resolving small-scale structures. In this paper, we report spatially resolved two-dimensional measurements of a quantity closely related to heat release rate. The diagnostic technique uses simultaneous OH and CH{sub 2}O planar laser-induced fluorescence (PLIF), and the pixel-by-pixel product of the OH and CH{sub 2}O PLIF signals has previously been shown to correlate well with local heat release rates. Results from this diagnostic technique, which we refer to as heat release rate imaging (HR imaging), are compared with traditional OH chemiluminescence measurements in several flames. Studies were performed in lean premixed ethylene flames stabilized between opposed jets and with a bluff body. Correlations between bulk strain rates and local heat release rates were obtained and the effects of curvature on heat release rate were investigated. The results show that the heat release rate tends to increase with increasing negative curvature for the flames investigated for which Lewis numbers are greater than unity. This correlation becomes more pronounced as the flame gets closer to global extinction.
Effects of multi-component diffusion and heat release on laminar diffusion flame liftoff
Li, Zhiliang; Chen, Ruey-Hung [Department of Mechanical, Materials and Aerospace Engineering, University of Central Florida, Orlando, FL 32816-2450 (United States); Phuoc, Tran X. [National Energy Technology Laboratory, Department of Energy, P.O. Box 10940, MS 84-340, Pittsburgh, PA 15261 (United States)
Numerical simulations were conducted of the liftoff and stabilization phenomena of laminar jet diffusion flames of inert-diluted C{sub 3}H{sub 8} and CH{sub 4} fuels. Both non-reacting and reacting jets were investigated, including multi-component diffusivities and heat release effects (buoyancy and gas expansion). The role of Schmidt number for non-reacting jets was investigated, with no conclusive Schmidt number criterion for liftoff previously arrived at in similarity solutions. The cold-flow simulation for He-diluted CH{sub 4} fuel does not predict flame liftoff; however, adding heat release reaction lead to the prediction of liftoff, which is consistent with experimental observations. Including reaction was also found to improve liftoff height prediction for C{sub 3}H{sub 8} flames, with the flame base location differing from that in the similarity solution - the intersection of the stoichiometric and iso-velocity (equal to 1-D flame speed) is not necessary for flame stabilization (and thus liftoff). Possible mechanisms other than that proposed for similarity solution may better help to explain the stabilization and liftoff phenomena. (author)
Cal Flame: Order (2015-CE-14015)
DOE ordered Cal Flame to pay a $8,000 civil penalty after finding Cal Flame had failed to certify that refrigerator basic model BBQ09849P-H complies with the applicable energy conservation standards.
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Laminar flame speed, ,cms Equivalence Ratio, Laminar flame speed, ,cms Equivalence Ratio, Methanol Ethanol n-Propanol n-Butanol n-Butanol sec-Butanol iso-Butanol ...
Production Of Fullerenic Soot In Flames
Howard, Jack B.; Vander Sande, John B.; Chowdhury, K. Das
A method for the production of fullerenic nanostructures is described in which unsaturated hydrocarbon fuel and oxygen are combusted in a burner chamber at a sub-atmospheric pressure, thereby establishing a flame. The condensibles of the flame are collected at a post-flame location. The condensibles contain fullerenic nanostructures, such as single and nested nanotubes, single and nested nanoparticles and giant fullerenes. The method of producing fullerenic soot from flames is also described.
Production of fullerenic nanostructures in flames
Howard, Jack B.; Vander Sande, John B.; Chowdhury, K. Das
A method for the production of fullerenic nanostructures is described in which unsaturated hydrocarbon fuel and oxygen are combusted in a burner chamber at a sub-atmospheric pressure, thereby establishing a flame. The condensibles of the flame are collected at a post-flame location. The condensibles contain fullerenic nanostructures, such as single and nested nanotubes, single and nested nanoparticles and giant fullerenes. The method of producing fullerenic soot from flames is also described.
Highly turbulent counterflow flames: A laboratory scale benchmark for practical systems
Coppola, Gianfilippo; Coriton, Bruno; Gomez, Alessandro
We propose a highly turbulent counterflow flame as a very useful benchmark of complexity intermediate between laminar flames and practical systems. By operating in a turbulent Reynolds number regime of relevance to practical systems such as gas turbines and internal combustion engines, it retains the interaction of turbulence and chemistry of such environments, but offers several advantages including: (a) the achievement of high Reynolds numbers without pilot flames, which is particularly advantageous from a modeling standpoint; (b) control of the transition from stable flames to local extinction/reignition conditions; (c) compactness of the domain by comparison with jet flames, with obvious advantages from both a diagnostic and, especially, a computational viewpoint; and (d) the reduction or, altogether, elimination of soot formation, thanks to the high strain rates and low residence times of such a system, and the establishment of conditions of large stoichiometric mixture fraction, as required for robust flame stabilization. We demonstrate the phenomenology of such highly strained turbulent flames under conditions spanning unpremixed, partially premixed and premixed regimes. The system lends itself to the validation of DNS and other computational models. It is also well-suited for the examination of practical fuel blends - a need that is becoming more and more pressing in view of the anticipated diversification of the future fossil fuel supply. (author)
Flex-flame burner and combustion method
Soupos, Vasilios; Zelepouga, Serguei; Rue, David M.; Abbasi, Hamid A.
A combustion method and apparatus which produce a hybrid flame for heating metals and metal alloys, which hybrid flame has the characteristic of having an oxidant-lean portion proximate the metal or metal alloy and having an oxidant-rich portion disposed above the oxidant lean portion. This hybrid flame is produced by introducing fuel and primary combustion oxidant into the furnace chamber containing the metal or metal alloy in a substoichiometric ratio to produce a fuel-rich flame and by introducing a secondary combustion oxidant into the furnace chamber above the fuel-rich flame in a manner whereby mixing of the secondary combustion oxidant with the fuel-rich flame is delayed for a portion of the length of the flame.
Nonlinear effects in the extraction of laminar flame speeds from expanding spherical flames
Kelley, A.P.; Law, C.K.
Various factors affecting the determination of laminar flames speeds from outwardly propagating spherical flames in a constant-pressure combustion chamber were considered, with emphasis on the nonlinear variation of the stretched flame speed to the flame stretch rate, and the associated need to nonlinearly extrapolate the stretched flame speed to yield an accurate determination of the laminar flame speed and Markstein length. Experiments were conducted for lean and rich n-butane/air flames at 1atm initial pressure, demonstrating the complex and nonlinear nature of the dynamics of flame evolution, and the strong influences of the ignition transient and chamber confinement during the initial and final periods of the flame propagation, respectively. These experimental data were analyzed using the nonlinear relation between the stretched flame speed and stretch rate, yielding laminar flame speeds that agree well with data determined from alternate flame configurations. It is further suggested that the fidelity in the extraction of the laminar flame speed from expanding spherical flames can be facilitated by using small ignition energy and a large combustion chamber. (author)
Combustion instabilities in sudden expansion oxy-fuel flames
Ditaranto, Mario; Hals, Joergen
An experimental study on combustion instability is presented with focus on oxy-fuel type combustion. Oxidants composed of CO{sub 2}/O{sub 2} and methane are the reactants flowing through a premixer-combustor system. The reaction starts downstream a symmetric sudden expansion and is at the origin of different instability patterns depending on oxygen concentration and Reynolds number. The analysis has been conducted through measurement of pressure, CH* chemiluminescence, and velocity. As far as stability is concerned, oxy-fuel combustion with oxygen concentration similar to that found in air combustion cannot be sustained, but requires at least 30% oxygen to perform in a comparable manner. Under these conditions and for the sudden expansion configuration used in this study, the instability is at low frequency and low amplitude, controlled by the flame length inside the combustion chamber. Above a threshold concentration in oxygen dependent on equivalence ratio, the flame becomes organized and concentrated in the near field. Strong thermoacoustic instability is then triggered at characteristic acoustic modes of the system. Different modes can be triggered depending on the ratio of flame speed to inlet velocity, but for all types of instability encountered, the heat release and pressure fluctuations are linked by a variation in mass-flow rate. An acoustic model of the system coupled with a time-lag-based flame model made it possible to elucidate the acoustic mode selection in the system as a function of laminar flame speed and Reynolds number. The overall work brings elements of reflection concerning the potential risk of strong pressure oscillations in future gas turbine combustors for oxy-fuel gas cycles. (author)
Yeh, Hsu-Chi; Chen, Bean T.; Cheng, Yung-Sung; Newton, George J.
A virtual impactor having improved efficiency and low wall losses in which a core of clean air is inserted into the aerosol flow while aerosol flow is maintained adjacent inner wall surfaces of the focusing portion of the impactor. The flow rate of the core and the length of the throat of the impactor's collection probe, as well as the dimensional relationships of other components of the impactor adjacent the separation region of the impactor, are selected to optimize separation efficiency.
Near field flow structure of isothermal swirling flows and reacting non-premixed swirling flames
Olivani, Andrea; Solero, Giulio; Cozzi, Fabio; Coghe, Aldo
Two confined lean non-premixed swirl-stabilized flame typologies were investigated in order to achieve detailed information on the thermal and aerodynamic field in the close vicinity of the burner throat and provide correlation with the exhaust emissions. Previous finding indicated the generation of a partially premixed flame with radial fuel injection and a purely diffusive flame with co-axial injection in a swirling co-flow. In the present work, the experimental study is reported which has been conducted on a straight exit laboratory burner with no quarl cone, fuelled by natural gas and air, and fired vertically upwards with the flame stabilized at the end of two concentric pipes with the annulus supplying swirled air and the central pipe delivering the fuel. Two fuel injection typologies, co-axial and radial (i.e., transverse), leading to different mixing mechanisms, have been characterized through different techniques: particle image velocimetry (PIV) and laser Doppler velocimetry (LDV) for a comprehensive analysis of the velocity field, still photography for the detection of flame front and main visible features, and thermocouples for the temperature distribution. Isothermal flow conditions have been included in the experimental investigation to provide a basic picture of the flow field and to comprehend the modifications induced by the combustion process. The results indicated that, although the global mixing process and the main flame structure are governed by the swirl motion imparted to the air stream, the two different fuel injection methodologies play an important role on mixture formation and flame stabilization in the primary mixing zone. Particularly, it has been found that, in case of axial injection, the turbulent interaction between the central fuel jet and the backflow generated by the swirl can induce an intermittent fuel penetration in the recirculated hot products and the formation of a central sooting luminous plume, a phenomenon totally
Enol Intermediates Unexpectedly Found in Flames
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Enol Intermediates Unexpectedly Found in Flames Enol Intermediates Unexpectedly Found in Flames Print Wednesday, 27 July 2005 00:00 For those studying flame chemistry and the properties of combustion intermediates by means of molecular beam mass spectrometry, the addition of tunable vacuum ultraviolet (VUV) from a synchrotron to photoionize the beam for mass spectrometry makes for a powerful technique capable of differentiating between isomers with the same molecular weight and composition. With
Autoignited laminar lifted flames of propane in coflow jets with tribrachial edge and mild combustion
Choi, B.C.; Kim, K.N.; Chung, S.H.
Characteristics of laminar lifted flames have been investigated experimentally by varying the initial temperature of coflow air over 800 K in the non-premixed jets of propane diluted with nitrogen. The result showed that the lifted flame with the initial temperature below 860 K maintained the typical tribrachial structure at the leading edge, which was stabilized by the balance mechanism between the propagation speed of tribrachial flame and the local flow velocity. For the temperature above 860 K, the flame was autoignited without having any external ignition source. The autoignited lifted flames were categorized in two regimes. In the case with tribrachial edge structure, the liftoff height increased nonlinearly with jet velocity. Especially, for the critical condition near blowout, the lifted flame showed a repetitive behavior of extinction and reignition. In such a case, the autoignition was controlled by the non-adiabatic ignition delay time considering heat loss such that the autoignition height was correlated with the square of the adiabatic ignition delay time. In the case with mild combustion regime at excessively diluted conditions, the liftoff height increased linearly with jet velocity and was correlated well with the square of the adiabatic ignition delay time. (author)
Yeh, H.C.; Chen, B.T.; Cheng, Y.S.; Newton, G.J.
A virtual impactor is described having improved efficiency and low wall losses in which a core of clean air is inserted into the aerosol flow while aerosol flow is maintained adjacent to the inner wall surfaces of the focusing portion of the impactor. The flow rate of the core and the length of the throat of the impactor's collection probe, as well as the dimensional relationships of other components of the impactor adjacent the separation region of the impactor, are selected to optimize separation efficiency. 4 figs.
Enol Intermediates Unexpectedly Found in Flames
U.S. Department of Energy (DOE) all webpages (Extended Search)
output, high-concentration intermediates, and major products. However, for improving combustion efficiency and controlling pollution, it is necessary to understand flame...
Aromatic and polycyclic aromatic hydrocarbon formation in a laminar premixed n-butane flame
Marinov, N.M.; Pitz, W.J.; Westbrook, C.K.; Vincitore, A.M.; Castaldi, M.J.; Senkan, S.M.; Melius, C.F.
Experimental and detailed chemical kinetic modeling work has been performed to investigate aromatic and polycyclic aromatic hydrocarbon (PAH) formation pathways in a premixed, rich, sooting, n-butane-oxygen-argon burner stabilized flame. An atmospheric pressure, laminar flat flame operated at an equivalence ratio of 2.6 was used to acquire experimental data for model validation. Gas composition analysis was conducted by an on-line gas chromatograph/mass spectrometer technique. Measurements were made in the main reaction and post-reaction zones for a number of low molecular weight species, aliphatics, aromatics, and polycyclic aromatic hydrocarbons (PAHs) ranging from two to five-fused aromatic rings. Reaction flux and sensitivity analysis were used to help identify the important reaction sequences leading to aromatic and PAH growth and destruction in the n-butane flame. Reaction flux analysis showed the propargyl recombination reaction was the dominant pathway to benzene formation. The consumption of propargyl by H atoms was shown to limit propargyl, benzene, and naphthalene formation in flames as exhibited by the large negative sensitivity coefficients. Naphthalene and phenanthrene production was shown to be plausibly formed through reactions involving resonantly stabilized cyclopentadienyl and indenyl radicals. Many of the low molecular weight aliphatics, combustion by-products, aromatics, branched aromatics, and PAHs were fairly well simulated by the model. Additional work is required to understand the formation mechanisms of phenyl acetylene, pyrene, and fluoranthene in the n-butane flame. 73 refs.
Fuel effects on flame lift-off under diesel conditions
Persson, Helena; Andersson, Oeivind; Egnell, Rolf
An apparent relation between the lift-off length under diesel conditions and the ignition quality of a fuel has previously been reported. To cast light on the underlying mechanism, the current study aims to separate flame lift-off effects of the chemical ignition delay from those of other fuel properties under diesel conditions. Flame lift-off was measured in an optical diesel engine by high-speed video imaging of OH-chemiluminescence. Fuel and ambient-gas properties were varied during the experiment. Only a weak correlation was found between ignition delay and lift-off length. The data indicate that this correlation is due to a common, stronger correlation with the ambient oxygen concentration. The chemical ignition delay and the fuel type had similar, weak effects on the lift-off length. A recently proposed mechanism for lift-off stabilization was used to interpret the results. It assumes that reactants approaching the lift-off position of the jet are mixed with high-temperature products found along the edges of the flame, which trigger autoignition. In this picture, the fuel effect is most likely due to differences in the amount of mixing with high-temperature products that is required for autoignition. In the current experiment, all lift-off effects seem to arise from variations in the reactant and product temperatures, induced by fuel and ambient properties. (author)
Design, Modeling, and Validation of a Flame Reformer for LNT...
Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)
Design, Modeling, and Validation of a Flame Reformer for LNT External Bypass Regeneration Design, Modeling, and Validation of a Flame Reformer for LNT External Bypass Regeneration ...
Jet flames of a refuse derived fuel
Weber, Roman; Kupka, Tomasz; Zajac, Krzysztof
This paper is concerned with combustion of a refuse derived fuel in a small-scale flame. The objective is to provide a direct comparison of the RDF flame properties with properties of pulverized coal flames fired under similar boundary conditions. Measurements of temperature, gas composition (O{sub 2}, CO{sub 2}, CO, NO) and burnout have demonstrated fundamental differences between the coal flames and the RDF flames. The pulverized coals ignite in the close vicinity of the burner and most of the combustion is completed within the first 300 ms. Despite the high volatile content of the RDF, its combustion extends far into the furnace and after 1.8 s residence time only a 94% burnout has been achieved. This effect has been attributed not only to the larger particle size of fluffy RDF particles but also to differences in RDF volatiles if compared to coal volatiles. Substantial amounts of oily tars have been observed in the RDF flames even though the flame temperatures exceeded 1300 C. The presence of these tars has enhanced the slagging propensity of RDF flames and rapidly growing deposits of high carbon content have been observed. (author)
On the extraction of laminar flame speed and Markstein length from outwardly propagating spherical flames
Chen, Zheng [State Key Laboratory for Turbulence and Complex Systems, Department of Mechanics and Aerospace Engineering, College of Engineering, Peking University, Beijing 100871 (China)
Large discrepancies among the laminar flame speeds and Markstein lengths of methane/air mixtures measured by different researchers using the same constant-pressure spherical flame method are observed. As an effort to reduce these discrepancies, one linear model (LM, the stretched flame speed changes linearly with the stretch rate) and two non-linear models (NM I and NM II, the stretched flame speed changes non-linearly with the stretch rate) for extracting the laminar flame speed and Markstein length from propagating spherical flames are investigated. The accuracy and performance of the LM, NM I, and NM II are found to strongly depend on the Lewis number. It is demonstrated that NM I is the most accurate for mixtures with large Lewis number (positive Markstein length) while NM II is the most accurate for mixtures with small Lewis number (negative Markstein length). Therefore, in order to get accurate laminar flame speed and Markstein length from spherical flame experiments, different non-linear models should be used for different mixtures. The validity of the theoretical results is further demonstrated by numerical and experimental studies. The results of this study can be used directly in spherical flame experiments measuring the laminar flame speed and Markstein length. (author)
Parameters of a supersonic combustion chamber with organization of combustion at the flame front
Solokhin, E.L.; Mironenko, V.A.; Ivanov, V.I.
In some engineering problems, it is necessary to burn fuel in the combustion chamber with supersonic flow. As a rule, the scheme of organization of the process in such a chamber presupposes a separate accompanying feed of fuel and oxidant in which combustion of fuel takes place in a diffusion flame front. In this article we give theoretical results of investigation of a supersonic combustion chamber in which combustion of the fuel mixture takes place in a oblique flame front stabilized by an external source (analogous to the subsonic combustion chambers of ramjets). The possibility of the existence of such an oblique flame front in a supersonic flow of fuel mixture was previously proved experimentally.
Jones, Jake S.
An apparatus and method of issuing commands to a computer by a user interfacing with a virtual reality environment. To issue a command, the user directs gaze at a virtual button within the virtual reality environment, causing a perceptible change in the virtual button, which then sends a command corresponding to the virtual button to the computer, optionally after a confirming action is performed by the user, such as depressing a thumb switch.
Jones, J.S.
An apparatus and method of issuing commands to a computer by a user interfacing with a virtual reality environment are disclosed. To issue a command, the user directs gaze at a virtual button within the virtual reality environment, causing a perceptible change in the virtual button, which then sends a command corresponding to the virtual button to the computer, optionally after a confirming action is performed by the user, such as depressing a thumb switch. 4 figs.
Effect of a uniform electric field on soot in laminar premixed ethylene/air flames
Wang, Y.; Yao, Q. [Key Laboratory of Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, 100084 Beijing (China); Nathan, G.J. [School of Mechanical Engineering, Centre for Energy Technology, The University of Adelaide, S.A. 5005 (Australia); Alwahabi, Z.T.; King, K.D.; Ho, K. [School of Chemical Engineering, Centre for Energy Technology, The University of Adelaide, S.A. 5005 (Australia)
The effect of a nominally uniform electric field on the initially uniform distribution of soot has been assessed for laminar premixed ethylene/air flames from a McKenna burner. An electrophoretic influence on charged soot particles was measured through changes to the deposition rate of soot on the McKenna plug, using laser extinction (LE). Soot volume fraction was measured in situ using laser-induced incandescence (LII). Particle size and morphologies were assessed through ex situ transmission electron microscopy (TEM) using thermophoretic sampling particle diagnostics (TSPD). The results show that the majority of these soot particles are positively charged. The presence of a negatively charged plug was found to decrease the particle residence times in the flame and to influence the formation and oxidation progress. A positively charged plug has the opposite effect. The effect on soot volume fraction, particles size and morphology with electric field strength is also reported. Flame stability was also found to be affected by the presence of the electric field, with the balance of the electrophoretic force and drag force controlling the transition to unstable flame flicker. The presence of charged species generated by the flame was found to reduce the dielectric field strength to one seventh that of air. (author)
Experimental and modeling investigation of aromatic and polycyclic aromatic hydrocarbon formation in a premixed ethylene flame
Castaldi, M.J.; Marinov, N.M.; Melius, C.F.
Experimental and detailed chemical kinetic modeling has been performed to investigate aromatic and polyaromatic hydrocarbon formation pathways in a rich, sooting, ethylene-oxygen-argon premixed flame. An atmospheric pressure, laminar flat flame operated at an equivalence ratio of 2.5 was used to acquire experimental data for model validation. Gas composition analysis was conducted by an on-line gas chromatograph/mass spectrometer (GC/MS) technique. Measurements were made in the flame and post-flame zone for a number of low molecular weight species, aliphatics, aromatics and polycyclic aromatic hydrocarbons (PAHs) ranging from two to five-aromatic fused rings. The modeling results show the key reaction sequences leading to aromatic and polycyclic aromatic hydrocarbon growth involve the combination of resonantly stabilized radicals. In particular, propargyl and 1-methylallenyl combination reactions lead to benzene and methyl substituted benzene formation, while polycyclic aromatics are formed from cyclopentadienyl radicals and fused rings that have a shared C{sub 5} side structure. Naphthalene production through the reaction step of cyclopentadienyl self-combination and phenanthrene formation from indenyl and cyclopentadienyl combination were shown to be important in the flame modeling study. The removal of phenyl by O{sub 2} leading to cyclopentadienyl formation is expected to play a pivotal role in the PAH or soot precursor growth process under fuel-rich oxidation conditions.
Aromatics oxidation and soot formation in flames
Howard, J.B.; Pope, C.J.; Shandross, R.A.; Yadav, T.
This project is concerned with the kinetics and mechanisms of aromatics oxidation and soot and fullerenes formation in flames. The scope includes detailed measurements of profiles of stable and radical species concentrations in low-pressure one-dimensional premixed flames. Intermediate species identifications and mole fractions, fluxes, and net reaction rates calculated from the measured profiles are used to test postulated reaction mechanisms. Particular objectives are to identify and to determine or confirm rate constants for the main benzene oxidation reactions in flames, and to characterize fullerenes and their formation mechanisms and kinetics.
Flame tolerant secondary fuel nozzle
Khan, Abdul Rafey; Ziminsky, Willy Steve; Wu, Chunyang; Zuo, Baifang; Stevenson, Christian Xavier
A combustor for a gas turbine engine includes a plurality of primary nozzles configured to diffuse or premix fuel into an air flow through the combustor; and a secondary nozzle configured to premix fuel with the air flow. Each premixing nozzle includes a center body, at least one vane, a burner tube provided around the center body, at least two cooling passages, a fuel cooling passage to cool surfaces of the center body and the at least one vane, and an air cooling passage to cool a wall of the burner tube. The cooling passages prevent the walls of the center body, the vane(s), and the burner tube from overheating during flame holding events.
Heat release and flame structure measurements of self-excited acoustically-driven premixed methane flames
Kopp-Vaughan, Kristin M.; Tuttle, Steven G.; Renfro, Michael W.; King, Galen B.
An open-open organ pipe burner (Rijke tube) with a bluff-body ring was used to create a self-excited, acoustically-driven, premixed methane-air conical flame, with equivalence ratios ranging from 0.85 to 1.05. The feed tube velocities corresponded to Re = 1780-4450. Coupled oscillations in pressure, velocity, and heat release from the flame are naturally encouraged at resonant frequencies in the Rijke tube combustor. This coupling creates sustainable self-excited oscillations in flame front area and shape. The period of the oscillations occur at the resonant frequency of the combustion chamber when the flame is placed {proportional_to}1/4 of the distance from the bottom of the tube. In this investigation, the shape of these acoustically-driven flames is measured by employing both OH planar laser-induced fluorescence (PLIF) and chemiluminescence imaging and the images are correlated to simultaneously measured pressure in the combustor. Past research on acoustically perturbed flames has focused on qualitative flame area and heat release relationships under imposed velocity perturbations at imposed frequencies. This study reports quantitative empirical fits with respect to pressure or phase angle in a self-generated pressure oscillation. The OH-PLIF images were single temporal shots and the chemiluminescence images were phase averaged on chip, such that 15 exposures were used to create one image. Thus, both measurements were time resolved during the flame oscillation. Phase-resolved area and heat release variations throughout the pressure oscillation were computed. A relation between flame area and the phase angle before the pressure maximum was derived for all flames in order to quantitatively show that the Rayleigh criterion was satisfied in the combustor. Qualitative trends in oscillating flame area were found with respect to feed tube flow rates. A logarithmic relation was found between the RMS pressure and both the normalized average area and heat release rate
The interaction of high-speed turbulence with flames: Turbulent flame speed
Poludnenko, A.Y.; Oran, E.S. [Laboratory for Computational Physics and Fluid Dynamics, Naval Research Laboratory, Washington, DC 20375 (United States)
Direct numerical simulations of the interaction of a premixed flame with driven, subsonic, homogeneous, isotropic, Kolmogorov-type turbulence in an unconfined system are used to study the mechanisms determining the turbulent flame speed, S{sub T}, in the thin reaction zone regime. High intensity turbulence is considered with the r.m.s. velocity 35 times the laminar flame speed, S{sub L}, resulting in the Damkoehler number Da=0.05. The simulations were performed with Athena-RFX, a massively parallel, fully compressible, high-order, dimensionally unsplit, reactive-flow code. A simplified reaction-diffusion model, based on the one-step Arrhenius kinetics, represents a stoichiometric H{sub 2}-air mixture under the assumption of the Lewis number Le=1. Global properties and the internal structure of the flame were analyzed in an earlier paper, which showed that this system represents turbulent combustion in the thin reaction zone regime. This paper demonstrates that: (1) The flame brush has a complex internal structure, in which the isosurfaces of higher fuel mass fractions are folded on progressively smaller scales. (2) Global properties of the turbulent flame are best represented by the structure of the region of peak reaction rate, which defines the flame surface. (3) In the thin reaction zone regime, S{sub T} is predominantly determined by the increase of the flame surface area, A{sub T}, caused by turbulence. (4) The observed increase of S{sub T} relative to S{sub L} exceeds the corresponding increase of A{sub T} relative to the surface area of the planar laminar flame, on average, by {approx}14%, varying from only a few percent to as high as {approx}30%. (5) This exaggerated response is the result of tight flame packing by turbulence, which causes frequent flame collisions and formation of regions of high flame curvature >or similar 1/{delta}{sub L}, or ''cusps,'' where {delta}{sub L} is the thermal width of the laminar flame. (6) The local flame speed in the cusps
Turbulence and combustion interaction: High resolution local flame front structure visualization using simultaneous single-shot PLIF imaging of CH, OH, and CH{sub 2}O in a piloted premixed jet flame
Li, Z.S.; Li, B.; Sun, Z.W.; Alden, M. [Division of Combustion Physics, Lund University, P.O. Box 118, S-221 00 Lund (Sweden); Bai, X.S. [Division of Fluid Mechanics, Lund University, P.O. Box 118, S-221 00 Lund (Sweden)
High resolution planar laser-induced fluorescence (PLIF) was applied to investigate the local flame front structures of turbulent premixed methane/air jet flames in order to reveal details about turbulence and flame interaction. The targeted turbulent flames were generated on a specially designed coaxial jet burner, in which low speed stoichiometric gas mixture was fed through the outer large tube to provide a laminar pilot flame for stabilization of the high speed jet flame issued through the small inner tube. By varying the inner tube flow speed and keeping the mixture composition as that of the outer tube, different flames were obtained covering both the laminar and turbulent flame regimes with different turbulent intensities. Simultaneous CH/CH{sub 2}O, and also OH PLIF images were recorded to characterize the influence of turbulence eddies on the reaction zone structure, with a spatial resolution of about 40 {mu}m and temporal resolution of around 10 ns. Under all experimental conditions, the CH radicals were found to exist only in a thin layer; the CH{sub 2}O were found in the inner flame whereas the OH radicals were seen in the outer flame with the thin CH layer separating the OH and CH{sub 2}O layers. The outer OH layer is thick and it corresponds to the oxidation zone and post-flame zone; the CH{sub 2}O layer is thin in laminar flows; it becomes broad at high speed turbulent flow conditions. This phenomenon was analyzed using chemical kinetic calculations and eddy/flame interaction theory. It appears that under high turbulence intensity conditions, the small eddies in the preheat zone can transport species such as CH{sub 2}O from the reaction zones to the preheat zone. The CH{sub 2}O species are not consumed in the preheat zone due to the absence of H, O, and OH radicals by which CH{sub 2}O is to be oxidized. The CH radicals cannot exist in the preheat zone due to the rapid reactions of this species with O{sub 2} and CO{sub 2} in the inner-layer of the
Light collection device for flame emission detectors
Woodruff, Stephen D.; Logan, Ronald G.; Pineault, Richard L.
A light collection device for use in a flame emission detection system such as an on-line, real-time alkali concentration process stream monitor is disclosed which comprises a sphere coated on its interior with a highly diffuse reflective paint which is positioned over a flame emission source, and one or more fiber optic cables which transfer the light generated at the interior of the sphere to a detecting device. The diffuse scattering of the light emitted by the flame uniformly distributes the light in the sphere, and the collection efficiency of the device is greater than that obtainable in the prior art. The device of the present invention thus provides enhanced sensitivity and reduces the noise associated with flame emission detectors, and can achieve substantial improvements in alkali detection levels.
Enol Intermediates Unexpectedly Found in Flames
U.S. Department of Energy (DOE) all webpages (Extended Search)
at ALS Chemical Dynamics Beamline 9.0.2. In the apparatus, premixed reagent gases enter the flame chamber through the porous flat face of a burner that translates...
Enol Intermediates Unexpectedly Found in Flames
U.S. Department of Energy (DOE) all webpages (Extended Search)
by a crossed tunable VUV beam. Photoions are mass-analyzed using a time-of-flight (TOF) mass spectrometer (MS). The luminous zone of the flame shown here (just to left...
Enol Intermediates Unexpectedly Found in Flames
U.S. Department of Energy (DOE) all webpages (Extended Search)
to be well understood in terms of average energy output, ... In the apparatus, premixed reagent gases enter the flame ... The team launched a systematic search for enols among 24 ...
Enol Intermediates Unexpectedly Found in Flames
U.S. Department of Energy (DOE) all webpages (Extended Search)
... to be well understood in terms of average energy output, ... In the apparatus, premixed reagent gases enter the flame ... The team launched a systematic search for enols among 24 ...
Cal Flame: Proposed Penalty (2015-CE-14015)
DOE alleged in a Notice of Proposed Civil Penalty that Cal Flame failed to certify refrigerator basic model BBQ09849P-H as compliant with the applicable energy conservation standards.
Diagnostics and Control of Natural Gas-Fired furnaces via Flame Image Analysis using Machine Vision & Artificial Intelligence Techniques
Shahla Keyvan
A new approach for the detection of real-time properties of flames is used in this project to develop improved diagnostics and controls for natural gas fired furnaces. The system utilizes video images along with advanced image analysis and artificial intelligence techniques to provide virtual sensors in a stand-alone expert shell environment. One of the sensors is a flame sensor encompassing a flame detector and a flame analyzer to provide combustion status. The flame detector can identify any burner that has not fired in a multi-burner furnace. Another sensor is a 3-D temperature profiler. One important aspect of combustion control is product quality. The 3-D temperature profiler of this on-line system is intended to provide a tool for a better temperature control in a furnace to improve product quality. In summary, this on-line diagnostic and control system offers great potential for improving furnace thermal efficiency, lowering NOx and carbon monoxide emissions, and improving product quality. The system is applicable in natural gas-fired furnaces in the glass industry and reheating furnaces used in steel and forging industries.
Enol Intermediates Unexpectedly Found in Flames
U.S. Department of Energy (DOE) all webpages (Extended Search)
Enol Intermediates Unexpectedly Found in Flames Print For those studying flame chemistry and the properties of combustion intermediates by means of molecular beam mass spectrometry, the addition of tunable vacuum ultraviolet (VUV) from a synchrotron to photoionize the beam for mass spectrometry makes for a powerful technique capable of differentiating between isomers with the same molecular weight and composition. With the help of a unique experimental apparatus, an international team of
Enol Intermediates Unexpectedly Found in Flames
U.S. Department of Energy (DOE) all webpages (Extended Search)
Enol Intermediates Unexpectedly Found in Flames Print For those studying flame chemistry and the properties of combustion intermediates by means of molecular beam mass spectrometry, the addition of tunable vacuum ultraviolet (VUV) from a synchrotron to photoionize the beam for mass spectrometry makes for a powerful technique capable of differentiating between isomers with the same molecular weight and composition. With the help of a unique experimental apparatus, an international team of
Enol Intermediates Unexpectedly Found in Flames
U.S. Department of Energy (DOE) all webpages (Extended Search)
Enol Intermediates Unexpectedly Found in Flames Print For those studying flame chemistry and the properties of combustion intermediates by means of molecular beam mass spectrometry, the addition of tunable vacuum ultraviolet (VUV) from a synchrotron to photoionize the beam for mass spectrometry makes for a powerful technique capable of differentiating between isomers with the same molecular weight and composition. With the help of a unique experimental apparatus, an international team of
Enol Intermediates Unexpectedly Found in Flames
U.S. Department of Energy (DOE) all webpages (Extended Search)
Enol Intermediates Unexpectedly Found in Flames Print For those studying flame chemistry and the properties of combustion intermediates by means of molecular beam mass spectrometry, the addition of tunable vacuum ultraviolet (VUV) from a synchrotron to photoionize the beam for mass spectrometry makes for a powerful technique capable of differentiating between isomers with the same molecular weight and composition. With the help of a unique experimental apparatus, an international team of
Enol Intermediates Unexpectedly Found in Flames
U.S. Department of Energy (DOE) all webpages (Extended Search)
Enol Intermediates Unexpectedly Found in Flames Print For those studying flame chemistry and the properties of combustion intermediates by means of molecular beam mass spectrometry, the addition of tunable vacuum ultraviolet (VUV) from a synchrotron to photoionize the beam for mass spectrometry makes for a powerful technique capable of differentiating between isomers with the same molecular weight and composition. With the help of a unique experimental apparatus, an international team of
Enol Intermediates Unexpectedly Found in Flames
U.S. Department of Energy (DOE) all webpages (Extended Search)
Enol Intermediates Unexpectedly Found in Flames Print For those studying flame chemistry and the properties of combustion intermediates by means of molecular beam mass spectrometry, the addition of tunable vacuum ultraviolet (VUV) from a synchrotron to photoionize the beam for mass spectrometry makes for a powerful technique capable of differentiating between isomers with the same molecular weight and composition. With the help of a unique experimental apparatus, an international team of
Enol Intermediates Unexpectedly Found in Flames
U.S. Department of Energy (DOE) all webpages (Extended Search)
Enol Intermediates Unexpectedly Found in Flames Print For those studying flame chemistry and the properties of combustion intermediates by means of molecular beam mass spectrometry, the addition of tunable vacuum ultraviolet (VUV) from a synchrotron to photoionize the beam for mass spectrometry makes for a powerful technique capable of differentiating between isomers with the same molecular weight and composition. With the help of a unique experimental apparatus, an international team of
Electric fields effect on liftoff and blowoff of nonpremixed laminar jet flames in a coflow
Kim, M.K.; Ryu, S.K.; Won, S.H. [School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-742 (Korea); Chung, S.H. [Clean Combustion Research Center, King Abdullah University of Science and Technology, Thuwal (Saudi Arabia)
The stabilization characteristics of liftoff and blowoff in nonpremixed laminar jet flames in a coflow have been investigated experimentally for propane fuel by applying AC and DC electric fields to the fuel nozzle with a single-electrode configuration. The liftoff and blowoff velocities have been measured by varying the applied voltage and frequency of AC and the voltage and the polarity of DC. The result showed that the AC electric fields extended the stabilization regime of nozzle-attached flame in terms of jet velocity. As the applied AC voltage increased, the nozzle-attached flame was maintained even over the blowout velocity without having electric fields. In such a case, a blowoff occurred directly without experiencing a lifted flame. While for the DC cases, the influence on liftoff was minimal. There existed three different regimes depending on the applied AC voltage. In the low voltage regime, the nozzle-detachment velocity of either liftoff or blowoff increased linearly with the applied voltage, while nonlinearly with the AC frequency. In the intermediate voltage regime, the detachment velocity decreased with the applied voltage and reasonably independent of the AC frequency. At the high voltage regime, the detachment was significantly influenced by the generation of discharges. (author)
Laminar flame speeds of moist syngas mixtures
Das, Apurba K. [Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, OH 44106 (United States); Kumar, Kamal; Sung, Chih-Jen [Department of Mechanical Engineering, University of Connecticut, Storrs, CT 06269 (United States)
This work experimentally investigates the effect of the presence of water vapor on the laminar flame speeds of moist syngas/air mixtures using the counterflow twin-flame configuration. The experimental results presented here are for fuel lean syngas mixtures with molar percentage of hydrogen in the hydrogen and carbon monoxide mixture varying from 5% to 100%, for an unburned mixture temperature of 323 K, and under atmospheric pressure. At a given equivalence ratio, the effect of varying amount of water vapor addition on the measured laminar flame speed is demonstrated. The experimental laminar flame speeds are also compared with computed values using chemical kinetic mechanisms reported in the literature. It is found that laminar flame speed varies non-monotonically with addition of water for the carbon monoxide rich mixtures. It first increases with increasing amount of water addition, reaches a maximum value, and then decreases. An integrated reaction path analysis is further conducted to understand the controlling mechanism responsible for the non-monotonic variation in laminar flame speed due to water addition. On the other hand, for higher values of H{sub 2}/CO ratio the laminar flame speed monotonically decreases with increasing water addition. It is shown that the competition between the chemical and thermal effects of water addition leads to the observed response. Furthermore, reaction rate sensitivity analysis as well as binary diffusion coefficient sensitivity analysis are conducted to identify the possible sources of discrepancy between the experimental and predicted values. The sensitivity results indicate that the reaction rate constant of H{sub 2}+OH = H{sub 2}O+H is worth revisiting and refinement of binary diffusion coefficient data of N{sub 2}-H{sub 2}O, N{sub 2}-H{sub 2}, and H{sub 2}-H{sub 2}O pairs can be considered. (author)
Response analysis of a laminar premixed M-flame to flow perturbations using a linearized compressible Navier-Stokes solver
Blanchard, M.; Schuller, T.; Sipp, D.; Schmid, P. J.
The response of a laminar premixed methane-air flame subjected to flow perturbations around a steady state is examined experimentally and using a linearized compressible Navier-Stokes solver with a one-step chemistry mechanism to describe combustion. The unperturbed flame takes an M-shape stabilized both by a central bluff body and by the external rim of a cylindrical nozzle. This base flow is computed by a nonlinear direct simulation of the steady reacting flow, and the flame topology is shown to qualitatively correspond to experiments conducted under comparable conditions. The flame is then subjected to acoustic disturbances produced at different locations in the numerical domain, and its response is examined using the linearized solver. This linear numerical model then allows the componentwise investigation of the effects of flow disturbances on unsteady combustion and the feedback from the flame on the unsteady flow field. It is shown that a wrinkled reaction layer produces hydrodynamic disturbances in the fresh reactant flow field that superimpose on the acoustic field. This phenomenon, observed in several experiments, is fully interpreted here. The additional perturbations convected by the mean flow stem from the feedback of the perturbed flame sheet dynamics onto the flow field by a mechanism similar to that of a perturbed vortex sheet. The different regimes where this mechanism prevails are investigated by examining the phase and group velocities of flow disturbances along an axis oriented along the main direction of the flow in the fresh reactant flow field. It is shown that this mechanism dominates the low-frequency response of the wrinkled shape taken by the flame and, in particular, that it fully determines the dynamics of the flame tip from where the bulk of noise is radiated.
A role of chemical kinetics in the simulation of the reaction kernel of methane jet diffusion flames
Takahashi, Fumiaki; Katta, V.R.
The detailed structure of the stabilizing region of an axisymmetric laminar methane jet diffusion flame has been studied numerically. Computations using a time-dependent, implicit, third-order accurate numerical scheme with buoyancy effects were performed using two different C{sub 2}-chemistry models and compared with the previous results using a C{sub 1}-chemistry model. The results were nearly identical for all kinetic models except that the C{sub 1}-chemistry model over-predicted the methyl-radical and formaldehyde concentrations on the fuel side of the flame and that the standoff distance of the flame base from the burner rim varied. The standoff distance was sensitive to the CH{sub 3} + H + (M) {yields} CH{sub 4} + (M) reaction. The highest reactivity spot (reaction kernel) was formed in the relatively low-temperature (<1,600 K) flame base, where the CH{sub 3} + O {yields} CH{sub 2}O + H reaction predominantly contributed to the heat release, providing a stationary ignition source to incoming reactants and thereby stabilizing the trailing diffusion flame.
Pentan isomers compound flame front structure
Mansurov, Z.A.; Mironenko, A.W.; Bodikov, D.U.; Rachmetkaliev, K.N.
The fuels (hexane, pentane, diethyl ether) and conditions investigated in this study are relevant to engine knock in spark- ignition engines. A review is provided of the field of low temperature hydrocarbon oxidation. Studies were made of radical and stable intermediate distribution in the front of cool flames: Maximum concentrations of H atoms and peroxy radicals were observed in the luminous zone of the cool flame front. Peroxy radicals appear before the luminous zone at 430 K due to diffusion. H atoms were found in cool flames of butane and hexane. H atoms diffuses from the luminous zone to the side of the fresh mixture, and they penetrate into the fresh mixture to a small depth. Extension of action sphear of peroxy radicals in the fresh mixture is much greater than that of H atoms due to their small activity and high concentrations.
Testing of a Hydrogen Diffusion Flame Array Injector at Gas Turbine Conditions
Weiland, Nathan T.; Sidwell, Todd G.; Strakey, Peter A.
High-hydrogen gas turbines enable integration of carbon sequestration into coal-gasifying power plants, though NO{sub x} emissions are often high. This work explores nitrogen dilution of hydrogen diffusion flames to reduce thermal NO{sub x} emissions and avoid problems with premixing hydrogen at gas turbine pressures and temperatures. The burner design includes an array of high-velocity coaxial fuel and air injectors, which balances stability and ignition performance, combustor pressure drop, and flame residence time. Testing of this array injector at representative gas turbine conditions (16 atm and 1750 K firing temperature) yields 4.4 ppmv NO{sub x} at 15% O{sub 2} equivalent. NO{sub x} emissions are proportional to flame residence times, though these deviate from expected scaling due to active combustor cooling and merged flame behavior. The results demonstrate that nitrogen dilution in combination with high velocities can provide low NO{sub x} hydrogen combustion at gas turbine conditions, with significant potential for further NO{sub x} reductions via suggested design changes.
Response of a laminar premixed flame to flow oscillations: A kinematic model and thermoacoustic instability results
Fleifil, M.; Annaswamy, A.M.; Ghoneim, A.F.; Ghoneim, Z.A.
Combustion instability is a resonance phenomenon that arises due to the coupling between the system acoustics and the unsteady heat release. The constructive feedback between the two processes, which is known to occur as a certain phase relationship between the pressure and the unsteady heat release rate is satisfied, depends on many parameters among which is the acoustic mode, the flame holder characteristics, and the dominant burning pattern. In this paper, the authors construct an analytical model to describe the dynamic response of a laminar premixed flame stabilized on the rim of a tube to velocity oscillation. They consider uniform and nonuniform velocity perturbations superimposed on a pipe flow velocity profile. The model results show that the magnitude of heat release perturbation and its phase with respect to the dynamic perturbation dependent primarily on the flame Strohal number, representing the ratio of the dominant frequency times the tube radius to the laminar burning velocity. In terms of this number, high-frequency perturbations pass through the flame while low frequencies lead to a strong response. The phase with respect to the velocity perturbation behaves in the opposite way. Results of this model are shown to agree with experimental observations and to be useful in determining how the combustion excited model is selected among all the acoustic unstable modes. The model is then used to obtain a time-domain differential equation describing the relationship between the velocity perturbation and the heat release response over the entire frequency range.
Computatonal and experimental study of laminar flames
Smooke, M.D.; Long, M.B.
This research has centered on an investigation of the effects of complex chemistry and detailed transport on the structure and extinction of hydrocarbon flames in counterflow, cylindrical and coflowing axisymmetric configurations. The authors have pursued both computational and experimental aspects of the research in parallel. The computational work has focused on the application of accurate and efficient numerical methods for the solution of the one and two-dimensional nonlinear boundary value problems describing the various reacting systems. Detailed experimental measurements were performed on axisymmetric coflow flames using two-dimensional imaging techniques. In particular, spontaneous Raman scattering and laser induced fluorescence were used to measure the temperature, major and minor species profiles.
Sub-millikelvin stabilization of a closed cycle cryocooler (Journal...
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K to 300 K, while the cooling power is virtually undiminished. The damping system is small, inexpensive, can be ... capacity; copper; thermal stability; materials properties Word ...
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and mirrors ARM's other long-term atmospheric measurement facilities around the world. Virtual Tour Coming in 2016 Heavily instrumented ARM facilities are strategically located at...
Hybrid fs/ps rotational CARS temperature and oxygen measurements in the product gases of canonical flat flames
Kearney, Sean Patrick
A hybrid fs/ps pure-rotational coherent anti-Stokes Raman scattering (CARS) scheme is systematically evaluated over a wide range of flame conditions in the product gases of two canonical flat-flame burners. Near-transform-limited, broadband femtosecond pump and Stokes pulses impulsively prepare a rotational Raman coherence, which is later probed using a high-energy, frequency-narrow picosecond beam generated by the second-harmonic bandwidth compression scheme that has recently been demonstrated for rotational CARS generation in H2/air flat flames. The measured spectra are free of collision effects and nonresonant background and can be obtained on a single-shot basis at 1 kHz. The technique is evaluated for temperature/oxygen measurements in near-adiabatic H2/air flames stabilized on the Hencken burner for equivalence ratios of φ = 0.20–1.20. Thermometry is demonstrated in hydrocarbon/air products for φ = 0.75–3.14 in premixed C2H4/air flat flames on the McKenna burner. Reliable spectral fitting is demonstrated for both shot-averaged and single-laser-shot data using a simple phenomenological model. Measurement accuracy is benchmarked by comparison to adiabatic-equilibrium calculations for the H2/air flames, and by comparison with nanosecond CARS measurements for the C2H4/air flames. Quantitative accuracy comparable to nanosecond rotational CARS measurements is observed, while the observed precision in both the temperature and oxygen data is extraordinarily high, exceeding nanosecond CARS, and on par with the best published thermometric precision by femtosecond vibrational CARS in flames, and rotational femtosecond CARS at low temperature. Threshold levels of signal-to-noise ratio to achieve 1–2% precision in temperature and O2/N2 ratio are identified. Our results show that pure-rotational fs/ps CARS is a robust and quantitative tool when applied across a wide
Hybrid fs/ps rotational CARS temperature and oxygen measurements in the product gases of canonical flat flames
Kearney, Sean Patrick
A hybrid fs/ps pure-rotational coherent anti-Stokes Raman scattering (CARS) scheme is systematically evaluated over a wide range of flame conditions in the product gases of two canonical flat-flame burners. Near-transform-limited, broadband femtosecond pump and Stokes pulses impulsively prepare a rotational Raman coherence, which is later probed using a high-energy, frequency-narrow picosecond beam generated by the second-harmonic bandwidth compression scheme that has recently been demonstrated for rotational CARS generation in H2/air flat flames. The measured spectra are free of collision effects and nonresonant background and can be obtained on a single-shot basis at 1 kHz. The technique is evaluated for temperature/oxygenmore » measurements in near-adiabatic H2/air flames stabilized on the Hencken burner for equivalence ratios of φ = 0.20–1.20. Thermometry is demonstrated in hydrocarbon/air products for φ = 0.75–3.14 in premixed C2H4/air flat flames on the McKenna burner. Reliable spectral fitting is demonstrated for both shot-averaged and single-laser-shot data using a simple phenomenological model. Measurement accuracy is benchmarked by comparison to adiabatic-equilibrium calculations for the H2/air flames, and by comparison with nanosecond CARS measurements for the C2H4/air flames. Quantitative accuracy comparable to nanosecond rotational CARS measurements is observed, while the observed precision in both the temperature and oxygen data is extraordinarily high, exceeding nanosecond CARS, and on par with the best published thermometric precision by femtosecond vibrational CARS in flames, and rotational femtosecond CARS at low temperature. Threshold levels of signal-to-noise ratio to achieve 1–2% precision in temperature and O2/N2 ratio are identified. Our results show that pure-rotational fs/ps CARS is a robust and quantitative tool when applied across a wide range of flame conditions spanning lean H2/air combustion to fuel-rich sooting hydrocarbon
Power-law wrinkling turbulence-flame interaction model for astrophysical flames
Jackson, Aaron P.; Townsley, Dean M.; Calder, Alan C.
We extend a model for turbulence-flame interactions (TFI) to consider astrophysical flames with a particular focus on combustion in Type Ia supernovae. The inertial range of the turbulent cascade is nearly always under-resolved in simulations of astrophysical flows, requiring the use of a model in order to quantify the effects of subgrid-scale wrinkling of the flame surface. We provide implementation details to extend a well-tested TFI model to low-Prandtl number flames for use in the compressible hydrodynamics code FLASH. A local, instantaneous measure of the turbulent velocity is calibrated for FLASH and verification tests are performed. Particular care is taken to consider the relation between the subgrid rms turbulent velocity and the turbulent flame speed, especially for high-intensity turbulence where the turbulent flame speed is not expected to scale with the turbulent velocity. Finally, we explore the impact of different TFI models in full-star, three-dimensional simulations of Type Ia supernovae.
Excitation of thermoacoustic oscillations by small premixed flames
Coats, C.M.; Chang, Z.; Williams, P.D.
Experiments have been carried out in which very small lean premixed flames closely representative of those formed by modern multiport domestic gas burners have been subjected to controlled acoustic perturbation. PLIF from CH has been used to visualise the flame response and the heat-release-rate fluctuations have been evaluated directly from the flame images. It is shown that small laminar flames can amplify the effects of acoustic velocity fluctuations by mechanisms that do not involve resonant heat loss to the burner and that the fluctuations in flame-front area are not adequately characterised by a Strouhal number alone. The measured transfer function is compared with the predictions of various analytical formulations and a new model of the flame oscillation is proposed which applies specifically to situations in which the design of the burner renders the flame base immobile. (author)
Flame-vortex interaction driven combustion dynamics in a backward-facing step combustor
Altay, H. Murat; Speth, Raymond L.; Hudgins, Duane E.; Ghoniem, Ahmed F.
The combustion dynamics of propane-hydrogen mixtures are investigated in an atmospheric pressure, lean, premixed backward-facing step combustor. We systematically vary the equivalence ratio, inlet temperature and fuel composition to determine the stability map of the combustor. Simultaneous pressure, velocity, heat release rate and equivalence ratio measurements and high-speed video from the experiments are used to identify and characterize several distinct operating modes. When fuel is injected far upstream from the step, the equivalence ratio entering the flame is temporally and spatially uniform, and the combustion dynamics are governed only by flame-vortex interactions. Four distinct dynamic regimes are observed depending on the operating parameters. At high but lean equivalence ratios, the flame is unstable and oscillates strongly as it is wrapped around the large unsteady wake vortex. At intermediate equivalence ratios, weakly oscillating quasi-stable flames are observed. Near the lean blowout limit, long stable flames extending from the corner of the step are formed. At atmospheric inlet temperature, the unstable mode resonates at the 1/4 wavemode of the combustor. As the inlet temperature is increased, the 5/4 wavemode of the combustor is excited at high but lean equivalence ratios, forming the high-frequency unstable flames. Higher hydrogen concentration in the fuel and higher inlet temperatures reduce the equivalence ratios at which the transitions between regimes are observed. We plot combustion dynamics maps or the response curves, that is the overall sound pressure level as a function of the equivalence ratio, for different operating conditions. We demonstrate that numerical results of strained premixed flames can be used to collapse the response curves describing the transitions among the dynamic modes onto a function of the heat release rate parameter alone, rather than a function dependent on the equivalence ratio, inlet temperature and fuel
Flame quality monitor system for fixed firing rate oil burners
Butcher, Thomas A.; Cerniglia, Philip
A method and apparatus for determining and indicating the flame quality, or efficiency of the air-fuel ratio, in a fixed firing rate heating unit, such as an oil burning furnace, is provided. When the flame brightness falls outside a preset range, the flame quality, or excess air, has changed to the point that the unit should be serviced. The flame quality indicator output is in the form of lights mounted on the front of the unit. A green light indicates that the flame is about in the same condition as when the burner was last serviced. A red light indicates a flame which is either too rich or too lean, and that servicing of the burner is required. At the end of each firing cycle, the flame quality indicator goes into a hold mode which is in effect during the period that the burner remains off. A yellow or amber light indicates that the burner is in the hold mode. In this mode, the flame quality lights indicate the flame condition immediately before the burner turned off. Thus the unit can be viewed when it is off, and the flame condition at the end of the previous firing cycle can be observed.
Flame and flow characteristics of double concentric jets
Huang, R.F.; Yang, J.T.; Lee, P.C.
The characteristic flame and flow modes of a double concentric type of combustor possessing a central air jet and an annular propane gas are experimentally studied. Subject to the effects of the gravitational, inertial, and pressure forces, the cold flow is classified into three primary patterns: annular fountain, unstable fountain, and recirculation bubble flows. Using direct and schlieren photography techniques, the flames in the velocity domain of annulus and central jets are systematically classified into several characteristic modes. At low central jet velocity, a central flame enclosed in a annular diffusion flame might exist. At high central jet velocity, only the annular flames exist. The existence of the central flame dominates the flame and flow behaviors at low central jet velocity. The interaction between the central jet and the recirculation bubble in the near wake region dominates the flame characteristics at high central jet velocity. The interaction between the flame behavior and the flow patterns in each characteristic mode is comprehensively discussed. The temperature profiles are probed by a fine-wire thermocouple. The radial temperature profiles for each characteristic flame mode at various levels are presented to show the thermal structures.
Mechanisms of flame stabilisation at low lifted height in a turbulent lifted slot-jet flame
Karami, Shahram; Hawkes, Evatt R.; Talei, Mohsen; Chen, Jacqueline H.
A turbulent lifted slot-jet flame is studied using direct numerical simulation (DNS). A one-step chemistry model is employed with a mixture-fraction-dependent activation energy which can reproduce qualitatively the dependence of the laminar burning rate on the equivalence ratio that is typical of hydrocarbon fuels. The basic structure of the flame base is first examined and discussed in the context of earlier experimental studies of lifted flames. Several features previously observed in experiments are noted and clarified. Some other unobserved features are also noted. Comparison with previous DNS modelling of hydrogen flames reveals significant structural differences. The statistics of flow andmore » relative edge-flame propagation velocity components conditioned on the leading edge locations are then examined. The results show that, on average, the streamwise flame propagation and streamwise flow balance, thus demonstrating that edge-flame propagation is the basic stabilisation mechanism. Fluctuations of the edge locations and net edge velocities are, however, significant. It is demonstrated that the edges tend to move in an essentially two-dimensional (2D) elliptical pattern (laterally outwards towards the oxidiser, then upstream, then inwards towards the fuel, then downstream again). It is proposed that this is due to the passage of large eddies, as outlined in Suet al.(Combust. Flame, vol. 144 (3), 2006, pp. 494–512). However, the mechanism is not entirely 2D, and out-of-plane motion is needed to explain how flames escape the high-velocity inner region of the jet. Finally, the time-averaged structure is examined. A budget of terms in the transport equation for the product mass fraction is used to understand the stabilisation from a time-averaged perspective. The result of this analysis is found to be consistent with the instantaneous perspective. The budget reveals a fundamentally 2D structure, involving transport in both the streamwise and transverse
Mechanisms of flame stabilisation at low lifted height in a turbulent lifted slot-jet flame
Karami, Shahram; Hawkes, Evatt R.; Talei, Mohsen; Chen, Jacqueline H.
A turbulent lifted slot-jet flame is studied using direct numerical simulation (DNS). A one-step chemistry model is employed with a mixture-fraction-dependent activation energy which can reproduce qualitatively the dependence of the laminar burning rate on the equivalence ratio that is typical of hydrocarbon fuels. The basic structure of the flame base is first examined and discussed in the context of earlier experimental studies of lifted flames. Several features previously observed in experiments are noted and clarified. Some other unobserved features are also noted. Comparison with previous DNS modelling of hydrogen flames reveals significant structural differences. The statistics of flow and relative edge-flame propagation velocity components conditioned on the leading edge locations are then examined. The results show that, on average, the streamwise flame propagation and streamwise flow balance, thus demonstrating that edge-flame propagation is the basic stabilisation mechanism. Fluctuations of the edge locations and net edge velocities are, however, significant. It is demonstrated that the edges tend to move in an essentially two-dimensional (2D) elliptical pattern (laterally outwards towards the oxidiser, then upstream, then inwards towards the fuel, then downstream again). It is proposed that this is due to the passage of large eddies, as outlined in Su
Mechanisms of flame stabilisation at low lifted height in a turbulent lifted slot-jet flame
Karami, Shahram; Hawkes, Evatt R.; Talei, Mohsen; Chen, Jacqueline H.
A turbulent lifted slot-jet flame is studied using direct numerical simulation (DNS). A one-step chemistry model is employed with a mixture-fraction-dependent activation energy which can reproduce qualitatively the dependence of the laminar burning rate on the equivalence ratio that is typical of hydrocarbon fuels. The basic structure of the flame base is first examined and discussed in the context of earlier experimental studies of lifted flames. Several features previously observed in experiments are noted and clarified. Some other unobserved features are also noted. Comparison with previous DNS modelling of hydrogen flames reveals significant structural differences. The statistics of flow and relative edge-flame propagation velocity components conditioned on the leading edge locations are then examined. The results show that, on average, the streamwise flame propagation and streamwise flow balance, thus demonstrating that edge-flame propagation is the basic stabilisation mechanism. Fluctuations of the edge locations and net edge velocities are, however, significant. It is demonstrated that the edges tend to move in an essentially two-dimensional (2D) elliptical pattern (laterally outwards towards the oxidiser, then upstream, then inwards towards the fuel, then downstream again). It is proposed that this is due to the passage of large eddies, as outlined in Su
The advanced flame quality indicator system
Oman, R.; Rossi, M.J.; Calia, V.S.; Davis, F.L.; Rudin, A.
By combining oil tank monitoring, systems diagnostics and flame quality monitoring in an affordable system that communicates directly with dealers by telephone modem, Insight Technologies offers new revenue opportunities and the capability for a new order of customer relations to oil dealers. With co-sponsorship from New York State Energy Research and Development Authority, we have incorporated several valuable functions to a new product based on the original Flame Quality Indicator concept licensed from the US DOE`s Brookhaven National Laboratory. The new system is the Advanced Flame Quality Indicator, or AFQI. As before, the AFQI monitors and reports the intensity of the burner flame relative to a calibration established when the burner is set up at AFQI installation. Repairs or adjustments are summoned by late-night outgoing telephone calls when limits are exceeded in either direction, indicating an impending contamination or other malfunction. A independently, a pressure transducer for monitoring oil tank level and filter condition, safety lockout alarms and a temperature monitor; all reporting automatically at instructed intervals via an on-board modem to a central station PC computer (CSC). Firmware on each AFQI unit and Insight-supplied software on the CSC automatically interact to maintain a customer database for an oil dealer, an OEM, or a regional service contractor. In addition to ensuring continuously clean and efficient operation, the AFQI offers the oil industry a new set of immediate payoffs, among which are reduced outages and emergency service calls, shorter service calls from cleaner operation, larger oil delivery drops, the opportunity to stretch service intervals to as along as three years in some cases, new selling features to keep and attract customers, and greatly enhanced customer contact, quality and reliability.
Computational and experimental study of laminar flames
Smooke, Mitchell
During the past three years, our research has centered on an investigation of the effects of complex chemistry and detailed transport on the structure and extinction of hydrocarbon flames in coflowing axisymmetric configurations. We have pursued both computational and experimental aspects of the research in parallel on both steady-state and time-dependent systems. The computational work has focused on the application of accurate and efficient numerical methods for the solution of the steady-state and time-dependent boundary value problems describing the various reacting systems. Detailed experimental measurements were performed on axisymmetric coflow flames using two-dimensional imaging techniques. Previously, spontaneous Raman scattering, chemiluminescence, and laser-induced fluorescence were used to measure the temperature, major and minor species profiles. Particle image velocimetry (PIV) has been used to investigate velocity distributions and for calibration of time-varying flames. Laser-induced incandescence (LII) with an extinction calibration was used to determine soot volume fractions, while soot surface temperatures were measured with three-color optical pyrometry using a color digital camera. A blackbody calibration of the camera allows for determination of soot volume fraction as well, which can be compared with the LII measurements. More recently, we have concentrated on a detailed characterization of soot using a variety of techniques including time-resolved LII (TiRe-LII) for soot primary particles sizes, multi-angle light scattering (MALS) for soot radius of gyration, and spectrally-resolved line of sight attenuation (spec-LOSA). Combining the information from all of these soot measurements can be used to determine the soot optical properties, which are observed to vary significantly depending on spatial location and fuel dilution. Our goal has been to obtain a more fundamental understanding of the important fluid dynamic and chemical interactions in
ARM - Measurement - Virtual temperature
U.S. Department of Energy (DOE) all webpages (Extended Search)
govMeasurementsVirtual temperature ARM Data Discovery Browse Data Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Measurement : Virtual temperature The virtual temperature Tv = T(1 + rv/{epsilon}), where rv is the mixing ratio, and {epsilon} is the ratio of the gas constants of air and water vapor ( 0.622). Categories Atmospheric State Instruments The above measurement is considered scientifically relevant for the following instruments. Refer to
Turbulent Nonpremixed Flames (TNF): Experimental Data Archives and Computational Submodels
DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]
In the 1990s an international collaboration formed around a series of workshops that became known collectively as the International Workshop on Measurement and Computation of Turbulent Non-Premixed Flames (TNF). An online library, hosted by Sandia National Laboratory (California) was established that provides data sets and submodels or "mechanisms" for the study of turbulence-chemistry interactions in turbulent nonpremixed and partially premixed combustion. Data are organized by flame types: simple jet flames, piloted jet flames, bluff body flames, and swirl flames. These data sets provide a means for collaborative comparisons of both measured and simulated/modeled research results and also assist scientists in determining priorities for further research. More than 20 data sets or databases are available from this website, along with various downloadable files of chemical mechanisms. The website also provides an extensive bibliography and the proceedings of the workshops themselves from 1996 through 2012. Information continues to be added to this collection.
Take a virtual tour of the campus of Thomas Jefferson National Accelerator Facility. You can see inside our two accelerators, three experimental areas, accelerator component fabrication and testing areas, high-performance computing areas and laser labs.
Take a virtual tour of the campus of Thomas Jefferson National Accelerator Facility. You can see inside our two accelerators, three experimental areas, accelerator component fabrication and testing areas, high-performance computing areas and laser labs.
Virtual Advanced Power Training Environments | The Ames Laboratory
U.S. Department of Energy (DOE) all webpages (Extended Search)
Virtual Advanced Power Training Environments
Development of Virtual Power Plants | The Ames Laboratory
U.S. Department of Energy (DOE) all webpages (Extended Search)
Development of Virtual Power Plants
Andrew M. Rudin; Thomas Butcher; Henry Troost
The flame quality indicator concept was developed at BNL specifically to monitor the brightness of the flame in a small oil burner and to provide a ''call for service'' notification when the brightness has changed from its setpoint, either high or low. In prior development work BNL has explored the response of this system to operational upsets such as excess air changes, fouled atomizer nozzles, poor fuel quality, etc. Insight Technologies, Inc. and Honeywell, Inc. have licensed this technology from the U.S. Department of Energy and have been cooperating to develop product offerings which meet industry needs with an optimal combination of function and price. Honeywell has recently completed the development of the Flame Quality Monitor (FQM or Honeywell QS7100F). This is a small module which connects via a serial cable to the burners primary operating control. Primary advantages of this approach are simplicity, cost, and ease of installation. Call-for-service conditions are output in the form of front panel indicator lights and contact closure which can trigger a range of external communication options. Under this project a field test was conducted of the FQM in cooperation with service organizations in Virginia, Pennsylvania, New Jersey, New York, and Connecticut. At total of 83 field sites were included. At each site the FQM was installed in parallel with another embodiment of this concept--the Insight AFQI. The AFQI incorporates a modem and provides the ability to provide detailed information on the trends in the flame quality over the course of the two year test period. The test site population was comprised of 79.5% boilers, 13.7% warm air furnaces, and 6.8% water heaters. Nearly all were of residential size--with firing rates ranging from 0.6 gallons of oil per hour to 1.25. During the course of the test program the monitoring equipment successfully identified problems including: plugged fuel lines, fouled nozzles, collapsed combustion chambers, and poor fuel
Soot precursor measurements in benzene and hexane diffusion flames
Kobayashi, Y.; Furuhata, T.; Amagai, K.; Arai, M.
To clarify the mechanism of soot formation in diffusion flames of liquid fuels, measurements of soot and its precursors were carried out. Sooting diffusion flames formed by a small pool combustion equipment system were used for this purpose. Benzene and hexane were used as typical aromatic and paraffin fuels. A laser-induced fluorescence (LIF) method was used to obtain spatial distributions of polycyclic aromatic hydrocarbons (PAHs), which are considered as soot particles. Spatial distributions of soot in test flames were measured by a laser-induced incandescence (LII) method. Soot diameter was estimated from the temporal change of LII intensity. A region of transition from PAHs to soot was defined from the results of LIF and LII. Flame temperatures, PAH species, and soot diameters in this transition region were investigated for both benzene and hexane flames. The results show that though the flame structures of benzene and hexane were different, the temperature in the PAHs-soot transition region of the benzene flame was similar to that of the hexane flame. Furthermore, the relationship between the PAH concentrations measured by gas chromatography in both flames and the PAH distributions obtained from LIF are discussed. It was found that PAHs with smaller molecular mass, such as benzene and toluene, remained in both the PAHs-soot transition and sooting regions, and it is thought that molecules heavier than pyrene are the leading candidates for soot precursor formation. (author)
Turbulence-Flame Interactions in Type Ia Supernovae (Journal...
Office of Scientific and Technical Information (OSTI)
turbulent intensity and l is the integral scale. For the larger integral scales characteristic of a real supernova, the flame structure is predicted to become complex and unsteady. ...
Shielded flashback-resistant diffusion flame burner for combustion diagnostics
Krupa, R.J.; Zizak, G.; Winefordner, J.D.
A burner design is presented which is of general utility for combustion diagnostics of high temperature, high burning velocity flames. (AIP)
Flame dynamics in a micro-channeled combustor
Hussain, Taaha; Balachandran, Ramanarayanan; Markides, Christos N.
The increasing use of Micro-Electro-Mechanical Systems (MEMS) has generated a significant interest in combustion-based power generation technologies, as a replacement of traditional electrochemical batteries which are plagued by low energy densities, short operational lives and low power-to-size and power-to-weight ratios. Moreover, the versatility of integrated combustion-based systems provides added scope for combined heat and power generation. This paper describes a study into the dynamics of premixed flames in a micro-channeled combustor. The details of the design and the geometry of the combustor are presented in the work by Kariuki and Balachandran [1]. This work showed that there were different modes of operation (periodic, a-periodic and stable), and that in the periodic mode the flame accelerated towards the injection manifold after entering the channels. The current study investigates these flames further. We will show that the flame enters the channel and propagates towards the injection manifold as a planar flame for a short distance, after which the flame shape and propagation is found to be chaotic in the middle section of the channel. Finally, the flame quenches when it reaches the injector slots. The glow plug position in the exhaust side ignites another flame, and the process repeats. It is found that an increase in air flow rate results in a considerable increase in the length (and associated time) over which the planar flame travels once it has entered a micro-channel, and a significant decrease in the time between its conversion into a chaotic flame and its extinction. It is well known from the literature that inside small channels the flame propagation is strongly influenced by the flow conditions and thermal management. An increase of the combustor block temperature at high flow rates has little effect on the flame lengths and times, whereas at low flow rates the time over which the planar flame front can be observed decreases and the time of
Experimental study of vorticity-strain rate interaction in turbulent partially-premixed jet flames using tomographic particle image velocimetry
Coriton, Bruno; Frank, Jonathan H.
In turbulent flows, the interaction between vorticity, ω, and strain rate, s, is considered a primary mechanism for the transfer of energy from large to small scales through vortex stretching. The ω-s coupling in turbulent jet flames is investigated using tomographic particle image velocimetry (TPIV). TPIV provides a direct measurement of the three-dimensional velocity field from which ω and s are determined. The effects of combustion and mean shear on the ω-s interaction are investigated in turbulent partially premixed methane/air jet flames with high and low probabilities of localized extinction as well as in a non-reacting isothermal air jet withmore » Reynolds number of approximately 13,000. Results show that combustion causes structures of high vorticity and strain rate to agglomerate in highly correlated, elongated layers that span the height of the probe volume. In the non-reacting jet, these structures have a more varied morphology, greater fragmentation, and are not as well correlated. The enhanced spatiotemporal correlation of vorticity and strain rate in the stable flame results in stronger ω-s interaction characterized by increased enstrophy and strain-rate production rates via vortex stretching and straining, respectively. The probability of preferential local alignment between ω and the eigenvector of the intermediate principal strain rate, s2, which is intrinsic to the ω-s coupling in turbulent flows, is larger in the flames and increases with the flame stability. The larger mean shear in the flame imposes a preferential orientation of ω and s2 tangential to the shear layer. The extensive and compressive principal strain rates, s1 and s3, respectively, are preferentially oriented at approximately 45° with respect to the jet axis. As a result, the production rates of strain and vorticity tend to be dominated by instances in which ω is parallel to the s1¯-s2¯ plane and orthogonal to s3¯.« less
Lean methane premixed laminar flames doped by components of diesel fuel II: n-propylcyclohexane
Pousse, E.; Porter, R.; Warth, V.; Glaude, P.A.; Fournet, R.; Battin-Leclerc, F. [Departement de Chimie-Physique des Reactions, Nancy Universite, CNRS, ENSIC, 1 rue Grandville, BP 20451, 54001 Nancy Cedex (France)
For a better understanding of the chemistry involved during the combustion of components of diesel fuel, the structure of a laminar lean premixed methane flame doped with n-propylcyclohexane has been investigated. The inlet gases contained 7.1% (molar) methane, 36.8% oxygen, and 0.81% n-propylcyclohexane (C{sub 9}H{sub 18}), corresponding to an equivalence ratio of 0.68 and a C{sub 9}H{sub 18}/CH{sub 4} ratio of 11.4%. The flame has been stabilized on a burner at a pressure of 6.7 kPa (50 Torr) using argon as diluent, with a gas velocity at the burner of 49.2 cm/s at 333 K. Quantified species included the usual methane C{sub 0}-C{sub 2} combustion products, but also 17 C{sub 3}-C{sub 5} hydrocarbons, seven C{sub 1}-C{sub 3} oxygenated compounds, and only four cyclic C{sub 6+} compounds, namely benzene, 1,3-cyclohexadiene, cyclohexene, and methylenecyclohexane. A new mechanism for the oxidation of n-propylcyclohexane has been proposed. It allows the proper simulation of profiles of most of the products measured in flames, as well as the satisfactory reproduction of experimental results obtained in a jet-stirred reactor. The main reaction pathways of consumption of n-propylcyclohexane have been derived from rate-of-production analysis. (author)
A lean methane premixed laminar flame doped with components of diesel fuel. I. n-Butylbenzene
Pousse, E.; Glaude, P.A.; Fournet, R.; Battin-Leclerc, F. [Departement de Chimie-Physique des Reactions, Nancy Universite, CNRS, ENSIC, 1 rue Grandville, BP 20451, 54001 Nancy Cedex (France)
To better understand the chemistry involved in the combustion of components of diesel fuel, the structure of a laminar lean premixed methane flame doped with n-butylbenzene has been investigated. The inlet gases contained 7.1% (molar) methane, 36.8% oxygen, and 0.96% n-butylbenzene corresponding to an equivalence ratio of 0.74 and a ratio C{sub 10}H{sub 14}/CH{sub 4} of 13.5%. The flame has been stabilized on a burner at a pressure of 6.7 kPa using argon as diluent, with a gas velocity at the burner of 49.2 cm/s at 333 K. Quantified species included the usual methane C{sub 0}-C{sub 2} combustion products, but also 16 C{sub 3}-C{sub 5} hydrocarbons, and 7 C{sub 1}-C{sub 3} oxygenated compounds, as well as 20 aromatic products. A new mechanism for the oxidation of n-butylbenzene is proposed whose predictions are in satisfactory agreement with measured species profiles in flames and flow reactor experiments. The main reaction pathways of consumption of n-butylbenzene have been derived from flow rate analyses. (author)
Transition from cool flame to thermal flame in compression ignition process
Yamada, Hiroyuki; Suzaki, Kotaro; Goto, Yuichi; Tezaki, Atsumu
The mechanism that initiates thermal flames in compression ignition has been studied. Experimentally, a homogeneous charge compression ignition (HCCI) engine was used with DME, n-heptane, and n-decane. Arrhenius plots of the heat release rate in the HCCI experiments showed that rates of heat release with DME, n-heptane, and n-decane exhibited a certain activation energy that is identical to that of the H{sub 2}O{sub 2} decomposition reaction. The same feature was observed in diesel engine operation using ordinary diesel fuel with advanced ignition timing to make ignition occur after the end of fuel injection. These experimental results were reproduced in nondimensional simulations using kinetic mechanisms for DME, n-heptane, and n-decane, the last being developed by extending the n-heptane mechanism. Methanol addition, which suppresses low-temperature oxidation (LTO) and delays the ignition timing, had no effect on the activation energy obtained from the Arrhenius plot of heat release rate. Nevertheless, methanol addition lowered the heat release rates during the prethermal flame process. This is because H{sub 2}O{sub 2} formation during cool flame was reduced by adding methanol. The mechanism during the transition process from cool flame to thermal flame can be explained quantitatively using thermal explosion theory, in which the rate-determining reaction is H{sub 2}O{sub 2} decomposition, assuming that heat release in this period is caused by partial oxidation of DME and HCHO initiated with the reaction with OH produced though H{sub 2}O{sub 2} decomposition. (author)
Investigations of swirl flames in a gas turbine model combustor
Weigand, P.; Meier, W.; Duan, X.R.; Stricker, W.; Aigner, M.
A gas turbine model combustor for swirling CH{sub 4}/air diffusion flames at atmospheric pressure with good optical access for detailed laser measurements is discussed. Three flames with thermal powers between 7.6 and 34.9 kW and overall equivalence ratios between 0.55 and 0.75 were investigated. These behave differently with respect to combustion instabilities: Flame A burned stably, flame B exhibited pronounced thermoacoustic oscillations, and flame C, operated near the lean extinction limit, was subject to sudden liftoff with partial extinction and reanchoring. One aim of the studies was a detailed experimental characterization of flame behavior to better understand the underlying physical and chemical processes leading to instabilities. The second goal of the work was the establishment of a comprehensive database that can be used for validation and improvement of numerical combustion models. The flow field was measured by laser Doppler velocimetry, the flame structures were visualized by planar laser-induced fluorescence (PLIF) of OH and CH radicals, and the major species concentrations, temperature, and mixture fraction were determined by laser Raman scattering. The flow fields of the three flames were quite similar, with high velocities in the region of the injected gases, a pronounced inner recirculation zone, and an outer recirculation zone with low velocities. The flames were not attached to the fuel nozzle and thus were partially premixed before ignition. The near field of the flames was characterized by fast mixing and considerable finite-rate chemistry effects. CH PLIF images revealed that the reaction zones were thin (=<0.5 mm) and strongly corrugated and that the flame zones were short (h=<50 mm). Despite the similar flow fields of the three flames, the oscillating flame B was flatter and opened more widely than the others. In the current article, the flow field, structures, and mean and rms values of the temperature, mixture fraction, and species
Electrical probe diagnostics for the laminar flame quenching distance
Karrer, Maxime; Makarov, Maxime; Bellenoue, Marc; Labuda, Sergei; Sotton, Julien
A simplified theory, previously developed for the general case of weakly ionized gas flow, is used to predict electrical probe response when the flame is quenched on the probe surface. This theory is based on the planar model of space charge sheaths around the measuring electrode. For the flame quenching case, by assuming that the sheath thickness is comparable with the thermal boundary layer thickness, probe current can be related to flame quenching distance. The theoretical assumptions made to obtain the analytical formulation of probe current were experimentally proved by using direct visualization and high-frequency PIV. The direct visualization method was also used to validate the results of flame quenching distance values obtained with electrical probe. The electrical probe diagnostics have been verified for both head-on and sidewall flame quenching regimes and for stoichiometric methane/air and propane/air mixtures in a pressure range of 0.05-0.6 MPa. (author)
Trapping and aerogelation of nanoparticles in negative gravity hydrocarbon flames
Chakrabarty, Rajan K.; Novosselov, Igor V.; Beres, Nicholas D.; Moosm�ller, Hans; Sorensen, Christopher M.; Stipe, Christopher B.
We report the experimental realization of continuous carbon aerogel production using a flame aerosol reactor by operating it in negative gravity (?g; up-side-down configuration). Buoyancy opposes the fuel and air flow forces in ?g, which eliminates convectional outflow of nanoparticles from the flame and traps them in a distinctive non-tipping, flicker-free, cylindrical flame body, where they grow to millimeter-size aerogel particles and gravitationally fall out. Computational fluid dynamics simulations show that a closed-loop recirculation zone is set up in ?g flames, which reduces the time to gel for nanoparticles by ?10{sup 6}?s, compared to positive gravity (upward rising) flames. Our results open up new possibilities of one-step gas-phase synthesis of a wide variety of aerogels on an industrial scale.
High efficiency virtual impactor
Loo, B.W.
Environmental monitoring of atmospheric air is facilitated by a single stage virtual impactor for separating an inlet flow (Q/sub 0/) having particulate contaminants into a coarse particle flow (Q/sub 1/) and a fine particle flow (Q/sub 2/) to enable collection of such particles on different filters for separate analysis. An inlet particle acceleration nozzle and coarse particle collection probe member having a virtual impaction opening are aligned along a single axis and spaced apart to define a flow separation region at which the fine particle flow (Q/sub 2/) is drawn radially outward into a chamber while the coarse particle flow (Q/sub 1/) enters the virtual impaction opening.
Formation and consumption of NO in H{sub 2} + O{sub 2} + N{sub 2} flames doped with NO or NH{sub 3} at atmospheric pressure
Shmakov, A.G.; Chernov, A.A.; Knyazkov, D.A.; Bolshova, T.A.; Korobeinichev, O.P.; Rybitskaya, I.V.; Konnov, A.A.
Flat premixed burner-stabilized H{sub 2} + O{sub 2} + N{sub 2} flames, neat or doped with 300-1000 ppm of NO or NH{sub 3}, were studied experimentally using molecular-beam mass-spectrometry and simulated numerically. Spatial profiles of temperature and concentrations of stable species, H{sub 2}, O{sub 2}, H{sub 2}O, NO, NH{sub 3}, and of H and OH radicals obtained at atmospheric pressure in lean ({phi} = 0.47), near-stoichiometric ({phi} = 1.1) and rich ({phi} = 2.0) flames are reported. Good agreement between measured and calculated structure of lean and near-stoichiometric flames was found. Significant discrepancy between simulated and measured profiles of NO concentration was observed in the rich flames. Sensitivity and reaction path analyses revealed reactions responsible for the discrepancy. Modification to the model was proposed to improve an overall agreement with the experiment. (author)
Chemical structures of low-pressure premixed methylcyclohexane flames as benchmarks for the development of a predictive combustion chemistry model
Skeen, Scott A.; Yang, Bin; Jasper, Ahren W.; Pitz, William J.; Hansen, Nils
The chemical compositions of three low-pressure premixed flames of methylcyclohexane (MCH) are investigated with the emphasis on the chemistry of MCH decomposition and the formation of aromatic species, including benzene and toluene. The flames are stabilized on a flat-flame (McKenna type) burner at equivalence ratios of φ = 1.0, 1.75, and 1.9 and at low pressures between 15 Torr (= 20 mbar) and 30 Torr (= 40 mbar). The complex chemistry of MCH consumption is illustrated in the experimental identification of several C7H12, C7H10, C6H12, and C6H10 isomers sampled from the flames as a function of distance from the burner.more » Three initiation steps for MCH consumption are discussed: ring-opening to heptenes and methyl-hexenes (isomerization), methyl radical loss yielding the cyclohexyl radical (dissociation), and H abstraction from MCH. Mole fraction profiles as a function of distance from the burner for the C7 species supplemented by theoretical calculations are presented, indicating that flame structures resulting in steeper temperature gradients and/or greater peak temperatures can lead to a relative increase in MCH consumption through the dissociation and isomerization channels. Trends observed among the stable C6 species as well as 1,3-pentadiene and isoprene also support this conclusion. Relatively large amounts of toluene and benzene are observed in the experiments, illustrating the importance of sequential H-abstraction steps from MCH to toluene and from cyclohexyl to benzene. Furthermore, modeled results using the detailed chemical model of Pitz et al. (Proc. Combust. Inst.2007, 31, 267–275) are also provided to illustrate the use of these data as a benchmark for the improvement or future development of a MCH mechanism.« less
System and method for optical monitoring of a combustion flame
Brown, Dale M; Sandvik, Peter M; Fedison, Jeffrey B; Matocha, Kevin S; Johnson, Thomas E
An optical spectrometer for combustion flame temperature determination includes at least two photodetectors positioned for receiving light from a combustion flame, each of the at least two photodetectors having a different, overlapping bandwidth for detecting a respective output signal in an ultraviolet emission band; and a computer for subtracting a respective output signal of a first one of the at least two photodetectors from a respective output signal of a second one of the at least two photodetectors to obtain a segment signal, and using the segment signal to determine the combustion flame temperature.
Flame Arrival Measurement By Instrumented Spark Plug or Head Gasket
Energy Science and Technology Software Center (OSTI)
PLUGBIN was developed to support Sandia technologies involving instrumented head gaskets and spark plugs for engine research and development. It acquires and processes measurements of flame arrival and pressure from a spark ignition. Flame arrival is determined from analog ionization-probe or visible-emission signals, and/or digitial signals from a dedicated flame arrival measurement processor. The pressure measurements are analyzed to determine the time of peak pressure and the time to burn 10 and 90 percent ofmore » the charge. Histograms are then calculated and displayed for each measurement.« less
Turbulent Flame Propagation Characteristics of High Hydrogen Content Fuels
Seitzman, Jerry; Lieuwen, Timothy
This final report describes the results of an effort to better understand turbulent flame propagation, especially at conditions relevant to gas turbines employing fuels with syngas or hydrogen mixtures. Turbulent flame speeds were measured for a variety of hydrogen/carbon monoxide (H2/CO) and hydrogen/methane (H2/CH4) fuel mixtures with air as the oxidizer. The measurements include global consumption speeds (ST,GC) acquired in a turbulent jet flame at pressures of 1-10 atm and local displacement speeds (ST,LD) acquired in a low-swirl burner at atmospheric pressure. The results verify the importance of fuel composition in determining turbulent flame speeds. For example, different fuel-air mixtures having the same unstretched laminar flame speed (SL,0) but different fuel compositions resulted in significantly different ST,GC for the same turbulence levels (u'). This demonstrates the weakness of turbulent flame speed correlations based simply on u'/SL,0. The results were analyzed using a steady-steady leading points concept to explain the sensitivity of turbulent burning rates to fuel (and oxidizer) composition. Leading point theories suggest that the premixed turbulent flame speed is controlled by the flame front characteristics at the flame brush leading edge, or, in other words, by the flamelets that advance farthest into the unburned mixture (the so-called leading points). For negative Markstein length mixtures, this is assumed to be close to the maximum stretched laminar flame speed (SL,max) for the given fuel-oxidizer mixture. For the ST,GC measurements, the data at a given pressure were well-correlated with an SL,max scaling. However the variation with pressure was not captured, which may be due to non-quasi-steady effects that are not included in the current model. For the ST,LD data, the leading points model again faithfully captured the variation of turbulent flame speed over a wide range of fuel-compositions and turbulence intensities. These results provide
Counterflow diffusion flame synthesis of ceramic oxide powders
Katz, Joseph L.; Miquel, Philippe F.
Ceramic oxide powders and methods for their preparation are revealed. Ceramic oxide powders are obtained using a flame process whereby one or more precursors of ceramic oxides are introduced into a counterflow diffusion flame burner wherein the precursors are converted into ceramic oxide powders. The nature of the ceramic oxide powder produced is determined by process conditions. The morphology, particle size, and crystalline form of the ceramic oxide powders may be varied by the temperature of the flame, the precursor concentration ratio, the gas stream and the gas velocity.
Counterflow diffusion flame synthesis of ceramic oxide powders
Katz, J.L.; Miquel, P.F.
Ceramic oxide powders and methods for their preparation are revealed. Ceramic oxide powders are obtained using a flame process whereby one or more precursors of ceramic oxides are introduced into a counterflow diffusion flame burner wherein the precursors are converted into ceramic oxide powders. The nature of the ceramic oxide powder produced is determined by process conditions. The morphology, particle size, and crystalline form of the ceramic oxide powders may be varied by the temperature of the flame, the precursor concentration ratio, the gas stream and the gas velocity. 24 figs.
Response of flame thickness and propagation speed under intense turbulence in spatially developing lean premixed methane–air jet flames
Sankaran, Ramanan; Hawkes, Evatt R.; Yoo, Chun Sang; Chen, Jacqueline H.
Direct numerical simulations of three-dimensional spatially-developing turbulent Bunsen flames were performed at three different turbulence intensities. We performed these simulations using a reduced methane–air chemical mechanism which was specifically tailored for the lean premixed conditions simulated here. A planar-jet turbulent Bunsen flame configuration was used in which turbulent preheated methane–air mixture at 0.7 equivalence ratio issued through a central jet and was surrounded by a hot laminar coflow of burned products. The turbulence characteristics at the jet inflow were selected such that combustion occured in the thin reaction zones (TRZ) regime. At the lowest turbulence intensity, the conditions fall onmore » the boundary between the TRZ regime and the corrugated flamelet regime, and progressively moved further into the TRZ regime by increasing the turbulent intensity. The data from the three simulations was analyzed to understand the effect of turbulent stirring on the flame structure and thickness. Furthermore, statistical analysis of the data showed that the thermal preheat layer of the flame was thickened due to the action of turbulence, but the reaction zone was not significantly affected. A global and local analysis of the burning velocity of the flame was performed to compare the different flames. Detailed statistical averages of the flame speed were also obtained to study the spatial dependence of displacement speed and its correlation to strain rate and curvature.« less
Response of flame thickness and propagation speed under intense turbulence in spatially developing lean premixed methane air jet flames
Sankaran, Ramanan; Hawkes, Evatt R.; Yoo, Chun Sang; Chen, Jacqueline H.
Direct numerical simulations of three-dimensional spatially-developing turbulent Bunsen flames were performed at three different turbulence intensities. We performed these simulations using a reduced methane�air chemical mechanism which was specifically tailored for the lean premixed conditions simulated here. A planar-jet turbulent Bunsen flame configuration was used in which turbulent preheated methane�air mixture at 0.7 equivalence ratio issued through a central jet and was surrounded by a hot laminar coflow of burned products. The turbulence characteristics at the jet inflow were selected such that combustion occured in the thin reaction zones (TRZ) regime. At the lowest turbulence intensity, the conditions fall onmore��the boundary between the TRZ regime and the corrugated flamelet regime, and progressively moved further into the TRZ regime by increasing the turbulent intensity. The data from the three simulations was analyzed to understand the effect of turbulent stirring on the flame structure and thickness. Furthermore, statistical analysis of the data showed that the thermal preheat layer of the flame was thickened due to the action of turbulence, but the reaction zone was not significantly affected. A global and local analysis of the burning velocity of the flame was performed to compare the different flames. Detailed statistical averages of the flame speed were also obtained to study the spatial dependence of displacement speed and its correlation to strain rate and curvature.��less
Response of flame thickness and propagation speed under intense turbulence in spatially developing lean premixed methane–air jet flames
Sankaran, Ramanan; Hawkes, Evatt R.; Yoo, Chun Sang; Chen, Jacqueline H.
Direct numerical simulations of three-dimensional spatially-developing turbulent Bunsen flames were performed at three different turbulence intensities. We performed these simulations using a reduced methane–air chemical mechanism which was specifically tailored for the lean premixed conditions simulated here. A planar-jet turbulent Bunsen flame configuration was used in which turbulent preheated methane–air mixture at 0.7 equivalence ratio issued through a central jet and was surrounded by a hot laminar coflow of burned products. The turbulence characteristics at the jet inflow were selected such that combustion occured in the thin reaction zones (TRZ) regime. At the lowest turbulence intensity, the conditions fall on the boundary between the TRZ regime and the corrugated flamelet regime, and progressively moved further into the TRZ regime by increasing the turbulent intensity. The data from the three simulations was analyzed to understand the effect of turbulent stirring on the flame structure and thickness. Furthermore, statistical analysis of the data showed that the thermal preheat layer of the flame was thickened due to the action of turbulence, but the reaction zone was not significantly affected. A global and local analysis of the burning velocity of the flame was performed to compare the different flames. Detailed statistical averages of the flame speed were also obtained to study the spatial dependence of displacement speed and its correlation to strain rate and curvature.
Pilat, J.F.
The term virtual nuclear weapons proliferation and arsenals, as opposed to actual weapons and arsenals, has entered in recent years the American lexicon of nuclear strategy, arms control, and nonproliferation. While the term seems to have an intuitive appeal, largely due to its cyberspace imagery, its current use is still vague and loose. The author believes, however, that if the term is clearly delineated, it might offer a promising approach to conceptualizing certain current problems of proliferation. The first use is in a reference to an old problem that has resurfaced recently: the problem of growing availability of weapon-usable nuclear materials in civilian nuclear programs along with materials made `excess` to defense needs by current arms reduction and dismantlement. It is argued that the availability of these vast materials, either by declared nuclear-weapon states or by technologically advanced nonweapon states, makes it possible for those states to rapidly assemble and deploy nuclear weapons. The second use has quite a different set of connotations. It is derived conceptually from the imagery of computer-generated reality. In this use, one thinks of virtual proliferation and arsenals not in terms of the physical hardware required to make the bomb but rather in terms of the knowledge/experience required to design, assemble, and deploy the arsenal. Virtual weapons are a physics reality and cannot be ignored in a world where knowledge, experience, materials, and other requirements to make nuclear weapons are widespread, and where dramatic army reductions and, in some cases, disarmament are realities. These concepts are useful in defining a continuum of virtual capabilities, ranging from those at the low end that derive from general technology diffusion and the existence of nuclear energy programs to those at the high end that involve conscious decisions to develop or maintain militarily significant nuclear-weapon capabilities.
High efficiency virtual impactor
Loo, Billy W.
Environmental monitoring of atmospheric air is facilitated by a single stage virtual impactor (11) for separating an inlet flow (Q.sub.O) having particulate contaminants into a coarse particle flow (Q.sub.1) and a fine particle flow (Q.sub.2) to enable collection of such particles on different filters (19a, 19b) for separate analysis. An inlet particle acceleration nozzle (28) and coarse particle collection probe member (37) having a virtual impaction opening (41) are aligned along a single axis (13) and spaced apart to define a flow separation region (14) at which the fine particle flow (Q.sub.2) is drawn radially outward into a chamber (21) while the coarse particle flow (Q.sub.1) enters the virtual impaction opening (41). Symmetrical outlet means (47) for the chamber (21) provide flow symmetry at the separation region (14) to assure precise separation of particles about a cutpoint size and to minimize losses by wall impaction and gravitational settling. Impulse defocusing means (42) in the probe member (37) provides uniform coarse particle deposition on the filter (19a) to aid analysis. Particle losses of less than 1% for particles in the 0 to 20 micron range may be realized.
Simple Analysis of Flame Dynamics via Flexible Convected Disturbance...
Office of Scientific and Technical Information (OSTI)
Journal Article: Simple Analysis of Flame Dynamics via Flexible Convected Disturbance ... OSTI Identifier: 1160232 Report Number(s): A-NETL-PUB-020 Journal ID: ISSN 0748-4658 ...
Probing flame chemistry with MBMS, theory, and modeling
Westmoreland, P.R.
The objective is to establish kinetics of combustion and molecular-weight growth in C{sub 3} hydrocarbon flames as part of an ongoing study of flame chemistry. Specific reactions being studied are (1) the growth reactions of C{sub 3}H{sub 5} and C{sub 3}H{sub 3} with themselves and with unsaturated hydrocarbons and (2) the oxidation reactions of O and OH with C{sub 3}`s. This approach combines molecular-beam mass spectrometry (MBMS) experiments on low-pressure flat flames; theoretical predictions of rate constants by thermochemical kinetics, Bimolecular Quantum-RRK, RRKM, and master-equation theory; and whole-flame modeling using full mechanisms of elementary reactions.
10b- Bifurcations in swirling flames.key
U.S. Department of Energy (DOE) all webpages (Extended Search)
in combustors With contributions by M. Falese, S. Hermeth, G. Staffelbach, L. Gicquel Computers & Fluids 89 (2014) 167-178 Comb. & Flame. 2014, 161, 184-196. Copyright Dr T....
A comparative experimental and computational study of methanol, ethanol, and n-butanol flames
Veloo, Peter S.; Wang, Yang L.; Egolfopoulos, Fokion N.; Westbrook, Charles K.
Laminar flame speeds and extinction strain rates of premixed methanol, ethanol, and n-butanol flames were determined experimentally in the counterflow configuration at atmospheric pressure and elevated unburned mixture temperatures. Additional measurements were conducted also to determine the laminar flame speeds of their n-alkane/air counterparts, namely methane, ethane, and n-butane in order to compare the effect of alkane and alcohol molecular structures on high-temperature flame kinetics. For both propagation and extinction experiments the flow velocities were determined using the digital particle image velocimetry method. Laminar flame speeds were derived through a non-linear extrapolation approach based on direct numerical simulations of the experiments. Two recently developed detailed kinetics models of n-butanol oxidation were used to simulate the experiments. The experimental results revealed that laminar flame speeds of ethanol/air and n-butanol/air flames are similar to those of their n-alkane/air counterparts, and that methane/air flames have consistently lower laminar flame speeds than methanol/air flames. The laminar flame speeds of methanol/air flames are considerably higher compared to both ethanol/air and n-butanol/air flames under fuel-rich conditions. Numerical simulations of n-butanol/air freely propagating flames, revealed discrepancies between the two kinetic models regarding the consumption pathways of n-butanol and its intermediates. (author)
Virtual Sensing | Department of Energy
Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)
Virtual Sensing Virtual Sensing Lead Performer: Lawrence Berkeley National Laboratory (LBNL) - Berkeley, CA Partners: -- Pacific Northwest National Laboratory (PNNL) - Richland, WA -- Oak Ridge National Laboratory (ORNL) - Oak Ridge, TN FY16 DOE Funding: $225,000 Project Term: Current - September 30, 2016 Funding Type: Direct Lab Funding PROJECT OBJECTIVE Virtual or inferential sensing can provide a lower-cost and less-invasive approach to monitor building performance and operation compared to
A study of partially premixed unconfined propane flames
Roekke, N.A.; Hustad, J.E.; Soenju, O.K. )
Unconfined turbulent partially premixed propane/air flames issuing from a straight tube into quiescent air at atmospheric pressure and temperature are investigated. Experiments on lifted flames are performed. Flame height and liftoff are reported together with emission indices for oxides of nitrogen (NO[sub 3]). The degree of partially premixing has been varied between a fuel mass fraction of 1.0 to 0.15. Six different nozzle diameters, d[sub 0], of 3.2, 6, 10, 20.5, 23.3, and 29.5 mm have been used. This resulted in outlet velocities, u[sub 0], varying from 1 to 130 m/s, flame heights up to 2.5 m, Froude numbers, Fr, from 3 to 3 [times] 10[sup 5], and thermal heat releases up to 350 kW. Flame height and liftoff show a strong dependence upon the ratio of the nozzle outlet velocity to the outlet diameter, the Froude number, and the fuel mass fraction Y[sub f]. Both modified, simplified, and newly developed expressions for height, liftoff and NO[sub x] emissions are presented and discussed. All the proposed expressions scale with Y[sub f][sup a]Fr[sup b] or Y[sub r][sup a]f(u[sub 0], d[sub 0]). The emission index for NO[sub x] scales very well with a previously developed expression based on the buoyant flame volume. The agreement between predictions and experimental data is generally good and well within the underlying experimental and theoretical uncertainties. The results from this study contain new data, as very little focus has previously been directed toward lifted partially premixed free flames of this size.
Nonlinear effects of stretch on the flame front propagation
Halter, F.; Tahtouh, T.; Mounaim-Rousselle, C. [Institut PRISME, Universite d'Orleans, 8 rue Leonard de Vinci, 45072 Orleans Cedex 2 (France)
In all experimental configurations, the flames are affected by stretch (curvature and/or strain rate). To obtain the unstretched flame speed, independent of the experimental configuration, the measured flame speed needs to be corrected. Usually, a linear relationship linking the flame speed to stretch is used. However, this linear relation is the result of several assumptions, which may be incorrected. The present study aims at evaluating the error in the laminar burning speed evaluation induced by using the traditional linear methodology. Experiments were performed in a closed vessel at atmospheric pressure for two different mixtures: methane/air and iso-octane/air. The initial temperatures were respectively 300 K and 400 K for methane and iso-octane. Both methodologies (linear and nonlinear) are applied and results in terms of laminar speed and burned gas Markstein length are compared. Methane and iso-octane were chosen because they present opposite evolutions in their Markstein length when the equivalence ratio is increased. The error induced by the linear methodology is evaluated, taking the nonlinear methodology as the reference. It is observed that the use of the linear methodology starts to induce substantial errors after an equivalence ratio of 1.1 for methane/air mixtures and before an equivalence ratio of 1 for iso-octane/air mixtures. One solution to increase the accuracy of the linear methodology for these critical cases consists in reducing the number of points used in the linear methodology by increasing the initial flame radius used. (author)
Measurement of the soot concentration and soot particle sizes in propane oxygen flames
Bockhorn, H.; Fetting, F.; Meyer, U.; Reck, R.; Wannemacher, G.
Soot concentrations and particle sizes were measured by light scattering and probe measurements in the burnt gas region of atmospheric pressure propane-oxygen flames and propane-oxygen flames to which hydrogen or ammonia were added. The results show that the soot concentrations in propane-oxygen flames, to which hydrogen is added are lower compared to propane-oxygen flames. The decrease of soot concentration is much stronger when ammonia is added. Associated with the reduction of soot concentration is a reduction of mean particle size of the soot particles and a lower breadth of the particle size distributions. Electron micrographs of soot particles from the probe measurements showed that soot particles from flames with high soot concentrations (propane oxygen flames) are aggregates with chain or cluster structure while the structure of the particles from flames with lower soot concentration (propane oxygen flames with hydrogen or ammonia added) is more compact. 24 refs.
Ultrafast Laser Facility - Virtual Tour | Photosynthetic Antenna...
U.S. Department of Energy (DOE) all webpages (Extended Search)
Ultrafast Laser Facility - Virtual Tour December 10, 2015 Ultrafast Laser Facility - Virtual Tour A look at the technology and science in the Ultrafast lab PARC Research Scientist ...
Dual-pump CARS temperature and major species concentration measurements in counter-flow methane flames using narrowband pump and broadband Stokes lasers
Thariyan, Mathew P.; Ananthanarayanan, Vijaykumar; Bhuiyan, Aizaz H.; Naik, Sameer V.; Gore, Jay P.; Lucht, Robert P.
Dual-pump coherent anti-Stokes Raman scattering (CARS) is used to measure temperature and species profiles in representative non-premixed and partially-premixed CH{sub 4}/O{sub 2}/N{sub 2} flames. A new laser system has been developed to generate a tunable single-frequency beam for the second pump beam in the dual-pump N{sub 2}-CO{sub 2} CARS process. The second harmonic output ({proportional_to}532 nm) from an injection-seeded Nd:YAG laser is used as one of the narrowband pump beams. The second single-longitudinal-mode pump beam centered near 561 nm is generated using an injection-seeded optical parametric oscillator, consisting of two non-linear {beta}-BBO crystals, pumped using the third harmonic output ({proportional_to}355 nm) of the same Nd:YAG laser. A broadband dye laser (BBDL), pumped using the second harmonic output of an unseeded Nd:YAG laser, is employed to produce the Stokes beam centered near 607 nm with full-width-at-half-maximum of {proportional_to}250 cm{sup -1}. The three beams are focused between two opposing nozzles of a counter-flow burner facility to measure temperature and major species concentrations in a variety of CH{sub 4}/O{sub 2}/N{sub 2} non-premixed and partially-premixed flames stabilized at a global strain rate of 20 s{sup -1} at atmospheric-pressure. For the non-premixed flames, excellent agreement is observed between the measured profiles of temperature and CO{sub 2}/N{sub 2} concentration ratios with those calculated using an opposed-flow flame code with detailed chemistry and molecular transport submodels. For partially-premixed flames, with the rich side premixing level beyond the stable premixed flame limit, the calculations overestimate the distance between the premixed and the non-premixed flamefronts. Consequently, the calculated temperatures near the rich, premixed flame are higher than those measured. Accurate prediction of the distance between the premixed and the non-premixed flames provides an interesting challenge for
Study of fuel-nitrogen reactions in rich, premixed flames
Roby, R.J.
The formation and removal of nitrogen-containing species involved in fuel-nitrogen reactions have been studied in atmospheric-pressure fuel-rich hydrogen/oxygen/argon flames. The fuel-nitrogen reaction mechanism was investigated by addition of ammonia, nitric oxide, or hydrogen cyanide alone or with various hydrocarbons to a base flame. Profiles of stable nitrogen species and hydroxyl radical were measured in the post-flame gases. Results show that an initial rapid decay of nitric oxide added to a hydrogen/oxygen/argon flame to approximately 60% of its initial value occurs within 1.0 mm of the burner surface (0.5 msec). The primary reaction for removal of nitric oxide was found to be H + NO + M = HNO + M. The reaction of nitric oxide with various hydrocarbons to form hydrogen cyanide was found to be first order in both the initial hydrocarbon concentration and the initial nitric oxide concentration. A kinetic model was developed that only partially predicts the results obtained. Analysis showed that, by varying the heat of formation of imidogen within the limits of its uncertainty, agreement between the calculations and the data could be improved for nitric oxide and nitrogen. However, the amine, nitrous oxide and hydrogen cyanide profiles were found not to be significantly affected. The significant discrepancy between the measured and calculated ammonia profiles is discussed in terms of the model predictions of both the ammonia formation and decay rates. The reaction: NM + H = N + H/sub 2/ is identified as a key rate-controlling step for removal of amine species in these flames. Evidence from the data and theoretical calculations suggests that the rate of this reaction at the current flame conditions may be as much as a factor of ten slower than the previously reported value.
Phenomena in oscillating downward propagating flames induced by external laser irradiation method
Park, June Sung; Fujita, Osamu; Honko, Teruaki; Yamada, Yuichiro; Ito, Hiroyuki; Nakamura, Yuji [Division of Mechanical and Space Engineering, Hokkaido University, Kita13 Nishi8, Kita-ku, Sapporo, Hokkaido (Japan)
Experiments in C{sub 2}H{sub 4}/CO{sub 2}-O{sub 2} premixed flames (Le < 1) propagating downwardly in a tube have been conducted to observe transition phenomena from laminar flame front to turbulent flame propagation triggered by external laser irradiation method. To investigate the exact motions of flame tip fluctuation at the initial moment of irradiating CO{sub 2} laser, the completely flat flame front is selected as a default flame, which is corresponding to the primary acoustic instability as reported by Searby (1992). According to the time-resolved observation, the flame front exposed to CO{sub 2} laser beam shows extremely unstable flame motions in which highly curved flame front towards unburned mixture is subject to diffusive-thermal instability. Then, the sudden enhanced burning state (increased flame surface) caused by flame instability induces the secondary acoustic instability which is akin to the observation in Ref. In the present study, we report the detailed descriptions of flame fronts on the transient behaviors leading the primary acoustic instability to turbulent motions actively induced by the absorption of externally irradiated CO{sub 2} laser beam. (author)
Ahsan R. Choudhuri
Lean flame extinction limits of binary fuel mixtures of methane (CH{sub 4}), propane (C{sub 3}H{sub 8}), and ethane (C{sub 2}H{sub 6}) were measured using a twin-flame counter-flow burner. Experiments were conducted to generate an extinction equivalence ratio vs. global stretch rate plot and an extrapolation method was used to calculate the equivalence ratio corresponding to an experimentally unattainable zero-stretch condition. The foregoing gases were selected because they are the primary constitutes of natural gas, which is the primary focus of the present study. To validate the experimental setup and methodology, the flame extinction limit of pure fuels at zero stretch conditions were also estimated and compared with published values. The lean flame extinction limits of methane (f{sub ext} = 4.6%) and propane (f{sub ext} = 2.25%) flames measured in the present study agreed with the values reported in the literature. It was observed that the flame extinction limit of fuel blends have a polynomial relation with the concentration of component fuels in the mixture. This behavior contradicts with the commonly used linear Le Chatelier's approximation. The experimentally determined polynomial relations between the flame extinction limits of fuel blends (i.e. methane-propane and methane-ethane) and methane concentration are as follows: (1) Methane-Propane--%f{sub ext} = (1.05 x 10{sup -9}) f{sup 5}-(1.3644 x 10{sup -7}) f{sup 4}+(6.40299 x 10{sup -6}) f{sup 3}-(1.2108459 x 10{sup -4}) f{sup 2}+(2.87305329 x 10{sup -3}) f+2.2483; (2) Methane-Ethane--%f{sub ext} = (2.1 x 10{sup -9})f{sup 5}-(3.5752 x 10{sup -7}) f{sup 4}+(2.095425 x 10{sup -5}) f{sup 3}-(5.037353 x 10{sup -4}) f{sup 2} + 6.08980409 f + 2.8923. Where f{sub ext} is the extinction limits of methane-propane and methane-ethane fuel blends, and f is the concentration (% volume) of methane in the fuel mixture. The relations were obtained by fitting fifth order curve (polynomial regression) to experimentally
Comparison of direct numerical simulation of lean premixed methane-air flames with strained laminar flame calculations.
Chen, Jacqueline H.; Hawkes, Evatt R.
Direct numerical simulation (DNS) with complex chemistry was used to study statistics of displacement and consumption speeds in turbulent lean premixed methane-air flames. The main focus of the study is an evaluation of the extent to which a turbulent flame in the thin reaction zones regime can be described by an ensemble of strained laminar flames. Conditional averages with respect to strain for displacement and consumption speeds are presented over a wide range of strain typically encountered in a turbulent flame, compared with previous studies that either made local pointwise comparisons or conditioned the data on small strain and curvature. The conditional averages for positive strains are compared with calculated data from two different canonical strained laminar configurations to determine which is the optimal representation of a laminar flame structure embedded in a turbulent flame: the reactant-to-product (R-to-P) configuration or the symmetric twin flame configuration. Displacement speed statistics are compared for the progress-variable isosurface of maximum reaction rate and an isosurface toward the fresh gases, which are relevant for both modeling and interpretation of experiment results. Displacement speeds in the inner reaction layer are found to agree very well with the laminar R-to-P calculations over a wide range of strain for higher Damkhler number conditions, well beyond the regime in which agreement was expected. For lower Damkhler numbers, a reduced response to strain is observed, consistent with previous studies and theoretical expectations. Compared with the inner layer, broader and shifted probability density functions (PDFs) of displacement speed were observed in the fresh gases, and the agreement with the R-to-P calculations deteriorated. Consumption speeds show a poorer agreement with strained laminar calculations, which is attributed to multidimensional effects and a more attenuated unsteady response to strain fluctuations; however, they
The Virtual Robotics Laboratory
Kress, R.L.; Love, L.J.
The growth of the Internet has provided a unique opportunity to expand research collaborations between industry, universities, and the national laboratories. The Virtual Robotics Laboratory (VRL) is an innovative program at Oak Ridge National Laboratory (ORNL) that is focusing on the issues related to collaborative research through controlled access of laboratory equipment using the World Wide Web. The VRL will provide different levels of access to selected ORNL laboratory secondary education programs. In the past, the ORNL Robotics and Process Systems Division has developed state-of-the-art robotic systems for the Army, NASA, Department of Energy, Department of Defense, as well as many other clients. After proof of concept, many of these systems sit dormant in the laboratories. This is not out of completion of all possible research topics. but from completion of contracts and generation of new programs. In the past, a number of visiting professors have used this equipment for their own research. However, this requires that the professor, and possibly his/her students, spend extended periods at the laboratory facility. In addition, only a very exclusive group of faculty can gain access to the laboratory and hardware. The VRL is a tool that enables extended collaborative efforts without regard to geographic limitations.
The Virtual Robotics Laboratory
Kress, R.L.; Love, L.J.
The growth of the Internet has provided a unique opportunity to expand research collaborations between industry, universities, and the national laboratories. The Virtual Robotics Laboratory (VRL) is an innovative program at Oak Ridge National Laboratory (ORNL) that is focusing on the issues related to collaborative research through controlled access of laboratory equipment using the World Wide Web. The VRL will provide different levels of access to selected ORNL laboratory equipment to outside universities, industrial researchers, and elementary and secondary education programs. In the past, the ORNL Robotics and Process Systems Division (RPSD) has developed state-of-the-art robotic systems for the Army, NASA, Department of Energy, Department of Defense, as well as many other clients. After proof of concept, many of these systems sit dormant in the laboratories. This is not out of completion of all possible research topics, but from completion of contracts and generation of new programs. In the past, a number of visiting professors have used this equipment for their own research. However, this requires that the professor, and possibly his students, spend extended periods at the laboratory facility. In addition, only a very exclusive group of faculty can gain access to the laboratory and hardware. The VRL is a tool that enables extended collaborative efforts without regard to geographic limitations.
Virtual environment tactile system
Renzi, R.
A method for providing a realistic sense of touch in virtual reality by means of programmable actuator assemblies is disclosed. Each tactile actuator assembly consists of a number of individual actuators whose movement is controlled by a computer and associated drive electronics. When an actuator is energized, the rare earth magnet and the associated contactor, incorporated within the actuator, are set in motion by the opposing electromagnetic field of a surrounding coil. The magnet pushes the contactor forward to contact the skin resulting in the sensation of touch. When the electromagnetic field is turned off, the rare earth magnet and the contactor return to their neutral positions due to the magnetic equilibrium caused by the interaction with the ferrous outer sleeve. The small size and flexible nature of the actuator assemblies permit incorporation into a glove, boot or body suit. The actuator has additional applications, such as, for example, as an accelerometer, an actuator for precisely controlled actuations or to simulate the sensation of braille letters. 28 figs.
Virtual environment tactile system
Renzi, Ronald
A method for providing a realistic sense of touch in virtual reality by means of programmable actuator assemblies is disclosed. Each tactile actuator assembly consists of a number of individual actuators whose movement is controlled by a computer and associated drive electronics. When an actuator is energized, the rare earth magnet and the associated contactor, incorporated within the actuator, are set in motion by the opposing electromagnetic field of a surrounding coil. The magnet pushes the contactor forward to contact the skin resulting in the sensation of touch. When the electromagnetic field is turned off, the rare earth magnet and the contactor return to their neutral positions due to the magnetic equilibrium caused by the interaction with the ferrous outer sleeve. The small size and flexible nature of the actuator assemblies permit incorporation into a glove, boot or body suit. The actuator has additional applications, such as, for example, as an accelerometer, an actuator for precisely controlled actuations or to simulate the sensation of braille letters.
Meet the Intelligence Community Online at the IC Virtual Career Fair on Thursday, March 3, 2016 from 2pm to 8pm.�� To register, please go to www.ICVirtualFair.com.
Virtual gap dielectric wall accelerator
Caporaso, George James; Chen, Yu-Jiuan; Nelson, Scott; Sullivan, Jim; Hawkins, Steven A
A virtual, moving accelerating gap is formed along an insulating tube in a dielectric wall accelerator (DWA) by locally controlling the conductivity of the tube. Localized voltage concentration is thus achieved by sequential activation of a variable resistive tube or stalk down the axis of an inductive voltage adder, producing a "virtual" traveling wave along the tube. The tube conductivity can be controlled at a desired location, which can be moved at a desired rate, by light illumination, or by photoconductive switches, or by other means. As a result, an impressed voltage along the tube appears predominantly over a local region, the virtual gap. By making the length of the tube large in comparison to the virtual gap length, the effective gain of the accelerator can be made very large.
Virtual Tours | National Nuclear Security Administration | (NNSA)
National Nuclear Security Administration (NNSA)
Virtual Tours Nuclear Weapons Mission at Sandia Sandia Labs: Who we are Related Topics apm
Virtual interconnection platform initiative scoping study
Liu, Yong; Kou, Gefei; Pan, Zuohong; Liu, Yilu; King Jr., Thomas J.
Due to security and liability concerns, the research community has limited access to realistic large-scale power grid models to test and validate new operation and control methodologies. It is also difficult for industry to evaluate the relative value of competing new tools without a common platform for comparison. This report proposes to develop a large-scale virtual power grid model that retains basic features and represents future trends of major U.S. electric interconnections. This model will include realistic power flow and dynamics information as well as a relevant geospatial distribution of assets. This model will be made widely available to the research community for various power system stability and control studies and can be used as a common platform for comparing the efficacies of various new technologies.
On flame kernel formation and propagation in premixed gases
Eisazadeh-Far, Kian; Metghalchi, Hameed [Northeastern University, Mechanical and Industrial Engineering Department, Boston, MA 02115 (United States); Parsinejad, Farzan [Chevron Oronite Company LLC, Richmond, CA 94801 (United States); Keck, James C. [Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)
Flame kernel formation and propagation in premixed gases have been studied experimentally and theoretically. The experiments have been carried out at constant pressure and temperature in a constant volume vessel located in a high speed shadowgraph system. The formation and propagation of the hot plasma kernel has been simulated for inert gas mixtures using a thermodynamic model. The effects of various parameters including the discharge energy, radiation losses, initial temperature and initial volume of the plasma have been studied in detail. The experiments have been extended to flame kernel formation and propagation of methane/air mixtures. The effect of energy terms including spark energy, chemical energy and energy losses on flame kernel formation and propagation have been investigated. The inputs for this model are the initial conditions of the mixture and experimental data for flame radii. It is concluded that these are the most important parameters effecting plasma kernel growth. The results of laminar burning speeds have been compared with previously published results and are in good agreement. (author)
Flame Synthesis of Carbon Nanotubes Using Low Calorific Value Gases
Jorge Camacho; Mahesh Subramanya; Ahsan R. Choudhuri
Nanostructures formed in diffusion flames of pure fuels [CH{sub 4}, C{sub 3}H{sub 8}, and C{sub 2}H{sub 2}] at different fuel flow rates have been analyzed. Synthesis samples have been also collected from diffusion flames of various fuel blends [H{sub 2}-CH{sub 4}, H{sub 2}-CO, H{sub 2}-C{sub 3}H{sub 8}, H{sub 2}-C{sub 2}H{sub 2}] at different combustion conditions. SEM images of particulate samples collected from H{sub 2}-CH{sub 4} diffusion flames show formation of nanostructures. However, the formation of nanostructures only occurs at a narrow window of fuel compositions (< 10% H{sub 2} concentration in the mixture) and flow conditions (Jet Exit Reynolds number Re{sub j} = 200). At higher H{sub 2} concentration and flow velocity, formation of nanostructures diminishes and H{sub 2}-CH{sub 4} flames produce amorphous carbon and soot particles.
Real Time Flame Monitoring of Gasifier and Injectors
Zelepouga, Serguei; Saveliev, Alexei
This project is a multistage effort with the final goal to develop a practical and reliable nonintrusive gasifier injector monitor to assess burner wear and need for replacement. The project team included the National Energy Technology Laboratory (NETL), Gas Technology Institute (GTI), North Carolina State University, and ConocoPhillips. This report presents the results of the sensor development and testing initially at GTI combustion laboratory with natural gas flames, then at the Canada Energy Technology Center (CANMET), Canada in the atmospheric coal combustor as well as in the pilot scale pressurized entrained flow gasifier, and finally the sensor capabilities were demonstrated at the Pratt and Whitney Rocketdyne (PWR) Gasifier and the Wabash River Repowering plant located in West Terre Haute, IN. The initial tests demonstrated that GTI gasifier sensor technology was capable of detecting shape and rich/lean properties of natural gas air/oxygen enriched air flames. The following testing at the Vertical Combustor Research Facility (VCRF) was a logical transition step from the atmospheric natural gas flames to pressurized coal gasification environment. The results of testing with atmospheric coal flames showed that light emitted by excited OH* and CH* radicals in coal/air flames can be detected and quantified. The maximum emission intensities of OH*, CH*, and black body (char combustion) occur at different axial positions along the flame length. Therefore, the excitation rates of CH* and OH* are distinct at different stages of coal combustion and can be utilized to identify and characterize processes which occur during coal combustion such as devolatilization, char heating and burning. To accomplish the goals set for Tasks 4 and 5, GTI utilized the CANMET Pressurized Entrained Flow Gasifier (PEFG). The testing parameters of the PEFG were selected to simulate optimum gasifier operation as well as gasifier conditions normally resulting from improper operation or
Laser-induced breakdown spectroscopy measurement in methane and biodiesel flames using an ungated detector
Eseller, Kemal E.; Yueh, Fang Y.; Singh, Jagdish P
Laser-induced breakdown spectroscopy (LIBS) has been applied to measure the equivalence ratio of CH4/air flames using gated detection. In this work, we have developed an ungated, miniature LIBS-based sensor for studying CH4/air and biodiesel flames. We have used this sensor to characterize the biodiesel flame. LIBS spectra of biodiesel flames were recorded with different ethanol concentrations in the biodiesel and also at different axial locations within the flame. The sensor performance was evaluated with a CH4/air flame. LIBS signals of N, O, and H from a CH4/air flame were used to determine the equivalence ratio. A linear relationship between the intensity ratio of H and O lines and the calculated equivalence ratio were obtained with this sensor.
Mingenbach, William A.
A device is provided for stabilizing a flexible membrane secured within a frame, wherein a plurality of elongated arms are disposed radially from a central hub which penetrates the membrane, said arms imposing alternately against opposite sides of the membrane, thus warping and tensioning the membrane into a condition of improved stability. The membrane may be an opaque or translucent sheet or other material.
Energy Science and Technology Software Center (OSTI)
Virtual Flow Simulator (VFS) is a state-of-the-art computational fluid mechanics (CFD) package that is capable of simulating multi-physics/multi-phase flows with the most advanced turbulence models (RANS, LES) over complex terrains. The flow solver is based on the Curvilinear Immersed Boundary (CURVIB) method to handle geometrically complex and moving domains. Different modules of the VFS package can provide different simulation capabilities for specific applications ranging from the fluid-structure interaction (FSI) of solid and deformable bodies, themore » two-phase free surface flow solver based on the level set method for ocean waves, sediment transport models in rivers and the large-scale models of wind farms based on actuator lines and surfaces. All numerical features of VFS package have been validated with known analytical and experimental data as reported in the related journal articles. VFS package is suitable for a broad range of engineering applications within different industries. VFS has been used in different projects with applications in wind and hydrokinetic energy, offshore and near-shore ocean studies, cardiovascular and biological flows, and natural streams and river morphodynamics. Over the last decade, the development of VFS has been supported and assisted with the help of various United States companies and federal agencies that are listed in the sponsor lists. In this version, VFS-Wind contains all the necessary modeling tools for wind energy applications, including land-based and offshore wind farms. VFS is highly scalable to run on either desktop computers or high performance clusters (up to 16,000 CPUs). This released version comes with a detailed user's manual and a set of case studies designed to facilitate the learning of the various aspects of the code in a comprehensive manner. The included documentation and support material has been elaborated in a collaboration effort with Sandia National Labs under the contract DE-EE0005482
Partially-Premixed Flames in Internal Combustion Engines
Robert W. Pitz; Michael C. Drake; Todd D. Fansler; Volker Sick
This was a joint university-industry research program funded by the Partnerships for the Academic-Industrial Research Program (PAIR). The research examined partially premixed flames in laboratory and internal combustion engine environments at Vanderbilt University, University of Michigan, and General Motors Research and Development. At Vanderbilt University, stretched and curved ''tubular'' premixed flames were measured in a unique optically accessible burner with laser-induced spontaneous Raman scattering. Comparisons of optically measured temperature and species concentration profiles to detailed transport, complex chemistry simulations showed good correspondence at low-stretch conditions in the tubular flame. However, there were significant discrepancies at high-stretch conditions near flame extinction. The tubular flame predictions were found to be very sensitive to the specific hydrogen-air chemical kinetic mechanism and four different mechanisms were compared. In addition, the thermo-diffusive properties of the deficient reactant, H2, strongly affected the tubular flame structure. The poor prediction near extinction is most likely due to deficiencies in the chemical kinetic mechanisms near extinction. At the University of Michigan, an optical direct-injected engine was built up for laser-induced fluorescence imaging experiments on mixing and combustion under stratified charge combustion conditions with the assistance of General Motors. Laser attenuation effects were characterized both experimentally and numerically to improve laser imaging during the initial phase of the gasoline-air mixture development. Toluene was added to the isooctane fuel to image the fuel-air equivalence ratio in an optically accessible direct-injected gasoline engine. Temperature effects on the toluene imaging of fuel-air equivalence ratio were characterized. For the first time, oxygen imaging was accomplished in an internal combustion engine by combination of two fluorescence trackers
Virtual Oxygen Sensor for Innovative NOx and PM Emission Control...
Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)
Virtual Oxygen Sensor for Innovative NOx and PM Emission Control Technologies Virtual Oxygen Sensor for Innovative NOx and PM Emission Control Technologies A virtual O2 sensor for ...
Mingenbach, W.A.
A device is provided for stabilizing a flexible membrane secured within a frame, wherein a plurality of elongated arms are disposed radially from a central hub which penetrates the membrane, said arms imposing alternately against opposite sides of the membrane, thus warping and tensioning the membrane into a condition of improved stability. The membrane may be an opaque or translucent sheet or other material. 10 figs.
Combustion measurements of an array of radial jet reattachment flames
Wu, J.; Seyed-Yagoobi, J.
Radial Jet Reattachment Combustion (RJRC) nozzle provides improved fuel/air mixing for use in impingement flame heating. The RJRC nozzle produces a very stable flame with a circumferentially symmetric surface temperature profile and low coefficients of pressure on the impingement surface. The RJRC also produces very little soot. To characterize the performance of an array of RJRC nozzles from combustion point of view, exhaust gas analyses are presented through CO, CO{sub 2}, O{sub 2}, and NO{sub x} measurements. The results are also compared to the single RJRC nozzle combustion characteristics. In the array configuration, the highly, moderately, and weakly interactive RJRC nozzles are considered. The interaction among nozzles is highly dependent upon the between-nozzle spacing.
Using powerful computers, physicists uncover mechanism that stabilizes
U.S. Department of Energy (DOE) all webpages (Extended Search)
plasma within tokamaks | Princeton Plasma Physics Lab Using powerful computers, physicists uncover mechanism that stabilizes plasma within tokamaks By Raphael Rosen November 17, 2015 Tweet Widget Google Plus One Share on Facebook A cross-section of the virtual plasma showing where the magnetic field lines intersect the plane. The central section has field lines that rotate exactly once. (Photo by Stephen Jardin) A cross-section of the virtual plasma showing where the magnetic field lines
Using powerful computers, physicists uncover mechanism that stabilizes
U.S. Department of Energy (DOE) all webpages (Extended Search)
plasma within tokamaks | Princeton Plasma Physics Lab Using powerful computers, physicists uncover mechanism that stabilizes plasma within tokamaks By Raphael Rosen November 17, 2015 Tweet Widget Google Plus One Share on Facebook A cross-section of the virtual plasma showing where the magnetic field lines intersect the plane. The central section has field lines that rotate exactly once. (Photo by Stephen Jardin) A cross-section of the virtual plasma showing where the magnetic field lines
Analysis of the laminar flamelet concept for nonpremixed laminar flames
Claramunt, K.; Consul, R.; Carbonell, D.; Perez-Segarra, C.D.
The goal of this paper is to investigate the application of the laminar flamelet concept to the multidimensional numerical simulation of nonpremixed laminar flames. The performance of steady and unsteady flamelets is analyzed. The deduction of the mathematical formulation of flamelet modeling is exposed and some commonly used simplifications are examined. Different models for the scalar dissipation rate dependence on the mixture fraction variable are analyzed. Moreover, different criteria to evaluate the Lagrangian-type flamelet lifetime for unsteady flamelets are investigated. Inclusion of phenomena such as differential diffusion with constant Lewis number for each species and radiation heat transfer are also studied. A confined co-flow axisymmetric nonpremixed methane/air laminar flame experimentally investigated by McEnally and Pfefferle (Combust. Sci. Technol. 116-117 (1996) 183-209) and numerically investigated by Bennett, McEnally, Pfefferle, and Smooke (Combust. Flame 123 (2000) 522-546), Consul, Perez-Segarra, Claramunt, Cadafalch, and Oliva (Combust. Theory Modelling 7 (3) (2003) 525-544), and Claramunt, Consul, Perez-Segarra, and Oliva (Combust. Flame 137 (2004) 444-457) has been used as a test case. Results obtained using the flamelet concept have been compared to data obtained from the full resolution of the complete transport equations using primitive variables. Finite-volume techniques over staggered grids are used to discretize the governing equations. A parallel multiblock algorithm based on domain decomposition techniques running with loosely coupled computers has been used. To assess the quality of the numerical solutions presented in this paper, a verification process based on the generalized Richardson extrapolation technique and on the grid convergence index (GCI) has been applied. (author)
Numerical investigation of spontaneous flame propagation under RCCI conditions
Bhagatwala, Ankit V; Sankaran, Ramanan; Kokjohn, Sage; Chen, Jacqueline H
This paper presents results from one and two-dimensional direct numerical simulations under Reactivity Controlled Compression Ignition (RCCI) conditions of a primary reference fuel (PRF) mixture consisting of n-heptane and iso-octane. RCCI uses in-cylinder blending of two fuels with different autoignition characteristics to control combustion phasing and the rate of heat release. These simulations employ an improved model of compression heating through mass source/sink terms developed in a previous work by Bhagatwala et al. (2014), which incorporates feedback from the flow to follow a predetermined experimental pressure trace. Two-dimensional simulations explored parametric variations with respect to temperature stratification, pressure profiles andmore » n-heptane concentration. Furthermore, statistics derived from analysis of diffusion/reaction balances locally normal to the flame surface were used to elucidate combustion characteristics for the different cases. Both deflagration and spontaneous ignition fronts were observed to co-exist, however it was found that higher n-heptane concentration provided a greater degree of flame propagation, whereas lower n-heptane concentration (higher fraction of iso-octane) resulted in more spontaneous ignition fronts. A significant finding was that simulations initialized with a uniform initial temperature and a stratified n-heptane concentration field, resulted in a large fraction of combustion occurring through flame propagation. The proportion of spontaneous ignition fronts increased at higher pressures due to shorter ignition delay when other factors were held constant. For the same pressure and fuel concentration, the contribution of flame propagation to the overall combustion was found to depend on the level of thermal stratification, with higher initial temperature gradients resulting in more deflagration and lower gradients generating more ignition fronts. Statistics of ignition delay are computed to assess the Zel�
Numerical investigation of spontaneous flame propagation under RCCI conditions
Bhagatwala, Ankit V; Sankaran, Ramanan; Kokjohn, Sage; Chen, Jacqueline H
This paper presents results from one and two-dimensional direct numerical simulations under Reactivity Controlled Compression Ignition (RCCI) conditions of a primary reference fuel (PRF) mixture consisting of n-heptane and iso-octane. RCCI uses in-cylinder blending of two fuels with different autoignition characteristics to control combustion phasing and the rate of heat release. These simulations employ an improved model of compression heating through mass source/sink terms developed in a previous work by Bhagatwala et al. (2014), which incorporates feedback from the flow to follow a predetermined experimental pressure trace. Two-dimensional simulations explored parametric variations with respect to temperature stratification, pressure profiles and n-heptane concentration. Furthermore, statistics derived from analysis of diffusion/reaction balances locally normal to the flame surface were used to elucidate combustion characteristics for the different cases. Both deflagration and spontaneous ignition fronts were observed to co-exist, however it was found that higher n-heptane concentration provided a greater degree of flame propagation, whereas lower n-heptane concentration (higher fraction of iso-octane) resulted in more spontaneous ignition fronts. A significant finding was that simulations initialized with a uniform initial temperature and a stratified n-heptane concentration field, resulted in a large fraction of combustion occurring through flame propagation. The proportion of spontaneous ignition fronts increased at higher pressures due to shorter ignition delay when other factors were held constant. For the same pressure and fuel concentration, the contribution of flame propagation to the overall combustion was found to depend on the level of thermal stratification, with higher initial temperature gradients resulting in more deflagration and lower gradients generating more ignition fronts. Statistics of ignition delay are computed to assess the Zel�
Fuel control for gas turbine with continuous pilot flame
Swick, Robert M.
An improved fuel control for a gas turbine engine having a continuous pilot flame and a fuel distribution system including a pump drawing fuel from a source and supplying a line to the main fuel nozzle of the engine, the improvement being a control loop between the pump outlet and the pump inlet to bypass fuel, an electronically controlled throttle valve to restrict flow in the control loop when main nozzle demand exists and to permit substantially unrestricted flow without main nozzle demand, a minimum flow valve in the control loop downstream of the throttle valve to maintain a minimum pressure in the loop ahead of the flow valve, a branch tube from the pilot flame nozzle to the control loop between the throttle valve and the minimum flow valve, an orifice in the branch tube, and a feedback tube from the branch tube downstream of the orifice to the minimum flow valve, the minimum flow valve being operative to maintain a substantially constant pressure differential across the orifice to maintain constant fuel flow to the pilot flame nozzle.
Characterization of acoustic effects on flame structures by beam deflection technique
Bedat, B.; Kostiuk, L.W.; Cheng, R.K.
This work shows that the acoustic effects are the causes of the small amplitude flame wrinkling and movements seen in all the different gravitational conditions. The comparison between the acoustic velocity and beam deflection spectra for the two conditions studied (glass beads and fiber glass) demonstrates clearly this flame/acoustic coupling. This acoustic study shows that the burner behaves like a Helmholtz resonator. The estimated resonance frequency corresponds well to the experimental measurements. The fiber glass damps the level of the resonance frequency and the flame motion. The changes shown in normalized beam deflection spectra give further support of this damping. This work demonstrates that the acoustics has a direct influence on flame structure in the laminar case and the preliminary results in turbulent case also show a strong coupling. The nature of this flame/acoustic coupling are still not well understood. Further investigation should include determining the frequency limits and the sensitivity of the flame to acoustic perturbations.
Virtual Control Systems Environment (VCSE)
Atkins, Will
Will Atkins, a Sandia National Laboratories computer engineer discusses cybersecurity research work for process control systems. Will explains his work on the Virtual Control Systems Environment project to develop a modeling and simulation framework of the U.S. electric grid in order to study and mitigate possible cyberattacks on infrastructure.
Virtual Control Systems Environment (VCSE)
Atkins, Will
Will Atkins, a Sandia National Laboratories computer engineer discusses cybersecurity research work for process control systems. Will explains his work on the Virtual Control Systems Environment project to develop a modeling and simulation framework of the U.S. electric grid in order to study and mitigate possible cyberattacks on infrastructure.
Instructions for Using Virtual Private Network (VPN)
Virtual Private Network (VPN) provides access to network drives and is recommended for use only from a EITS provided laptop.
Unsteady behavior of locally strained diffusion flames affected by curvature and preferential diffusion
Yoshida, Kenji; Takagi, Toshimi
Experimental and numerical studies are made of transient H{sub 2}/N{sub 2}--air counterflow diffusion flames unsteadily strained by an impinging micro jet. Two-dimensional temperature measurements by laser Rayleigh scattering method and numerical computations taking into account detailed chemical kinetics are conducted paying attention to transient local extinction and reignition in relation to the unsteadiness, flame curvature and preferential diffusion effects. The results are as follows. (1) Transient local flame extinction is observed where the micro jet impinges. But, the transient flame can survive instantaneously in spite of quite high stretch rate where the steady flame cannot exist. (2) Reignition is observed after the local extinction due to the micro air jet impingement. The temperature after reignition becomes significantly higher than that of the original flame. This high temperature is induced by the concentration of H{sub 2} species due to the preferential diffusion in relation to the concave curvature. The predicted behaviors of the local transient extinction and reignition are well confirmed by the experiments. (3) The reignition is induced after the formation of combustible premixed gas mixture and the consequent flame propagation. (4) The reignition is hardly observed after the extinction by micro fuel jet impingement. This is due to the dilution of H{sub 2} species induced by the preferential diffusion in relation to the convex curvature. (5) The maximum flame temperature cannot be rationalized by the stretch rate but changes widely depending on the unsteadiness and the flame curvature in relation with preferential diffusion.
Turbulent Flame Speeds and NOx Kinetics of HHC Fuels with Contaminants and High Dilution Levels
Peterson, Eric; Krejci, Michael; Mathieu, Olivier; Vissotski, Andrew; Ravi, Sankat; Plichta, Drew; Sikes, Travis; Levacque, Anthony; Camou, Alejandro; Aul, Christopher
This final report documents the technical results of the 3-year project entitled, "Turbulent Flame Speeds and NOx Kinetics of HHC Fuels with Contaminants and High Dilution Levels," funded under the NETL of DOE. The research was conducted under six main tasks: 1) program management and planning; 2) turbulent flame speed measurements of syngas mixtures; 3) laminar flame speed measurements with diluents; 4) NOx mechanism validation experiments; 5) fundamental NOx kinetics; and 6) the effect of impurities on NOx kinetics. Experiments were performed using primary constant-volume vessels for laminar and turbulent flame speeds and shock tubes for ignition delay times and species concentrations. In addition to the existing shock- tube and flame speed facilities, a new capability in measuring turbulent flame speeds was developed under this grant. Other highlights include an improved NOx kinetics mechanism; a database on syngas blends for real fuel mixtures with and without impurities; an improved hydrogen sulfide mechanism; an improved ammonia kintics mechanism; laminar flame speed data at high pressures with water addition; and the development of an inexpensive absorption spectroscopy diagnostic for shock-tube measurements of OH time histories. The Project Results for this work can be divided into 13 major sections, which form the basis of this report. These 13 topics are divided into the five areas: 1) laminar flame speeds; 2) Nitrogen Oxide and Ammonia chemical kinetics; 3) syngas impurities chemical kinetics; 4) turbulent flame speeds; and 5) OH absorption measurements for chemical kinetics.
Cost efficiency of flame-guniting the lining of open-hearth and electric steelmaking furnaces
Voronov, M.V.; Kozenko, N.I.; Moiseenko, V.D.; Bondarenko, A.G.
The use of flame-guniting for lining repair to the open-hearth and electric steelmaking furnaces of a number of Soviet plants is reviewed. Equipment and technology for flame-guniting the lining of furnaces, which provide for both local and general repairs to the walls, roofs, and bottoms of furnaces, are discussed. Methods are given for calculating expenditures for repair work and determining the cost efficiency of flame guniting relative to the increased number of heats per lining life. Results are given from calculations of the projected cost-efficiency of using flame-guniting for furnace lining repair at the metallurgical plants of the Ukranian Ministry of Ferrous Metallurgy.
Dimpled/grooved face on a fuel injection nozzle body for flame stabilization and related method
Uhm, Jong Ho; Johnson, Thomas Edward; Kim, Kwanwoo; Zuo, Baifang
A fuel injection head for a fuel nozzle used in a gas turbine combustor includes a substantially hollow body formed with an upstream end face, a downstream end face and a peripheral wall extending therebetween. A plurality of pre-mix tubes or passages extend axially through the hollow body with inlets at the upstream end face and outlets at the downstream end face. An exterior surface of the downstream end face is formed with three-dimensional surface features that increase a total surface area of the exterior surface as compared to a substantially flat, planar downstream end face.
Experimental investigation into the effect of reformer gas addition on flame speed and flame front propagation in premixed, homogeneous charge gasoline engines
Conte, Enrico; Boulouchos, Konstantinos
The effect of reformer gas addition to gasoline in internal combustion engines is assessed based on in-cylinder measurement techniques. These include ion sensors, an optical spark plug and heat release analysis from the cylinder pressure. A detailed analysis of these measurements is presented, giving insight into the combustion process and into the energy release. The flame front shape and propagation in the combustion chamber are reconstructed and the flame speed is estimated. The laminar flame speed has been observed to increase linearly with the energy fraction of reformer gas in the fuel blend. From pure gasoline to pure reformer gas the laminar flame speed increases by a factor of 4.4. The relative increase in the turbulent flame speed is lower. These results confirm what can be observed from the heat release analysis, that reformer gas addition mainly shortens the first phase of the combustion process. Different reformer gas compositions were tested, varying the ratio of hydrogen to inert species. Finally, flame propagation and flame speed at EGR-burn limit and at lean-burn limit are investigated. (author)
Effects of fuel type and equivalence ratios on the flickering of triple flames
Sahu, K.B.; Kundu, A.; Ganguly, R.; Datta, A.
An experimental study has been conducted in axisymmetric, co-flowing triple flames with different equivalence ratios of the inner and outer reactant streams (2<{phi}{sub in}<3 and 0{<=}{phi}{sub out}<0.7). Different fuel combinations, like propane/propane, propane/methane or methane/methane in the inner and outer streams respectively, have been used in the experiments. The structures of the triple flames have been compared for the different fuel combinations and equivalence ratios. The conditions under which triple flames exhibit oscillation have been identified. During the oscillation, the non-premixed flame and the outer lean premixed flame flicker strongly, while the inner rich premixed flame remains more or less stable. The flickering frequency has been evaluated through image processing and fast Fourier transform (FFT) of the average pixel intensity of the image frames. It is observed that, for all the fuel combinations, the frequency decreases with the increase in the outer equivalence ratio, while it is relatively invariant with the change in the inner equivalence ratio. However, an increase in the inner equivalence ratio affects the structure of the flame by increasing the heights of the inner premixed flame and non-premixed flame and also enlarges the yellow soot-laden zone at the tip of the inner flame. A scaling analysis of the oscillating flames has been performed based on the measured parameters, which show a variation of Strouhal number (St) with Richardson number (Ri) as St {proportional_to} Ri{sup 0.5}. The fuel type is found to have no influence on this correlation. (author)
Detailed characterization of the dynamics of thermoacoustic pulsations in a lean premixed swirl flame
Meier, W.; Weigand, P.; Duan, X.R.; Giezendanner-Thoben, R.
A nozzle configuration for technically premixed gas turbine flames was operated with CH{sub 4} and air at atmospheric pressure. The flames were confined by a combustion chamber with large quartz windows, allowing the application of optical and laser diagnostics. In a distinct range of operating conditions the flames exhibited strong self-excited thermoacoustic pulsations at a frequency around 290 Hz. A flame with P=25kW thermal power and an equivalence ratio of {phi}=0.7 was chosen as a target flame in order to analyze the dynamics and the feedback mechanism of the periodic instability in detail. The velocity field was measured by three-component laser Doppler velocimetry, the flame structures were measured by chemiluminescence imaging and planar laser-induced fluorescence of OH, and the joint probability density functions of major species concentrations, mixture fraction, and temperature were measured by laser Raman scattering. All measuring techniques were applied in a phase-locked mode with respect to the phase angle of the periodic pulsation. In addition to the pulsating flame, a nonpulsating flame with increased fuel flow rate (P=30kW, {phi}=0.83) was studied for comparison. The measurements revealed significant differences between the structures of the pulsating and the nonpulsating (or ''quiet'') flame. Effects of finite-rate chemistry and unmixedness were observed in both flames but were more pronounced in the pulsating flame. The phase-locked measurements revealed large variations of all measured quantities during an oscillation cycle. This yielded a clear picture of the sequence of events and allowed the feedback mechanism of the instability to be identified and described quantitatively. The data set presents a very good basis for the verification of numerical combustion simulations because the boundary conditions of the experiment were well-defined and the most important quantities were measured with a high accuracy. (author)
A lean methane premixed laminar flame doped with components of diesel fuel part III: Indane and comparison between n-butylbenzene, n-propylcyclohexane and indane
Pousse, E.; Tian, Z.Y.; Glaude, P.A.; Fournet, R.; Battin-Leclerc, F. [Laboratoire des Reactions et de Genie des Procedes, CNRS, Nancy Universite, 1 rue Grandville, BP 20451, 54001 NANCY Cedex (France)
To better understand the chemistry of the combustion of components of diesel fuel, the structure of a laminar lean premixed methane flame doped with indane has been investigated. The inlet gases contained 7.1% (molar) of methane, 36.8% of oxygen and 0.9% of indane corresponding to an equivalence ratio of 0.67 and a ratio C{sub 10}H{sub 14}/CH{sub 4} of 12.8%. The flame has been stabilized on a burner at a pressure of 6.7 kPa (50 Torr) using argon as diluent, with a gas velocity at the burner of 49.1 cm s{sup -1} at 333 K. Quantified species included the usual methane C{sub 0}-C{sub 2} combustion products, but also 16 C{sub 3}-C{sub 5} non-aromatic hydrocarbons, 6 C{sub 1}-C{sub 3} non-aromatic oxygenated compounds, as well as 22 aromatic products, namely benzene, toluene, xylenes, phenylacetylene, ethylbenzene, styrene, propenylbenzene, allylbenzene, n-propylbenzene, methylstyrenes, ethyltoluenes, trimethylbenzenes, n-butylbenzene, dimethylethylbenzene, indene, methylindenes, methylindane, benzocyclobutene, naphthalene, phenol, benzaldehyde, and benzofuran. A new mechanism for the oxidation of indane was proposed whose predictions were in satisfactory agreement with measured species profiles in both flames and jet-stirred reactor experiments. The main reaction pathways of consumption of indane have been derived from flow rate analyses in the two types of reactors. A comparison of the effect of the addition of three components of diesel fuel, namely indane, n-butylbenzene and n-propylcyclohexane (parts I and II of this series of paper), on the structure of a laminar lean premixed methane flame is also presented. (author)
LASER STABILIZATION FOR NEAR ZERO NO{sub x} GAS TURBINE COMBUSTION SYSTEMS
Vivek Khanna
Historically, the development of new industrial gas turbines has been primarily driven by the intent to achieve higher efficiency, lower operating costs and lower emissions. Higher efficiency and lower cost is obtained through higher turbine operating temperatures, while reduction in emissions is obtained by extending the lean operating limit of the combustor. However reduction in the lean stability limit of operation is limited greatly by the chemistry of the combustion process and by the occurrence of thermo-acoustic instabilities. Solar Turbines, CFD Research Corporation, and Los Alamos National Laboratory have teamed to advance the technology associated with laser-assisted ignition and flame stabilization, to a level where it could be incorporated onto a gas turbine combustor. The system being developed is expected to enhance the lean stability limit of the swirl stabilized combustion process and assist in reducing combustion oscillations. Such a system has the potential to allow operation at the ultra-lean conditions needed to achieve NO{sub x} emissions below 5 ppm without the need of exhaust treatment or catalytic technologies. The research effort was focused on analytically modeling laser-assisted flame stabilization using advanced CFD techniques, and experimentally demonstrating the technology, using a solid-state laser and low-cost durable optics. A pulsed laser beam was used to generate a plasma pool at strategic locations within the combustor flow field such that the energy from the plasma became an ignition source and helped maintain a flame at ultra lean operating conditions. The periodic plasma generation and decay was used to nullify the fluctuations in the heat release from the flame itself, thus decoupling the heat release from the combustor acoustics and effectively reducing the combustion oscillations. The program was built on an existing technology base and includes: extending LANL's existing laser stabilization experience to a sub
Computer Assisted Virtual Environment - CAVE
Erickson, Phillip; Podgorney, Robert; Weingartner, Shawn; Whiting, Eric
Research at the Center for Advanced Energy Studies is taking on another dimension with a 3-D device known as a Computer Assisted Virtual Environment. The CAVE uses projection to display high-end computer graphics on three walls and the floor. By wearing 3-D glasses to create depth perception and holding a wand to move and rotate images, users can delve into data.
Computer Assisted Virtual Environment - CAVE
Erickson, Phillip; Podgorney, Robert; Weingartner, Shawn; Whiting, Eric
Research at the Center for Advanced Energy Studies is taking on another dimension with a 3-D device known as a Computer Assisted Virtual Environment. The CAVE uses projection to display high-end computer graphics on three walls and the floor. By wearing 3-D glasses to create depth perception and holding a wand to move and rotate images, users can delve into data.
A. Arbree et al.
The use of virtual data for enhancing the collaboration between large groups of scientists is explored in several ways: by defining ''virtual'' parameter spaces which can be searched and shared in an organized way by a collaboration of scientists in the course of their analysis; by providing a mechanism to log the provenance of results and the ability to trace them back to the various stages in the analysis of real or simulated data; by creating ''check points'' in the course of an analysis to permit collaborators to explore their own analysis branches by refining selections, improving the signal to background ratio, varying the estimation of parameters, etc.; by facilitating the audit of an analysis and the reproduction of its results by a different group, or in a peer review context. We describe a prototype for the analysis of data from the CMS experiment based on the virtual data system Chimera and the object-oriented data analysis framework ROOT. The Chimera system is used to chain together several steps in the analysis process including the Monte Carlo generation of data, the simulation of detector response, the reconstruction of physics objects and their subsequent analysis, histogramming and visualization using the ROOT framework.
Fuel properties to enable lifted-flame combustion
Kurtz, Eric
The Fuel Properties to Enable Lifted-Flame Combustion project responded directly to solicitation DE-FOA-0000239 AOI 1A, Fuels and Lubricants for Advanced Combustion Regimes. This subtopic was intended to encompass clean and highly-efficient, liquid-fueled combustion engines to achieve extremely low engine-out nitrogen oxides (NOx) and particulate matter (PM) as a target and similar efficiency as state-of-the-art direct injection diesel engines. The intent of this project was to identify how fuel properties can be used to achieve controllable Leaner Lifted Flame Combustion (LLFC) with low NOx and PM emissions. Specifically, this project was expected to identify and test key fuel properties to enable LLFC and their compatibility with current fuel systems and to enhance combustion models to capture the effect of fuel properties on advanced combustion. Successful demonstration of LLFC may reduce the need for after treatment devices, thereby reducing costs and improving thermal efficiency. The project team consisted of key technical personnel from Ford Motor Company (FMC), the University of Wisconsin-Madison (UW), Sandia National Laboratories (SNL) and Lawrence Livermore National Laboratories (LLNL). Each partner had key roles in achieving project objectives. FMC investigated fuel properties relating to LLFC and sooting tendency. Together, FMC and UW developed and integrated 3D combustion models to capture fuel property combustion effects. FMC used these modeling results to develop a combustion system and define fuel properties to support a single-cylinder demonstration of fuel-enabled LLFC. UW investigated modeling the flame characteristics and emissions behavior of different fuels, including those with different cetane number and oxygen content. SNL led spray combustion experiments to quantify the effect of key fuel properties on combustion characteristics critical for LLFC, as well as single cylinder optical engine experiments to improve fundamental
Effects of Coaxial Air on Nitrogen-Diluted Hydrogen Jet Diffusion Flame Length and NOx Emission
Weiland, N.T.; Chen, R.-H.; Strakey, P.A.
Turbulent nitrogen-diluted hydrogen jet diffusion flames with high velocity coaxial air flows are investigated for their NOx emission levels. This study is motivated by the DOE turbine program�s goal of achieving 2 ppm dry low NOx from turbine combustors running on nitrogen-diluted high-hydrogen fuels. In this study, effects of coaxial air velocity and momentum are varied while maintaining low overall equivalence ratios to eliminate the effects of recirculation of combustion products on flame lengths, flame temperatures, and resulting NOx emission levels. The nature of flame length and NOx emission scaling relationships are found to vary, depending on whether the combined fuel and coaxial air jet is fuel-rich or fuel-lean. In the absence of differential diffusion effects, flame lengths agree well with predicted trends, and NOx emissions levels are shown to decrease with increasing coaxial air velocity, as expected. Normalizing the NOx emission index with a flame residence time reveals some interesting trends, and indicates that a global flame strain based on the difference between the fuel and coaxial air velocities, as is traditionally used, is not a viable parameter for scaling the normalized NOx emissions of coaxial air jet diffusion flames.
Global NOx Measurements in Turbulent Nitrogen-Diluted Hydrogen Jet Flames
Weiland, N.T.; Strakey, P.A.
Turbulent hydrogen diffusion flames diluted with nitrogen are currently being studied to assess their ability to achieve the DOE Turbine Program�s aggressive emissions goal of 2 ppm NOx in a hydrogen-fueled IGCC gas turbine combustor. Since the unstrained adiabatic flame temperatures of these diluted flames are not low enough to eliminate thermal NOx formation the focus of the current work is to study how the effects of flame residence time and global flame strain can be used to help achieve the stated NOx emissions goal. Dry NOx measurements are presented as a function of jet diameter nitrogen dilution and jet velocity for a turbulent hydrogen/nitrogen jet issuing from a thin-lipped tube in an atmospheric pressure combustor. The NOx emission indices from these experiments are normalized by the flame residence time to ascertain the effects of global flame strain and fuel Lewis Number on the NOx emissions. In addition dilute hydrogen diffusion flame experiments were performed in a high-pressure combustor at 2 4 and 8 atm. The NOx emission data from these experiments are discussed as well as the results from a Computational Fluid Dynamics modeling effort currently underway to help explain the experimental data.
Timewise morphology of turbulent diffusion flame by means of image processing
Torii, Shuichi; Yano, Toshiaki; Tsuchino, Fumihiro
An experimental study is performed to investigate the dynamic behavior of jet diffusion flames from a vertical circular nozzle. A real-time image processing on slow-motion video recording using the high-speed video camera is employed to clarify the flame morphology. Emphasis is placed on the timewise variation of the flame length, H, the peripheral distance of the flame, L, and the projected area of the flame contour, S, based on the RGB values of the flame. Here, RGB implies the three primary colors, i.e., red, green and blue, respectively. Propane is used as fuel and a burner tube of 2.40 mm inside diameter is employed here. It is found from the study that (1) a real-time color image processing with the aid of a slow-motion video recording discriminates the flame shape and discloses the flame behavior with time, (2) H, L and S vary periodically with time, and (3) the time-averaged value of L{sup 2}/S and its turbulence intensity, which is defined here, are intensified with an increase in the Reynolds number.
Temperature and species-concentration measurements in turbulent flames by the CARS technique
Goss, L.P.; Schreiber, P.W.; Switzer, G.L.; Trump, D.D.
Simultaneous temperature and N/sub 2/-concentration data have been obtained employing a 10-Hz coherent anti-stokes Raman spectroscopy system on two propane-air turbulent-jet diffusion flames with Reynolds numbers of 2000 and 6000. Average values, probability density functions, and correlation plots show reasonable trends for both centerline and radial profiles of the turbulent flames.
Analysis of the flamelet concept in the numerical simulation of laminar partially premixed flames
Consul, R.; Oliva, A.; Perez-Segarra, C.D.; Carbonell, D.; de Goey, L.P.H.
The aim of this work is to analyze the application of flamelet models based on the mixture fraction variable and its dissipation rate to the numerical simulation of partially premixed flames. Although the main application of these models is the computation of turbulent flames, this work focuses on the performance of flamelet concept in laminar flame simulations removing, in this way, turbulence closure interactions. A well-known coflow methane/air laminar flame is selected. Five levels of premixing are taken into account from an equivalence ratio {phi}={infinity} (nonpremixed) to {phi}=2.464. Results obtained using the flamelet approaches are compared to data obtained from the detailed solution of the complete transport equations using primitive variables. Numerical simulations of a counterflow flame are also presented to support the discussion of the results. Special emphasis is given to the analysis of the scalar dissipation rate modeling. (author)
Critical radius for sustained propagation of spark-ignited spherical flames
Kelley, Andrew P.; Jomaas, Grunde; Law, Chung K.
An experimental study was performed to determine the requirements for sustained propagation of spark-ignited hydrogen-air and butane-air flames at atmospheric and elevated pressures. Results show that sustained propagation is always possible for mixtures whose Lewis number is less than unity, as long as a flame can be initially established. However, for mixtures whose Lewis number is greater than unity, sustained propagation depends on whether the initially ignited flame can attain a minimum radius. This minimum radius was determined for mixtures of different equivalence ratios and pressures, and was found to agree moderately well with the theoretically predicted critical radius beyond which there is no solution for the adiabatic, quasi-steady propagation of the spherical flame. The essential roles of pressure, detailed chemistry, and the need to use local values in the quantitative evaluation of the flame response parameters are emphasized. (author)
Laws of convective vortex formation behind a flame front during its propagation in a tube
Abrukov, S.A.; Samsonov, V.P.
This paper examines laws and conditions of convective vortex formation in combustion products during the propagation of a slow, stable flame in a vertical, half-open tube. The main element of the experimental unit was the reaction tube and weightless conditions were created in a freely falling container holding the reaction tube. Propane-air and CO-air mixtures were used. The structure of the flow behind the flame front was studied by the interferometric method. Frames are show from an interference film illustrating the typical pattern of vortex formation behind the flame front when the flame propagates upward at a velocity of 7 cm/sec. Analyses of the interferograms shows that the flame is stable before the vortices appear and that the flow of combustion products is laminar.
Plasma flame for mass purification of contaminated air with chemical and biological warfare agents
Uhm, Han S.; Shin, Dong H.; Hong, Yong C.
An elimination of airborne simulated chemical and biological warfare agents was carried out by making use of a plasma flame made of atmospheric plasma and a fuel-burning flame, which can purify the interior air of a large volume in isolated spaces such as buildings, public transportation systems, and military vehicles. The plasma flame generator consists of a microwave plasma torch connected in series to a fuel injector and a reaction chamber. For example, a reaction chamber, with the dimensions of a 22 cm diameter and 30 cm length, purifies an airflow rate of 5000 lpm contaminated with toluene (the simulated chemical agent) and soot from a diesel engine (the simulated aerosol for biological agents). Large volumes of purification by the plasma flame will free mankind from the threat of airborne warfare agents. The plasma flame may also effectively purify air that is contaminated with volatile organic compounds, in addition to eliminating soot from diesel engines as an environmental application.
Nitrogen and hydrogen CARS temperature measurements in a hydrogen/air flame using a near-adiabatic flat-flame burner
Hancock, R.D.; Bertagnolli, K.E.; Lucht, R.P.
Coherent anti-Stokes Raman scattering (CARS) spectroscopy of diatomic nitrogen and hydrogen was used to measure flame temperatures in hydrogen/air flames produced using a nonpremixed, near-adiabatic, flat-flame Hencken burner. The CARS temperature measurements are compared with adiabatic flame temperatures calculated by the NASA-Lewis equilibrium code for equivalence ratios from 0.5--2.5. The nitrogen CARS temperatures are in excellent agreement with the equilibrium code calculations. Comparison of nitrogen CARS data and the equilibrium code calculations confirms that for sufficiently high flow rates the Hencken burner produces nearly adiabatic flames. Hydrogen CARS temperature measurements are compared to both nitrogen CARS temperature measurements and equilibrium code predictions in order to evaluate and improve the accuracy of hydrogen CARS as a temperature diagnostic tool. Hydrogen CARS temperatures for fuel-rich flames are on average 70 K ({approximately}3%) above the equilibrium code predictions and nitrogen CARS temperatures. The difference between temperatures measured using hydrogen and nitrogen CARS is probably due primarily to uncertainties in hydrogen linewidths and line-broadening mechanisms at these conditions.
Understanding and predicting soot generation in turbulent non-premixed jet flames.
Wang, Hai; Kook, Sanghoon; Doom, Jeffrey; Oefelein, Joseph Charles; Zhang, Jiayao; Shaddix, Christopher R.; Schefer, Robert W.; Pickett, Lyle M.
This report documents the results of a project funded by DoD's Strategic Environmental Research and Development Program (SERDP) on the science behind development of predictive models for soot emission from gas turbine engines. Measurements of soot formation were performed in laminar flat premixed flames and turbulent non-premixed jet flames at 1 atm pressure and in turbulent liquid spray flames under representative conditions for takeoff in a gas turbine engine. The laminar flames and open jet flames used both ethylene and a prevaporized JP-8 surrogate fuel composed of n-dodecane and m-xylene. The pressurized turbulent jet flame measurements used the JP-8 surrogate fuel and compared its combustion and sooting characteristics to a world-average JP-8 fuel sample. The pressurized jet flame measurements demonstrated that the surrogate was representative of JP-8, with a somewhat higher tendency to soot formation. The premixed flame measurements revealed that flame temperature has a strong impact on the rate of soot nucleation and particle coagulation, but little sensitivity in the overall trends was found with different fuels. An extensive array of non-intrusive optical and laser-based measurements was performed in turbulent non-premixed jet flames established on specially designed piloted burners. Soot concentration data was collected throughout the flames, together with instantaneous images showing the relationship between soot and the OH radical and soot and PAH. A detailed chemical kinetic mechanism for ethylene combustion, including fuel-rich chemistry and benzene formation steps, was compiled, validated, and reduced. The reduced ethylene mechanism was incorporated into a high-fidelity LES code, together with a moment-based soot model and models for thermal radiation, to evaluate the ability of the chemistry and soot models to predict soot formation in the jet diffusion flame. The LES results highlight the importance of including an optically-thick radiation model
Physicists ID Mechanism that Stabilizes Plasma in Tokamaks
U.S. Department of Energy (DOE) all webpages (Extended Search)
Physicists ID Mechanism that Stabilizes Plasma in Tokamaks Physicists ID Mechanism that Stabilizes Plasma in Tokamaks Calculations Run at NERSC Create 3D Simulations of Fusion Plasmas January 4, 2016 Contact: Kathy Kincade, firstname.lastname@example.com, +1 510 495 2124 jardinfusion A cross-section of the virtual plasma showing where the magnetic field lines intersect the plane. The central section has field lines that rotate exactly once. Image: Stephen Jardin A team of physicists led by Stephen Jardin of
Virtualized Network Control. Final Report
Ghani, Nasir
This document is the final report for the Virtualized Network Control (VNC) project, which was funded by the United States Department of Energy (DOE) Office of Science. This project was also informally referred to as Advanced Resource Computation for Hybrid Service and TOpology NEtworks (ARCHSTONE). This report provides a summary of the project's activities, tasks, deliverable, and accomplishments. It also provides a summary of the documents, software, and presentations generated as part of this projects activities. Namely, the Appendix contains an archive of the deliverables, documents, and presentations generated a part of this project.
Booster Neutrino Experiment - Virtual Tour
U.S. Department of Energy (DOE) all webpages (Extended Search)
Virtual Tour This series of pages about MiniBooNE will help you understand more about the what, why, and how of our experiment. When you begin the tour, a new window will open and you can use the next and back buttons to navigate. You may exit at any time by clicking on the "X" button in the upper right hand corner of the window. Start the tour here... This tour was created by Jessica Falco in 2000 and updated by Kelly O'Hear in 2002. Jessica and Kelly were high school students who
CCI Virtual Tour | The Ames Laboratory
U.S. Department of Energy (DOE) all webpages (Extended Search)
CCI Virtual Tour Daniel Bouk, a student in the Community College Internship (CCI) program talks about his experience working in Ames Laboratory's Engineering Services department
Virtual Reality for Nuclear Material Handling
Office of Energy Efficiency and Renewable Energy (EERE)
AIKEN, S.C. – EM's Savannah River National Laboratory (SRNL) is applying a high-tech solution to complex and dangerous workforce training: virtual reality.
A numerical and experimental investigation of premixed methane-air flame transient response
Habib N. Najm; Phillip H. Paul; Omar M. Knio; Andrew McIlroy
The authors report the results of a numerical and experimental investigation of the response of premixed methane-air flames to transient strain-rate disturbances induced by a two-dimensional counter-rotating vortex-pair. The numerical and experimental time histories of flow and flame evolution are matched over a 10 ms interaction time. Measurements and computations of CH and OH peak data evolution are reported, and found to indicate mis-prediction of the flame time scales in the numerical model. Qualitative transient features of OH at rich conditions are not predicted in the computations. On the other hand, evolution of computed and measured normalized HCO fractions are in agreement. The computed CH{sub 3}O response exhibits a strong transient driven by changes to internal flame structure, namely temperature profile steepening, induced by the flow field. Steady state experimental PLIF CH{sub 3}O data is reported, but experimental transient CH{sub 3}O data is not available. The present analysis indicates that the flame responds at time scales that are quite distinct from ``propagation'' time scale derived from flame thickness and burning speed. Evidently, these propagation time scales are not adequate for characterizing the transient flame response.
Laminar round jet diffusion flame buoyant instabilities: Study on the disappearance of varicose structures at ultra-low Froude number
Boulanger, Joan [Gas Turbine Laboratory, Institute for Aerospace Research, Ottawa, Ontario (Canada)
At very low Froude number, buoyancy instabilities of round laminar jet diffusion flames disappear (except for small tip oscillations referred to as flickering) and those flames look stable and smooth. This study examines the contributions of the different phenomena in the flow dynamics that may explain this effect. It is observed that, at ultra-low Froude/Reynolds numbers, the material influenced by buoyancy is the plume of the flame and not the flame itself (reaction zone) that is short. Therefore, the vorticity creation zone does not profit from the reaction neighbourhood promoting a sharp gradient of density. Expansion and stretch are also important as they push vorticity creation terms more inside the flame and closer to the burner rim compared to moderate Froude flames. In these latter, the vorticity is continuously created around the flame reaction zone, along its developed height and closer to the vertical direction (in average). (author)
Modeling of 1,3-hexadiene, 2,4-hexadiene and 1,4-hexadiene-doped methane flames: Flame modeling, benzene and styrene formation
Sharma, Sandeep; Harper, Michael R.; Green, William H.
In this work, we have developed a detailed chemical kinetic model and reacting flow simulation for the hexadiene-doped 2-d methane diffusion flames studied experimentally by McEnally and Pfefferle. The GRI-Mech 2.11 methane oxidation and Lawrence Livermore butane oxidation mechanisms were used as the base mechanism to which hexadiene chemistry generated by Reaction Mechanism Generator (RMG) was added. Some important chemically activated pathways leading to aromatic species formation, including the reactions on C{sub 5}H{sub 7}, C{sub 6}H{sub 10}, C{sub 6}H{sub 9}, C{sub 6}H{sub 7}, C{sub 8}H{sub 8} and C{sub 8}H{sub 9} potential energy surfaces, are examined in great detail using quantum chemistry (CBS-QB3) and master equation analysis as implemented in Variflex. An efficient program to solve the doped methane diffusion flame was developed. The solver uses the method of lines to solve the species mass balance equation arising in the diffusion flame. It assumes that the temperature and velocity profiles of the doped flame are the same as those of the undoped flame. The mole fractions of various species as predicted by our model are compared to the experimentally measured mole fractions. The agreement between theory and experiments is quite good for most molecules. The added hexadiene dopants to the flame decompose to produce significant amount of cyclopentadienyl radical, which combines with methyl radical to produce benzene. We also show that styrene is formed primarily by recombination of cyclopentadienyl and propargyl radicals, a pathway which to our knowledge, has not been included in prior flame simulations. (author)
Jessen, P.L.; Price, H.J.
This patent relates to sine-wave generators and in particular describes a generator with a novel feedback circuit resulting in improved frequency stability. The generator comprises two triodes having a common cathode circuit connected to oscillate at a frequency and amplitude at which the loop galn of the circutt ls unity, and another pair of triodes having a common cathode circuit arranged as a conventional amplifier. A signal is conducted from the osciliator through a frequency selective network to the amplifier and fed back to the osciliator. The unique feature of the feedback circuit is the amplifier operates in the nonlinear portion of its tube characteristics thereby providing a relatively constant feedback voltage to the oscillator irrespective of the amplitude of its input signal.
Appearance, temperature, and NO{sub x} emission of two inverse diffusion flames with different port design
Sze, L.K.; Cheung, C.S.; Leung, C.W.
Experiments were carried out to investigate the appearance, temperature distribution, and NO{sub x} emission index of two inverse diffusion flames, one with circumferentially arranged ports (CAPs) and the other with co-axial (CoA) jets, both burning LPG with 70% butane and 30% propane. Flame appearances were investigated first with a fixed fueling rate at different airflow rates equivalent to air jet Reynolds numbers (Re) of 1000 to 4500; and then at a fixed airflow rate with different fueling rates equivalent to overall equivalence ratios (F) of 1.0 to 2.0. The CAP flame is found to consist of two zones: a lower entrainment zone and an upper mixing and combustion zone. The CoA flame in most cases is similar to a diffusion flame. The two-zone structure can be observed only at Re larger than 2500. The temperature distributions of the flames are similar at overall equivalence ratios of 1.0 and 1.2 for Re=2500, except that the corresponding CoA flame is longer. The flame temperature is higher in the CAP flame than the CoA flame at higher overall equivalence ratios. A measurement of centerline oxygen concentrations shows that the oxygen concentration reaches a minimum value at a flame height of 50 mm in the CAP flame but decreases more gradually in the CoA flame. It can be concluded that there is more intense air-fuel mixing in a CAP flame than the CoA flame. Investigation of the emission index of NO{sub x} (EINO{sub x}) for both flames at Re=2500 and overall equivalence ratios of 1.0 to 6.0 reveals that the EINO{sub x} curve of each flame is bell-shaped, with a maximum value of 3.2 g/kg at F=1.2 for the CAP flame and 3 g/kg at F=2.2 for the CoA flame.
Investigation of critical equivalence ratio and chemical speciation in flames of ethylbenzene-ethanol blends
Therrien, Richard J.; Ergut, Ali; Levendis, Yiannis A.; Richter, Henning; Howard, Jack B.; Carlson, Joel B.
This work investigates five different one-dimensional, laminar, atmospheric pressure, premixed ethanol/ethylbenzene flames (0%, 25%, 50%, 75% and 90% ethanol by weight) at their soot onset threshold ({phi}{sub critical}). Liquid ethanol/ethylbenzene mixtures were pre-vaporized in nitrogen, blended with an oxygen-nitrogen mixture and, upon ignition, burned in premixed one-dimensional flames at atmospheric pressure. The flames were controlled so that each was at its visual soot onset threshold, and all had similar temperature profiles (determined by thermocouples). Fixed gases, light volatile hydrocarbons, polycyclic aromatic hydrocarbons (PAH), and oxygenated aromatic hydrocarbons were directly sampled at three locations in each flame. The experimental results were compared with a detailed kinetic model, and the modeling results were used to perform a reaction flux analysis of key species. The critical equivalence ratio was observed to increase in a parabolic fashion as ethanol concentration increased in the fuel mixture. The experimental results showed increasing trends of methane, ethane, and ethylene with increasing concentrations of ethanol in the flames. Carbon monoxide was also seen to increase significantly with the increase of ethanol in the flame, which removes carbon from the PAH and soot formation pathways. The PAH and oxygenated aromatic hydrocarbon values were very similar in the 0%, 25% and 50% ethanol flames, but significantly lower in the 75% and 90% ethanol flames. These results were in general agreement with the model and were reflected by the model soot predictions. The model predicted similar soot profiles for the 0%, 25% and 50% ethanol flames, however it predicted significantly lower values in the 75% and 90% ethanol flames. The reaction flux analysis revealed benzyl to be a major contributor to single and double ring aromatics (i.e., benzene and naphthalene), which was identified in a similar role in nearly sooting or highly sooting
Simulations of flame acceleration and deflagration-to-detonation transitions in methane-air systems
Kessler, D.A.; Gamezo, V.N.; Oran, E.S. [Laboratory for Computational Physics and Fluid Dynamics, Naval Research Laboratory, Washington, DC (United States)
Flame acceleration and deflagration-to-detonation transitions (DDT) in large obstructed channels filled with a stoichiometric methane-air mixture are simulated using a single-step reaction mechanism. The reaction parameters are calibrated using known velocities and length scales of laminar flames and detonations. Calculations of the flame dynamics and DDT in channels with obstacles are compared to previously reported experimental data. The results obtained using the simple reaction model qualitatively, and in many cases, quantitatively match the experiments and are found to be largely insensitive to small variations in model parameters. (author)
Temperature measurement of axisymmetric flames under the influence of magnetic field using Talbot interferometry
Agarwal, Shilpi E-mail: firstname.lastname@example.com Kumar, Manoj E-mail: firstname.lastname@example.com Shakher, Chandra E-mail: firstname.lastname@example.com
Combustion process control is related with ecological improvement and the problem of energy efficiency; hence it has a wide interest at both economical and scientific levels. Application of a magnetic field is one of the most promising methods of combustion control. The presence of magnetic field induces the changes in flame behavior. The effect of uniform magnetic field developed by permanent magnet is studied by Talbot interferometry using circular gratings. Experimental results show a small decrease in flame temperature and increase in flame dimensions.
Igniter for gas discharge pipe with a flame detection system
Guerra, R.E.
This patent describes a method of burning waste gas, using an igniter of the type having a nozzle, a main gas conduit extending to the nozzle, and an electrical spark means for creating a spark in the nozzle. It comprises: mounting the igniter to a waste gas discharge pipe with the nozzle directed across the opening of the gas discharge pipe; supplying a gaseous fuel to the main gas conduit; igniting the gaseous fuel with the electrical spark means, creating a flame for igniting the waste gas being discharged from the gas discharge pipe; providing the igniter with an auxiliary gas line extending to the vicinity of the nozzle; and supplying a second and lower volume source of waste gas to the auxiliary gas line for burning at the nozzle.
TSTA Piping and Flame Arrestor Operating Experience Data
Cadwallader, Lee C.; Willms, R. Scott
The Tritium Systems Test Assembly (TSTA) was a facility dedicated to tritium handling technology and experiment research at the Los Alamos National Laboratory. The facility operated from 1984 to 2001, running a prototype fusion fuel processing loop with ~100 grams of tritium as well as small experiments. There have been several operating experience reports written on this facility's operation and maintenance experience. This paper describes analysis of two additional components from TSTA, small diameter gas piping that handled small amounts of tritium in a nitrogen carrier gas, and the flame arrestor used in this piping system. The operating experiences and the component failure rates for these components are discussed in this paper. Comparison data from other applications are also presented.
Hansen, Nils
Research focused on detailed studies of the complex combustion chemistry of oxygenated, bio-derived fuels. In particular, studies were done of the flame chemistry of simple methyl and ethyl esters chosen as surrogates for the long-chain esters that are primary constituents of biodiesel fuels. The principal goals of these studies were: (1) show how fuel-specific structural differences including degree of unsaturation, linear vs. branched chain structures, and methoxy vs. ethoxy functions affect fueldestruction pathways, (2) understand the chemistry leading to potential increases in the emissions of hazardous air pollutants including aldehydes and ketones inherent in the use of biodiesel fuels, and (3) define the key chemical reaction mechanisms responsible for observed reductions in polycyclic aromatic hydrocarbons and particulate matter when oxygenated fuels are used as replacements for conventional fuels.
Emissions from ethanol-blended fossil fuel flames
Akcayoglu, Azize
A fundamental study to investigate the emission characteristics of ethanol-blended fossil fuels is presented. Employing a heterogeneous experimental setup, emissions are measured from diffusion flames around spherical porous particles. Using an infusion pump, ethanol-fossil fuel blend is transpired into a porous sphere kept in an upward flowing air stream. A typical probe of portable digital exhaust gas analyzer is placed in and around the flame with the help of a multi-direction traversing mechanism to measure emissions such as un-burnt hydrocarbons, carbon monoxide and carbon dioxide. Since ethanol readily mixes with water, emission characteristics of ethanol-water blends are also studied. For comparison purpose, emissions from pure ethanol diffusion flames are also presented. A simplified theoretical analysis has been carried out to determine equilibrium surface temperature, composition of the fuel components in vapor-phase and heat of reaction of each blend. These theoretical predictions are used in explaining the emission characteristics of flames from ethanol blends. (author) This paper presents the results of an experimental study of flow structure in horizontal equilateral triangular ducts having double rows of half delta-wing type vortex generators mounted on the duct's slant surfaces. The test ducts have the same axial length and hydraulic diameter of 4 m and 58.3 mm, respectively. Each duct consists of double rows of half delta wing pairs arranged either in common flow-up or common flow-down configurations. Flow field measurements were performed using a Particle Image Velocimetry Technique for hydraulic diameter based Reynolds numbers in the range of 1000-8000. The secondary flow field differences generated by two different vortex generator configurations were examined in detail. The secondary flow is found stronger behind the second vortex generator pair than behind the first pair but becomes weaker far from the second pair in the case of Duct1. However
2015 IC Virtual Career Fair | Department of Energy
Office of Environmental Management (EM)
2015 IC Virtual Career Fair 2015 IC Virtual Career Fair Instructions for Applicants Please use the following process to submit an application and resume for DOE's 2015 IC Virtual...
Building Controls Virtual Test Bed
Energy Science and Technology Software Center (OSTI)
The Building Controls Virtual Test Bed (BCVTB) is a modular software environment that is based on the Ptolemy II software environment. The BCVTB can be used for design and analysis of heterogenous systems, such as building energy and controls systems. Our additions to Ptolemy II allow users to Couple to Ptolemy II simulation software such as EnergyPlus, MATLAB/Simulink or Dymola for data exchange during run-time. Future versions of the BCVTS will also contain an interfacemore » to BACnet which is a communication protocol for building Control systems, and interfaces to digital/analog converters that allow communication with controls hardware. Through Ptolemy II, the BCVTB provides a graphical model building environment, synchronizes the exchanged data and visualizes the system evolution during run- time.« less
CBEI: Virtual Refrigerant Charge Sensing and Load Metering -...
Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)
Virtual Refrigerant Charge Sensing and Load Metering - 2015 Peer Review CBEI: Virtual Refrigerant Charge Sensing and Load Metering - 2015 Peer Review Presenter: James Braun, Purdue ...
SMART Wind Consortium Composites Subgroup Virtual Meeting: Advanced...
Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)
SMART Wind Consortium Composites Subgroup Virtual Meeting: Advanced Manufacturing of Wind Turbine Blades SMART Wind Consortium Composites Subgroup Virtual Meeting: Advanced...
T-678: Red Hat Enterprise Virtualization Hypervisor VLAN Packet...
Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)
8: Red Hat Enterprise Virtualization Hypervisor VLAN Packet Processing Flaw Lets Remote Users Deny Service T-678: Red Hat Enterprise Virtualization Hypervisor VLAN Packet...
Linear and non-linear forced response of a conical, ducted, laminar premixed flame
Karimi, Nader; Brear, Michael J.; Jin, Seong-Ho; Monty, Jason P. [Department of Mechanical Engineering, University of Melbourne, Parkville, 3010 Vic. (Australia)
This paper presents an experimental study on the dynamics of a ducted, conical, laminar premixed flame subjected to acoustic excitation of varying amplitudes. The flame transfer function is measured over a range of forcing frequencies and equivalence ratios. In keeping with previous works, the measured flame transfer function is in good agreement with that predicted by linear kinematic theory at low amplitudes of acoustic velocity excitation. However, a systematic departure from linear behaviour is observed as the amplitude of the velocity forcing upstream of the flame increases. This non-linearity is mostly in the phase of the transfer function and manifests itself as a roughly constant phase at high forcing amplitude. Nonetheless, as predicted by non-linear kinematic arguments, the response always remains close to linear at low forcing frequencies, regardless of the forcing amplitude. The origin of this phase behaviour is then sought through optical data post-processing. (author)
Kutsuna, Masamichi; Shigeyama, Toshikazu [Research Center for the Early Universe, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan)
We investigate the effects of the magnetic field on the propagation of laminar flames of nuclear reactions taking place in white dwarfs with masses close to the Chandrasekhar limit. We calculate the velocities of laminar flames parallel and perpendicular to uniform magnetic fields as eigenvalues of steady solutions for magnetic hydrodynamical equations. As a result, we find that even when the magnetic pressure does not dominate the entire pressure it is possible for the magnetic field to suppress the flame propagation through the thermal conduction. Above the critical magnetic field, the flame velocity decreases with increasing magnetic field strength as v {approx} B{sup -1}. In media with densities of 10{sup 7}, 10{sup 8}, and 10{sup 9} g cm{sup -3}, the critical magnetic fields are orders of {approx}10{sup 10}, 10{sup 11}, and 10{sup 12} G, respectively.
Combustion flame-plasma hybrid reactor systems, and chemical reactant sources
Kong, Peter C
Combustion flame-plasma hybrid reactor systems, chemical reactant sources, and related methods are disclosed. In one embodiment, a combustion flame-plasma hybrid reactor system comprising a reaction chamber, a combustion torch positioned to direct a flame into the reaction chamber, and one or more reactant feed assemblies configured to electrically energize at least one electrically conductive solid reactant structure to form a plasma and feed each electrically conductive solid reactant structure into the plasma to form at least one product is disclosed. In an additional embodiment, a chemical reactant source for a combustion flame-plasma hybrid reactor comprising an elongated electrically conductive reactant structure consisting essentially of at least one chemical reactant is disclosed. In further embodiments, methods of forming a chemical reactant source and methods of chemically converting at least one reactant into at least one product are disclosed.
Combustor oscillating pressure stabilization and method
Gemmen, Randall S.; Richards, George A.; Yip, Mui-Tong Joseph; Robey, Edward H.; Cully, Scott R.; Addis, Richard E.
High dynamic pressure oscillations in hydrocarbon-fueled combustors typically occur when the transport time of the fuel to the flame front is at some fraction of the acoustic period. These oscillations are reduced to acceptably lower levels by restructuring or repositioning the flame front in the combustor to increase the transport time. A pilot flame front located upstream of the oscillating flame and pulsed at a selected frequency and duration effectively restructures and repositions the oscillating flame in the combustor to alter the oscillation-causing transport time.
Combustor oscillating pressure stabilization and method
Gemmen, R.S.; Richards, G.A.; Yip, M.T.J.; Robey, E.H.; Cully, S.R.; Addis, R.E.
High dynamic pressure oscillations in hydrocarbon-fueled combustors typically occur when the transport time of the fuel to the flame front is at some fraction of the acoustic period. These oscillations are reduced to acceptably lower levels by restructuring or repositioning the flame front in the combustor to increase the transport time. A pilot flame front located upstream of the oscillating flame and pulsed at a selected frequency and duration effectively restructures and repositions the oscillating flame in the combustor to alter the oscillation-causing transport time. 7 figs.
Design, Modeling, and Validation of a Flame Reformer for LNT External
Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)
Bypass Regeneration | Department of Energy Design, Modeling, and Validation of a Flame Reformer for LNT External Bypass Regeneration Design, Modeling, and Validation of a Flame Reformer for LNT External Bypass Regeneration 2005 Diesel Engine Emissions Reduction (DEER) Conference Presentations and Posters 2005_deer_midlam-mohler.pdf (432.95 KB) More Documents & Publications Eaton Aftertreatment System (EAS) for On-Highway Diesel Engines Diesel Reformers for On-board Hydrogen Applications
Experimental Endeavour on a Pillar of Flame: Space Shuttle Rises with
Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)
Ambitious Technology Aboard | Department of Energy Experimental Endeavour on a Pillar of Flame: Space Shuttle Rises with Ambitious Technology Aboard Experimental Endeavour on a Pillar of Flame: Space Shuttle Rises with Ambitious Technology Aboard May 17, 2011 - 5:15pm Addthis Smoke cloud from Endeavour's Final Launge | Photo: NASA, Troy Cryder Smoke cloud from Endeavour's Final Launge | Photo: NASA, Troy Cryder Charles Rousseaux Charles Rousseaux Senior Communications Specialist (detailee)
Non-Sooting, Low Flame Temperature Mixing-Controlled DI Diesel Combustion |
Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)
Department of Energy Sooting, Low Flame Temperature Mixing-Controlled DI Diesel Combustion Non-Sooting, Low Flame Temperature Mixing-Controlled DI Diesel Combustion 2003 DEER Conference Presentation: Sandia National Laboratories 2003_deer_pickett.pdf (538.33 KB) More Documents & Publications Effects of Ambient Density and Temperature on Soot Formation under High-EGR Conditions Fuels and Combustion Strategies for High-Efficiency Clean-Combustion Engines Optical-Engine and Surrogate-Fuels
EIS-0351: Operation of Flaming Gorge Dam, Colorado River Storage Project, Colorado River, UT
The Secretary of the United States Department of the Interior (Secretary), acting through the Bureau of Reclamation (Reclamation), is considering whether to implement a proposed action under which Flaming Gorge Dam would be operated to achieve the flow and temperature regimes recommended in the September 2000 report Flow and Temperature Recommendations for Endangered Fishes in the Green River Downstream of Flaming Gorge Dam (2000 Flow and Temperature Recommendations), published by the Upper Colorado River Endangered Fish Recovery Program (Recovery Program).
Spark ignited turbulent flame kernel growth. Annual report, January--December, 1992
Santavicca, D.A.
Cyclic combustion variations in spark-ignition engines limit the use of dilute charge strategies for achieving low NO{sub x} emissions and improved fuel economy. Results from an experimental study of the effect of incomplete fuel-air mixing (ifam) on spark-ignited flame kernel growth in turbulent propane-air mixtures are presented. The experiments were conducted in a turbulent flow system that allows for independent variation of flow parameters, ignition system parameters, and the degree of fuel-air mixing. Measurements were made at 1 atm and 300 K conditions. Five cases were studied; a premixed and four incompletely mixed cases with 6%, 13%, 24% and 33% RMS (root-mean-square) fluctuations in the fuel/air equivalence ratio. High speed laser shadowgraphy at 4,000 frames-per-second was used to record flame kernel growth following spark ignition, from which the equivalent flame kernel radius as a function of time was determined. The effect of ifam was evaluated in terms of the flame kernel growth rate, cyclic variations in the flame kernel growth, and the rate of misfire. The results show that fluctuations in local mixture strength due to ifam cause the flame kernel surface to become wrinkled and distorted; and that the amount of wrinkling increases as the degree of ifam. Ifam was also found to result in a significant increase in cyclic variations in the flame kernel growth. The average flame kernel growth rates for the premixed and the incompletely mixed cases were found to be within the experimental uncertainty except for the 33%-RMS-fluctuation case where the growth rate is significantly lower. The premixed and 6%-RMS-fluctuation cases had a 0% misfire rate. The misfire rates were 1% and 2% for the 13%-RMS-fluctuation and 24%-RMS-fluctuation cases, respectively; however, it drastically increased to 23% in the 33%-RMS-fluctuation case.
Effects of alpha-zirconium phosphate on thermal degradation and flame retardancy of transparent intumescent fire protective coating
Xing, Weiyi; Zhang, Ping; Song, Lei; Wang, Xin; Hu, Yuan
Graphical abstract: - Highlights: � A transparent intumescent fire protective coating was obtained by UV-cured technology. � OZrP could enhance the thermal stability and anti-oxidation of the coating. � OZrP could reduce the combustion properties of the coatings. - Abstract: Organophilic alpha-zirconium phosphate (OZrP) was used to improve the thermal and fire retardant behaviors of the phenyl di(acryloyloxyethyl)phosphate (PDHA)-triglycidyl isocyanurate acrylate (TGICA)-2-phenoxyethyl acrylate (PHEA) (PDHA-TGICA-PHEA) coating. The morphology of nanocomposite coating was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The effect of OZrP on the flame retardancy, thermal stability, fireproofing time and char formation of the coatings was investigated by microscale combustion calorimeter (MCC), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), laser Raman spectroscopy (LRS) and scanning electric microscope (SEM). The results showed that by adding OZrP, the peak heat release rate and total heat of combustion were significantly reduced. The highest improvement was achieved with 0.5 wt% OZrP. XPS analysis indicated that the performance of anti-oxidation of the coating was improved with the addition of OZrP, and SEM images showed that a good synergistic effect was obtained through a ceramic-like layer produced by OZrP covered on the surface of char.
Soot surface temperature measurements in pure and diluted flames at atmospheric and elevated pressures
Berry Yelverton, T.L.; Roberts, W.L. [Department of Mechanical and Aerospace Engineering, Campus Box 7910, North Carolina State University, 3211 Broughton Hall, Raleigh, NC 27695 (United States)
Soot surface temperature was measured in laminar jet diffusion flames at atmospheric and elevated pressures. The soot surface temperature was measured in flames at one, two, four, and eight atmospheres with both pure and diluted (using helium, argon, nitrogen, or carbon dioxide individually) ethylene fuels with a calibrated two-color soot pyrometry technique. These two dimensional temperature profiles of the soot aid in the analysis and understanding of soot production, leading to possible methods for reducing soot emission. Each flame investigated was at its smoke point, i.e., at the fuel flow rate where the overall soot production and oxidation rates are equal. The smoke point was chosen because it was desirable to have similar soot loadings for each flame. A second set of measurements were also taken where the fuel flow rate was held constant to compare with earlier work. These measurements show that overall flame temperature decreases with increasing pressure, with increasing pressure the position of peak temperature shifts to the tip of the flame, and the temperatures measured were approximately 10% lower than those calculated assuming equilibrium and neglecting radiation. (author)
Experimental study of stationary flame propagation in a tube under conditions of weightlessness
Samsonov, V.P.; Abrukov, S.A.; Danilkin, V.A.; Davydov, A.E.; Tyameikin, V.Y.
The development of detailed concepts of the effect of gravitational conditions on a wide class of combustion phenomena has been hindered by the lack of a sufficient amount of experimental data on combustion under conditions of weightlessness. The present study investigates the changes in form of a laminar flame under the influence of natural thermal convection with stationary propagation in a vertical tube under normal gravitational conditions and under conditions of weightlessness, in which case convection is absent. Lean propane/CO/air mixtures were ignited in a reaction tube suspended in a weightlessness simulation chamber. High speed photographic recording of the flame front revealed that for flame propagation from an open lower end under normal gravitational conditions the flame front is more convex than under weightless conditions. Under conditions of weightlessness the form of the flame front is the same for propagation from either end. Equations are derived describing the change in flame front convexity produced by convection. Some divergence of the calculation results from the experimental data may be explained by the fact that the equations do not consider factors such as thermal expansion and viscosity of the combustion products, and the peculiarities of convective ascent of these products.
Ebaugh, Larry R.; Sadler, Collin P.; Carter, Gary D.
An improved fin stabilized projectile including multiple stabilizer fins upon a stabilizer unit situated at the aft end of the projectile is provided, the improvement wherein the stabilizer fins are joined into the stabillizer unit by an injection molded engineering grade polymer.
Two implementations of shared virtual space environments.
Disz, T. L.
While many issues in the area of virtual reality (VR) research have been addressed in recent years, the constant leaps forward in technology continue to push the field forward. VR research no longer is focused only on computer graphics, but instead has become even more interdisciplinary, combining the fields of networking, distributed computing, and even artificial intelligence. In this article we discuss some of the issues associated with distributed, collaborative virtual reality, as well as lessons learned during the development of two distributed virtual reality applications.
Jefferson Lab Virtual Tour | Jefferson Lab
U.S. Department of Energy (DOE) all webpages (Extended Search)
Virtual Tour To see a virtual tour of some of the facilities at Jefferson Lab, click the name of a building below or hover over a building on the map. When hovering, you can read about the facility, or click the building image to take a video tour. To see the entire tour, click here. You can also learn about our 12GeV Upgrade. Virtual Tour VARC CEBAF TestLab accel FEL HallA HallB HallC Jefferson Lab's mission is to provide forefront scientific facilities, opportunities and leadership essential
Experimental and numerical study of the accuracy of flame-speed measurements for methane/air combustion in a slot burner
Selle, L.; Ferret, B. [Universite de Toulouse, INPT, UPS, IMFT, Institut de Mecanique des Fluides de Toulouse (France); CNRS, IMFT, Toulouse (France); Poinsot, T. [Universite de Toulouse, INPT, UPS, IMFT, Institut de Mecanique des Fluides de Toulouse (France); CNRS, IMFT, Toulouse (France); CERFACS, Toulouse (France)
Measuring the velocities of premixed laminar flames with precision remains a controversial issue in the combustion community. This paper studies the accuracy of such measurements in two-dimensional slot burners and shows that while methane/air flame speeds can be measured with reasonable accuracy, the method may lack precision for other mixtures such as hydrogen/air. Curvature at the flame tip, strain on the flame sides and local quenching at the flame base can modify local flame speeds and require corrections which are studied using two-dimensional DNS. Numerical simulations also provide stretch, displacement and consumption flame speeds along the flame front. For methane/air flames, DNS show that the local stretch remains small so that the local consumption speed is very close to the unstretched premixed flame speed. The only correction needed to correctly predict flame speeds in this case is due to the finite aspect ratio of the slot used to inject the premixed gases which induces a flow acceleration in the measurement region (this correction can be evaluated from velocity measurement in the slot section or from an analytical solution). The method is applied to methane/air flames with and without water addition and results are compared to experimental data found in the literature. The paper then discusses the limitations of the slot-burner method to measure flame speeds for other mixtures and shows that it is not well adapted to mixtures with a Lewis number far from unity, such as hydrogen/air flames. (author)
Robotics virtual rail system and method
Bruemmer, David J.; Few, Douglas A.; Walton, Miles C.
A virtual track or rail system and method is described for execution by a robot. A user, through a user interface, generates a desired path comprised of at least one segment representative of the virtual track for the robot. Start and end points are assigned to the desired path and velocities are also associated with each of the at least one segment of the desired path. A waypoint file is generated including positions along the virtual track representing the desired path with the positions beginning from the start point to the end point including the velocities of each of the at least one segment. The waypoint file is sent to the robot for traversing along the virtual track.
National Energy Literacy Virtual Town Hall
The webinar will be a dynamic, virtual conversation for educators about ongoing efforts from across the country in utilizing the Department of Energy's Energy Literacy Framework to address one of our nation's' biggest national challenges, energy illiteracy.
Virtual tour: INL's space battery facility
Johnson, Steve
This virtual tour shows how INL fuels and tests nuclear power systems for deep space missions. To learn more about INL's contribution to the Mars Science Laboratory, visit http://www.inl.gov/marsrover.
BioenergizeME Virtual Science Fair: Bioenergy
This infographic was created by students from Sun Valley High School in Aston, PA, as part of the U.S. Department of Energy-BioenergizeME Virtual Science Fair.
Methane and methanol oxidation in supercritical water: Chemical kinetics and hydrothermal flame studies
Steeper, R.R.
Supercritical water oxidation (SCWO) is an emerging technology for the treatment of wastes in the presence of a large concentration of water at conditions above water`s thermodynamic critical point. A high-pressure, optically accessible reaction cell was constructed to investigate the oxidation of methane and methanol in this environment. Experiments were conducted to examine both flame and non-flame oxidation regimes. Optical access enabled the use of normal and shadowgraphy video systems for visualization, and Raman spectroscopy for in situ measurement of species concentrations. Flame experiments were performed by steadily injecting pure oxygen into supercritical mixtures of water and methane or methanol at 270 bar and at temperatures from 390 to 510{degrees}C. The experiments mapped conditions leading to the spontaneous ignition of diffusion flames in supercritical water. Above 470{degrees}C, flames spontaneously ignite in mixtures containing only 6 mole% methane or methanol. This data is relevant to the design and operation of commercial SCWO processes that may be susceptible to inadvertent flame formation. Non-flame oxidation kinetics experiments measured rates of methane oxidation in supercritical water at 270 bar and at temperatures from 390 to 442{degrees}C. The initial methane concentration was nominally 0.15 gmol/L, a level representative of commercial SCWO processes. The observed methane concentration histories were fit to a one-step reaction rate expression indicating a reaction order close to two for methane and zero for oxygen. Experiments were also conducted with varying water concentrations (0 to 8 gmol/L) while temperature and initial reactant concentrations were held constant. The rate of methane oxidation rises steadily with water concentration up to about 5 gmol/L and then abruptly falls off at higher concentrations.
Plutonium inventories for stabilization and stabilized materials
Williams, A.K.
The objective of the breakout session was to identify characteristics of materials containing plutonium, the need to stabilize these materials for storage, and plans to accomplish the stabilization activities. All current stabilization activities are driven by the Defense Nuclear Facilities Safety Board Recommendation 94-1 (May 26, 1994) and by the recently completed Plutonium ES&H Vulnerability Assessment (DOE-EH-0415). The Implementation Plan for accomplishing stabilization of plutonium-bearing residues in response to the Recommendation and the Assessment was published by DOE on February 28, 1995. This Implementation Plan (IP) commits to stabilizing problem materials within 3 years, and stabilizing all other materials within 8 years. The IP identifies approximately 20 metric tons of plutonium requiring stabilization and/or repackaging. A further breakdown shows this material to consist of 8.5 metric tons of plutonium metal and alloys, 5.5 metric tons of plutonium as oxide, and 6 metric tons of plutonium as residues. Stabilization of the metal and oxide categories containing greater than 50 weight percent plutonium is covered by DOE Standard {open_quotes}Criteria for Safe Storage of Plutonium Metals and Oxides{close_quotes} December, 1994 (DOE-STD-3013-94). This standard establishes criteria for safe storage of stabilized plutonium metals and oxides for up to 50 years. Each of the DOE sites and contractors with large plutonium inventories has either started or is preparing to start stabilization activities to meet these criteria.
Experimental study of Markstein number effects on laminar flamelet velocity in turbulent premixed flames
Weiss, M.; Zarzalis, N. [Division of Combustion Technology, Engler-Bunte-Institute, University of Karlsruhe (TH), Karlsruhe (Germany); Suntz, R. [Institute for Chemical Technology, University of Karlsruhe (TH), Karlsruhe (Germany)
Effects of turbulent flame stretch on mean local laminar burning velocity of flamelets, u{sub n}, were investigated experimentally in an explosion vessel at normal temperature and pressure. In this context, the wrinkling, A{sub t}/A{sub l}, and the burning velocity, u{sub t}, of turbulent flames were measured simultaneously. With the flamelet assumption the mean local laminar burning velocity of flamelets, u{sub n}=u{sub t} x (A{sub t}/A{sub l}){sup -1}, was calculated for different turbulence intensities. The results were compared to the influence of stretch on spherically expanding laminar flames. For spherically expanding laminar flames the stretched laminar burning velocity, u{sub n}, varied linearly with the Karlovitz stretch factor, yielding Markstein numbers that depend on the mixture composition. Six different mixtures with positive and negative Markstein numbers were investigated. The measurements of the mean local laminar burning velocity of turbulent flamelets were used to derive an efficiency parameter, I, which reflects the impact of the Markstein number and turbulent flame stretch - expressed by the turbulent Karlovitz stretch factor - on the local laminar burning velocity of flamelets. The results showed that the efficiency is reduced with increasing turbulence intensity and the reduction can be correlated to unsteady effects. (author)
Absorption and scattering of laser radiation by the diffusion flame of aviation kerosene
Gvozdev, S V; Glova, A F; Dubrovskii, V Yu; Durmanov, S T; Krasyukov, A G; Lysikov, A Yu; Smirnov, G V; Solomakhin, V B
The absorption coefficient of the radiation of a repetitively pulsed Nd : YAG laser with an average output power up to 6 W and of a cw ytterbium optical fibre laser with an output power up to 3 kW was measured in the diffusion flame of aviation kerosene burning on a free surface in the atmospheric air. The absorption coefficient as a function of flame length, radiation power, and radiation intensity, which was varied in the {approx}10{sup 3} - 5 Multiplication-Sign 10{sup 4} W cm{sup -2} range, was obtained for two distances (1 and 2 cm) between the laser beam axis and the surface. The coefficient of radiation absorption by kerosene flame was compared with that in ethanol and kerosene - ethanol mixture flames. The radiation power scattered by a small segment of the kerosene flame irradiated by Nd : YAG laser radiation was measured as a function of longitudinal and azimuthal coordinates. An estimate was made of the total scattered radiation power.
Flame Inhibition by Phosphorus-Containing Compounds over a Range of Equivalence Ratios
Jayaweera, T M; Melius, C F; Pitz, W J; Westbrook, C K; Korobeinichev, O P; Shvartsberg, V M; Shmakov, A G; Rybitskaya, I V; Curran, H
There is much interest in the combustion mechanism of organophosphorus compounds (OPCs) due to their role as potential halon replacements in fire suppression. A continuing investigation of the inhibition activity of organophosphorus compounds under a range of equivalence ratios was performed experimentally and computationally, as measured by the burning velocity. Updates to a previous mechanism were made by the addition and modification of reactions in the mechanism for a more complete description of the recombination reactions. In this work, the laminar flame speed is measured experimentally and calculated numerically for a premixed propane/air flame, under a range of equivalence ratios, undoped and doped with dimethyl methylphosphonate (DMMP). A detailed investigation of the catalytic cycles involved in the recombination of key flame radicals is made for two equivalence ratios, lean and rich. From this, the importance of different catalytic cycles involved in the lean versus rich case is discussed. Although the importance of certain cycles is different under different stoichiometries, the OPCs are similarly effective across the range, demonstrating the robustness of OPCs as flame suppressants. In addition, it is shown that the phosphorus compounds are most active in the high temperature region of the flame. This may, in part, explain their high level of inhibition effectiveness.
In situ flame chemistry tracing by imaging photoelectron photoion coincidence spectroscopy
O�wald, P.; K�hler, M.; Hemberger, P.; Bodi, A.; Gerber, T.; Bierkandt, T.; Akyildiz, E.; Kasper, T.
Adaptation of a low-pressure flat flame burner with a flame-sampling interface to the imaging photoelectron photoion coincidence spectrometer (iPEPICO) of the VUV beamline at the Swiss Light Source is presented. The combination of molecular-beam mass spectrometry and iPEPICO provides a new powerful analytical tool for the detailed investigation of reaction networks in flames. First results demonstrate the applicability of the new instrument to comprehensive flame diagnostics and the potentially high impact for reaction mechanism development for conventional and alternative fuels. Isomer specific identification of stable and radical flame species is demonstrated with unrivaled precision. Radical detection and identification is achieved for the initial H-abstraction products of fuel molecules as well as for the reaction controlling H, O, and OH radicals. Furthermore, quantitative evaluation of changing species concentrations during the combustion process and the applicability of respective results for kinetic model validation are demonstrated. Utilization of mass-selected threshold photoelectron spectra is shown to ensure precise signal assignment and highly reliable spatial profiles.
Effects of CO addition on the characteristics of laminar premixed CH{sub 4}/air opposed-jet flames
Wu, C.-Y. [Advanced Engine Research Center, Kao Yuan University, Kaohsiung County, 821 (China); Chao, Y.-C.; Chen, C.-P.; Ho, C.-T. [Department of Aeronautics and Astronautics, National Cheng Kung University, Tainan, 701 (China); Cheng, T.S. [Department of Mechanical Engineering, Chung Hua University, Hsinchu, 300 (China)
The effects of CO addition on the characteristics of premixed CH{sub 4}/air opposed-jet flames are investigated experimentally and numerically. Experimental measurements and numerical simulations of the flame front position, temperature, and velocity are performed in stoichiometric CH{sub 4}/CO/air opposed-jet flames with various CO contents in the fuel. Thermocouple is used for the determination of flame temperature, velocity measurement is made using particle image velocimetry (PIV), and the flame front position is measured by direct photograph as well as with laser-induced predissociative fluorescence (LIPF) of OH imaging techniques. The laminar burning velocity is calculated using the PREMIX code of Chemkin collection 3.5. The flame structures of the premixed stoichiometric CH{sub 4}/CO/air opposed-jet flames are simulated using the OPPDIF package with GRI-Mech 3.0 chemical kinetic mechanisms and detailed transport properties. The measured flame front position, temperature, and velocity of the stoichiometric CH{sub 4}/CO/air flames are closely predicted by the numerical calculations. Detailed analysis of the calculated chemical kinetic structures reveals that as the CO content in the fuel is increased from 0% to 80%, CO oxidation (R99) increases significantly and contributes to a significant level of heat-release rate. It is also shown that the laminar burning velocity reaches a maximum value (57.5 cm/s) at the condition of 80% of CO in the fuel. Based on the results of sensitivity analysis, the chemistry of CO consumption shifts to the dry oxidation kinetics when CO content is further increased over 80%. Comparison between the results of computed laminar burning velocity, flame temperature, CO consumption rate, and sensitivity analysis reveals that the effect of CO addition on the laminar burning velocity of the stoichiometric CH{sub 4}/CO/air flames is due mostly to the transition of the dominant chemical kinetic steps. (author)
Chemistry of destroying chemical warfare agents in flame. Technical project report, April 1994-May 1995
Korobeinichev, O.P.; Chernov, A.A.; Shvartsberg, V.M.; Il`in, S.B.; Mokrushin, V.V.
The goal of the research is to increase our understanding of flame chemistry of organophosphorus compounds (OPC). This class of chemicals includes chemical warfare agents. (CWAs) such as the nerve agents GB GD and VX, stockpiles of which in the United States and Former Soviet Union are scheduled for destruction by incineration or other technologies. Although high CWA destruction efficiency has been demonstrated in incinerator tests in the U.S. it is necessary to improve technology for achievement higher efficiency and lower level of pollutants. The knowledge of detailed destruction chemistry of the CWA and simulants can be obtained by studying the structure of flames, doped with simulants and CWA and by the development of the combustion model which will include the chemical mechanism of destroying CWA in flame. Alkyl phosphates and alkyl phosphonates are typical organophosphorus compounds, that are simulants of sarin.
Evidence of thermonuclear flame spreading on neutron stars from burst rise oscillations
Chakraborty, Manoneeta; Bhattacharyya, Sudip E-mail: firstname.lastname@example.com
Burst oscillations during the rising phases of thermonuclear X-ray bursts are usually believed to originate from flame spreading on the neutron star surface. However, the decrease of fractional oscillation amplitude with rise time, which provides a main observational support for the flame spreading model, have so far been reported from only a few bursts. Moreover, the non-detection and intermittent detections of rise oscillations from many bursts are not yet understood considering the flame spreading scenario. Here, we report the decreasing trend of fractional oscillation amplitude from an extensive analysis of a large sample of Rossi X-ray Timing Explorer Proportional Counter Array bursts from 10 neutron star low-mass X-ray binaries. This trend is 99.99% significant for the best case, which provides, to the best of our knowledge, by far the strongest evidence of such a trend. Moreover, it is important to note that an opposite trend is not found in any of the bursts. The concave shape of the fractional amplitude profiles for all the bursts suggests latitude-dependent flame speeds, possibly due to the effects of the Coriolis force. We also systematically study the roles of low fractional amplitude and low count rate for non-detection and intermittent detections of rise oscillations, and attempt to understand them within the flame spreading scenario. Our results support a weak turbulent viscosity for flame spreading, and imply that burst rise oscillations originate from an expanding hot spot, thus making these oscillations a more reliable tool to constrain the neutron star equations of state.
Mitigation of thermoacoustic instability utilizing steady air injection near the flame anchoring zone
Murat Altay, H.; Hudgins, Duane E.; Speth, Raymond L.; Annaswamy, Anuradha M.; Ghoniem, Ahmed F.
The objective of this work is to investigate the effectiveness of steady air injection near the flame anchoring zone in suppressing thermoacoustic instabilities driven by flame-vortex interaction mechanism. We perform a systematic experimental study which involves using two different configurations of air injection in an atmospheric pressure backward-facing step combustor. The first configuration utilizes a row of micro-diameter holes allowing for air injection in the cross-stream direction just upstream of the step. The second configuration utilizes an array of micro-diameter holes located on the face of the step, allowing for air injection in the streamwise direction. The effects of each of these configurations are analyzed to determine which one is more effective in suppressing thermoacoustic instabilities at different operating conditions. The tests are conducted while varying the equivalence ratio and the inlet temperature. The secondary air temperature is always the same as the inlet temperature. We used pure propane or propane/hydrogen mixtures as fuels. Combustion dynamics are explored through simultaneous pressure and heat release-rate measurements, and high-speed video images. When the equivalence ratio of the reactant mixture is high, it causes the flame to flashback towards the inlet channel. When air is injected in the cross-stream direction, the flame anchors slightly upstream of the step, which suppresses the instability. When air is injected in the streamwise direction near the edge of step, thermoacoustic instability could be eliminated at an optimum secondary air flow rate, which depends on the operating conditions. When effective, the streamwise air injection prevents the shedding of an unsteady vortex, thus eliminating the flame-vortex interaction mechanism and resulting in a compact, stable flame to form near the step. (author)
Enhancement of a laminar premixed methane/oxygen/nitrogen flame speed using femtosecond-laser-induced plasma
Yu Xin; Peng Jiangbo; Yi Yachao; Zhao Yongpeng; Chen Deying; Yu Junhua [National Key Laboratory of Science and Technology on Tunable Laser, Harbin Institute of Technology, Harbin 150080 (China); Institute of Opto-electronics, Harbin Institute of Technology, Harbin 150080 (China); Yang Peng; Sun Rui [Institute of Combustion Engineering, Harbin Institute of Technology, Harbin 150001 (China)
We first investigate the effects of femtosecond-laser-induced plasma on the flame speed of a laminar premixed methane/oxygen/nitrogen flame with a wide range of the equivalence ratios (0.8-1.05) at atmospheric pressure. It is experimentally found that the flame speed increases 20.5% at equivalence ratios 1.05. The self-emission spectra from the flame and the plasma are studied and an efficient production of active radicals under the action of femtosecond (fs)-laser pulses has been observed. Based on the experimental data obtained, the presence of oxygen atom and hydrocarbon radicals is suggested to be a key factor enhancing flame speed.
Combustion Stability in Complex Engineering Flows | Argonne Leadership
U.S. Department of Energy (DOE) all webpages (Extended Search)
Computing Facility NOx prediction in a swirl-type DLN combustor NOx prediction in a swirl-type DLN combustor: (left) zoom near one-of-six swirling premixers, (right) several axial locations. NOx accumulates in the low-velocity region at the center of the swirling vortex. Virtual testing enables engineers to design next-generation, low-emission combustion systems. Lee Shunn, Cascade Technologies; Shoreh Hajiloo, GE Global Research Combustion Stability in Complex Engineering Flows PI Name: Lee
A laser and molecular beam mass spectrometer study of low-pressure dimethyl ether flames
Andrew McIlroy; Toby D. Hain; Hope A. Michelsen; Terrill A. Cool
The oxidation of dimethyl ether (DME) is studied in low-pressure flames using new molecular beam mass spectrometer and laser diagnostics. Two 30.0-Torr, premixed DME/oxygen/argon flames are investigated with stoichiometries of 0.98 and 1.20. The height above burner profiles of nine stable species and two radicals are measured. These results are compared to the detailed chemical reaction mechanism of Curran and coworkers. Generally good agreement is found between the model and data. The largest discrepancies are found for the methyl radical profiles where the model predicts qualitatively different trends in the methyl concentration with stoichiometry than observed in the experiment.
Adhesion of diamond coatings synthesized by oxygen-acetylene flame CVD on tungsten carbide
Marinkovic, S.; Stankovic, S.; Dekanski, A.
The results of a study concerned with chemical vapor deposition of diamond on tungsten carbide cutting tools using an oxygen-acetylene flame in a normal ambient environment are presented. Effects of preparation conditions on the adhesion of the coating have been investigated, including different surface treatment, different position of the flame with respect to the coated surface, effect of an intermediate poorly crystalline diamond layer, etc. In particular, effect of polishing and ultrasonic lapping with diamond powder was compared with that of a corresponding treatment with SiC powder.
Method for producing flame retardant porous products and products produced thereby
Salyer, I.O.
A method for fire retarding porous products used for thermal energy storage and products produced thereby is provided. The method includes treating the surface of the phase change material-containing porous products with a urea fire-retarding agent. Upon exposure to a flame, the urea forms an adduct with the phase change material which will not sustain combustion (is self-extinguishing) in air. No halogens or metal oxides are contained in the fire retardant, so no potentially noxious halide smoke or fumes are emitted if the product is continuously exposed to a flame. 1 fig.
Method for producing flame retardant porous products and products produced thereby
Salyer, Ival O.
A method for fire retarding porous products used for thermal energy storage and products produced thereby is provided. The method includes treating the surface of the phase change material-containing porous products with a urea fire-retarding agent. Upon exposure to a flame, the urea forms an adduct with the phase change material which will not sustain combustion (is self-extinguishing) in air. No halogens or metal oxides are contained in the fire retardant, so no potentially noxious halide smoke or fumes are emitted if the product is continuously exposed to a flame.
Method for Producing Flame Retardant Porous Products and Products Produced Thereby
Salyer, Ival O.
A method for fire retarding porous products used for thermal energy storage and products produced thereby is provided. The method includes treating the surface of the phase change material-containing porous products with a urea fire-retarding agent. Upon exposure to a flame, the urea forms an adduct with the phase change material which will not sustain combustion (is self-extinguishing) in air. No halogens or metal oxides are contained in the fire retardant, so no potentially noxious halide smoke or fumes are emitted if the product is continuously exposed to a flame.
Ion mobility spectrometer with virtual aperture grid
Pfeifer, Kent B. (Los Lunas, NM); Rumpf, Arthur N. (Albuquerque, NM)
An ion mobility spectrometer does not require a physical aperture grid to prevent premature ion detector response. The last electrodes adjacent to the ion collector (typically the last four or five) have an electrode pitch that is less than the width of the ion swarm and each of the adjacent electrodes is connected to a source of free charge, thereby providing a virtual aperture grid at the end of the drift region that shields the ion collector from the mirror current of the approaching ion swarm. The virtual aperture grid is less complex in assembly and function and is less sensitive to vibrations than the physical aperture grid.
The Conforming Virtual Element Method for the convection-diffusion-reaction equation with variable coeffcients.
Manzini, Gianmarco; Cangiani, Andrea; Sutton, Oliver
This document describes the conforming formulations for virtual element approximation of the convection-reaction-diffusion equation with variable coefficients. Emphasis is given to construction of the projection operators onto polynomial spaces of appropriate order. These projections make it possible the virtual formulation to achieve any order of accuracy. We present the construction of the internal and the external formulation. The difference between the two is in the way the projection operators act on the derivatives (laplacian, gradient) of the partial differential equation. For the diffusive regime we prove the well-posedness of the external formulation and we derive an estimate of the approximation error in the H1-norm. For the convection-dominated case, the streamline diffusion stabilization (aka SUPG) is also discussed.
The parallel virtual file system for portals.
Schutt, James Alan
This report presents the result of an effort to re-implement the Parallel Virtual File System (PVFS) using Portals as the transport. This report provides short overviews of PVFS and Portals, and describes the design and implementation of PVFS over Portals. Finally, the results of performance testing of both stock PVFS and PVFS over Portals are presented.
DOE Sustainability Awards Best Practices Virtual Workshop
The Sustainability Performance Office (SPO) will host a virtual best practices workshop on April 23, 2014 (2:00-3:30 PM EDT) to recognize the winners of the 2013 DOE Sustainability Awards. Award winners will present on their accomplishments and answer brief questions on their programs and projects. Please join us in celebrating the 2013 DOE Sustainability Awards winners.
Ames Lab 101: C6: Virtual Engineering
Ames Laboratory scientist Doug McCorkle explains the importance of virtual engineering and talks about the C6. The C6 is a three-dimensional, fully-immersive synthetic environment residing in the center atrium of Iowa State University's Howe Hall.
Webcast: National Energy Literacy Virtual Town Hall | Department of Energy
Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)
Webcast: National Energy Literacy Virtual Town Hall Webcast: National Energy Literacy Virtual Town Hall Webcast: National Energy Literacy Virtual Town Hall On August 5, 2014, the Department of Energy (DOE) hosted a dynamic virtual conversation of ongoing efforts from across the country in utilizing the Energy Literacy Framework to address one of our nations' biggest national challenges, "Energy Illiteracy." The goal of this webinar was to share resources in energy education and provide
OH-Planar Fluorescence Measurements of Pressurized, Hydrogen Premixed Flames in the SimVal Combustor
Strakey, P.A.; Woodruff, S.D.; Williams, T.C.; Schefer, R.W.
Planar laser-induced fluorescence measurements of the hydroxyl radical in lean, premixed natural gas flames augmented with hydrogen are presented. The experiments were conducted in the Simulation Validation combustor at the National Energy Technology Laboratory at operating pressures from 1 to 8 atmospheres. The data, which were collected in a combustor with well-controlled boundary conditions, are intended to be used for validating computational fluid dynamics models under conditions directly relevant to land-based gas turbine engines. The images, which show significant effects of hydrogen on local flame quenching, are discussed in terms of a turbulent premixed combustion regime and nondimensional parameters such as Karlovitz number. Pressure was found to thin the OH region, but only had a secondary effect on overall flame shape compared with the effects of hydrogen addition, which was found to decrease local quenching and shorten the turbulent flame brush. A method to process the individual images based on local gradients of fluorescence intensity is proposed, and results are presented. Finally, the results of several large eddy simulations are presented and compared with the experimental data in an effort to understand the issues related to model validation, especially for simulations that do not include OH as an intermediate species.
High-Pressure Turbulent Flame Speeds and Chemical Kinetics of Syngas Blends with and without Impurities
Peterson, Eric; Mathieu, Olivier; Morones, Anibal; Ravi, Sankar; Keesee, Charles; Hargis, Joshua; Vivanco, Jose
This Topical Report documents the first year of the project, from October 1, 2013 through September 30, 2014. Efforts for this project included experiments to characterize the atmospheric-pressure turbulent flame speed vessel over a range of operating conditions (fan speeds and turbulent length scales). To this end, a new LDV system was acquired and set up for the detailed characterization of the turbulence field. Much progress was made in the area of impurity kinetics, which included a numerical study of the effect of impurities such as NO2, NO, H2S, and NH3 on ignition delay times and laminar flame speeds of syngas blends at engine conditions. Experiments included a series of laminar flame speed measurements for syngas (CO/H2) blends with various levels of CH4 and C2H6 addition, and the results were compared to the chemical kinetics model of NUI Galway. Also, a final NOx kinetics mechanism including ammonia was assembled, and a journal paper was written and is now in press. Overall, three journal papers and six conference papers related to this project were published this year. Finally, much progress was made on the design of the new high-pressure turbulent flame speed facility. An overall design that includes a venting system was decided upon, and the detailed design is in progress.
Glass composition development for stabilization of lead based paints
Marra, J.C.
Exposure to lead can lead to adverse health affects including permanent damage to the central nervous system. Common means of exposure to lead are from ingestion of lead paint chips or breathing of dust from deteriorating painted surfaces. The U.S. Army has over 101 million square feet of buildings dating to World War II or earlier. Many of these structures were built before the 1978 ban on lead based paints. The U.S. Army Corps of Engineers CERL is developing technologies to remove and stabilize lead containing organic coatings. Promising results have been achieved using a patented flame spray process that utilizes a glass frit to stabilize the hazardous constituents. When the glass frit is sprayed onto the paint containing substrate, differences in thermal expansion coefficients between the frit and the paint results in spalling of the paint from the substrate surface. The removed fragments are then collected and remelted to stabilize the hazardous constituents and allow for disposal as non-hazardous waste. Similar successful results using a patented process involving microwave technology for paint removal have also been achieved. In this process, the painted surface is coated with a microwave coupling compound that when exposed to microwave energy results in the spalling of the hazardous paint from the surface. The fragments can again be accumulated and remelted for stabilization and disposal.
Laminar burning velocities and flame instabilities of butanol isomers-air mixtures
Gu, Xiaolei; Huang, Zuohua; Wu, Si; Li, Qianqian [State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an 710049 (China)
Laminar burning velocities and flame instabilities of the butanol-air premixed flames and its isomers are investigated using the spherically expanding flame with central ignition at initial temperature of 428 K and initial pressures of 0.10 MPa, 0.25 MPa, 0.50 MPa and 0.75 MPa. Laminar burning velocities and sensitivity factor of n-butanol-air mixtures are computed using a newly developed kinetic mechanism. Unstretched laminar burning velocity, adiabatic temperature, Lewis number, Markstein length, critical flame radius and Peclet number are obtained over a wide range of equivalence ratios. Effect of molecular structure on laminar burning velocity of the isomers of butanol is analyzed from the aspect of C-H bond dissociation energy. Study indicates that although adiabatic flame temperatures of the isomers of butanol are the same, laminar burning velocities give an obvious difference among the isomers of butanol. This indicates that molecular structure has a large influence on laminar burning velocities of the isomers of butanol. Branching (-CH3) will decrease laminar burning velocity. Hydroxyl functional group (-OH) attaching to the terminal carbon atoms gives higher laminar burning velocity compared to that attaching to the inner carbon atoms. Calculated dissociation bond energies show that terminal C-H bonds have larger bond energies than that of inner C-H bonds. n-Butanol, no branching and with hydroxyl functional group (-OH) attaching to the terminal carbon atom, gives the largest laminar burning velocity. tert-Butanol, with highly branching and hydroxyl functional group (-OH) attaching to the inner carbon atom, gives the lowest laminar burning velocity. Laminar burning velocities of iso-butanol and sec-butanol are between those of n-butanol and tert-butanol. The instant of transition to cellularity is experimentally determined for the isomers of butanol and subsequently interpreted on the basis of hydrodynamic and diffusion-thermal instabilities. Little effect
Effects of radiation and compression on propagating spherical flames of methane/air mixtures near the lean flammability limit
Chen, Zheng [State Key Laboratory for Turbulence and Complex Systems, Department of Mechanics and Aerospace Engineering, College of Engineering, Peking University, Beijing 100871 (China)
Large discrepancies between the laminar flame speeds and Markstein lengths measured in experiments and those predicted by simulations for ultra-lean methane/air mixtures bring a great concern for kinetic mechanism validation. In order to quantitatively explain these discrepancies, a computational study is performed for propagating spherical flames of lean methane/air mixtures in different spherical chambers using different radiation models. The emphasis is focused on the effects of radiation and compression. It is found that the spherical flame propagation speed is greatly reduced by the coupling between thermal effect (change of flame temperature or unburned gas temperature) and flow effect (inward flow of burned gas) induced by radiation and/or compression. As a result, for methane/air mixtures near the lean flammability limit, the radiation and compression cause large amounts of under-prediction of the laminar flame speeds and Markstein lengths extracted from propagating spherical flames. Since radiation and compression both exist in the experiments on ultra-lean methane/air mixtures reported in the literature, the measured laminar flame speeds and Markstein lengths are much lower than results from simulation and thus cannot be used for kinetic mechanism validation. (author)
RCRA facility stabilization initiative
Not Available
The RCRA Facility Stabilization Initiative was developed as a means of implementing the Corrective Action Program`s management goals recommended by the RIS for stabilizing actual or imminent releases from solid waste management units that threaten human health and the environment. The overall goal of stabilization is to, as situations warrant, control or abate threats to human health and/or the environment from releases at RCRA facilities, and/or to prevent or minimize the further spread of contamination while long-term remedies are pursued. The Stabilization initiative is a management philosophy and should not be confused with stabilization technologies.
Explosion bomb measurements of ethanol-air laminar gaseous flame characteristics at pressures up to 1.4 MPa
Bradley, D.; Lawes, M.; Mansour, M.S. [School of Mechanical Engineering, University of Leeds, Leeds LS2 9JT (United Kingdom)
The principal burning characteristics of a laminar flame comprise the fuel vapour pressure, the laminar burning velocity, ignition delay times, Markstein numbers for strain rate and curvature, the stretch rates for the onset of flame instabilities and of flame extinction for different mixtures. With the exception of ignition delay times, measurements of these are reported and discussed for ethanol-air mixtures. The measurements were in a spherical explosion bomb, with central ignition, in the regime of a developed stable, flame between that of an under or over-driven ignition and that of an unstable flame. Pressures ranged from 0.1 to 1.4 MPa, temperatures from 300 to 393 K, and equivalence ratios were between 0.7 and 1.5. It was important to ensure the relatively large volume of ethanol in rich mixtures at high pressures was fully evaporated. The maximum pressure for the measurements was the highest compatible with the maximum safe working pressure of the bomb. Many of the flames soon became unstable, due to Darrieus-Landau and thermo-diffusive instabilities. This effect increased with pressure and the flame wrinkling arising from the instabilities enhanced the flame speed. Both the critical Peclet number and the, more rational, associated critical Karlovitz stretch factor were evaluated at the onset of the instability. With increasing pressure, the onset of flame instability occurred earlier. The measured values of burning velocity are expressed in terms of their variations with temperature and pressure, and these are compared with those obtained by other researchers. Some comparisons are made with the corresponding properties for iso-octane-air mixtures. (author)
A two-step chemical scheme for kerosene-air premixed flames
Franzelli, B.; Riber, E.; Sanjose, M.; Poinsot, T.
A reduced two-step scheme (called 2S-KERO-BFER) for kerosene-air premixed flames is presented in the context of Large Eddy Simulation of reacting turbulent flows in industrial applications. The chemical mechanism is composed of two reactions corresponding to the fuel oxidation into CO and H{sub 2}O, and the CO - CO{sub 2} equilibrium. To ensure the validity of the scheme for rich combustion, the pre-exponential constants of the two reactions are tabulated versus the local equivalence ratio. The fuel and oxidizer exponents are chosen to guarantee the correct dependence of laminar flame speed with pressure. Due to a lack of experimental results, the detailed mechanism of Dagaut composed of 209 species and 1673 reactions, and the skeletal mechanism of Luche composed of 91 species and 991 reactions have been used to validate the reduced scheme. Computations of one-dimensional laminar flames have been performed with the 2S{sub K}ERO{sub B}FER scheme using the CANTERA and COSILAB softwares for a wide range of pressure ([1; 12] atm), fresh gas temperature ([300; 700] K), and equivalence ratio ([0.6; 2.0]). Results show that the flame speed is correctly predicted for the whole range of parameters, showing a maximum for stoichiometric flames, a decrease for rich combustion and a satisfactory pressure dependence. The burnt gas temperature and the dilution by Exhaust Gas Recirculation are also well reproduced. Moreover, the results for ignition delay time are in good agreement with the experiments. (author)
Apparatus and method for stabilization or oxidation of polymeric materials
Paulauskas, Felix L [Knoxville, TN; Sherman, Daniel M [Knoxville, TN
An apparatus for treating polymeric materials comprises a treatment chamber adapted to maintain a selected atmosphere at a selected temperature; a means for supporting the polymeric material within the chamber; and, a source of ozone-containing gas, which decomposes at the selected temperature yielding at least one reactive oxidative species whereby the polymer is stabilized and cross linked through exposure to the oxidative species in the chamber at the selected temperature. The ozone may be generated by a plasma discharge or by various chemical processes. The apparatus may be configured for either batch-type or continuous-type processing. The apparatus and method are especially useful for preparing polymer fibers, particularly PAN fibers, for later carbonization treatments as well as to make flame-retardant fabrics.
Residential heating oil price virtually unchanged
U.S. Energy Information Administration (EIA) (indexed site)
heating oil price virtually unchanged The average retail price for home heating oil fell 1-tenth of a cent from a week ago to $2.13 per gallon. That's down 76 cents from a year ago, based on the residential heating fuel survey by the U.S. Energy Information Administration. Heating oil prices in the New England region are at $2.07 per gallon, down 2-tenths of a cent from last week, and down 78
DOE Solid-State Lighting program technology fact sheet that addresses key questions about color stability and color shift in LED lighting applications.
Evolution of soot size distribution in premixed ethylene/air and ethylene/benzene/air flames: Experimental and modeling study
Echavarria, Carlos A.; Sarofim, Adel F.; Lighty, JoAnn S.; D'Anna, Andrea
The effect of benzene concentration in the initial fuel on the evolution of soot size distribution in ethylene/air and ethylene/benzene/air flat flames was characterized by experimental measurements and model predictions of size and number concentration within the flames. Experimentally, a scanning mobility particle sizer was used to allow spatially resolved and online measurements of particle concentration and sizes in the nanometer-size range. The model couples a detailed kinetic scheme with a discrete-sectional approach to follow the transition from gas-phase to nascent particles and their coagulation to larger soot particles. The evolution of soot size distribution (experimental and modeled) in pure ethylene and ethylene flames doped with benzene showed a typical nucleation-sized (since particles do not actually nucleate in the classical sense particle inception is often used in place of nucleation) mode close to the burner surface, and a bimodal behavior at greater height above burner (HAB). However, major features were distinguished between the data sets. The growth of nucleation and agglomeration-sized particles was faster for ethylene/benzene/air flames, evidenced by the earlier presence of bimodality in these flames. The most significant changes in size distribution were attributed to an increase in benzene concentration in the initial fuel. However, these changes were more evident for high temperature flames. In agreement with the experimental data, the model also predicted the decrease of nucleation-sized particles in the postflame region for ethylene flames doped with benzene. This behavior was associated with the decrease of soot precursors after the main oxidation zone of the flames. (author)
Flame front imaging in an internal-combustion engine simulator by laser-induced fluorescence of acetaldehyde
Arnold, A.; Becker, H.; Suntz, R.; Monkhouse, P.; Wolfrum, J. ); Maly, R.; Pfister, W. )
Acetaldehyde has been used as a fluorescent dopant for two-dimensional imaging of the flame front in an internal-combustion-engine simulator. The molecule was excited with a XeCl-laser-light sheet at 308 nm, and broadband fluorescence centered at 400 nm was detected. In this way, the flame front could be marked by mapping regions of unburned gas. Also, the intake process into the engine could be followed.
Physical and chemical comparison of soot in hydrocarbon and biodiesel fuel diffusion flames: A study of model and commercial fuels
Matti Maricq, M.
Data are presented to compare soot formation in both surrogate and practical fatty acid methyl ester biodiesel and petroleum fuel diffusion flames. The approach here uses differential mobility analysis to follow the size distributions and electrical charge of soot particles as they evolve in the flame, and laser ablation particle mass spectrometry to elucidate their composition. Qualitatively, these soot properties exhibit a remarkably similar development along the flames. The size distributions begin as a single mode of precursor nanoparticles, evolve through a bimodal phase marking the onset of aggregate formation, and end in a self preserving mode of fractal-like particles. Both biodiesel and hydrocarbon fuels yield a common soot composition dominated by C{sub x}H{sub y}{sup +} ions, stabilomer PAHs, and fullerenes in the positive ion mass spectrum, and C{sub x}{sup -} and C{sub 2x}H{sup -} in the negative ion spectrum. These ion intensities initially grow with height in the diffusion flames, but then decline during later stages, consistent with soot carbonization. There are important quantitative differences between fuels. The surrogate biodiesel fuel methyl butanoate substantially reduces soot levels, but soot formation and evolution in this flame are delayed relative to both soy and petroleum fuels. In contrast, soots from soy and hexadecane flames exhibit nearly quantitative agreement in their size distribution and composition profiles with height, suggesting similar soot precursor chemistry. (author)
Virtual and super - virtual refraction method: Application to synthetic data and 2012 of Karangsambung survey data
Nugraha, Andri Dian; Adisatrio, Philipus Ronnie
Seismic refraction survey is one of geophysical method useful for imaging earth interior, definitely for imaging near surface. One of the common problems in seismic refraction survey is weak amplitude due to attenuations at far offset. This phenomenon will make it difficult to pick first refraction arrival, hence make it challenging to produce the near surface image. Seismic interferometry is a new technique to manipulate seismic trace for obtaining Green's function from a pair of receiver. One of its uses is for improving first refraction arrival quality at far offset. This research shows that we could estimate physical properties such as seismic velocity and thickness from virtual refraction processing. Also, virtual refraction could enhance the far offset signal amplitude since there is stacking procedure involved in it. Our results show super - virtual refraction processing produces seismic image which has higher signal-to-noise ratio than its raw seismic image. In the end, the numbers of reliable first arrival picks are also increased.
Three-dimensional simulations of cellular non-premixed jet flames
Valaer, A.L.; Frouzakis, C.E.; Boulouchos, K.; Papas, P.; Tomboulides, A.G.
The formation, dynamics and structure of cellular flames in circular non-premixed jets are examined with three-dimensional numerical simulations incorporating detailed descriptions of chemistry and transport. Similar to past experiments reported in the literature, CO{sub 2}-diluted hydrogen in diluted or pure oxygen co-flowing streams in the proximity of the extinction limit are considered. As in the experiments, several preferred cellular states are found to co-exist with the particular state realized depending on initial conditions as well as on the jet characteristics. The simulations provide additionally the temporal transitions to different stationary or rotating cellular flames, their detailed structure, and the dependence of the scaling of the realized number of cells with the vorticity thickness. (author)
Soot formation in methane/air nonpremixed flames doped with small quantities of C3 hydrocarbons
McEnally, C.S.; Pfefferle, L.D.
Gas temperature, C1 to C12 stable hydrocarbon concentrations, and soot volume fractions were measured in an axisymmetry methane/air coflowing nonpremixed flame whose fuel was doped with one mole per cent allene, propene, and propane. The additives did not significantly alter the temperature field, methane mole fractions, or chain-carrying radical concentrations. However, soot volume fractions were increased, in the order allene > propene > propane. The hydrocarbon species measurements indicated that soot formation increases because the additives undergo reaction sequences that raise the concentrations of the benzene and phenyl radical precursors C{sub 3}H{sub 3}, C{sub 4}H{sub 3}, and C{sub 4}H{sub 5}, and consequently enhance the benzene/phenyl formation rate. Therefore, creation of these precursors and of the first aromatic ring are crucial rate-limiting soot formation steps in methane flames.
Elimination of dimethyl methylphosphonate by plasma flame made of microwave plasma and burning hydrocarbon fuel
Cho, S. C.; Uhm, H. S.; Hong, Y. C.; Park, Y. G.; Park, J. S.
Elimination of dimethyl methylphosphonate (DMMP) in liquid phase was studied by making use of a microwave plasma burner, exhibiting a safe removal capability of stockpiled chemical weapons. The microwave plasma burner consisted of a fuel injector and a plasma flame exit connected in series to a microwave plasma torch. The burner flames were sustained by injecting hydrocarbon fuels into the microwave plasma torch in air discharge. The Fourier transform infrared spectra indicated near perfect elimination of DMMP in the microwave plasma burner. This was confirmed by gas chromatography spectra as supporting data, revealing the disappearance of even intermediary compounds in the process of DMMP destruction. The experimental results and the physical configuration of the microwave plasma burner may provide an effective means of on-site removal of chemical warfare agents found on a battlefield.
Intumescent flame retardants for polymers. I. The poly(acrylonitrile)-ammonium polyphosphate-hexabromocyclododecane system
Ballistreri, A.; Montaudo, G.; Puglisi, C.; Scamporrino, E.; Vitalini, D.
The influence of ammonium polyphosphate (APP) and hexabromocyclododecane (HBCD) as flame retardant (FR) on poly(acrylonitrile) (PAN) has been examined. The APP-HBCD system behaves as an intumescent flame retardant (IFR) formulation, APP being the char-forming agent and HBCD the blowing agent. A negligible gas-phase mode of action was ascertained for HBCD with this substrate. A synergism between the two FR agents was observed, corresponding to about 50% increased efficacy with respect to the separate effects of the two components. Thermogravimetry (TG), oxygen index (OI), nitrous oxide index (NOI) experiments and phosphorous residue measurements were performed to substantiate the conclusion that a condensed phase mechanism of action accounts for all the facts observed.
Effect of ignition conditions on upward flame spread on a composite material in a corner configuration
Ohlemiller, T.; Cleary, T.; Shields, J.
This paper focuses on the issue of fire growth on composite materials beyond the region immediately subjected to an ignition source. Suppression of this growth is one of the key issues in realizing the safe usage of composite structural materials. A vinyl ester/glass composite was tested in the form of a 90{degrees} comer configuration with an inert ceiling segment 2.44 m above the top of the fire source. The igniter was a propane burner, either 23 or 38 cm in width with power output varied from 30 to 150 Kw. Upward flame spread rate and heat release rate were measured mainly for a brominated vinyl ester resin but limited results were also obtained for a non-flame retarded vinyl ester and a similar composite coated with an intumescent paint. Rapid fire growth beyond the igniter region was seen for the largest igniter power case; the intumescent coating successfully prevented fire growth for this case.
Stabilized radio frequency quadrupole
Lancaster, H.D.; Fugitt, J.A.; Howard, D.R.
Disclosed is a long-vane stabilized radio frequency resonator for accelerating charged particles and including means defining a radio frequency resonator cavity, a plurality of long vanes mounted in the defining means for dividing the cavity into sections, and means interconnecting opposing ones of the plurality of vanes for stabilizing the resonator. 5 figs.
Stabilized radio frequency quadrupole
Lancaster, Henry D.; Fugitt, Jock A.; Howard, Donald R.
A long-vane stabilized radio frequency resonator for accelerating charged particles and including means defining a radio frequency resonator cavity, a plurality of long vanes mounted in the defining means for dividing the cavity into sections, and means interconnecting opposing ones of the plurality of vanes for stabilizing the resonator.
Low and High Temperature Combustion Chemistry of Butanol Isomers in Premixed Flames and Autoignition Systems
Sarathy, S M; Pitz, W J; Westbrook, C K; Mehl, M; Yasunaga, K; Curran, H J; Tsujimura, T; Osswald, P; Kohse-Hoinghaus, K
Butanol is a fuel that has been proposed as a bio-derived alternative to conventional petroleum derived fuels. The structural isomer in traditional 'bio-butanol' fuel is n-butanol, but newer conversion technologies produce iso-butanol as a fuel. In order to better understand the combustion chemistry of bio-butanol, this study presents a comprehensive chemical kinetic model for all the four isomers of butanol (e.g., 1-, 2-, iso- and tert-butanol). The proposed model includes detailed high temperature and low temperature reaction pathways. In this study, the primary experimental validation target for the model is premixed flat low-pressure flame species profiles obtained using molecular beam mass spectrometry (MBMS). The model is also validated against previously published data for premixed flame velocity and n-butanol rapid compression machine and shock tube ignition delay. The agreement with these data sets is reasonably good. The dominant reaction pathways at the various pressures and temperatures studied are elucidated. At low temperature conditions, we found that the reaction of alphahydroxybutyl with O{sub 2} was important in controlling the reactivity of the system, and for correctly predicting C{sub 4} aldehyde profiles in low pressure premixed flames. Enol-keto isomerization reactions assisted by HO{sub 2} were also found to be important in converting enols to aldehydes and ketones in the low pressure premixed flames. In the paper, we describe how the structural features of the four different butanol isomers lead to differences in the combustion properties of each isomer.
Temperature of aircraft cargo flame exposure during accidents involving fuel spills
Mansfield, J.A.
This report describes an evaluation of flame exposure temperatures of weapons contained in alert (parked) bombers due to accidents that involve aircraft fuel fires. The evaluation includes two types of accident, collisions into an alert aircraft by an aircraft that is on landing or take-off, and engine start accidents. Both the B-1B and B-52 alert aircraft are included in the evaluation.
Effects of swirl-flow on flame propagation in a constant-volume vessel
Cai, P.; Watanabe, Kazunori; Obara, Tetsuro; Yoshihashi, Teruo; Ohyagi, Shigeharu
Flame propagation in a closed vessel is one of the fundamental topics in the combustion science and technology. This problem has been studied mostly for application to engine combustion because the combustion processes in a premixed spark ignition engine are well simulated by those processes in a constant-volume combustion chamber. One of the most important objective to study this phenomena is to elucidate the combustion phenomena to increase the thermal efficiency of engine by enhancing the combustion process. In real engines, a number of technical methods such as swirl, tumble, squish and jet flows ere developed to shorten a burning time. All of these methods make use of flows in the combustion chamber. The fundamental problem is then to elucidate a mechanism of reduction of the burning time by the flows and their turbulence. In the present work, experiments were conducted to investigate the effects of swirl-flow on the flame propagation in a disc-shaped constant-volume vessel of 100 mm in diameter and 30 mm in depth. Figure A-1 shows a schematic of the apparatus. Gaseous mixtures used were methane diluted with air at an atmospheric pressure, and their equivalence ratios were varied as a parameter. Ignition timing was varied to change the velocity of swirling flow before the flame propagation. As results, a burning time was found to be decreased as the swirling flow increased and a maximum pressure was increased as the velocity increased as a total heat loss decreased. Flame front structures were clearly observed by the instantaneous schlieren photography.
PLIF measurement of fuel concentration distribution in transient hydrogen jet flame
Tomita, Eiji; Hamamoto, Yoshisuke; Yoshiyama, Sadami; Toda, Hitoshi
To know the concentration field of fuel spray or jet is very important because the following combustion process strongly depends on it. Recently, planar laser induced fluorescence (PLIF) measurement is often used to clarify two-dimensional concentration field of fuel and other species. In this study, PLIF measurement was applied to investigate the concentration distribution of a transient hydrogen jet with combustion. The jet penetrates with entraining ambient air and hydrogen is mixed with the air. Each experimental run of the jet shows different configuration and concentration distribution although averaged jet shows axisymmetric ones. Normalized concentration in radial direction presents Gaussian distribution and normalized concentration in axial direction is expressed by the relation inverse to the axial direction. The mixture was ignited near the nozzle exit after some delay time (t = 3.6ms) during injection ({approximately}11ms). For example, the fuel concentration in the transient jet at t = 1.0 and 1.4ms after the spark ignition (t = 4.6 and 5.0 ms respectively) was obtained as shown in a figure. The behavior of the flame development was measured in the transient flame jet by analyzing these images. The velocities of the jet and flame tips were also determined.
Structure of turbulent hydrogen jet diffusion flames with or without swirl
Takahashi, Fumiaki; Vangsness, M.D.; Durbin, M.D.; Schmoll, W.J.
The aerodynamic and thermal structure of double-concentric turbulent hydrogen jet diffusion flames with or without swirl has been investigated using three-component laser-Doppler velocimetry (LDV) and coherent anti-Stokes Raman spectroscopy. The LDV data were conditionally sampled upon the origin of the fluid (jet, annulus, or external) to avoid the velocity-bias problem and to gain more detailed information on the turbulent structure. As the mean jet velocity was increased, the turbulent flame zone shifted inward and the thermal layer became thinner, whereas swirl created a radial velocity even at the annulus air exit, thereby shifting the flame zone outward and broadening the thermal layer. The probability-density functions (pdf) of velocity components,m their 21 moments (up to fourth order), temperature pdf, mean, and root-mean-square fluctuation temperature were determined at numerous radial locations at seven axial heights in the near field (<26.5 jet diameters). The data can be used to validate computational models.
BioenergizeME Virtual Science Fair: Science & Technology Sustainable
Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)
Transportation Fuels | Department of Energy Science & Technology Sustainable Transportation Fuels BioenergizeME Virtual Science Fair: Science & Technology Sustainable Transportation Fuels BioenergizeME Virtual Science Fair: Science & Technology Sustainable Transportation Fuels This infographic was created by students from Sun Valley High School in Aston, PA, as part of the U.S. Department of Energy-BioenergizeME Virtual Science
CBEI: Virtual Refrigerant Charge Sensing and Load Metering - 2015 Peer
Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)
Review | Department of Energy Virtual Refrigerant Charge Sensing and Load Metering - 2015 Peer Review CBEI: Virtual Refrigerant Charge Sensing and Load Metering - 2015 Peer Review Presenter: James Braun, Purdue University View the Presentation CBEI: Virtual Refrigerant Charge Sensing and Load Metering - 2015 Peer Review (2.39 MB) More Documents & Publications CBEI: FDD for Advanced RTUs - 2015 Peer Review Control and Diagnostics for Rooftop Units - 2014 BTO Peer Review CBEI: Coordinating
Implementing virtual reality interfaces for the geosciences
Bethel, W.; Jacobsen, J.; Austin, A.; Lederer, M.; Little, T.
For the past few years, a multidisciplinary team of computer and earth scientists at Lawrence Berkeley National Laboratory has been exploring the use of advanced user interfaces, commonly called {open_quotes}Virtual Reality{close_quotes} (VR), coupled with visualization and scientific computing software. Working closely with industry, these efforts have resulted in an environment in which VR technology is coupled with existing visualization and computational tools. VR technology may be thought of as a user interface. It is useful to think of a spectrum, ranging the gamut from command-line interfaces to completely immersive environments. In the former, one uses the keyboard to enter three or six-dimensional parameters. In the latter, three or six-dimensional information is provided by trackers contained either in hand-held devices or attached to the user in some fashion, e.g. attached to a head-mounted display. Rich, extensible and often complex languages are a vehicle whereby the user controls parameters to manipulate object position and location in a virtual world, but the keyboard is the obstacle in that typing is cumbersome, error-prone and typically slow. In the latter, the user can interact with these parameters by means of motor skills which are highly developed. Two specific geoscience application areas will be highlighted. In the first, we have used VR technology to manipulate three-dimensional input parameters, such as the spatial location of injection or production wells in a reservoir simulator. In the second, we demonstrate how VR technology has been used to manipulate visualization tools, such as a tool for computing streamlines via manipulation of a {open_quotes}rake.{close_quotes} The rake is presented to the user in the form of a {open_quotes}virtual well{close_quotes} icon, and provides parameters used by the streamlines algorithm.
Residential heating oil prices virtually unchanged
U.S. Energy Information Administration (EIA) (indexed site)
4 Residential heating oil prices virtually unchanged The average retail price for home heating oil rose 2-tenths of a cent from a week ago to $4.24 per gallon. That's up 8.2 cents from a year ago, based on the residential heating fuel survey by the U.S. Energy Information Administration. Heating oil prices in the New England region fell to 4.16 per gallon, down 1.7 cents from last week, and up 3.2 cents from a year ago. This is Marcela Rourk, with EIA, in Washington. For more information,
Residential heating oil prices virtually unchanged
U.S. Energy Information Administration (EIA) (indexed site)
heating oil prices virtually unchanged The average retail price for home heating oil fell 4-tenths of a penny from a week ago to $3.95 per gallon. That's down 8-tenths of a penny from a year ago, based on the residential heating fuel survey by the U.S. Energy Information Administration. Heating oil prices in the New England region rose 3.92 per gallon, up 3-tenths of a cent from last week, and up 3 cents from a year ago
The effect of initial temperature on flame acceleration and deflagration-to-detonation transition phenomenon
Ciccarelli, G.; Boccio, J.L.; Ginsberg, T.; Finfrock, C.; Gerlach, L.; Tagawa, H.; Malliakos, A.
The High-Temperature Combustion Facility at BNL was used to conduct deflagration-to-detonation transition (DDT) experiments. Periodic orifice plates were installed inside the entire length of the detonation tube in order to promote flame acceleration. The orifice plates are 27.3-cm-outer diameter, which is equivalent to the inner diameter of the tube, and 20.6-cm-inner diameter. The detonation tube length is 21.3-meters long, and the spacing of the orifice plates is one tube diameter. A standard automobile diesel engine glow plug was used to ignite the test mixture at one end of the tube. Hydrogen-air-steam mixtures were tested at a range of temperatures up to 650K and at an initial pressure of 0.1 MPa. In most cases, the limiting hydrogen mole fraction which resulted in DDT corresponded to the mixture whose detonation cell size, {lambda}, was equal to the inner diameter of the orifice plate, d (e.g., d/{lambda}=1). The only exception was in the dry hydrogen-air mixtures at 650K where the DDT limit was observed to be 11 percent hydrogen, corresponding to a value of d/{lambda} equal to 5.5. For a 10.5 percent hydrogen mixture at 650K, the flame accelerated to a maximum velocity of about 120 mIs and then decelerated to below 2 mIs. By maintaining the first 6.1 meters of the vessel at the ignition end at 400K, and the rest of the vessel at 650K, the DDT limit was reduced to 9.5 percent hydrogen (d/{lambda}=4.2). This observation indicates that the d/{lambda}=1 DDT limit criteria provides a necessary condition but not a sufficient one for the onset of DDT in obstacle laden ducts. In this particular case, the mixture initial condition (i.e., temperature) resulted in the inability of the mixture to sustain flame acceleration to the point where DDT could occur. It was also observed that the distance required for the flame to accelerate to the point of detonation initiation, referred to as the run-up distance, was found to be a function of both the hydrogen mole fraction
Manipulative Virtual Tools for Tool Mark Characterization | The...
U.S. Department of Energy (DOE) all webpages (Extended Search)
Manipulative Virtual Tools for Tool Mark Characterization DESCRIPTION: The goal of this project is to develop a methodology whereby a three-dimensional (3-D) computer simulation of...
A Stochastic Reactor Based Virtual Engine Model Employing Detailed...
Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)
Detailed Chemistry for Kinetic Studies of In-Cylinder Combustion and Exhaust Aftertreatment A Stochastic Reactor Based Virtual Engine Model Employing Detailed Chemistry for ...
OSTIblog Articles in the DOE Virtual University Topic | OSTI...
Office of Scientific and Technical Information (OSTI)
integrates and makes searchable the disparate and decentralized... Related Topics: DOE Virtual University, mission, National Library of Energy (NLE) - Beta, strategy, training
Virtual Hydropower Prospecting – Searching for Hydropower Gold
Douglas G. Hall
The availability of geographic information system (GIS) tools and analytical modeling of natural streams has made it possible to perform virtual "river inventories" that were formerly done using topographic maps, stream flow estimates, and physical reconnaissance. The Idaho National Laboratory (INL) in collaboration with the U.S. Geological Survey (USGS) virtually assessed the gross power potential of all natural streams in the United States of America and identified feasible potential project sites and estimated their developable power potential. The results of this virtual prospecting have been incorporated into a GIS application called the Virtual Hydropower Prospector that is available for public use on the Internet.
Farm to Flight Virtual Resources | Argonne National Laboratory
U.S. Department of Energy (DOE) all webpages (Extended Search)
Farm to Flight Virtual Resources "Advanced biofuels are important to the aviation ... Farm to Flight - Can Biofuels Green Aviation? exploring this real world challenge. ...
BioenergizeME Virtual Science Fair: Science & Technology Sustainable...
Science & Technology Sustainable Transportation Fuels This infographic was created by ... in Aston, PA, as part of the U.S. Department of Energy-BioenergizeME Virtual Science
The Heavy Ion Fusion Science Virtual National Laboratory
U.S. Department of Energy (DOE) all webpages (Extended Search)
Fusion Science Virtual National Laboratory Python in a Parallel Environment Dave Grote - LLNL & LBNL NUG2013 User Day Wednesday, February 15, 2013 Slide 2 The Heavy Ion Fusion ...
T-588: HP Virtual SAN Appliance Stack Overflow
Office of Energy Efficiency and Renewable Energy (EERE)
A vulnerability has been reported in HP StorageWorks P4000 Virtual SAN Appliance Software, which can be exploited by malicious people to compromise a vulnerable system.
Manipulative Virtual Tools for Tool Mark Characterization | The...
U.S. Department of Energy (DOE) all webpages (Extended Search)
Manipulative Virtual Tools for Tool Mark Characterization FWPProject Description: The goal of this project is to develop a methodology whereby a three-dimensional (3-D) computer...
Surface controlled blade stabilizer
Russell, Larry R.
Drill string stabilizer apparatus, controllable to expand and retract entirely from the surface by control of drill string pressure, wherein increase of drill string pressure from the surface closes a valve to create a piston means which is moved down by drill string pressure to expand the stabilizer blades, said valve being opened and the piston moving upward upon reduction of drill string pressure to retract the stabilizer blades. Upward and downward movements of the piston and an actuator sleeve therebelow are controlled by a barrel cam acting between the housing and the actuator sleeve.
Propagation and extinction of premixed C{sub 5}-C{sub 12}n-alkane flames
Ji, Chunsheng; Dames, Enoch; Wang, Yang L.; Wang, Hai; Egolfopoulos, Fokion N. [Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, CA 90089-1453 (United States)
Laminar flame speeds and extinction strain rates of premixed C{sub 5}-C{sub 12}n-alkane flames were determined at atmospheric pressure and elevated unburned mixture temperatures, over a wide range of equivalence ratios. Experiments were performed in the counterflow configuration and flow velocities were measured using Laser Doppler Velocimetry. The laminar flame speeds were obtained using a non-linear extrapolation technique utilizing numerical simulations of the counterflow experiments with detailed descriptions of chemical kinetics and molecular transport. Compared to linearly extrapolated values, the laminar flame speeds obtained using non-linear extrapolations were found to be 1-4 cm/s lower depending on the equivalence ratio. It was determined that the laminar flame speeds of all n-alkane/air mixtures considered in this investigation are similar to each other and sensitive largely to the H{sub 2}/CO and C{sub 1}-C{sub 4} hydrocarbon kinetics. Additionally, the resistance to extinction decreases as the fuel molecular weight increases. Simulations of the experiments were performed using the recently developed JetSurF 0.2 reaction model consisting of 194 species and 1459 reactions. The laminar flame speeds were predicted with good accuracy for all the n-alkane-air mixtures considered. The experimental extinction strain rates are well predicted by the model for fuel-lean mixtures. For stoichiometric and fuel-rich mixtures, the predicted extinction strain rates are approximately 10% lower than the experimental values. Insights into the physical and chemical processes that control the response of n-alkane flames are provided through detailed sensitivity analyses on both reaction rates and binary diffusion coefficients. (author)
Magnuson, D.W.; Smith, D.F.
High-frequency oscillators for the generation of microwaves, particularly a system for stabilizing frequency-modulated klystron oscillators of the reflex type, are described. The system takos advantage of the fact that a change in oscillator frequency will alter the normal phase displacement between the cavity and its modulator, creating an error voltage which is utilized to regulate the frequency of the oscillator and stabilize it.
Sub-millikelvin stabilization of a closed cycle cryocooler
Dubuis, Guy; He, Xi; Božović, Ivan
In this study, intrinsic temperature oscillations (with the amplitude up to 1 K) of a closed cycle cryocooler are stabilized by a simple thermal damping system. It employs three different materials with different thermal conductivity and capacity at various temperatures. The amplitude of oscillations of the sample temperature is reduced to less than 1 mK, in the temperature range from 4 K to 300 K, while the cooling power is virtually undiminished. The damping system is small, inexpensive, can be retrofitted to most existing closed cycle cryocoolers, and may improve measurements of any temperature-sensitive physics properties.
Influence of a combustion-driven oscillation on global mixing in the flame from a refinery flare
Langman, A.S.; Nathan, G.J.
An assessment of the influence of strong combustion-driven oscillations on mixing rates and visible radiation in the flame from a full-scale refinery flare is reported. Importantly, the oscillations were generated naturally, with no external forcing, and at a high Reynolds number of 4 x 10{sup 6}. These conditions differentiate this study from those of previous investigations, which all involved some external forcing and were at a Re too low to ensure fully turbulent flow within the flame. A frame-by-frame analysis of video footage, providing good resolution of the instantaneous edge of each flame, was used to assess flame dimensions, and so to determine a global residence time. Since the flames are in the fast-chemistry regime, the visual imagers can be used to determine a global mixing rate. The analysis reveals a consistent picture that the combustion-driven oscillations do not result in a significant change to the global mixing rate, but do increase the visible radiation. This is in contrast to previous investigations, using externally forced jets, where forcing at the preferred mode has been found to increase mixing rates and reduce radiation. (author)
On the influence of singlet oxygen molecules on the speed of flame propagation in methane-air mixture
Starik, A.M.; Kozlov, V.E.; Titova, N.S.
The effect of the presence of singlet oxygen molecules O{sub 2}(a{sup 1}{delta}{sub g}) in a CH{sub 4}-air mixture on the speed of laminar flame propagation is considered. The known experimental data on the laminar flame speed and ignition delay are used to validate the developed kinetic model involving electronically excited oxygen molecules O{sub 2}(a{sup 1}{delta}{sub g}) and O{sub 2}(b{sup 1}{sigma}{sub g}{sup +}). Numerical simulation shows that the presence of 10% O{sub 2}(a{sup 1}{delta}{sub g}) in molecular oxygen enables to increase significantly (by a factor of 1.7) the speed of flame propagation in a fuel-lean ({phi}=0.45) methane-air mixture. The main reason for such an acceleration of flame propagation is the intensification of chain reactions due to addition of singlet delta oxygen molecules. For a fuel-rich mixture ({phi}=1.9), the growth in the flame speed is significantly smaller and attains a factor of 1.4. (author)
Determination, correlation, and mechanistic interpretation of effects of hydrogen addition on laminar flame speeds of hydrocarbon�air mixtures
Tang, C. L.; Huang, Z. H.; Law, C. K.
The stretch-affected propagation speeds of expanding spherical flames of n-butane�air mixtures with hydrogen addition were measured at atmospheric pressure and subsequently processed through a nonlinear regression analysis to yield the stretch-free laminar flame speeds. Based on a hydrogen addition parameter (RH) and an effective fuel equivalence ratio (?F), these laminar flame speeds were found to increase almost linearly with RH, for ?F between 0.6 and 1.4 and RHRH from 0 to 0.5, with the slope of the variation assuming a minimum around stoichiometry. These experimental results also agree well with computed values using a detailed reaction mechanism. Furthermore, a mechanistic investigation aided by sensitivity analysis identified that kinetic effects through the global activation energy, followed by thermal effects through the adiabatic flame temperature, have the most influence on the increase in the flame speeds and the associated linear variation with RH due to hydrogen addition. Nonequidiffusion effects due to the high mobility of hydrogen, through the global Lewis number, have the least influence. Further calculations for methane, ethene, and propane as the fuel showed similar behavior, leading to possible generalization of the phenomena and correlation.
A Study of Strain Rate Effects for Turbulent Premixed Flames with Application to LES of a Gas Turbine Combustor Model
Kemenov, Konstantin A.; Calhoon, William H.
Large-scale strain rate field, a resolved quantity which is easily computable in large-eddy simulations (LES), could have profound effects on the premixed flame properties by altering the turbulent flame speed and inducing local extinction. The role of the resolved strain rate has been investigated in a posterior LES study of GE lean premixed dry low NOx emissions LM6000 gas turbine combustor model. A novel approach which is based on the coupling of the lineareddy model with a one-dimensional counter-flow solver has been applied to obtain the parameterizations of the resolved premixed flame properties in terms of the reactive progress variable,more » the local strain rate measure, and local Reynolds and Karlovitz numbers. The strain rate effects have been analyzed by comparing LES statistics for several models of the turbulent flame speed, i.e, with and without accounting for the local strain rate effects, with available experimental data. The sensitivity of the simulation results to the inflow velocity conditions as well as the grid resolution have been also studied. Overall, the results suggest the necessity to represent the strain rate effects accurately in order to improve LES modeling of the turbulent flame speed.« less
Effects of Turbulence on the Combustion Properties of Partially Premixed Flames of Canola Methyl Ester and Diesel Blends
Dhamale, N.; Parthasarathy, R. N.; Gollahalli, S. R.
Canola methyl ester (CME) is a biofuel that is a renewable alternative energy resource and is produced by the transesterification of canola oil. The objective of this study was to document the effects of turbulence on the combustion characteristics of blends of CME and No 2 diesel fuel in a partially-premixed flame environment. The experiments were conducted with mixtures of pre-vaporized fuel and air at an initial equivalence ratio of 7 and three burner exit Reynolds numbers, 2700, 3600, and 4500. Three blends with 25, 50, and 75% volume concentration of CME were studied. The soot volume fraction was highestmore » for the pure diesel flames and did not change significantly with Reynolds number due to the mutually compensating effects of increased carbon input rate and increased air entrainment as the Reynolds number was increased. The global NOx emission index was highest and the CO emission index was the lowest for the pure CME flame, and varied non-monotonically with biofuel content in the blend The mean temperature and the NOx concentration at three-quarter flame height were generally correlated, indicating that the thermal mechanism of NOx formation was dominant in the turbulent biofuel flames also.« less
A Study of Strain Rate Effects for Turbulent Premixed Flames with Application to LES of a Gas Turbine Combustor Model
Kemenov, Konstantin A.; Calhoon, William H.
Large-scale strain rate field, a resolved quantity which is easily computable in large-eddy simulations (LES), could have profound effects on the premixed flame properties by altering the turbulent flame speed and inducing local extinction. The role of the resolved strain rate has been investigated in a posterior LES study of GE lean premixed dry low NOx emissions LM6000 gas turbine combustor model. A novel approach which is based on the coupling of the lineareddy model with a one-dimensional counter-flow solver has been applied to obtain the parameterizations of the resolved premixed flame properties in terms of the reactive progress variable, the local strain rate measure, and local Reynolds and Karlovitz numbers. The strain rate effects have been analyzed by comparing LES statistics for several models of the turbulent flame speed, i.e, with and without accounting for the local strain rate effects, with available experimental data. The sensitivity of the simulation results to the inflow velocity conditions as well as the grid resolution have been also studied. Overall, the results suggest the necessity to represent the strain rate effects accurately in order to improve LES modeling of the turbulent flame speed.
An object-oriented extension for debugging the virtual machine
Pizzi, R.G. Jr.
A computer is nothing more then a virtual machine programmed by source code to perform a task. The program`s source code expresses abstract constructs which are compiled into some lower level target language. When a virtual machine breaks, it can be very difficult to debug because typical debuggers provide only low-level target implementation information to the software engineer. We believe that the debugging task can be simplified by introducing aspects of the abstract design and data into the source code. We introduce OODIE, an object-oriented extension to programming languages that allows programmers to specify a virtual environment by describing the meaning of the design and data of a virtual machine. This specification is translated into symbolic information such that an augmented debugger can present engineers with a programmable debugging environment specifically tailored for the virtual machine that is to be debugged.
Methods and systems relating to an augmented virtuality environment
Nielsen, Curtis W; Anderson, Matthew O; McKay, Mark D; Wadsworth, Derek C; Boyce, Jodie R; Hruska, Ryan C; Koudelka, John A; Whetten, Jonathan; Bruemmer, David J
Systems and methods relating to an augmented virtuality system are disclosed. A method of operating an augmented virtuality system may comprise displaying imagery of a real-world environment in an operating picture. The method may further include displaying a plurality of virtual icons in the operating picture representing at least some assets of a plurality of assets positioned in the real-world environment. Additionally, the method may include displaying at least one virtual item in the operating picture representing data sensed by one or more of the assets of the plurality of assets and remotely controlling at least one asset of the plurality of assets by interacting with a virtual icon associated with the at least one asset.
Towards secure virtual directories : a risk analysis framework.
Claycomb, William R.
Directory services are used by almost every enterprise computing environment to provide data concerning users, computers, contacts, and other objects. Virtual directories are components that provide directory services in a highly customized manner. Unfortunately, though the use of virtual directory services are widespread, an analysis of risks posed by their unique position and architecture has not been completed. We present a detailed analysis of six attacks to virtual directory services, including steps for detection and prevention. We also describe various categories of attack risks, and discuss what is necessary to launch an attack on virtual directories. Finally, we present a framework to use in analyzing risks to individual enterprise computing virtual directory instances. We show how to apply this framework to an example implementation, and discuss the benefits of doing so.
Combustion characteristics of pulverized coal and air/gas premixed flame in a double swirl combustor
Kamal, M.M.
An experimental work was performed to investigate the co-firing of pulverized coal and premixed gas/air streams in a double swirl combustor. The results showed that the NOx emissions are affected by the relative rates of thermal NOx formation and destruction via the pyrolysis of the fuel-N species in high temperature fuel-rich zones. Various burner designs were tested in order to vary the temperature history and the residence time across both coal and gas flames inside the furnace. It was found that by injecting the coal with a gas/air mixture as a combined central jet surrounded by a swirled air stream, a double flame envelope develops with high temperature fuel-rich conditions in between the two reaction zones such that the pyrolysis reactions to N{sub 2} are accelerated. A further reduction in the minimum NOx emissions, as well as in the minimum CO concentrations, was reported for the case where the coal particles are fed with the gas/air mixture in the region between the two swirled air streams. On the other hand, allocating the gas/air mixture around the swirled air-coal combustion zone provides an earlier contact with air and retards the NOx reduction mechanism in such a way that the elevated temperatures around the coal particles allow higher overall NOx emissions. The downstream impingement of opposing air jets was found more efficient than the impinging of particle non-laden premixed flames for effective NOx reduction. In both cases, there is an upstream flow from the stagnation region to the coal primary combustion region, but with the case of air impingement, the hot fuel-rich zone develops earlier. The optimum configuration was found by impinging all jets of air and coal-gas/air mixtures that pronounced minimum NOx and CO concentrations of 310 and 480ppm, respectively.
Virtuality Distributions and Pion Transition Form Factor
Radyushkin, Anatoly V.
Using the example of hard exclusive transition process γ*γ → π0 at the handbag level, we outline basics of a new approach to transverse momentum dependence in hard processes. In coordinate representation, matrix elements of operators (in the simplest case, bilocal O(0,z)) describing a hadron with momentum p, are functions of (pz) and z2 parametrized through virtuality distribution amplitudes (VDA) Φ(x, σ), with x being Fourier-conjugate to (pz) and σ Laplace-conjugate to z2. For intervals with z+=0, we introduce the transverse momentum distribution amplitude (TMDA) Ψ(x, k_perp), and write it in terms of VDA Φ(x,σ). We propose models for softmore » VDAs/TMDAs, and use them for comparison of handbag results with experimental (BaBar and BELLE) data. We also discuss the generation of hard tails of TMDAs from initially soft forms.« less
Extension of a Virtual Refrigerant Charge Sensor
Kim, Woohyun; Braun, J.
The primary goal of the work described in this paper was to evaluate and extend a virtual refrigerant charge sensor (VRC) for determining refrigerant charge for equipment having variable-speed compressors and fans. To evaluate the accuracy of the VRC, data were first collected from previous laboratory tests for different systems and over a wide range of operating conditions. In addition, new laboratory tests were performed to consider conditions not available within the existing data set. The systems for the new laboratory tests were two residential ductless split heat pump systems that employ a variable-speed compressor and R-410a as the refrigerant. Based on the evaluations, the original virtual charge sensor (termed model I) was found to work well in estimating the refrigerant charge for systems with a variable-speed compressor under many operating conditions. However, for extreme test conditions such as low outdoor temperatures and low compressor speed, the VRC needed to be improved. To overcome the limitations, the model associated with the VRC sensor was modified to include a term involving the inlet quality to the evaporator estimated from the condenser outlet condition (termed model II). Both model I and II showed good performance in terms of predicting charge levels for systems with a constant speed compressor, but model II gave better performance for systems with a variable-speed compressor. However, when the superheat of the compressor was zero, neither model I nor II could accurately predict charge level. Therefore, a third approach (Model III) was developed that includes the discharge superheat of the compressor. This model improved performance for a laboratory-tested system that included a number of points with no superheat entering the compressor.
Fiber optic spectroscopic digital imaging sensor and method for flame properties monitoring
Zelepouga, Serguei A.; Rue, David M.; Saveliev, Alexei V.
A system for real-time monitoring of flame properties in combustors and gasifiers which includes an imaging fiber optic bundle having a light receiving end and a light output end and a spectroscopic imaging system operably connected with the light output end of the imaging fiber optic bundle. Focusing of the light received by the light receiving end of the imaging fiber optic bundle by a wall disposed between the light receiving end of the fiber optic bundle and a light source, which wall forms a pinhole opening aligned with the light receiving end.
Systems and methods for detecting a flame in a fuel nozzle of a gas turbine
Kraemer, Gilbert Otto; Storey, James Michael; Lipinski, John; Mestroni, Julio Enrique; Williamson, David Lee; Marshall, Jason Randolph; Krull, Anthony
A system may detect a flame about a fuel nozzle of a gas turbine. The gas turbine may have a compressor and a combustor. The system may include a first pressure sensor, a second pressure sensor, and a transducer. The first pressure sensor may detect a first pressure upstream of the fuel nozzle. The second pressure sensor may detect a second pressure downstream of the fuel nozzle. The transducer may be operable to detect a pressure difference between the first pressure sensor and the second pressure sensor.
Turbulent Flame Speeds and NOx Kinetics of HHC Fuels with Contaminants and High Dilution Levels
Petersen, Eric; Krejci, Michael; Mathieu, Olivier; Vissotski, Andrew; Ravi, Sankar; Sikes, Travis; Levacque, Anthony; Aul, Christopher; Peterson, Eric
This progress report documents the first year of the project, from October 1, 2010 through September 30, 2011. Laminar flame speeds and ignition delay times have been measured for hydrogen and various compositions of H2/CO (syngas) at elevated pressures and elevated temperatures. Two constant-volume cylindrical vessels were used to visualize the spherical growth of the flame through the use of a schlieren optical setup to measure the laminar flame speed of the mixture. Hydrogen experiments were performed at initial pressures up to 10 atm and initial temperatures up to 443 K. A syngas composition of 50/50 was chosen to demonstrate the effect of carbon monoxide on H2-O2 chemical kinetics at standard temperature and pressures up to 10 atm. All atmospheric mixtures were diluted with standard air, while all elevated-pressure experiments were diluted with a He:O2 of 7:1 to minimize hydrodynamic instabilities. The laminar flame speed measurements of hydrogen and syngas are compared to available literature data over a wide range of equivalence ratios where good agreement can be seen with several data sets. Additionally, an improved chemical kinetics model is shown for all conditions within the current study. The model and the data presented herein agree well, which demonstrates the continual, improved accuracy of the chemical kinetics model. A high-pressure shock tube was used to measure ignition delay times for several baseline compositions of syngas at three pressures across a wide range of temperatures. The compositions of syngas (H2/CO) presented in this study include 80/20, 50/50, 40/60, 20/80, and 10/90, all of which are compared to previously published ignition delay times from a hydrogen-oxygen mixture to demonstrate the effect of carbon monoxide addition. Generally, an increase in carbon monoxide increases the ignition delay time, but there does seem to be a pressure dependency. At low temperatures and pressures higher than about 12 atm, the ignition delay times
Predictions of Transient Flame Lift-Off Length With Comparison to Single-Cylinder Optical Engine Experiments
Senecal, P. K.; Pomraning, E.; Anders, J. W.; Weber, M. R.; Gehrke, C. R.; Polonowski, C. J.; Mueller, C. J.
A state-of-the-art, grid-convergent simulation methodology was applied to three-dimensional calculations of a single-cylinder optical engine. A mesh resolution study on a sector-based version of the engine geometry further verified the RANS-based cell size recommendations previously presented by Senecal et al. ("Grid Convergent Spray Models for Internal Combustion Engine CFD Simulations," ASME Paper No. ICEF2012-92043). Convergence of cylinder pressure, flame lift-off length, and emissions was achieved for an adaptive mesh refinement cell size of 0.35 mm. Furthermore, full geometry simulations, using mesh settings derived from the grid convergence study, resulted in excellent agreement with measurements of cylinder pressure, heat release rate,more » and NOx emissions. On the other hand, the full geometry simulations indicated that the flame lift-off length is not converged at 0.35 mm for jets not aligned with the computational mesh. Further simulations suggested that the flame lift-off lengths for both the nonaligned and aligned jets appear to be converged at 0.175 mm. With this increased mesh resolution, both the trends and magnitudes in flame lift-off length were well predicted with the current simulation methodology. Good agreement between the overall predicted flame behavior and the available chemiluminescence measurements was also achieved. Our present study indicates that cell size requirements for accurate prediction of full geometry flame lift-off lengths may be stricter than those for global combustion behavior. This may be important when accurate soot predictions are required.« less
Predictions of Transient Flame Lift-Off Length With Comparison to Single-Cylinder Optical Engine Experiments
Senecal, P. K.; Pomraning, E.; Anders, J. W.; Weber, M. R.; Gehrke, C. R.; Polonowski, C. J.; Mueller, C. J.
A state-of-the-art, grid-convergent simulation methodology was applied to three-dimensional calculations of a single-cylinder optical engine. A mesh resolution study on a sector-based version of the engine geometry further verified the RANS-based cell size recommendations previously presented by Senecal et al. ("Grid Convergent Spray Models for Internal Combustion Engine CFD Simulations," ASME Paper No. ICEF2012-92043). Convergence of cylinder pressure, flame lift-off length, and emissions was achieved for an adaptive mesh refinement cell size of 0.35 mm. Furthermore, full geometry simulations, using mesh settings derived from the grid convergence study, resulted in excellent agreement with measurements of cylinder pressure, heat release rate, and NOx emissions. On the other hand, the full geometry simulations indicated that the flame lift-off length is not converged at 0.35 mm for jets not aligned with the computational mesh. Further simulations suggested that the flame lift-off lengths for both the nonaligned and aligned jets appear to be converged at 0.175 mm. With this increased mesh resolution, both the trends and magnitudes in flame lift-off length were well predicted with the current simulation methodology. Good agreement between the overall predicted flame behavior and the available chemiluminescence measurements was also achieved. Our present study indicates that cell size requirements for accurate prediction of full geometry flame lift-off lengths may be stricter than those for global combustion behavior. This may be important when accurate soot predictions are required.
Computational and experimental study of the effects of adding dimethyl ether and ethanol to nonpremixed ethylene/air flames
Bennett, Beth Anne V.; McEnally, Charles S.; Pfefferle, Lisa D.; Smooke, Mitchell D.; Colket, Meredith B.
Two sets of axisymmetric laminar coflow flames, each consisting of ethylene/air nonpremixed flames with various amounts (up to 10%) of either dimethyl ether (CH{sub 3}-O-CH{sub 3}) or ethanol (CH{sub 3}-CH{sub 2}-OH) added to the fuel stream, have been examined both computationally and experimentally. Computationally, the local rectangular refinement method, which incorporates Newton's method, is used to solve the fully coupled nonlinear conservation equations on solution-adaptive grids for each flame in two spatial dimensions. The numerical model includes C6 chemical kinetic mechanisms with up to 59 species, detailed transport, and an optically thin radiation submodel. Experimentally, thermocouples are used to measure gas temperatures, and mass spectrometry is used to determine concentrations of over 35 species along the flame centerline. Computational results are examined throughout each flame, and validation of the model occurs through comparison with centerline measurements. Very good agreement is observed for temperature, major species, and several minor species. As the level of additive is increased, temperatures, some major species (CO{sub 2}, C{sub 2}H{sub 2}), flame lengths, and residence times are essentially unchanged. However, peak centerline concentrations of benzene (C{sub 6}H{sub 6}) increase, and this increase is largest when dimethyl ether is the additive. Computational and experimental results support the hypothesis that the dominant pathway to C{sub 6}H{sub 6} formation begins with the oxygenates decomposing into methyl radical (CH{sub 3}), which combines with C2 species to form propargyl (C{sub 3}H{sub 3}), which reacts with itself to form C{sub 6}H{sub 6}. (author)
Warren, J.A. ); Langer, J.S. )
We propose an approximate method for studying steady-state properties and linear stability of the dendritic arrays that are formed in directional solidification of alloys. Our analysis is valid at high growth rates where the primary spacing between dendrites is larger than the velocity-dependent solutal diffusion length. We compute a neutral stability boundary and find that, in the situations where we expect our results to be valid, the experimental data of Somboonsuk, Mason, and Trivedi (Metall. Trans. A 15A, 967 (1984)) lie in the stable region, well away from the boundary.
Dinwoodie, Thomas L.
A stabilized PV system comprises an array of photovoltaic (PV) assemblies mounted to a support surface. Each PV assembly comprises a PV module and a support assembly securing the PV module to a position overlying the support surface. The array of modules is circumscribed by a continuous, belt-like perimeter assembly. Cross strapping, extending above, below or through the array, or some combination of above, below and through the array, secures a first position along the perimeter assembly to at least a second position along the perimeter assembly thereby stabilizing the array against wind uplift forces. The first and second positions may be on opposite sides on the array.
Temperature, Oxygen, and Soot-Volume-Fraction Measurements in a Turbulent C2H4-Fueled Jet Flame
Kearney, Sean P.; Guildenbecher, Daniel Robert; Winters, Caroline; Farias, Paul Abraham; Grasser, Thomas W.; Hewson, John C.
We present a detailed set of measurements from a piloted, sooting, turbulent C 2 H 4 - fueled diffusion flame. Hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (CARS) is used to monitor temperature and oxygen, while laser-induced incandescence (LII) is applied for imaging of the soot volume fraction in the challenging jet-flame environment at Reynolds number, Re = 20,000. Single-laser shot results are used to map the mean and rms statistics, as well as probability densities. LII data from the soot-growth region of the flame are used to benchmark the soot source term for one-dimensional turbulence (ODT) modeling of this turbulent flame. The ODT code is then used to predict temperature and oxygen fluctuations higher in the soot oxidation region higher in the flame.
Nanostructures for enzyme stabilization
Kim, Jungbae; Grate, Jay W.; Wang, Ping
The last decade has witnessed notable breakthroughs in nanotechnology with development of various nanostructured materials such as mesoporous materials and nanoparticles. These nanostructures have been used as a host for enzyme immobilization via various approaches, such as enzyme adsorption, covalent attachment, enzyme encapsulation, and sophisticated combinations of methods. This review discusses the stabilization mechanisms behind these diverse approaches; such as confinement, pore size and volume, charge interaction, hydrophobic interaction, and multipoint attachment. In addition, we will introduce recent rigorous approaches to improve the enzyme stability in these nanostructures or develop new nanostructures for the enzyme stabilization. Especially, we will introduce our recent invention of a nanostructure, called single enzyme nanoparticles (SENs). In the form of SENs, each enzyme molecule is surrounded with a nanometer scale network, resulting in stabilization of enzyme activity without any serious limitation for the substrate transfer from solution to the active site. SENs can be further immobilized into mesoporous silica with a large surface area, providing a hierarchical approach for stable, immobilized enzyme systems for various applications, such as bioconversion, bioremediation, and biosensors.
Anderson, O.A.
A device for heating and confining a high temperature gas or plasma utilizing the linear pinch effect is described. The pinch discharge produced is the form of an elongated cylinder. The electrical discharge current is returned in parallel along an axial and a concentric conductor whereby the magnetic field of the conductors compresses and stabilizes the pinch discharge against lateral instability. (AEC)
Donnelly, William; Jacobson, Ted
The requirements for stability of a Lorentz violating theory are analyzed. In particular we conclude that Einstein-aether theory can be stable when its modes have any phase velocity, rather than only the speed of light as was argued in a recent paper.
Stabilized chromium oxide film
Garwin, Edward L.; Nyaiesh, Ali R.
Stabilized air-oxidized chromium films deposited on high-power klystron ceramic windows and sleeves having a thickness between 20 and 150.ANG. are useful in lowering secondary electron emission yield and in avoiding multipactoring and window failure due to overheating. The ceramic substrate for the film is chosen from alumina, sapphire or beryllium oxide.
Stabilized chromium oxide film
Nyaiesh, A.R.; Garwin, E.L.
Stabilized air-oxidized chromium films deposited on high-power klystron ceramic windows and sleeves having a thickness between 20 and 150A are useful in lowering secondary electron emission yield and in avoiding multipactoring and window failure due to overheating. The ceramic substrate for the film is chosen from alumina, sapphire or beryllium oxide.
NOx reduction in diesel fuel flames by additions of water and CO{sub 2}
Li, S.C.
Natural gas has the highest heating value per unit mass (50.1 MJ/kg, LHV) of any of the hydrocarbon fuels (e.g., butane, liquid diesel fuel, gasoline, etc.). Since it has the lowest carbon content per unit mass, combustion of natural gas produces much less carbon dioxide, soot particles, and oxide of nitrogen than combustion of liquid diesel fuel. In view of anticipated strengthening of regulations on pollutant emissions from diesel engines, alternative fuels, such as compressed natural gas (CNG) and liquefied natural gas (LNG) have been experimentally introduced to replace the traditional diesel fuels in heavy-duty trucks, transit buses, off-road vehicles, locomotives, and stationary engines. To help in applying natural gas in Diesel engines and increasing combustion efficiency, the emphasis of the present paper is placed on the detailed flame chemistry of methane-air combustion. The present work is the continued effort in finding better methods to reduce NO{sub x}. The goal is to identify a reliable chemical reaction mechanism for natural gas in both premixed and diffusion flames and to establish a systematic reduced mechanism which may be useful for large-scale numerical modeling of combustion behavior in natural gas engines.
Proceedings of the international workshop on measurement and computation of turbulent nonpremixed flames
Barlow, R.S.
This report documents the proceedings of the International Workshop on Measurement and Computation of Turbulent Nonpremixed Flames, held in Naples, Italy on July 26--27, 1996. Contents include materials that were distributed to participants at the beginning of the workshop, as well as a Summary of Workshop Accomplishments that was generated at the close to this Naples meeting. The Naples workshop involved sixty-one people from eleven countries. The primary objectives were: (1) to select a set of well-documented and relatively simple flames that would be appropriate for collaborative comparisons of model predictions; and (2) to specify common submodels to be used in these predictions, such that models for the coupling of turbulence and chemistry might be isolated and better understood. Studies involve hydrogen and natural gas fuels. These proceedings are also published on the Web and those interested in the ongoing process of data selection and model comparison should consult the workshop page for the most recent and complete information on these collaborative research efforts. The URL is: http://www/ca.sandia/gov/tdf/Workshop.html.
Transported PDF Modeling of Nonpremixed Turbulent CO/H-2/N-2 Jet Flames
Zhao, xinyu; Haworth, D. C.; Huckaby, E. David
Turbulent CO/H{sub 2}/N{sub 2} (�syngas�) flames are simulated using a transported composition probability density function (PDF) method. A consistent hybrid Lagrangian particle/Eulerian mesh algorithm is used to solve the modeled PDF transport equation. The model includes standard k�? turbulence, gradient transport for scalars, and Euclidean minimum spanning tree (EMST) mixing. Sensitivities of model results to variations in the turbulence model, the treatment of radiation heat transfer, the choice of chemical mechanism, and the PDF mixing model are explored. A baseline model reproduces the measured mean and rms temperature, major species, and minor species profiles reasonably well, and captures the scaling that is observed in the experiments. Both our results and the literature suggest that further improvements can be realized with adjustments in the turbulence model, the radiation heat transfer model, and the chemical mechanism. Although radiation effects are relatively small in these flames, consideration of radiation is important for accurate NO prediction. Chemical mechanisms that have been developed specifically for fuels with high concentrations of CO and H{sub 2} perform better than a methane mechanism that was not designed for this purpose. It is important to account explicitly for turbulence�chemistry interactions, although the details of the mixing model do not make a large difference in the results, within reasonable limits.
Designing user models in a virtual cave environment
Brown-VanHoozer, S.; Hudson, R.; Gokhale, N.
In this paper, the results of a first study into the use of virtual reality for human factor studies and design of simple and complex models of control systems, components, and processes are described. The objective was to design a model in a virtual environment that would reflect more characteristics of the user`s mental model of a system and fewer of the designer`s. The technology of a CAVE{trademark} virtual environment and the methodology of Neuro Linguistic Programming were employed in this study.
onVCP - Virtual Community Platform | Argonne National Laboratory
U.S. Department of Energy (DOE) all webpages (Extended Search)
omega OMEGA and OMEGA EP Two glass laser systems make up the Omega Laser Facility: the 60-beam, 30kJ UV OMEGA laser that has been operational since 1995, and the OMEGA EP addition with four new beamlines that was completed in 2008. Each of OMEGA EP's beamlines can deliver 6.5 kJ UV to one side of a target. Two of the
onVCP - Virtual Community Platform onVCP - Virtual Community Platform Uniting government, non-governmental, and private-sector partners through the capability rich online Virtual
High-temperature aerosol formation in wood pellets flames: Spatially resolved measurements
Wiinikka, Henrik; Gebart, Rikard; Boman, Christoffer; Bostroem, Dan; Nordin, Anders; OEhman, Marcus
The formation and evolution of high-temperature aerosols during fixed bed combustion of wood pellets in a realistic combustion environment were investigated through spatially resolved experiments. The purpose of this work was to investigate the various stages of aerosol formation from the hot flame zone to the flue gas channel. The investigation is important both for elucidation of the formation mechanisms and as a basis for development and validation of particle formation models that can be used for design optimization. Experiments were conducted in an 8-kW-updraft fired-wood-pellets combustor. Particle samples were withdrawn from the centerline of the combustor through 10 sampling ports by a rapid dilution sampling probe. The corresponding temperatures at the sampling positions were in the range 200-1450{sup o}C. The particle sample was size-segregated in a low-pressure impactor, allowing physical and chemical resolution of the fine particles. The chemical composition of the particles was investigated by SEM/EDS and XRD analysis. Furthermore, the experimental results were compared to theoretical models for aerosol formation processes. The experimental data show that the particle size distribution has two peaks, both of which are below an aerodynamic diameter of 2.5 {mu}m (PM{sub 2.5}). The mode diameters of the fine and coarse modes in the PM{sub 2.5} region were {approx}0.1 and {approx}0.8 {mu}m, respectively. The shape of the particle size distribution function continuously changes with position in the reactor due to several mechanisms. Early, in the flame zone, both the fine mode and the coarse mode in the PM{sub 2.5} region were dominated by particles from incomplete combustion, indicated by a significant amount of carbon in the particles. The particle concentrations of both the fine and the coarse mode decrease rapidly in the hot oxygen-rich flame due to oxidation of the carbon-rich particles. After the hot flame, the fine mode concentration and particle
Surface-stabilized gold nanocatalysts
Dai, Sheng [Knoxville, TN; Yan, Wenfu [Oak Ridge, TN
A surface-stabilized gold nanocatalyst includes a solid support having stabilizing surfaces for supporting gold nanoparticles, and a plurality of gold nanoparticles having an average particle size of less than 8 nm disposed on the stabilizing surfaces. The surface-stabilized gold nanocatalyst provides enhanced stability, such as at high temperature under oxygen containing environments. In one embodiment, the solid support is a multi-layer support comprising at least a first layer having a second layer providing the stabilizing surfaces disposed thereon, the first and second layer being chemically distinct.
Virtual sine arm kinematic mount system
Xu, Z.; Randall, K.J.
A novel kinematic mount system for a vertical focusing mirror of the soft x-ray spectroscopy beamline at the Advanced Photon Source is described. The system contains three points in a horizontal plane. Each point consists of two horizontal linear precision stages, a spherical ball bearing, and a vertical precision stage. The horizontal linear stages are aligned orthogonally and are conjoined by a spherical ball bearing, supported by the vertical linear stage at each point. The position of each confined horizontal stage is controlled by a motorized micrometer head by spring-loading the flat tip of the micrometer head onto a tooling ball fixing on the carriage of the stage. A virtual sine arm is formed by tilting the upstream horizontal stage down and the two downstream horizontal stages up by a small angle. The fine pitch motion is achieved by adjusting the upstream stage. This supporting structure is extremely steady due to a relatively large span across the supporting points and yields extremely high resolution on the pitch motion. With a one degree tilt and a microstepping motor, the authors achieved a 0.4 nanoradian resolution on the mirror pitch motion.
Virtuality Distributions and Pion Transition Form Factor
Radyushkin, Anatoly V.
Using the example of hard exclusive transition process γ*γ → π0 at the handbag level, we outline basics of a new approach to transverse momentum dependence in hard processes. In coordinate representation, matrix elements of operators (in the simplest case, bilocal O(0,z)) describing a hadron with momentum p, are functions of (pz) and z2 parametrized through virtuality distribution amplitudes (VDA) Φ(x, σ), with x being Fourier-conjugate to (pz) and σ Laplace-conjugate to z2. For intervals with z+=0, we introduce the transverse momentum distribution amplitude (TMDA) Ψ(x, k_perp), and write it in terms of VDA Φ(x,σ). We propose models for soft VDAs/TMDAs, and use them for comparison of handbag results with experimental (BaBar and BELLE) data. We also discuss the generation of hard tails of TMDAs from initially soft forms.
Integrated Virtual Lab in Supporting Heavy Duty Engine and Vehicle...
Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)
Presentation discusses a virtual lab which can model sophisticated future vehicle systems using three layers of model fidelity supporting each other. deer11zhang.pdf (2.07 MB) ...
Power in Collaboration: National Energy Literacy Virtual Meet-Up
The webinar will be a dynamic virtual conversation of ongoing efforts from across the country in utilizing the Department of Energy's Energy Literacy Framework to address one of our nation's...
BioenergizeME Virtual Science Fair: Biomass History A timeline
This infographic was created by students from Sun Valley High School in Aston, PA, as part of the U.S. Department of Energy-BioenergizeME Virtual Science Fair.
BioenergizeME Virtual Science Fair: Bioenegy Benefits Environmental Forestry
This infographic was created by students from Sun Valley High School in Aston, PA, as part of the U.S. Department of Energy-BioenergizeME Virtual Science Fair.
BioenergizeME Virtual Science Fair: Environmental Impacts
This infographic was created by students from Sun Valley High School in Aston, PA, as part of the U.S. Department of Energy-BioenergizeME Virtual Science Fair.
BioenergizeME Virtual Science Fair: Environmental Impacts of Bioenergy
This infographic was created by students from Sun Valley High School in Aston, PA, as part of the U.S. Department of Energy-BioenergizeME Virtual Science Fair.
BioenergizeME Virtual Science Fair: History of Bioenergy
This infographic was created by students from Sun Valley High School in Aston, PA, as part of the U.S. Department of Energy-BioenergizeME Virtual Science Fair.
Virtual cathode microwave generator having annular anode slit
Kwan, Thomas J. T.; Snell, Charles M.
A microwave generator is provided for generating microwaves substantially from virtual cathode oscillation. Electrons are emitted from a cathode and accelerated to an anode which is spaced apart from the cathode. The anode has an annular slit therethrough effective to form the virtual cathode. The anode is at least one range thickness relative to electrons reflecting from the virtual cathode. A magnet is provided to produce an optimum magnetic field having the field strength effective to form an annular beam from the emitted electrons in substantial alignment with the annular anode slit. The magnetic field, however, does permit the reflected electrons to axially diverge from the annular beam. The reflected electrons are absorbed by the anode in returning to the real cathode, such that substantially no reflexing electrons occur. The resulting microwaves are produced with a single dominant mode and are substantially monochromatic relative to conventional virtual cathode microwave generators.
BioenergizeME Virtual Science Fair: Bioenergy Careers
Office of Energy Efficiency and Renewable Energy (EERE)
This infographic was created by students from Sun Valley High School in Aston, PA, as part of the U.S. Department of Energy-BioenergizeME Virtual Science Fair.
DOE ZERH Virtual Office Hours (4 of 4)
TitleZERH Virtual Office Hours: Get the Answers You Need Quickly & EfficientlyDescriptionWhether you're new to DOE Zero Energy Ready Home or have been involved for a few years, our partners...
DOE ZERH Virtual Office Hours (2 of 4)
TitleZERH Virtual Office Hours: Get the Answers You Need Quickly & EfficientlyDescriptionWhether you're new to DOE Zero Energy Ready Home or have been involved for a few years, our partners...
BioenergizeME Virtual Science Fair: Microbiology and Bioenergy
This infographic was created by students from Toledo High School in Toledo, OR, as part of the U.S. Department of Energy-BioenergizeME Virtual Science Fair.
BioenergizeME Virtual Science Fair: Environmental benefit of Bioenergy
This infographic was created by students from Sun Valley High School in Aston, PA, as part of the U.S. Department of Energy-BioenergizeME Virtual Science Fair.
DOE ZERH Virtual Office Hours (3 of 4)
TitleZERH Virtual Office Hours: Get the Answers You Need Quickly & EfficientlyDescriptionWhether you're new to DOE Zero Energy Ready Home or have been involved for a few years, our partners...
DOE ZERH Virtual Office Hours (1 of 4)
TitleZERH Virtual Office Hours: Get the Answers You Need Quickly & EfficientlyDescriptionWhether you're new to DOE Zero Energy Ready Home or have been involved for a few years, our partners...
T-678: Red Hat Enterprise Virtualization Hypervisor VLAN Packet Processing Flaw Lets Remote Users Deny Service
Office of Energy Efficiency and Renewable Energy (EERE)
Red Hat Enterprise Virtualization Hypervisor VLAN Packet Processing Flaw Lets Remote Users Deny Service.
Noe, J.B.
A temperature stabilized transistor amplifier having a pair of transistors coupled in cascade relation that are capable of providing amplification through a temperature range of - 100 un. Concent 85% F to 400 un. Concent 85% F described. The stabilization of the amplifier is attained by coupling a feedback signal taken from the emitter of second transistor at a junction between two serially arranged biasing resistances in the circuit of the emitter of the second transistor to the base of the first transistor. Thus, a change in the emitter current of the second transistor is automatically corrected by the feedback adjustment of the base-emitter potential of the first transistor and by a corresponding change in the base-emitter potential of the second transistor. (AEC)
Nonpremixed ignition, laminar flame propagation, and mechanism reduction of n-butanol, iso-butanol, and methyl butanoate
Lu, Wei; Kelley, A. P.; Law, C. K.
The non-premixed ignition temperature of n-butanol (CH{sub 3}CH{sub 2}CH{sub 2}CH{sub 2}OH), iso-butanol ((CH{sub 3}){sub 2}CHCH{sub 2}OH) and methyl butanoate (CH{sub 3}CH{sub 2}CH{sub 2}COOCH{sub 3}) was measured in a liquid pool assembly by heated oxidizer in a stagnation flow for system pressures of 1 and 3 atm. In addition, the stretch-corrected laminar flame speeds of mixtures of air�n-butanol/iso-butanol/methyl butanoate were determined from the outwardly propagating spherical flame at initial pressures of up to 2 atm, for an extensive range of equivalence ratio. The ignition temperature and laminar flame speeds of n-butanol and methyl butanoate were computationally simulated with three recently developed kinetic mechanisms in the literature. Dominant reaction pathways to ignition and flame propagation were identified and discussed through a chemical explosive mode analysis (CEMA) and sensitivity analysis. The detailed models were further reduced through a series of systematic strategies. The reduced mechanisms provided excellent agreement in both homogeneous and diffusive combustion environments and greatly improved the computation efficiency.
U.S. Department of Energy (DOE) all webpages (Extended Search)
Chemistry - Sandia Energy Energy Search Icon Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable Energy Future Stationary Power Energy Conversion Efficiency Solar Energy Wind Energy Water Power Supercritical CO2 Geothermal Natural Gas Safety, Security & Resilience of the Energy Infrastructure Energy Storage Nuclear Power & Engineering Grid Modernization Battery Testing Nuclear Energy Defense Waste Management Programs Advanced Nuclear Energy
U.S. Department of Energy (DOE) all webpages (Extended Search)
Infrastructure Energy Storage Nuclear Power & Engineering Grid Modernization Battery Testing ... Heavy Duty Fuels DISI Combustion HCCISCCI Fundamentals Spray Combustion Modeling ...
Kliche, C.A.
Whether you're involved in surface mine design, surface mine production, construction, education, or regulation, this is an important new book for your library. It describes the basic rock slope failure modes and methods of analysis--both kinematic and kinetic techniques. Chapters include geotechnical and geomechanical analysis techniques, hydrology, rock slope stabilization techniques, and geotechnical instrumentation and monitoring. Numerous examples, drawings and photos enhance the text.
Thomas, David G.
The subject invention is directed to a floating platform for supporting nuclear reactors and the like at selected offshore sites. The platform is provided with a stabilizer mechanism which significantly reduces the effects of wave action upon the platform and which comprises a pair of relatively small floats attached by rigid booms to the platform at locations spaced therefrom for reducing wave pitch, acceleration, and the resonance period of the wave.
Unlocking Customer Value: The Virtual Power Plant | Department of Energy
Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)
Unlocking Customer Value: The Virtual Power Plant Unlocking Customer Value: The Virtual Power Plant The utility world has changed drastically in the last 10 years. New technologies like Smart Meters and fully functional Smart Grid concepts have made large inroads into the utility space and no one should want to be left behind. Utilities also face additional pressures from regulatory bodies who are continuing to encourage carbon reduction and greater customer flexibility. Utilities need to
A Stochastic Reactor Based Virtual Engine Model Employing Detailed
Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)
Chemistry for Kinetic Studies of In-Cylinder Combustion and Exhaust Aftertreatment | Department of Energy A Stochastic Reactor Based Virtual Engine Model Employing Detailed Chemistry for Kinetic Studies of In-Cylinder Combustion and Exhaust Aftertreatment A Stochastic Reactor Based Virtual Engine Model Employing Detailed Chemistry for Kinetic Studies of In-Cylinder Combustion and Exhaust Aftertreatment The model consists of an in-cylinder combustion engine model, an interconnecting exhaust
Virtual Vehicle - Component-in-the-Loop | Argonne National Laboratory
U.S. Department of Energy (DOE) all webpages (Extended Search)
Virtual Tours Nuclear Weapons Mission at Sandia Sandia Labs: Who we are Related Topics apm
Virtual Vehicle - Component-in-the-Loop Preparing a plug-in hybrid electric vehicle (PHEV) battery for testing on Argonne's Battery-in-the-Loop system Preparing a plug-in hybrid electric vehicle (PHEV) battery for testing on Argonne's Battery-in-the-Loop system How do you evaluate unique vehicle configurations without building each vehicle from the ground up? Argonne researchers have developed
A Systematic Procedure For Synthesizing Virtual Oscillators For
U.S. Department of Energy (DOE) all webpages (Extended Search)
Inverter-Based Power Systems - Energy Innovation Portal A Systematic Procedure For Synthesizing Virtual Oscillators For Inverter-Based Power Systems National Renewable Energy Laboratory Contact NREL About This Technology Publications: PDF Document Publication Virtual Oscillator Control Fact Sheet (116 KB) Technology Marketing Summary Microgrids are a collection of energy sources interfaced to an ac electric distribution network that can be operated independently from the bulk ac system.
PNNL offers 'virtual tour' of Shallow Underground Laboratory | National
National Nuclear Security Administration (NNSA)
Nuclear Security Administration | (NNSA) PNNL offers 'virtual tour' of Shallow Underground Laboratory Friday, January 17, 2014 - 4:07pm For the first time, some of the world's most sensitive radiation detection systems and fundamental physics research can be seen from your desktop computer or mobile device. PNNL recently launched a virtual tour showcasing its Shallow Underground Laboratory (SUL), a facility dedicated in 2011 as part of the $224-million capability replacement project jointly
Building virtual connections, saving real money | Y-12 National Security
U.S. Department of Energy (DOE) all webpages (Extended Search)
Complex Building virtual ... Building virtual connections, saving real money Posted: August 29, 2016 - 10:34am Kia Moua (left) and Lee Bzorgi prepare for a video teleconference with aspiring roboticists at Northern Kentucky University. Y-12 is talking robotics with college students a state away. Through video teleconferencing, Y-12 is using its people and technological capabilities to reach out and (almost) touch aspiring roboticists at Northern Kentucky University, located just south of
Simulation analysis of within-day flow fluctuation effects on trout below flaming Gorge Dam.
Railsback, S. F.; Hayse, J. W.; LaGory, K. E.; Environmental Science Division; EPRI
In addition to being renewable, hydropower has the advantage of allowing rapid load-following, in that the generation rate can easily be varied within a day to match the demand for power. However, the flow fluctuations that result from load-following can be controversial, in part because they may affect downstream fish populations. At Flaming Gorge Dam, located on the Green River in northeastern Utah, concern has been raised about whether flow fluctuations caused by the dam disrupt feeding at a tailwater trout fishery, as fish move in response to flow changes and as the flow changes alter the amount or timing of the invertebrate drift that trout feed on. Western Area Power Administration (Western), which controls power production on submonthly time scales, has made several operational changes to address concerns about flow fluctuation effects on fisheries. These changes include reducing the number of daily flow peaks from two to one and operating within a restricted range of flows. These changes significantly reduce the value of the power produced at Flaming Gorge Dam and put higher load-following pressure on other power plants. Consequently, Western has great interest in understanding what benefits these restrictions provide to the fishery and whether adjusting the restrictions could provide a better tradeoff between power and non-power concerns. Directly evaluating the effects of flow fluctuations on fish populations is unfortunately difficult. Effects are expected to be relatively small, so tightly controlled experiments with large sample sizes and long study durations would be needed to evaluate them. Such experiments would be extremely expensive and would be subject to the confounding effects of uncontrollable variations in factors such as runoff and weather. Computer simulation using individual-based models (IBMs) is an alternative study approach for ecological problems that are not amenable to analysis using field studies alone. An IBM simulates how a
Synchrotron photoionization mass spectrometry study of intermediates in fuel-rich 1,2-dimethoxyethane flame
Lin, Z. K.; Han, D. L.; Li, S. F.; Li, Y. Y.; Yuan, T.
Intermediates in a fuel-rich premixed laminar 1,2-dimethoxyethane (DME) flame are studied by molecular beam mass spectrometry combined with tunable synchrotron vacuum ultraviolet photoionization. About 30 intermediate species are identified in the present work, and their mole fraction profiles are evaluated. The experimental results show that the formations of intermediates, both hydrocarbons and oxygenated hydrocarbons, are closely linked to the structure of fuel, which is consistent with the previous reports. Species produced from H atom abstraction and beta scission of DME usually have much higher concentrations than others. The oxygen atoms in DME are considered to act as partitions of the primary intermediates; therefore farther reactions among these primary intermediates are difficult to occur, resulting in absence of most large intermediate species.
Guidoni, S. E.; Plowman, J. E.
Candle-flame-shaped flares are archetypical structures that provide indirect evidence of magnetic reconnection. A flare resembling Tsuneta's famous 1992 candle-flame flare occurred on 2011 January 28; we present its temperature and electron density diagnostics. This flare was observed with Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA), Hinode/X-Ray Telescope (XRT), and Solar Terrestrial Relations Observatory Ahead (STEREO-A)/Extreme Ultraviolet Imager, resulting in high-resolution, broad temperature coverage, and stereoscopic views of this iconic structure. The high-temperature images reveal a brightening that grows in size to form a tower-like structure at the top of the posteruption flare arcade, a feature that has been observed in other long-duration events. Despite the extensive work on the standard reconnection scenario, there is no complete agreement among models regarding the nature of this high-intensity elongated structure. Electron density maps reveal that reconnected loops that are successively connected at their tops to the tower develop a density asymmetry of about a factor of two between the two legs, giving the appearance of ''half-loops''. We calculate average temperatures with a new fast differential emission measure (DEM) method that uses SDO/AIA data and analyze the heating and cooling of salient features of the flare. Using STEREO observations, we show that the tower and the half-loop brightenings are not a line-of-sight projection effect of the type studied by Forbes and Acton. This conclusion opens the door for physics-based explanations of these puzzling, recurrent solar flare features, previously attributed to projection effects. We corroborate the results of our DEM analysis by comparing them with temperature analyses from Hinode/XRT.
Claxton, Gerald L.
A stabilizing suspension system is provided for vehicles carrying telescopic booms or aerial work platforms having a fixed axle and a oscillating axle. Hydraulic cylinders are connected to each end of the oscillating axle, each cylinder being capable of extending and retracting. An off level sensor senses the angle of tilt of the chassis in both left and right directions and, when a predetermined threshold of tilt has been detected, the hydraulic cylinder on the downhill side of the chassis is locked against retracting, but is free to move in the downhill direction to allow the downhill wheel to remain in contact with the ground.
Stabilization of graphene nanopore
Lee, Jaekwang; Yang, Zhiqing; Zhou, Wu; Pennycook, Stephen J.; Pantelides, Sokrates T.; Chisholm, Matthew F.
Graphene is an ultrathin, impervious membrane. The controlled introduction of nanoscale pores in graphene would lead to applications that involve water purification, chemical separation, and DNA sequencing. However, graphene nanopores are unstable against filling by carbon adatoms. Using aberration-corrected scanning transmission electron microscopy and density-functional calculations, we report that Si atoms stabilize graphene nanopores by bridging the dangling bonds around the perimeter of the hole. Si-passivated pores remain intact even under intense electron beam irradiation, and they were observed several months after the sample fabrication, demonstrating that these structures are intrinsically robust and stable against carbon filling. Theoretical calculations reveal the underlying mechanism for this stabilization effect: Si atoms bond strongly to the graphene edge, and their preference for tetrahedral coordination forces C adatoms to form dendrites sticking out of the graphene plane, instead of filling the nanopore. Our results provide a novel way to develop stable nanopores, which is a major step toward reliable graphene-based molecular translocation devices.
Opposed-flow virtual cyclone for particle concentration
Rader, Daniel J.; Torczynski, John R.
An opposed-flow virtual cyclone for aerosol collation which can accurately collect, classify, and concentrate (enrich) particles in a specific size range. The opposed-flow virtual cyclone is a variation on the virtual cyclone and has its inherent advantages (no-impact particle separation in a simple geometry), while providing a more robust design for concentrating particles in a flow-through type system. The opposed-flow virtual cyclone consists of two geometrically similar virtual cyclones arranged such that their inlet jets are inwardly directed and symmetrically opposed relative to a plane of symmetry located between the two inlet slits. A top plate bounds both jets on the "top" side of the inlets, while the other or lower wall curves "down" and away from each inlet jet. Each inlet jet will follow the adjacent lower wall as it turns away, and that particles will be transferred away from the wall and towards the symmetry plane by centrifugal action. After turning, the two jets merge smoothly along the symmetry line and flow parallel to it through the throat. Particles are transferred from the main flows, across a dividing streamline, and into a central recirculating region, where particle concentrations become greatly increased relative to the main stream.
Virtual Simulation of Vision 21 Energy Plants
Syamlal, Madhava; Felix, Paul E.; Osawe, Maxwell O.; Fiveland, Woodrow A.; Sloan, David G.; Zitney, Stephen E.; Joop, Frank; Cleetus, Joseph; Lapshin, Igor B.
The Vision 21 Energy plants will be designed by combining several individual power, chemical, and fuel-conversion technologies. These independently developed technologies or technology modules can be interchanged and combined to form the complete Vision 21 plant that achieves the needed level of efficiency and environmental performance at affordable costs. The knowledge about each technology module must be captured in computer models so that the models can be linked together to simulate the entire Vision 21 power plant in a Virtual Simulation environment. Eventually the Virtual Simulation will find application in conceptual design, final design, plant operation and control, and operator training. In this project we take the first step towards developing such a Vision 21 Simulator. There are two main knowledge domains of a plant--the process domain (what is in the pipes), and the physical domain (the pipes and equipment that make up the plant). Over the past few decades, commercial software tools have been developed for each of these functions. However, there are three main problems that inhibit the design and operation of power plants: (1) Many of these tools, largely developed for chemicals and refining, have not been widely adopted in the power industry. (2) Tools are not integrated across functions. For example, the knowledge represented by computational fluid dynamics (CFD) models of equipment is not used in process-level simulations. (3) No tool exists for readily integrating the design and behavioral knowledge about components. These problems must be overcome to develop the Vision 21 Simulator. In this project our major objective is to achieve a seamless integration of equipment-level and process-level models and apply the integrated software to power plant simulations. Specifically we are developing user-friendly tools for linking process models (Aspen Plus) with detailed equipment models (FLUENT CFD and other proprietary models). Such integration will
Fishbine, H.L.; Sewell, C. Jr.
Negative feedback amplifiers, and particularly a negative feedback circuit which is economical on amode power consumption, are described. Basically, the disclosed circuit comprises two tetrode tubes where the output of the first tube is capacitamce coupled to the grid of the second tube, which in turn has its plate coupled to the cathode of the first tube to form a degenerative feedback circuit. Operating potential for screen of the second tube is supplied by connecting the cathode resistor of the first tube to the screen, while the screen is by-passed to the cathode of its tube for the amplified frequencies. Also, the amplifier incorporates a circuit to stabilize the transconductance of the tubes by making the grid potential of each tube interdependent on anode currents of both lubes by voltage divider circuitry.
Virtual QCD corrections to Higgs boson plus four parton processes
Ellis, R.K.; Giele, W.T.; Zanderighi, G.
We report on the calculation of virtual processes contributing to the production of a Higgs boson and two jets in hadron-hadron collisions. The coupling of the Higgs boson to gluons, via a virtual loop of top quarks, is treated using an effective theory, valid in the large top quark mass limit. The calculation is performed by evaluating one-loop diagrams in the effective theory. The primary method of calculation is a numerical evaluation of the virtual amplitudes as a Laurent series in D-4, where D is the dimensionality of space-time. For the cases H{yields}qqqq and H{yields}qqq{sup '}q{sup '} we confirm the numerical results by an explicit analytic calculation.
Virtual electrodes for high-density electrode arrays
Cela, Carlos J.; Lazzi, Gianluca
The present embodiments are directed to implantable electrode arrays having virtual electrodes. The virtual electrodes may improve the resolution of the implantable electrode array without the burden of corresponding complexity of electronic circuitry and wiring. In a particular embodiment, a virtual electrode may include one or more passive elements to help steer current to a specific location between the active electrodes. For example, a passive element may be a metalized layer on a substrate that is adjacent to, but not directly connected to an active electrode. In certain embodiments, an active electrode may be directly coupled to a power source via a conductive connection. Beneficially, the passive elements may help to increase the overall resolution of the implantable array by providing additional stimulation points without requiring additional wiring or driver circuitry for the passive elements.
Virtual Library on Genetics from Oak Ridge National Laboratory
DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]
The World Wide Web (WWW) Virtual Library is a collaborative effort to provide topic indices that break down into many subtopics guiding users to vast resources of information around the world. ORNL hosts the Virtual Library on Genetics as part of the WWWVL's Biosciences topic area. The VL on Genetics is also a collection of links to information resources that supported the DOE Human Genome Project. That project has now evolved into Genomics: GTL. GTL is DOE's next step in genomics--builds on data and resources from the Human Genome Project, the Microbial Genome Program, and systems biology. GTL will accelerate understanding of dynamic living systems for solutions to DOE mission challenges in energy and the environment. The section of the Virtual Library on Genetics that is titled Organisms guides users to genetic information resources and gene sequences for animals, insects, microbes, and plant life.
Flame-synthesis limits and self-catalytic behavior of carbon nanotubes using a double-faced wall stagnation flow burner
Woo, S.K.; Hong, Y.T.; Kwon, O.C.
Flame-synthesis limits of carbon nanotubes (CNTs) are measured using a double-faced wall stagnation flow (DWSF) burner that shows potential in mass production of CNTs. With nitrogen-diluted premixed ethylene-air flames established on the nickel-coated stainless steel double-faced plate wall, the limits of CNT formation are determined using field-emission scanning and transmission electron microscopies and Raman spectroscopy. Also, self-catalytic behavior of the synthesized CNTs is evaluated using the DWSF burner with a CNT-deposited stainless steel double-faced plate wall. Results show narrow fuel-equivalence ratio limits of multi-walled CNT (MWCNT)-synthesis at high flame stretch rates and substantially extended limits at low flame stretch rates. This implies that the synthesis limits are very sensitive to the fuel-equivalence ratio variation for the high stretch rate conditions, yielding a lot of impurities and soot rather than MWCNTs. The enhanced ratio of tube inner diameter to wall thickness of the MWCNTs synthesized using a CNT self-catalytic flame-synthesis process is observed, indicating that the quality of metal-catalytic, flame-synthesized MWCNTs can be much improved via the process. Thus, using a DWSF burner with the CNT self-catalytic process has potential in mass production of MWCNTs with improved quality. (author)
EGR Distribution in Engine Cylinders Using Advanced Virtual Simulation
Fan, Xuetong
Exhaust Gas Recirculation (EGR) is a well-known technology for reduction of NOx in diesel engines. With the demand for extremely low engine out NOx emissions, it is important to have a consistently balanced EGR flow to individual engine cylinders. Otherwise, the variation in the cylinders' NOx contribution to the overall engine emissions will produce unacceptable variability. This presentation will demonstrate the effective use of advanced virtual simulation in the development of a balanced EGR distribution in engine cylinders. An initial design is analyzed reflecting the variance in the EGR distribution, quantitatively and visually. Iterative virtual lab tests result in an optimized system.
CASL-U-2015-0067-000 Virtual Environment
U.S. Department of Energy (DOE) all webpages (Extended Search)
7-000 Virtual Environment for Reactor Applications (VERA) Workshop Session 2: Hands on Training Rose Montgomery The Tennessee Valley Authority April 1, 2015 CASL-U-2015-0067-000 1 Virtual Environment for Reactor Applications (VERA) Hands-On Training The American Nuclear Society ANFM Topical Meeting presents April 1, 2015 Hilton Head, SC Please check in to receive your student packet and RSA token to log onto the computers. CASL-U-2015-0067-000 2 2 CASL-U-2015-0067-000 2 CASL-U-2015-0067-000
D. L. Straub; B. T. Chorpening; E. D. Huckaby; J. D. Thornton; W. L. Fincham
In-situ monitoring of combustion phenomena is a critical need for optimal operation and control of advanced gas turbine combustion systems. The concept described in this paper is based on naturally occurring flame ionization processes that accompany the combustion of hydrocarbon fuels. Previous work has shown that flame ionization techniques may be applied to detect flashback, lean blowout, and some aspects of thermo-acoustic combustion instabilities. Previous work has focused on application of DC electric fields. By application of time-varying electric fields, significant improvements to sensor capabilities have been observed. These data have been collected in a lean premixed combustion test rig operating at 0.51-0.76 MPa (5-7.5 atm) with air preheated to 588 K (600�F). Five percent of the total fuel flow is injected through the centerbody tip as a diffusion pilot. The fuel composition is varied independently by blending approximately 5% (volume) propane with the pipeline natural gas. The reference velocity through the premixing annulus is kept constant for all conditions at a nominal value of 70 m/s. The fuel-air equivalence ratio is varied independently from 0.46 � 0.58. Relative to the DC field version, the time-varying combustion control and diagnostic sensor (TV-CCADS) shows a significant improvement in the correlation between the measured flame ionization current and local fuel-air equivalence ratio. In testing with different fuel compositions, the triangle wave data show the most distinct change in flame ionization current in response to an increase in propane content. Continued development of this sensor technology will improve the capability to control advanced gas turbine combustion systems, and help address issues associated with variations in fuel supplies.
Gas-flow measurements in a jet flame using cross-correlation of high speed particle-images
Shioji, Masahiro; Kawasaki, Kiyoshi; Kawanabe, Hiroshi; Ikegami, Makoto
Time changes of a two-dimensional distribution of velocities in a methane jet flame and a nitrogen jet are measured by cross-correlation particle image velocimetry (PIV). The mean velocity and the intensity of turbulence are obtained and compared with those measured by HWA in order to ascertain the accuracy of PIV. Furthermore, the effect of combustion on turbulence characteristics is discussed based on the deformation of eddies with time change and distribution of time and spatial scales.
Rotational coherent anti-Stokes Raman spectroscopy (CARS) applied to thermometry in high-pressure hydrocarbon flames
Vestin, Fredrik; Sedarsky, David; Collin, Robert; Alden, Marcus; Linne, Mark; Bengtsson, Per-Erik
Dual-broadband rotational coherent anti-Stokes Raman spectroscopy (DB-RCARS) has been investigated for thermometry under high-pressure and high-temperature conditions, in the product gas of fuel-lean hydrocarbon flames up to 1 MPa. Initial calibration measurements made in nitrogen, oxygen, and air, at pressures up to 1.55 MPa and temperatures up to 1800 K, showed good agreement between experimental and theoretical spectra. In the high-pressure flames, high-quality single-shot spectra were recorded in which nitrogen lines dominated, and peaks from CO{sub 2} and O{sub 2} were also visible. A spectral model including the species N{sub 2}, CO{sub 2}, and O{sub 2}, as well as the best available Raman linewidth models for flame thermometry, were used to evaluate the experimental spectra. Experimental problems as well as considerations related to the spectral evaluation are discussed. This work demonstrates the significant potential of DB-RCARS thermometry for applications in high-pressure and high-temperature environments. (author)
Uncertainty Analysis for a Virtual Flow Meter Using an Air-Handling...
Office of Scientific and Technical Information (OSTI)
Unit Chilled Water Valve Citation Details In-Document Search Title: Uncertainty Analysis for a Virtual Flow Meter Using an Air-Handling Unit Chilled Water Valve A virtual ...
V-189: Oracle VirtualBox 'tracepath' Bug Lets Local Guest Users...
Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)
Oracle VirtualBox 'tracepath' Bug Lets Local Guest Users Deny Service on the Target Host V-189: Oracle VirtualBox 'tracepath' Bug Lets Local Guest Users Deny Service on the Target...
GloudSim: Google trace based cloud simulator with virtual machines...
Office of Scientific and Technical Information (OSTI)
GloudSim: Google trace based cloud simulator with virtual machines: GloudSim: Google trace based cloud simulator with virtual machines Citation Details In-Document Search Title: ...
Virtual Oxygen Sensor for Innovative NOx and PM Emission Control Technologies
A virtual O2 sensor for the intake manifold of a diesel engine equipped with EGR, along with a virtual intake manifold O2 sensor, show good accuracy with stationary measurements
Stabilized radio-frequency quadrupole
Lancaster, H.D.; Fugitt, J.A.; Howard, D.R.
A long-vane stabilized radio frequency resonator for accelerating charged particles and including means defining a radio frequency resonator cavity, a plurality of long vanes mounted in the defining means for dividing the cavity into sections, and means interconnecting opposing ones of the plurality of vanes for stabilizing the resonator.
A Virtualized Computing Platform For Fusion Control Systems
Frazier, T; Adams, P; Fisher, J; Talbot, A
The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory is a stadium-sized facility that contains a 192-beam, 1.8-Megajoule, 500-Terawatt, ultraviolet laser system together with a 10-meter diameter target chamber with room for multiple experimental diagnostics. NIF is the world's largest and most energetic laser experimental system, providing a scientific center to study inertial confinement fusion (ICF) and matter at extreme energy densities and pressures. NIF's laser beams are designed to compress fusion targets to conditions required for thermonuclear burn, liberating more energy than required to initiate the fusion reactions. 2,500 servers, 400 network devices and 700 terabytes of networked attached storage provide the foundation for NIF's Integrated Computer Control System (ICCS) and Experimental Data Archive. This talk discusses the rationale & benefits for server virtualization in the context of an operational experimental facility, the requirements discovery process used by the NIF teams to establish evaluation criteria for virtualization alternatives, the processes and procedures defined to enable virtualization of servers in a timeframe that did not delay the execution of experimental campaigns and the lessons the NIF teams learned along the way. The virtualization architecture ultimately selected for ICCS is based on the Open Source Xen computing platform and 802.1Q open networking standards. The specific server and network configurations needed to ensure performance and high availability of the control system infrastructure will be discussed.
New JLab/Hall A Deeply Virtual Compton Scattering results
Defurne, Maxime
New data points for unpolarized Deeply Virtual Compton Scattering cross sections have been extracted from the E00-110 experiment at Q2=1.9 GeV2 effectively doubling the statistics available in the valence region. A careful study of systematic uncertainties has been performed.
The Benefits and Risks of Virtual Bidding in Multi-Settlement Markets
Isemonger, Alan G.
While it is possible that multi-settlement markets can exist without virtual trading, it is equally clear that virtual trading can provide many market benefits. The main one: In the absence of explicit virtual bidding (EVB), the price arbitrage trades that are benign in other commodity markets affect the reliability of the underlying electricity markets, resulting in a situation where EVB is most useful when it neutralizes the deleterious reliability effects of implicit virtual bidding and physical arbitrage. (author)
Implementation of two-equation soot flamelet models for laminar diffusion flames
Carbonell, D.; Oliva, A.; Perez-Segarra, C.D.
The two-equation soot model proposed by Leung et al. [K.M. Leung, R.P. Lindstedt, W.P. Jones, Combust. Flame 87 (1991) 289-305] has been derived in the mixture fraction space. The model has been implemented using both Interactive and Non-Interactive flamelet strategies. An Extended Enthalpy Defect Flamelet Model (E-EDFM) which uses a flamelet library obtained neglecting the soot formation is proposed as a Non-Interactive method. The Lagrangian Flamelet Model (LFM) is used to represent the Interactive models. This model uses direct values of soot mass fraction from flamelet calculations. An Extended version (E-LFM) of this model is also suggested in which soot mass fraction reaction rates are used from flamelet calculations. Results presented in this work show that the E-EDFM predict acceptable results. However, it overpredicts the soot volume fraction due to the inability of this model to couple the soot and gas-phase mechanisms. It has been demonstrated that the LFM is not able to predict accurately the soot volume fraction. On the other hand, the extended version proposed here has been shown to be very accurate. The different flamelet mathematical formulations have been tested and compared using well verified reference calculations obtained solving the set of the Full Transport Equations (FTE) in the physical space. (author)
A numerical study of soot aggregate formation in a laminar coflow diffusion flame
Zhang, Q.; Thomson, M.J. [Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, Ontario, M5S 3G8 (Canada); Guo, H.; Liu, F.; Smallwood, G.J. [Institute for Chemical Process and Environmental Technology, National Research Council of Canada, Building M-9, 1200 Montreal Road, Ottawa, Ontario, K1A 0R6 (Canada)
Soot aggregate formation in a two-dimensional laminar coflow ethylene/air diffusion flame is studied with a pyrene-based soot model, a detailed sectional aerosol dynamics model, and a detailed radiation model. The chemical kinetic mechanism describes polycyclic aromatic hydrocarbon formation up to pyrene, the dimerization of which is assumed to lead to soot nucleation. The growth and oxidation of soot particles are characterized by the HACA surface mechanism and pyrene-soot surface condensation. The mass range of the solid soot phase is divided into thirty-five discrete sections and two equations are solved in each section to model the formation of the fractal-like soot aggregates. The coagulation model is improved by implementing the aggregate coagulation efficiency. Several physical processes that may cause sub-unitary aggregate coagulation efficiency are discussed. Their effects on aggregate structure are numerically investigated. The average number of primary soot particles per soot aggregate n{sub p} is found to be a strong function of the aggregate coagulation efficiency. Compared to the available experimental data, n{sub p} is well reproduced with a constant 20% aggregate coagulation efficiency. The predicted axial velocity, OH mole fraction, and C{sub 2}H{sub 2} mole fraction are validated against experimental data in the literature. Reasonable agreements are obtained. Finally, a sensitivity study of the effects of particle coalescence on soot volume fraction and soot aggregate nanostructure is conducted using a coalescence cutoff diameter method. (author)
Development of flame retardant PV module encapsulants: Volume 1. Final report
Galica, J.P.
This Phase 1 final report covers the work performed by Springborn Testing and Research, Inc., for the period October 1, 1997 to June 30, 1998 under the Department of Energy Cooperative Agreement Number DE-FC36-97GO10255, entitled Development of Flame Retardant PV Module Encapsulants. While use of roof-mounted arrays has always been an attractive means of deploying PV, only within recent years have such building integrated concepts (BIPV) found renewed interest among module makers and end-users. Prior to building integrated and rooftop applications, flammability requirements for modules have not been a great industry concern. However, with growing interest in BIPV and the requirement for building code requirements for commercial and industrial structures, flammability issues have become a barrier to entry for many module constructions into this potentially huge domestic market for PV. The overall goal of the 3 phase PV BONUS two project is to develop and commercialize a line of fire retardant encapsulation materials to serve the emerging building integrated and building mounted PV market. The objectives of the Phase 1 effort are limited to concept development and business planning activities.
Multi-ported, internally recuperated burners for direct flame impingement heating applications
Abbasi, Hamid A.; Kurek, Harry; Chudnovsky, Yaroslav; Lisienko, Vladimir G.; Malikov, German K.
A direct flame impingement method and apparatus employing at least one multi-ported, internally recuperated burner. The burner includes an innermost coaxial conduit having a first fluid inlet end and a first fluid outlet end, an outermost coaxial conduit disposed around the innermost coaxial conduit and having a combustion products outlet end proximate the first fluid inlet end of the innermost coaxial conduit and a combustion products inlet end proximate the first fluid outlet end of the innermost coaxial conduit, and a coaxial intermediate conduit disposed between the innermost coaxial conduit and the outermost coaxial conduit, whereby a second fluid annular region is formed between the innermost coaxial conduit and the intermediate coaxial conduit and a combustion products annular region is formed between the intermediate coaxial conduit and the outermost coaxial conduit. The intermediate coaxial conduit has a second fluid inlet end proximate the first fluid inlet end of the innermost coaxial conduit and a second fluid outlet end proximate the combustion products inlet end of the outermost coaxial conduit.
Phase stabilities at a glance: Stability diagrams of nickel dipnictides
Bachhuber, F.; Rothballer, J.; Weihrich, R.; Söhnel, T.
In the course of the recent advances in chemical structure prediction, a straightforward type of diagram to evaluate phase stabilities is presented based on an expedient example. Crystal structures and energetic stabilities of dipnictides NiPn{sub 2} (Pn = N, P, As, Sb, Bi) are systematically investigated by first principles calculations within the framework of density functional theory using the generalized gradient approximation to treat exchange and correlation. These dipnictides show remarkable polymorphism that is not yet understood systematically and offers room for the discovery of new phases. Relationships between the concerned structures including the marcasite, the pyrite, the arsenopyrite/CoSb{sub 2}, and the NiAs{sub 2} types are highlighted by means of common structural fragments. Electronic stabilities of experimentally known and related AB{sub 2} structure types are presented graphically in so-called stability diagrams. Additionally, competing binary phases are taken into consideration in the diagrams to evaluate the stabilities of the title compounds with respect to decomposition. The main purpose of the stability diagrams is the introduction of an image that enables the estimation of phase stabilities at a single glance. Beyond that, some of the energetically favored structure types can be identified as potential new phases.
BioenergizeME Virtual Science Fair: History of Biomass | Department of
Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)
Energy History of Biomass BioenergizeME Virtual Science Fair: History of Biomass BioenergizeME Virtual Science Fair: History of Biomass This infographic was created by students from Daniel Boone Area High School in Birdsboro, PA, as part of the U.S. Department of Energy-BioenergizeME Virtual Science
Numerical analysis of the effect of acetylene and benzene addition to low-pressure benzene-rich flat flames on polycyclic aromatic hydrocarbon formation
Kunioshi, Nilson; Komori, Seisaku; Fukutani, Seishiro
A modification of the CHEMKIN II package has been proposed for modeling addition of an arbitrary species at an arbitrary temperature to an arbitrary distance from the burner along a flat flame. The modified program was applied to the problem of addition of acetylene or benzene to different positions of a 40-Torr, {phi}=2.4 benzene/O{sub 2}/40%-N{sub 2} premixed flame to reach final equivalence ratios of {phi}=2.5 and 2.681. The results obtained showed that acetylene addition to early positions of the flame led to significant increase in pyrene production rates, but pyrene concentrations were lower in the flames with acetylene addition in both the {phi}=2.5 and 2.681 cases. Addition of benzene to the flame did not alter pyrene production rates in either the {phi}=2.5 or 2.681 cases; however, for {phi}=2.5, pyrene concentrations increased with benzene addition, while for {phi}=2.681, pyrene contents decreased in comparison to the correspondent flames with no addition. Acetylene addition led to a significant increase in pyrene production rates, but the pyrene levels dropped due to increase in the flow velocity. Pyrene production rates were not sensitive to benzene addition, but pyrene contents increased with benzene addition when the flow velocity decreased. These results show that PAH concentration changes accompanying species addition to flames should be interpreted carefully, because an increase or decrease in the content of a PAH species does not necessarily reflect an effect on its formation rate or mechanism. (author)
Generation IV Nuclear Energy Systems Construction Cost Reductions through the Use of Virtual Environments - Task 4 Report: Virtual Mockup Maintenance Task Evaluation
Timothy Shaw; Anthony Baratta; Vaughn Whisker
Task 4 report of 3 year DOE NERI-sponsored effort evaluating immersive virtual reality (CAVE) technology for design review, construction planning, and maintenance planning and training for next generation nuclear power plants. Program covers development of full-scale virtual mockups generated from 3D CAD data presented in a CAVE visualization facility. This report focuses on using Full-scale virtual mockups for nuclear power plant training applications.
Plutonium stabilization and packaging system
This document describes the functional design of the Plutonium Stabilization and Packaging System (Pu SPS). The objective of this system is to stabilize and package plutonium metals and oxides of greater than 50% wt, as well as other selected isotopes, in accordance with the requirements of the DOE standard for safe storage of these materials for 50 years. This system will support completion of stabilization and packaging campaigns of the inventory at a number of affected sites before the year 2002. The package will be standard for all sites and will provide a minimum of two uncontaminated, organics free confinement barriers for the packaged material.
Periodic local MP2 method employing orbital specific virtuals
Usvyat, Denis Schütz, Martin; Maschio, Lorenzo
We introduce orbital specific virtuals (OSVs) to represent the truncated pair-specific virtual space in periodic local Møller-Plesset perturbation theory of second order (LMP2). The OSVs are constructed by diagonalization of the LMP2 amplitude matrices which correspond to diagonal Wannier-function (WF) pairs. Only a subset of these OSVs is adopted for the subsequent OSV-LMP2 calculation, namely, those with largest contribution to the diagonal pair correlation energy and with the accumulated value of these contributions reaching a certain accuracy. The virtual space for a general (non diagonal) pair is spanned by the union of the two OSV sets related to the individual WFs of the pair. In the periodic LMP2 method, the diagonal LMP2 amplitude matrices needed for the construction of the OSVs are calculated in the basis of projected atomic orbitals (PAOs), employing very large PAO domains. It turns out that the OSVs are excellent to describe short range correlation, yet less appropriate for long range van der Waals correlation. In order to compensate for this bias towards short range correlation, we augment the virtual space spanned by the OSVs by the most diffuse PAOs of the corresponding minimal PAO domain. The Fock and overlap matrices in OSV basis are constructed in the reciprocal space. The 4-index electron repulsion integrals are calculated by local density fitting and, for distant pairs, via multipole approximation. New procedures for determining the fit-domains and the distant-pair lists, leading to higher efficiency in the 4-index integral evaluation, have been implemented. Generally, and in contrast to our previous PAO based periodic LMP2 method, the OSV-LMP2 method does not require anymore great care in the specification of the individual domains (to get a balanced description when calculating energy differences) and is in that sense a black box procedure. Discontinuities in potential energy surfaces, which may occur for PAO-based calculations if one is not
Turbulent flame speeds and NOx kinetics of HHC fuels with contaminants and high dilution levels
Petersen, Eric; Krejci, Michael; Mathieu, Olivier; Vissotski, Andrew; Ravi, Sankar; Plichta, Drew; Sikes, Travis; Levacque, Anthony; Aul, Christopher; Petersen, Eric
This progress report documents the second year of the project, from October 1, 2011 through September 30, 2012. Characterization of the new turbulent flame speed vessel design was completed. Turbulence statistics of three impellers with different geometric features were measured using particle image velocimetry inside a Plexiglas model (~1:1 scale) of a cylindrical flame speed vessel (30.5 cm ID � 35.6 cm L). With four impellers arranged in a central-symmetric configuration, turbulence intensities between 1.2 and 1.7 m/s with negligible mean flow (0.1u�) were attained at the lowest fan speeds. Acceptable ranges for homogeneity and isotropy ratios of the velocity fields were set within a narrow bandwidth near unity (0.9-1.1). Homogeneity ratios were unaffected by changes to the impeller geometry, and the prototype with the higher number of blades caused the flow to become anisotropic. The integral length scale of the flow fields varied between 27 and 20 mm, which correlates well with those typically observed inside a gas turbine combustor. The mechanism to independently vary the intensity level and the integral length scale was established, where turbulence intensity level was dependent on the rotational speed of the fan, and the integral length scale decreased with increasing blade pitch angle. Ignition delay times of H?/O? mixtures highly diluted with Ar and doped with various amounts of N?O (100, 400, 1600, 3200 ppm) were measured in a shock tube behind reflected shock waves over a wide range of temperatures (940-1675 K). The pressure range investigated during this work (around 1.6, 13, and 30 atm) allows studying the effect of N?O on hydrogen ignition at pressure conditions that have never been heretofore investigated. Ignition delay times were decreased when N?O was added to the mixture only for the higher nitrous oxide concentrations, and some changes in the activation energy were also observed at 1.5 and 30 atm. When it occurred, the decrease in the ignition
Stabilized polyacrylic saccharide protein conjugates
Callstrom, Matthew R.; Bednarski, Mark D.; Gruber, Patrick R.
This invention is directed to water soluble protein polymer conjugates which are stabile in hostile environments. The conjugate comprises a protein which is linked to an acrylic polymer at multiple points through saccharide linker groups.
Exploring Infiniband Hardware Virtualization in OpenNebula towards Efficient High-Performance Computing
Pais Pitta de Lacerda Ruivo, Tiago; Bernabeu Altayo, Gerard; Garzoglio, Gabriele; Timm, Steven; Kim, Hyun-Woo; Noh, Seo-Young; Raicu, Ioan
has been widely accepted that software virtualization has a big negative impact on high-performance computing (HPC) application performance. This work explores the potential use of Infiniband hardware virtualization in an OpenNebula cloud towards the efficient support of MPI-based workloads. We have implemented, deployed, and tested an Infiniband network on the FermiCloud private Infrastructure-as-a-Service (IaaS) cloud. To avoid software virtualization towards minimizing the virtualization overhead, we employed a technique called Single Root Input/Output Virtualization (SRIOV). Our solution spanned modifications to the Linux's Hypervisor as well as the OpenNebula manager. We evaluated the performance of the hardware virtualization on up to 56 virtual machines connected by up to 8 DDR Infiniband network links, with micro-benchmarks (latency and bandwidth) as well as w a MPI-intensive application (the HPL Linpack benchmark).
Lovisi, L.; Mucciarelli, A.; Lanzoni, B.; Ferraro, F. R.; Dalessandro, E.
We present spectroscopic observations acquired with FLAMES and XSHOOTER at the Very Large Telescope for a sample of 15 blue straggler stars (BSSs) in the globular cluster (GC) M30. The targets have been selected to sample the two BSS sequences discovered, with seven BSSs along the blue sequence and eight along the red one. No difference in the kinematical properties of the two groups of BSSs has been found. In particular, almost all the observed BSSs have projected rotational velocities lower than {approx}30 km s{sup -1}, with only one (blue) fast rotating BSS (>90 km s{sup -1}), identified as a W UMa binary. This rotational velocity distribution is similar to those obtained in 47 Tucanae and NGC 6397, while M4 remains the only GC studied so far that harbors a large fraction of fast rotating BSSs. All stars hotter than {approx}7800 K (regardless of the parent BSS sequence) show iron abundances larger than those measured from normal cluster stars, with a clear-cut trend with the effective temperature. This behavior suggests that particle transport mechanisms driven by radiative levitation occur in the photosphere of these stars, as already observed for the BSSs in NGC 6397. Finally, four BSSs belonging to the red sequence (not affected by radiative levitation) show a strong depletion of [O/Fe], with respect to the abundance measured in red giant branch and horizontal branch stars. This O-depletion is compatible with the chemical signature expected in BSSs formed by mass-transfer processes in binary systems, in agreement with the mechanism proposed for the formation of BSSs in the red sequence.
A detailed kinetic modeling study of toluene oxidation in a premixed laminar flame
Tian, Z; Pitz, W J; Fournet, R; Glaude, P; Battin-Leclerc, F
An improved chemical kinetic model for the toluene oxidation based on experimental data obtained in a premixed laminar low-pressure flame with vacuum ultraviolet (VUV) photoionization and molecular beam mass spectrometry (MBMS) techniques has been proposed. The present mechanism consists of 273 species up to chrysene and 1740 reactions. The rate constants of reactions of toluene, decomposition, reaction with oxygen, ipso-additions and metatheses with abstraction of phenylic H-atom are updated; new pathways of C{sub 4} + C{sub 2} species giving benzene and fulvene are added. Based on the experimental observations, combustion intermediates such as fulvenallene, naphtol, methylnaphthalene, acenaphthylene, 2-ethynylnaphthalene, phenanthrene, anthracene, 1-methylphenanthrene, pyrene and chrysene are involved in the present mechanism. The final toluene model leads to an overall satisfactory agreement between the experimentally observed and predicted mole fraction profiles for the major products and most combustion intermediates. The toluene depletion is governed by metathese giving benzyl radicals, ipso-addition forming benzene and metatheses leading to C{sub 6}H{sub 4}CH{sub 3} radicals. A sensitivity analysis indicates that the unimolecular decomposition via the cleavage of a C-H bond has a strong inhibiting effect, while decomposition via C-C bond breaking, ipso-addition of H-atom to toluene, decomposition of benzyl radicals and reactions related to C{sub 6}H{sub 4}CH{sub 3} radicals have promoting effect for the consumption of toluene. Moreover, flow rate analysis is performed to illustrate the formation pathways of mono- and polycyclic aromatics.
Correlation between speciated hydrocarbon emissions and flame ionization detector response for gasoline/alcohol blends .
Wallner, T.
The U.S. renewable fuel standard has made it a requirement to increase the production of ethanol and advanced biofuels to 36 billion by 2022. Ethanol will be capped at 15 billion, which leaves 21 billion to come from other sources such as butanol. Butanol has a higher energy density and lower affinity for water than ethanol. Moreover, alcohol fueled engines in general have been shown to positively affect engine-out emissions of oxides of nitrogen and carbon monoxide compared with their gasoline fueled counterparts. In light of these developments, the variety and blend levels of oxygenated constituents is likely to increase in the foreseeable future. The effect on engine-out emissions for total hydrocarbons is less clear due to the relative insensitivity of the flame ionization detector (FID) toward alcohols and aldehydes. It is well documented that hydrocarbon (HC) measurement using a conventional FID in the presence of oxygenates in the engine exhaust stream can lead to a misinterpretation of HC emissions trends for alcohol fuel blends. Characterization of the exhaust stream for all expected hydrocarbon constituents is required to accurately determine the actual concentration of unburned fuel components in the exhaust. In addition to a conventional exhaust emissions bench, this characterization requires supplementary instrumentation capable of hydrocarbon speciation and response factor independent quantification. Although required for certification testing, this sort of instrumentation is not yet widely available in engine development facilities. Therefore, an attempt is made to empirically determine FID correction factors for oxygenate fuels. Exhaust emissions of an engine fueled with several blends of gasoline and ethanol, n-butanol and iso-Butanol were characterized using both a conventional FID and a Fourier transform infrared. Based on these results, a response factor predicting the actual hydrocarbon emissions based solely on FID results as a function of
Virtual-state internal nuclear fusion in metal lattices
Bussard, R.W. )
A model of deuterium-deuterium (D-D) fusion in metal lattices is presented based on two phenomena: reactions between virtual-state pairs of deuterons bound by electrons of high effective mass m and deuterium energy upscattering by fast ions from fusion or tritium reactions with virtual-state nuclear structure groups in palladium nuclei. Since m is a decreasing function of deuterium ion bulk density n/sub 0/ the exponential barrier tunneling factor decreases rapidly with m. As a result, the fusion rate reaches a maximum at a loading density above zero but less than saturation. This can explain observations of transient neutron output from the (/sup 3/He,n) branch, of D-D fusion.
Higher harmonics generation in relativistic electron beam with virtual cathode
Kurkin, S. A. Badarin, A. A.; Koronovskii, A. A.; Hramov, A. E.
The study of the microwave generation regimes with intense higher harmonics taking place in a high-power vircator consisting of a relativistic electron beam with a virtual cathode has been made. The characteristics of these regimes, in particular, the typical spectra and their variations with the change of the system parameters (beam current, the induction of external magnetic field) as well as physical processes occurring in the system have been analyzed by means of 3D electromagnetic simulation. It has been shown that the system under study demonstrates the tendency to the sufficient growth of the amplitudes of higher harmonics in the spectrum of current oscillations in the VC region with the increase of beam current. The obtained results allow us to consider virtual cathode oscillators as promising high power mmw-to-THz sources.
Parallel garbage collection on a virtual memory system
Abraham, S.G.; Patel, J.H.
Since most artificial intelligence applications are programmed in list processing languages, it is important to design architectures to support efficient garbage collection. This paper presents an architecture and an associated algorithm for parallel garbage collection on a virtual memory system. All the previously proposed parallel algorithms attempt to collect cells released by the list processor during the garbage collection cycle. We do not attempt to collect such cells. As a consequence, the list processor incurs little overhead in the proposed scheme, since it need not synchronize with the collector. Most parallel algorithms are designed for shared memory machines which have certain implicit synchronization functions on variable access. The proposed algorithm is designed for virtual memory systems where both the list processor and the garbage collector have private memories. The enforcement of coherence between the two private memories can be expensive and is not necessary in our scheme. 15 refs., 3 figs.
Wafer bonded virtual substrate and method for forming the same
Atwater, Jr., Harry A.; Zahler, James M.; Morral, Anna Fontcuberta i
A method of forming a virtual substrate comprised of an optoelectronic device substrate and handle substrate comprises the steps of initiating bonding of the device substrate to the handle substrate, improving or increasing the mechanical strength of the device and handle substrates, and thinning the device substrate to leave a single-crystal film on the virtual substrate such as by exfoliation of a device film from the device substrate. The handle substrate is typically Si or other inexpensive common substrate material, while the optoelectronic device substrate is formed of more expensive and specialized electro-optic material. Using the methodology of the invention a wide variety of thin film electro-optic materials of high quality can be bonded to inexpensive substrates which serve as the mechanical support for an optoelectronic device layer fabricated in the thin film electro-optic material.
Research Highlight: Virtual Oscillator Control Maintains Grid Operations
U.S. Department of Energy (DOE) all webpages (Extended Search)
with High Inverter Penetrations | Energy Systems Integration | NREL Research Highlight: Virtual Oscillator Control Maintains Grid Operations with High Inverter Penetrations June 21, 2016 Today's power grids rely on massive generators rotating at the correct speed to produce power at a certain frequency: 60 cycles per second in the United States. These generators give inertia to the entire power grid, which enables it to absorb disturbances with minimal deviations in frequency. Under such
Research Highlight: Virtual Oscillator Control Maintains Grid Operations
U.S. Department of Energy (DOE) all webpages (Extended Search)
with High Inverter Penetrations | Grid Modernization | NREL Research Highlight: Virtual Oscillator Control Maintains Grid Operations with High Inverter Penetrations June 21, 2016 Today's power grids rely on massive generators rotating at the correct speed to produce power at a certain frequency: 60 cycles per second in the United States. These generators give inertia to the entire power grid, which enables it to absorb disturbances with minimal deviations in frequency. Under such
Upcoming Release of the University of Minnesota's Virtual Wind Simulator
U.S. Department of Energy (DOE) all webpages (Extended Search)
Upcoming Release of the University of Minnesota's Virtual Wind Simulator - Sandia Energy Energy Search Icon Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable Energy Future Stationary Power Energy Conversion Efficiency Solar Energy Wind Energy Water Power Supercritical CO2 Geothermal Natural Gas Safety, Security & Resilience of the Energy Infrastructure Energy Storage Nuclear Power & Engineering Grid Modernization Battery Testing Nuclear
Identification of combustion intermediates in a low-pressure premixed laminar 2,5-dimethylfuran/oxygen/argon flame with tunable synchrotron photoionization
Wu, Xuesong; Huang, Zuohua; Wei, Lixia [State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an 710049 (China); Yuan, Tao; Zhang, Kuiwen [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029 (China)
Low-pressure (4.0 kPa) premixed laminar 2,5-dimethylfuran (DMF)/oxygen/argon flame with an equivalence ratio of 2.0 was studied with tunable vacuum ultraviolet (VUV) synchrotron radiation photoionization and molecular-beam mass spectrometry. Photoionization mass spectra of DMF/O{sub 2}/Ar flame were recorded and the photoionization efficiency curves of the combustion intermediates were measured. Flame species, including isomeric intermediates, are identified by comparing the measured ionization energies with those reported in literatures or those calculated with Gaussian-3 procedure. More than 70 species have been detected, including furan and its derivatives, aromatics, and free radicals. Possible reaction pathways of DMF, 2-methylfuran, and furan are proposed based on the intermediates identified. DMF can be consumed by H-abstraction and pyrolysis reactions. 2-Methylfuran and furan can be consumed by H-abstraction, H-addition and pyrolysis reactions. (author)
Amphiphiles for protein solubilization and stabilization (Patent...
Office of Scientific and Technical Information (OSTI)
Amphiphiles for protein solubilization and stabilization Citation Details In-Document Search Title: Amphiphiles for protein solubilization and stabilization The invention provides ...
Simulating flame lift-off characteristics of diesel and biodiesel fuels using detailed chemical-kinetic mechanisms and LES turbulence model.
Som, S; Longman, D. E.; Luo, Z; Plomer, M; Lu, T; Senecal, P.K.; Pomraning, E
Combustion in direct-injection diesel engines occurs in a lifted, turbulent diffusion flame mode. Numerous studies indicate that the combustion and emissions in such engines are strongly influenced by the lifted flame characteristics, which are in turn determined by fuel and air mixing in the upstream region of the lifted flame, and consequently by the liquid breakup and spray development processes. From a numerical standpoint, these spray combustion processes depend heavily on the choice of underlying spray, combustion, and turbulence models. The present numerical study investigates the influence of different chemical kinetic mechanisms for diesel and biodiesel fuels, as well as Reynolds-averaged Navier-Stokes (RANS) and large eddy simulation (LES) turbulence models on predicting flame lift-off lengths (LOLs) and ignition delays. Specifically, two chemical kinetic mechanisms for n-heptane (NHPT) and three for biodiesel surrogates are investigated. In addition, the RNG k-{epsilon} (RANS) model is compared to the Smagorinsky based LES turbulence model. Using adaptive grid resolution, minimum grid sizes of 250 {micro}m and 125 {micro}m were obtained for the RANS and LES cases respectively. Validations of these models were performed against experimental data from Sandia National Laboratories in a constant volume combustion chamber. Ignition delay and flame lift-off validations were performed at different ambient temperature conditions. The LES model predicts lower ignition delays and qualitatively better flame structures compared to the RNG k-{epsilon} model. The use of realistic chemistry and a ternary surrogate mixture, which consists of methyl decanoate, methyl 9-decenoate, and NHPT, results in better predicted LOLs and ignition delays. For diesel fuel though, only marginal improvements are observed by using larger size mechanisms. However, these improved predictions come at a significant increase in computational cost.
U31: Vehicle Stability and Dynamics: Electronic Stability Control
Petrolino, Joseph; Spezia, Tony; Arant, Michael; Delorenzis, Damon; LaClair, Tim J; Lim, Alvin; Pape, Doug
A team led by NTRCI is working to improve the roll and yaw stability of heavy duty combination trucks through developing stability algorithms, assembling demonstration hardware, and investigating robust wireless communication. Modern electronic stability control (ESC) products automatically slow a vehicle rounding a corner too quickly or apply individual brakes when necessary to improve the steering characteristics of a vehicle. Air brake systems in North America provide no electronic communication between a tractor and semitrailer, limiting the degree to which control systems can be optimized. Prior research has demonstrated stability improvements where dynamic measurements and control commands are communicated between units of a vehicle. Three related activities were undertaken: (1) Develop an algorithm for the optimum yaw and roll control of a combination vehicle. Vehicle state parameters needed to control the vehicle and the proper brake response were determined. An integrated stability control for the tractor and semitrailer requires communication between the two units. Dynamic models were used to assess the algorithm. (2) Implement the ESC algorithm in the laboratory. Hardware components suitable for the harsh environment for measurement, sensor-to-controller communication, and semitrailer-to-tractor communication and brake actuation were specified and assembled as a working system. The goal was to collect the needed vehicle state information, transmit the information to the ESC system, and then actuate the brakes in response to controller commands. (3) Develop a wireless network with the data rate and reliability necessary to communicate dynamic signals for a vehicle stability control system. Adaptive connectivity-aware, multi-hop routing was selected because it can perform in the harsh environment where packet collisions and fading often will exist. The protocol is to give high priority to urgent messages.
Kinetic simulations of the formation and stability of the field-reversed configuration
Omelchenko, Yu. A.
The Field-Reversed Configuration (FRC) is a high-beta compact toroidal plasma confined primarily by poloidal fields. In the FRC the external field is reversed on axis by the diamagnetic current carried by thermal plasma particles. A three-dimensional, hybrid, particle-in-cell (zero-inertia fluid electrons, and kinetic ions), code FLAME, previously used to study ion rings [Yu. A. Omelchenko and R. N. Sudan, J. Comp. Phys. 133, 146 (1997)], is applied to investigate FRC formation and tilt instability. Axisymmetric FRC equilibria are obtained by simulating the standard experimental reversed theta-pinch technique. These are used to study the nonlinear tilt mode in the ''kinetic'' and ''fluid-like'' cases characterized by ''small'' ({approx}3) and ''large'' ({approx}12) ratios of the characteristic radial plasma size to the mean ion gyro-radius, respectively. The formation simulations have revealed the presence of a substantial toroidal (azimuthal) magnetic field inside the separatrix, generated due to the stretching of the poloidal field by a sheared toroidal electron flow. This is shown to be an important tilt-stabilizing effect in both cases. On the other hand, the tilt mode stabilization by finite Larmor radius effects has been found relatively insignificant for the chosen equilibria. (c) 2000 American Institute of Physics.
Determination of total biogenic sulfur gases by filter/flash vaporization/flame photometry
Farwell, S.O.; Liebowitz, D.P.; Kagel, R.A.; Adams, D.F.
Complete conversion of H/sub 2/S, COS, CH/sub 3/SH, CH/sub 3/SCH/sub 3/, CS/sub 2/, and CH/sub 3/SSCH/sub 3/ to SO/sub 2/ has been shown to occur in a quartz tube held at a furnace temperature of 1050/sup 0/C for sample air flows from 30 mL/min to 2.8 L/min. The resultant SO/sub 2/-containing air flow is passed through an inline, precleaned Gelman Spectrograde filter which collects an average of 1.5 +- 0.3 ..mu..g of S/47 mm filter prior to SO/sub 2/ breakthrough. The sulfur collected on the filters is extracted with a recovery of 100 +- 3%. Final quantitative determinations of the sulfur in the filter extracts are performed via the flash vaporization/flame photometric (FV/FPD) technique using platinum boats. Equivalent FV/FPD linear responses were observed for H/sub 2/SO/sub 4/, Na/sub 2/SO/sub 4/, K/sub 2/SO/sub 4/, and (NH/sub 4/)/sub 2/SO/sub 4/ standards in the range of 0.4 to 12 ng of S. Repeated analyses of sulfate standards showed a relative standard deviation (RSD) = +-7.0%. Experimental results obtained for NaHCO/sub 3/, Na/sub 2/CO/sub 3/, NaOH, NaCl, KHCO/sub 3/, K/sub 2/CO/sub 3/, KOH, NH/sub 4/HCO/sub 3/, (NH/sub 4/)/sub 2/CO/sub 3/, NH/sub 3/(aq), FeCl/sub 3/, MnCl/sub 2/, and Na/sub 2/HgCl/sub 4/ as chemical impregnants in glass fiber filters for SO/sub 2/ collection and their compatibility with the FV/FPD system are also described.
Effects of Flaming Gorge Dam hydropower operations on flow and stage in the Green River, Utah and Colorado
Yin, S.C.L.; Cho, H.E.; McCoy, J.J.; Palmer, S.C.
This report presents the development of Flaming Gorge Reservoir release patterns and resulting downstream flows and stages for four potential hydropower operational scenarios. The release patterns were developed for three representative hydrologic years: moderate, dry, and wet. Computer models were used to estimate flows and stages in the Green River resulting from these release patterns for the moderate water year. The four hydropower operational scenarios for Flaming Gorge Dam were year-round high fluctuating flows, seasonally adjusted high fluctuating flows, seasonally adjusted moderate fluctuating flows, and seasonally adjusted steady flows. The year-round high fluctuating flow scenario assumes that the monthly total reservoir releases would be the same as historical releases. The remaining seasonally adjusted flow scenarios would comply with the 1992 Biological Opinion of the US Fish and Wildlife Service, which requires high flows in the spring and limited hourly fluctuations, especially in summer and autumn releases, to protect endangered fish. Within one year, the maximum daily river stage fluctuations resulting from hydropower operations under the seasonally adjusted high fluctuating flow scenario would be similar to the maximum daily fluctuations under the year-round high fluctuating flow scenario. However, reduced or no fluctuations would occur in some time periods under the former scenario. The maximum daily river stage fluctuations under the seasonally adjusted moderate fluctuating flow scenario would be about half of those under the seasonally adjusted high fluctuating flow scenario.
Effects of hydropower operations on recreational use and nonuse values at Glen Canyon and Flaming Gorge Dams
Carlson, J.L.
Increases in streamflows are generally positively related to the use values of angling and white-water boating, and constant flows tend to increase the use values more than fluctuating flows. In most instances, however, increases in streamflows beyond some threshold level cause the use values to decrease. Expenditures related to angling and white-water boating account for about $24 million of activity in the local economy around Glen Canyon Dam and $24.8 million in the local economy around flaming Gorge Dam. The range of operational scenarios being considered in the Western Area Power Administration`s Electric Power Marketing Environmental Impact Statement, when use rates are held constant, could change the combined use value of angling and white-water boating below Glen Canyon Dam, increasing it by as much as 50%, depending on prevailing hydrological conditions. Changes in the combined use value below Flaming Gorge Dam could range from a decrease of 9% to an increase of 26%. Nonuse values, such as existence and bequest values, could also make a significant contribution to the total value of each site included in this study; however, methodological and data limitations prevented estimating how each operational scenario could change nonuse values.
Effects of repetitive pulsing on multi-kHz planar laser-induced incandescence imaging in laminar and turbulent flames
Michael, James B.; Venkateswaran, Prabhakar; Shaddix, Christopher R.; Meyer, Terrence R.
Planar laser-induced incandescence (LII) imaging is reported at repetition rates up to 100 kHz using a burst-mode laser system to enable studies of soot formation dynamics in highly turbulent flames. Furthermore, to quantify the accuracy and uncertainty of relative soot volume fraction measurements, the temporal evolution of the LII field in laminar and turbulent flames is examined at various laser operating conditions. Under high-speed repetitive probing, it is found that LII signals are sensitive to changes in soot physical characteristics when operating at high laser fluences within the soot vaporization regime. For these laser conditions, strong planar LII signals aremore » observed at measurement rates up to 100 kHz but are primarily useful for qualitative tracking of soot structure dynamics. However, LII signals collected at lower fluences allow sequential planar measurements of the relative soot volume fraction with a sufficient signal-to-noise ratio at repetition rates of 10–50 kHz. Finally, guidelines for identifying and avoiding the onset of repetitive probe effects in the LII signals are discussed, along with other potential sources of measurement error and uncertainty.« less
Evaluation of metallic foils for preconcentration of sulfur-containing gases with subsequent flash desorption/flame photometric detection
Kagel, R.A.; Farwell, S.O.
Ag, Ni, Pd, Pt, Rh, and W foils were examined for their collective efficiencies toward seven sulfur-containing gases, i.e., H/sub 2/S, CH/sub 3/SH, CH/sub 3/SCH/sub 3/, CH/sub 3/SSCH/sub 3/, CS/sub 2/, COS, and SO/sub 2/. Low- and sub-part-per-billion (v/v) concentrations of these individual sulfur gases in air were drawn through a fluorocarbon resin cell containing a mounted 30-mm x 7-mm x 0.025-mm metal foil. The preconcentrated species were then thermally desorbed by a controlled pulse of current through the foil. The desorbed sample plug was swept in precleaned zero air from the fluorocarbon resin cell to a flame photometric detector. Sampling flow rate, ambient temperature, sample humidity, and common oxidants were examined for their effects on the collection efficiencies of these sulfur compounds on platinum and palladium foils. Analytical characteristics of this metal foil collection/flash desorption/flame photometric detector (MFC/FD/FPD) technique include a sulfur gas detectability of less than 50 pptr (parts per trillion) (v/v), a response repeatability of at least 95%, and field portable collection cells and instrumentation. The results are discussed both in terms of potential analytical applications of MFC/FD/FPD and in terms of their relationship to characterized models of gas adsorption on solid surfaces. 33 references, 6 figures, 3 tables.
Runtime Performance and Virtual Network Control Alternatives in VM-Based High-Fidelity Network Simulations
Yoginath, Srikanth B; Perumalla, Kalyan S; Henz, Brian J
In prior work (Yoginath and Perumalla, 2011; Yoginath, Perumalla and Henz, 2012), the motivation, challenges and issues were articulated in favor of virtual time ordering of Virtual Machines (VMs) in network simulations hosted on multi-core machines. Two major components in the overall virtualization challenge are (1) virtual timeline establishment and scheduling of VMs, and (2) virtualization of inter-VM communication. Here, we extend prior work by presenting scaling results for the first component, with experiment results on up to 128 VMs scheduled in virtual time order on a single 12-core host. We also explore the solution space of design alternatives for the second component, and present performance results from a multi-threaded, multi-queue implementation of inter-VM network control for synchronized execution with VM scheduling, incorporated in our NetWarp simulation system.
Prediction of Combustion Stability and Flashback in Turbines with High-Hydrogen Fuel
Lieuwen, Tim; Santavicca, Dom; Yang, Vigor
During the duration of this sponsorship, we broadened our understanding of combustion instabilities through both analytical and experimental work. Predictive models were developed for flame response to transverse acoustic instabilities and for quantifying how a turbulent flame responds to velocity and fuel/air ratio forcing. Analysis was performed on the key instability mechanisms controlling heat release response for flames over a wide range of instability frequencies. Importantly, work was done closely with industrial partners to transition existing models into internal instability prediction codes. Experimentally, the forced response of hydrogen-enriched natural gas/air premixed and partially premixed flames were measured. The response of a lean premixed flame was investigated, subjected to velocity, equivalence ratio, and both forcing mechanisms simultaneously. In addition, important physical mechanisms controlling the response of partially premixed flames to inlet velocity and equivalence ratio oscillations were analyzed. This final technical report summarizes our findings and major publications stemming from this program.
DOE AVESTAR Center Deploys 3-D Virtual Training System | Department of
Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)
Energy AVESTAR Center Deploys 3-D Virtual Training System DOE AVESTAR Center Deploys 3-D Virtual Training System October 2, 2012 - 1:00pm Addthis Washington, DC - The U.S. Department of Energy's AVESTAR Center has taken a major step forward with the successful deployment and site acceptance testing of a new 3-D virtual immersive training system for integrated gasification combined cycle (IGCC) power plants with carbon capture. The training center, launched in 2011, continues to build its
2015 SunShot Incubator Virtual Showcase Slides | Department of Energy
Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)
5 SunShot Incubator Virtual Showcase Slides 2015 SunShot Incubator Virtual Showcase Slides Download the slides from the 2015 SunShot Initiative Incubator Virtual Showcase webinar on March 4, 2015 below. You can also read the transcript. Click here to download the webinar slides. (10.34 MB) More Documents & Publications 2014 SunShot Initiative Portfolio Book: Technology to Market PRESENTATION: OVERVIEW OF THE SUNSHOT INITIATIVE Revitalizing American Competitiveness in Solar Technologies
Integrated Virtual Lab in Supporting Heavy Duty Engine and Vehicle Emission
Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)
Rulemaking | Department of Energy Virtual Lab in Supporting Heavy Duty Engine and Vehicle Emission Rulemaking Integrated Virtual Lab in Supporting Heavy Duty Engine and Vehicle Emission Rulemaking Presentation discusses a virtual lab which can model sophisticated future vehicle systems using three layers of model fidelity supporting each other. deer11_zhang.pdf (2.07 MB) More Documents & Publications Vehicle Technologies Office: Fact sheet on Adoption of New Fuel-Efficient Technologies
A virtual simulator designed for collision prevention in proton therapy
Jung, Hyunuk; Kum, Oyeon; Han, Youngyih Park, Hee Chul; Kim, Jin Sung; Choi, Doo Ho
Purpose: In proton therapy, collisions between the patient and nozzle potentially occur because of the large nozzle structure and efforts to minimize the air gap. Thus, software was developed to predict such collisions between the nozzle and patient using treatment virtual simulation. Methods: Three-dimensional (3D) modeling of a gantry inner-floor, nozzle, and robotic-couch was performed using SolidWorks based on the manufacturer's machine data. To obtain patient body information, a 3D-scanner was utilized right before CT scanning. Using the acquired images, a 3D-image of the patient's body contour was reconstructed. The accuracy of the image was confirmed against the CT image of a humanoid phantom. The machine components and the virtual patient were combined on the treatment-room coordinate system, resulting in a virtual simulator. The simulator simulated the motion of its components such as rotation and translation of the gantry, nozzle, and couch in real scale. A collision, if any, was examined both in static and dynamic modes. The static mode assessed collisions only at fixed positions of the machine's components, while the dynamic mode operated any time a component was in motion. A collision was identified if any voxels of two components, e.g., the nozzle and the patient or couch, overlapped when calculating volume locations. The event and collision point were visualized, and collision volumes were reported. Results: All components were successfully assembled, and the motions were accurately controlled. The 3D-shape of the phantom agreed with CT images within a deviation of 2 mm. Collision situations were simulated within minutes, and the results were displayed and reported. Conclusions: The developed software will be useful in improving patient safety and clinical efficiency of proton therapy.
Stability of Molten Core Materials
Layne Pincock; Wendell Hintze
The purpose of this report is to document a literature and data search for data and information pertaining to the stability of nuclear reactor molten core materials. This includes data and analysis from TMI-2 fuel and INL's LOFT (Loss of Fluid Test) reactor project and other sources.
Basis Document for Sludge Stabilization
Vault personnel have begun a program of radiographing plutonium metal cans. Metal that appears to be corroded will be processed through the furnaces in Glovebox HC-21C. The fire suppression system activation temperature will be deleted because it is not maintained by PFP Stabilization.
Potassium hydroxide clay stabilization process
Sydansk, R.
An aqueous solution having potassium hydroxide dissolved therein is injected into a subterranean sandstone formation containing water-sensitive fine particles, including clays. Potassium hydroxide stabilizes the fine particles for a substantial period of time thereby substantially preventing formation permeability damage caused by encroachment of aqueous solutions having a distinct ionic makeup into the treated formation.
Stability of charged thin shells
Eiroa, Ernesto F.; Simeone, Claudio
In this article we study the mechanical stability of spherically symmetric thin shells with charge, in Einstein-Maxwell and Einstein-Born-Infeld theories. We analyze linearized perturbations preserving the symmetry, for shells around vacuum and shells surrounding noncharged black holes.
Modelling Complex Fenestration Systems using physical and virtual models
Thanachareonkit, Anothai; Scartezzini, Jean-Louis
Physical or virtual models are commonly used to visualize the conceptual ideas of architects, lighting designers and researchers; they are also employed to assess the daylighting performance of buildings, particularly in cases where Complex Fenestration Systems (CFS) are considered. Recent studies have however revealed a general tendency of physical models to over-estimate this performance, compared to those of real buildings; these discrepancies can be attributed to several reasons. In order to identify the main error sources, a series of comparisons in-between a real building (a single office room within a test module) and the corresponding physical and virtual models was undertaken. The physical model was placed in outdoor conditions, which were strictly identical to those of the real building, as well as underneath a scanning sky simulator. The virtual model simulations were carried out by way of the Radiance program using the GenSky function; an alternative evaluation method, named Partial Daylight Factor method (PDF method), was also employed with the physical model together with sky luminance distributions acquired by a digital sky scanner during the monitoring of the real building. The overall daylighting performance of physical and virtual models were assessed and compared. The causes of discrepancies between the daylighting performance of the real building and the models were analysed. The main identified sources of errors are the reproduction of building details, the CFS modelling and the mocking-up of the geometrical and photometrical properties. To study the impact of these errors on daylighting performance assessment, computer simulation models created using the Radiance program were also used to carry out a sensitivity analysis of modelling errors. The study of the models showed that large discrepancies can occur in daylighting performance assessment. In case of improper mocking-up of the glazing for instance, relative divergences of 25-40% can be
User's Guide Virtual Hydropower Prospector Version 1.1
Douglas G. Hall; Sera E. White; Julie A. Brizzee; Randy D. Lee
The Virtual Hydropower Prospector is a web-based geographic information system (GIS) application for displaying U.S. water energy resource sites on hydrologic region maps. The application assists the user in locating sites of interest and performing preliminary, development feasibility assessments. These assessments are facilitated by displaying contextual features in addition to the water energy resource sites such as hydrograpy, roads, power infrastructure, populated places, and land use and control. This guide provides instructions for operating the application to select what features are displayed and the extent of the map view. It also provides tools for selecting features of particular interest and displaying their attribute information.
Decentralised optimisation of cogeneration in virtual power plants
Wille-Haussmann, Bernhard; Erge, Thomas; Wittwer, Christof
Within several projects we investigated grid structures and management strategies for active grids with high penetration of renewable energy resources and distributed generation (RES and DG). Those ''smart grids'' should be designed and managed by model based methods, which are elaborated within these projects. Cogeneration plants (CHP) can reduce the greenhouse gas emissions by locally producing heat and electricity. The integration of thermal storage devices is suitable to get more flexibility for the cogeneration operation. If several power plants are bound to centrally managed clusters, it is called ''virtual power plant''. To operate smart grids optimally, new optimisation and model reduction techniques are necessary to get rid with the complexity. There is a great potential for the optimised management of CHPs, which is not yet used. Due to the fact that electrical and thermal demands do not occur simultaneously, a thermally driven CHP cannot supply electrical peak loads when needed. With the usage of thermal storage systems it is possible to decouple electric and thermal production. We developed an optimisation method based on mixed integer linear programming (MILP) for the management of local heat supply systems with CHPs, heating boilers and thermal storages. The algorithm allows the production of thermal and electric energy with a maximal benefit. In addition to fuel and maintenance costs it is assumed that the produced electricity of the CHP is sold at dynamic prices. This developed optimisation algorithm was used for an existing local heat system with 5 CHP units of the same type. An analysis of the potential showed that about 10% increase in benefit is possible compared to a typical thermally driven CHP system under current German boundary conditions. The quality of the optimisation result depends on an accurate prognosis of the thermal load which is realised with an empiric formula fitted with measured data by a multiple regression method. The key
Generalized parton distributions from deep virtual compton scattering at CLAS
Guidal, M.
Here, we have analyzed the beam spin asymmetry and the longitudinally polarized target spin asymmetry of the Deep Virtual Compton Scattering process, recently measured by the Jefferson Lab CLAS collaboration. Our aim is to extract information about the Generalized Parton Distributions of the proton. By fitting these data, in a largely model-independent procedure, we are able to extract numerical values for the two Compton Form Factorsmore » $$H_{Im}$$ and $$\\tilde{H}_{Im}$$ with uncertainties, in average, of the order of 30%.« less
T-608: HP Virtual Server Environment Lets Remote Authenticated Users Gain Elevated Privileges
A potential security vulnerability has been identified in HP Virtual Server Environment for Windows. The vulnerability could be exploited remotely to elevate privileges.
U.S. Department of Energy (DOE) all webpages (Extended Search)
Physics Chris Hegna, Professor, Nuclear Engineering and Engineering Physics Carl Sovinec, ... 035003 (2010). 54 P. M. Bellan, Fundamentals of Plasma Physics, Cambridge ...
SVOPME: A scalable virtual organization privileges management environment
Garzoglio, Gabriele; Wang, Nanbor; Sfiligoi, Igor; Levshina, Tanya; Anathan, Balamurali; /Tech-X, Boulder
Grids enable uniform access to resources by implementing standard interfaces to resource gateways. In the Open Science Grid (OSG), privileges are granted on the basis of the user's membership to a Virtual Organization (VO). However, Grid sites are solely responsible to determine and control access privileges to resources using users identity and personal attributes, which are available through Grid credentials. While this guarantees full control on access rights to the sites, it makes VO privileges heterogeneous throughout the Grid and hardly fits with the Grid paradigm of uniform access to resources. To address these challenges, we are developing the Scalable Virtual Organization Privileges Management Environment (SVOPME), which provides tools for VOs to define and publish desired privileges and assists sites to provide the appropriate access policies. Moreover, SVOPME provides tools for Grid sites to analyze site access policies for various resources, verify compliance with preferred VO policies, and generate directives for site administrators on how the local access policies can be amended to achieve such compliance without taking control of local configurations away from site administrators. This paper discusses what access policies are of interest to the OSG community and how SVOPME implements privilege management for OSG.
Modal test optimization using VETO (Virtual Environment for Test Optimization)
Klenke, S.E.; Reese, G.M.; Schoof, L.A.; Shierling, C.
We present a software environment integrating analysis and test-based models to support optimal modal test design through a Virtual Environment for Test Optimization (VETO). A goal in developing this software tool is to provide test and analysis organizations with a capability of mathematically simulating the complete test environment in software. Derived models of test equipment, instrumentation and hardware can be combined within the VETO to provide the user with a unique analysis and visualization capability to evaluate new and existing test methods. The VETO assists analysis and test engineers in maximizing the value of each modal test. It is particularly advantageous for structural dynamics model reconciliation applications. The VETO enables an engineer to interact with a finite element model of a test object to optimally place sensors and exciters and to investigate the selection of data acquisition parameters needed to conduct a complete modal survey. Additionally, the user can evaluate the use of different types of instrumentation such as filters, amplifiers and transducers for which models are available in the VETO. The dynamic response of most of the virtual instruments (including the device under test) is modeled in the state space domain. Design of modal excitation levels and appropriate test instrumentation are facilitated by the VETO`s ability to simulate such features as unmeasured external inputs, A/D quantization effects, and electronic noise. Measures of the quality of the experimental design, including the Modal Assurance Criterion, and the Normal Mode Indicator Function are available.
Virtual laboratories: Collaborative environments and facilities-on-line
Thomas, C.E. Jr.; Cavallini, J.S.; Seweryniak, G.R.; Kitchens, T.A.; Hitchcock, D.A.; Scott, M.A.; Welch, L.C.; Aiken, R.J. |; Stevens, R.L.
The Department of Energy (DOE) has major research laboratories in a number of locations in the US, typically co-located with large research instruments or research facilities valued at tens of millions to even billions of dollars. Present budget exigencies facing the entire nation are felt very deeply at DOE, just as elsewhere. Advances over the last few years in networking and computing technologies make virtual collaborative environments and conduct of experiments over the internetwork structure a possibility. The authors believe that development of these collaborative environments and facilities-on-line could lead to a ``virtual laboratory`` with tremendous potential for decreasing the costs of research and increasing the productivity of their capital investment in research facilities. The majority of these cost savings would be due to increased productivity of their research efforts, better utilization of resources and facilities, and avoiding duplication of expensive facilities. A vision of how this might all fit together and a discussion of the infrastructure necessary to enable these developments is presented.
I/O Performance of Virtualized Cloud Environments
Ghoshal, Devarshi; Canon, Shane; Ramakrishnan, Lavanya
The scientific community is exploring the suitability of cloud infrastructure to handle High Performance Computing (HPC) applications. The goal of Magellan, a project funded through DOE ASCR, is to investigate the potential role of cloud computing to address the computing needs of the Department of Energy?s Office of Science, especially for mid-range computing and data-intensive applications which are not served through existing DOE centers today. Prior work has shown that applications with significant communication orI/O tend to perform poorly in virtualized cloud environments. However, there is a limited understanding of the I/O characteristics in virtualized cloud environments. This paper will present our results in benchmarking the I/O performance over different cloud and HPC platforms to identify the major bottlenecks in existing infrastructure. We compare the I/O performance using IOR benchmark on two cloud platforms - Amazon and Magellan. We analyze the performance of different storage options available, different instance types in multiple availability zones. Finally, we perform large-scale tests in order to analyze the variability in the I/O patterns over time and region. Our results highlight the overhead and variability in I/O performance on both public and private cloud solutions. Our results will help applications decide between the different storage options enabling applications to make effective choices.
Local invariants of stabilizer codes
Nest, Maarten van den; Dehaene, Jeroen; Moor, Bart de
In Phys. Rev. A 58, 1833 (1998), Grassl et al. presented a family of polynomial invariants which separate the orbits of multiqubit density operators {rho} under the action of the local unitary group. We consider this family of invariants for the class of those {rho} that are the projection operators describing stabilizer codes and give a complete translation of these invariants into the binary framework in which stabilizer codes are usually described. Such an investigation of local invariants of quantum codes is of natural importance in quantum coding theory, since locally equivalent codes have the same error-correcting capabilities and local invariants are powerful tools to explore their structure. Moreover, the present result is relevant in the context of multipartite entanglement and the development of the measurement-based model of quantum computation known as the one-way quantum computer.
Biological sludge stabilization reactor evaluations
Corbitt, R.A.; Bowen, P.T.; Smith, P.E.
Anaerobic digestion was chosen as the means to stabilize primary and thickened waste activated sludge for a 0.88 m{sup 3}/s (20 mgd) advanced wastewater reclamation facility. Two stage digestion was proposed to produce Class B sludge. Reactor shape was an important variable in design of the first stage digestion. Evaluation of conventional and egg shaped anaerobic digesters was performed. Based on the economic and non-economic criteria analysis, egg shaped reactors were selected.
Artificial neural network implementation of chemistry with pdf simulation of H{sub 2}/CO{sub 2} flames
Christo, F.C.; Masri, A.R.; Nebot, E.M.
A novel approach using artificial neural networks for representing chemical reactions is developed and successfully implemented with a modeled velocity-scalar joint pdf transport equation for H{sub 2}CO{sub 2} turbulent jet diffusion flames. The chemical kinetics are represented using a three-step reduced mechanism, and the transport equation is solved by a Monte Carlo method. A detailed analysis of computational performance and a comparison between the neural network approach and other methods used to represent the chemistry, namely the look-up table, or the direct integration procedures, are presented. A multilayer perceptron architecture is chosen for the neural network. The training algorithm is based on a back-propagation supervised learning procedure with individual momentum terms and adaptive learning rate adjustment for the weights matrix. A new procedure for the selection of training samples using dynamic randomization is developed and is aimed at reducing the possibility of the network being trapped in a local minimum. This algorithm achieved an impressive acceleration in convergence compared with the use of a fixed set of selected training samples. The optimization process of the neural network is discussed in detail. The feasibility of using neural network models to represent highly nonlinear chemical reactions is successfully illustrated. The prediction of the flow field and flame characteristics using the neural network approach is in good agreement with those obtained using other methods, and is also in reasonable agreement with the experimental data. The computational benefits of the neural network approach over the look-up table and the direct integration methods, both in CPU time and RAM storage requirements are not great for a chemical mechanisms of less than three reactions. The neural network approach becomes superior, however, for more complex reaction schemes.
Coherency Does Not Equate to Stability
U.S. Department of Energy (DOE) all webpages (Extended Search)
to Stability As-grown nanotwin (NT) copper (A) SEM image. (B) An edge-on inverse ... M. Kumar, "Topological view of the thermal stability of nanotwinned copper", Appl. Phys. ...
Amphiphiles for protein solubilization and stabilization (Patent...
Office of Scientific and Technical Information (OSTI)
The invention provides amphiphiles for manipulating membrane proteins. The amphiphiles can ... and stabilization of membrane proteins, including photosynthetic protein ...
Stabilizing System Pressure | Department of Energy
Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)
Stabilizing System Pressure Stabilizing System Pressure This tip sheet summarizes three methods used to stabilize compressed air system pressure: adequate primary and secondary storage, Pressure/Flow Controllers (P/FCs), and dedicated compressors. COMPRESSED AIR TIP SHEET #8 Stabilizing System Pressure (August 2004) (243.38 KB) More Documents & Publications Compressed Air Storage Strategies Compressed Air System Control Strategies Analyzing Your Compressed Air System
A Stability of LCLS Linac Modulators
Decker, F.-J.; Krasnykh, A.; Morris, B.; Nguyen, M.; /SLAC
Information concerning to a stability of LCLS RF linac modulators is allocated in this paper. In general a 'pulse-to-pulse' modulator stability (and RF phase as well) is acceptable for the LCLS commission and FEL programs. Further modulator stability improvements are possible and approaches are discussed based on our experimental results.
Stabilizing oscillating universes against quantum decay
Mithani, Audrey T.; Vilenkin, Alexander
We investigate the effect of vacuum corrections, due to the trace anomaly and Casimir effect, on the stability of an oscillating universe with respect to decay by tunneling to the singularity. We find that these corrections do not generally stabilize an oscillating universe. However, stability may be achieved for some specially fine-tuned non-vacuum states.
Longitudinal target-spin asymmetries for deeply virtual Compton scattering
Seder, E.; Biselli, A.; Pisano, S.; Niccolai, S.; Smith, G. D.; Joo, K.; Adhikari, K.; Amaryan, M. J.; Anderson, M. D.; Anefalos Pereira, S.; Avakian, H.; Battaglieri, M.; Bedlinskiy, I.; Bono, J.; Boiarinov, S.; Bosted, P.; Briscoe, W.; Brock, J.; Brooks, W. K.; Bültmann, S.; Burkert, V. D.; Carman, D. S.; Carlin, C.; Celentano, A.; Chandavar, S.; Charles, G.; Colaneri, L.; Cole, P. L.; Contalbrigo, M.; Crabb, D.; Crede, V.; D'Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Doughty, D.; Dupre, R.; El Fassi, L.; Elouadrhiri, L.; Eugenio, P.; Fedotov, G.; Fegan, S.; Filippi, A.; Fleming, J. A.; Fradi, A.; Garillon, B.; Garçon, M.; Gevorgyan, N.; Ghandilyan, Y.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Gohn, W.; Gothe, R. W.; Griffioen, K. A.; Guegan, B.; Guidal, M.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Harrison, N.; Hattawy, M.; Hirlinger Saylor, N.; Holtrop, M.; Hughes, S. M.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Jo, H. S.; Joosten, S.; Keith, C. D.; Keller, D.; Khachatryan, G.; Khandaker, M.; Kim, A.; Kim, W.; Klein, A.; Klein, F. J.; Koirala, S.; Kubarovsky, V.; Kuhn, S. E.; Lenisa, P.; Livingston, K.; Lu, H. Y.; MacGregor, I. J. D.; Markov, N.; Mayer, M.; McKinnon, B.; Meekins, D. G.; Mineeva, T.; Mirazita, M.; Mokeev, V.; Montgomery, R.; Moody, C. I.; Moutarde, H.; Movsisyan, A.; Munoz Camacho, C.; Nadel-Turonski, P.; Niculescu, I.; Osipenko, M.; Ostrovidov, A. I.; Paolone, M.; Pappalardo, L. L.; Park, K.; Park, S.; Pasyuk, E.; Peng, P.; Phelps, W.; Pogorelko, O.; Price, J. W.; Prok, Y.; Protopopescu, D.; Puckett, A. J. R.; Ripani, M.; Rizzo, A.; Rosner, G.; Rossi, P.; Roy, P.; Sabatié, F.; Salgado, C.; Schott, D.; Schumacher, R. A.; Senderovich, I.; Simonyan, A.; Skorodumina, I.; Sokhan, D.; Sparveris, N.; Stepanyan, S.; Stoler, P.; Strakovsky, I. I.; Strauch, S.; Sytnik, V.; Taiuti, M.; Tang, W.; Tian, Y.; Ungaro, M.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Wei, X.; Weinstein, L. B.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhang, J.; Zonta, I.
A measurement of the electroproduction of photons off protons in the deeply inelastic regime was performed at Jefferson Lab using a nearly 6-GeV electron beam, a longitudinally polarized proton target and the CEBAF Large Acceptance Spectrometer. Target-spin asymmetries for ep → e'p'y events, which arise from the interference of the deeply virtual Compton scattering and the Bethe-Heitler processes, were extracted over the widest kinematics in Q2, xB, t and Φ, for 166 four-dimensional bins. In the framework of Generalized Parton Distributions (GPDs), at leading twist the t dependence of these asymmetries provides insight on the spatial distribution of the axial charge of the proton, which appears to be concentrated in its center. In conclusion, these results bring important and necessary constraints for the existing parametrizations of chiral-even GPDs.
A Virtual Visit to Bioenergy Research at the National Laboratories
For National Bioenergy Day on October 22, bioenergy facilities across the country are holding open houses to increase public awareness of bioenergy and its role in the clean energy landscape. By the same token, the Bioenergy Technologies Office (BETO) is offering this virtual open house of its national laboratories—the facilities at the core of BETO's research and development. If you want to know how Energy Department bioenergy funding is making an impact, be sure to take a look at our national labs—47% of BETO funding this past year went to the national laboratories. Of that funding, about half went to the National Renewable Energy Laboratory. Pacific Northwest National Laboratory, Idaho National Laboratory, and Oak Ridge National Laboratory also received a large share.
Orbit correction using virtual monitors at Jefferson Lab
Chao, Yu-Chiu; Bowling, B.; Witherspoon, S.; Zeijts, J. van; Watson, W.A. III
An orbit correction algorithm is developed to achieve the following goals for the CEBAF accelerator at Jefferson Lab.: (1) Pre-processing of orbit input to account for estimated misalignment and monitor errors. (2) Automatic elimination of blind spots caused by response matrix degeneracy. (3) Transparency of exception handling to interchangeable generic steering engines. (4) CEBAF-specific demands on control of injection angle, path length, orbit effects on optics, simultaneous multiple pass steering, and orbit control at un-monitored locations. All of the above can be accomplished by the introduction of virtual monitors into the processed input orbit, whose theoretical basis is to be discussed in this report. Implementation of all or part of these features and operational experience during the CEBAF variable energy runs will also be discussed.
Longitudinal target-spin asymmetries for deeply virtual Compton scattering
Seder, E.; Biselli, A.; Pisano, S.; Niccolai, S.; Smith, G. D.; Joo, K.; Adhikari, K.; Amaryan, M. J.; Anderson, M. D.; Anefalos Pereira, S.; et al
A measurement of the electroproduction of photons off protons in the deeply inelastic regime was performed at Jefferson Lab using a nearly 6-GeV electron beam, a longitudinally polarized proton target and the CEBAF Large Acceptance Spectrometer. Target-spin asymmetries for ep → e'p'y events, which arise from the interference of the deeply virtual Compton scattering and the Bethe-Heitler processes, were extracted over the widest kinematics in Q2, xB, t and Φ, for 166 four-dimensional bins. In the framework of Generalized Parton Distributions (GPDs), at leading twist the t dependence of these asymmetries provides insight on the spatial distribution of the axialmore » charge of the proton, which appears to be concentrated in its center. In conclusion, these results bring important and necessary constraints for the existing parametrizations of chiral-even GPDs.« less
Optimization of a Virtual Power Plant to Provide Frequency Support.
Neely, Jason C.; Johnson, Jay; Gonzalez, Sigifredo; Lave, Matthew Samuel; Delhotal, Jarod James
Increasing the penetration of distributed renewable sources, including photovoltaic (PV) sources, poses technical challenges for grid management. The grid has been optimized over decades to rely upon large centralized power plants with well-established feedback controls, but now non-dispatchable, renewable sources are displacing these controllable generators. This one-year study was funded by the Department of Energy (DOE) SunShot program and is intended to better utilize those variable resources by providing electric utilities with the tools to implement frequency regulation and primary frequency reserves using aggregated renewable resources, known as a virtual power plant. The goal is to eventually enable the integration of 100s of Gigawatts into US power systems.
Applying Nonlinear Signal Analysis Technologies to Flame Scanner Signals to Improve Staging of Cyclone Boilers for NOx control
Flynn, T. J.; Bailey, R. T.; Fuller, T. A.; FINNEY, Charles E A; Daw, C Stuart; Stallings, J.; Himes, R.; Bermke, R.
Cyclone{trademark} boiler owners continue to drive down NO{sub x} emissions by increasingly sophisticated staging and air distribution schemes. For example, Alliant Energy has employed RMT's SmartBurn{reg_sign} technology, and Ameren UE has pioneered neural nets to reduce emissions. Over the last 11 years under sponsorship of EPRI, the team of ORNL and B&W has developed pulverized coal burner diagnostic technology by applying nonlinear signal analysis techniques to flame scanner signals. The team has extended the technology to cyclones to facilitate deeper staging of the cyclones to reduce NO{sub x} emissions. Development projects were conducted at the Alliant Energy Edgewater Units 3 and 4, and Ameren UE Sioux Unit 1. Nonlinear analysis statistics were correlated to upsets in cyclone operation resulting from poor air distribution in the burner and barrel. The team demonstrated that the lighter and main flame scanners can be used to independently guide adjustments to the burner and barrel.
Breakthrough: MFiX: Building Industry-Scale Machines in a Virtual World |
Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)
Department of Energy Breakthrough: MFiX: Building Industry-Scale Machines in a Virtual World Breakthrough: MFiX: Building Industry-Scale Machines in a Virtual World July 11, 2012 - 1:34pm Addthis Mfix is open-source, virtual modeling software that makes coal gasification processes more efficient than was ever possible through lab tests. Modeling reduces the cost and time of testing and building actual systems and ultimately results in lower costs, improved power plant efficiency, and new
An inter-realm, cyber-security infrastructure for virtual supercomputing
Al-Muhtadi, J.; Feng, W. C.; Fisk, M. E.
Virtual supercomputing, (ise ., high-performance grid computing), is poised to revolutionize the way we think about and use computing. However, the security of the links interconnecting the nodes within such an environment will be its Achilles heel, particularly when secure communication is required to tunnel through heterogeneous domains. In this paper we examine existing security mechanisms, show their inadequacy, and design a comprehensive cybersecurity infrastructure that meets the security requirements of virtual supercomputing. Keywords Security, virtual supercomputing, grid computing, high-performance computing, GSS-API, SSL, IPsec, component-based software, dynamic reconfiguration.
Effect of fuel rate and annealing process of LiFePO{sub 4} cathode material for Li-ion batteries synthesized by flame spray pyrolysis method
Halim, Abdul; Setyawan, Heru; Machmudah, Siti; Nurtono, Tantular; Winardi, Sugeng
In this study the effect of fuel rate and annealing on particle formation of LiFePO{sub 4} as battery cathode using flame spray pyrolysis method was investigated numerically and experimentally. Numerical study was done using ANSYS FLUENT program. In experimentally, LiFePO{sub 4} was synthesized from inorganic aqueous solution followed by annealing. LPG was used as fuel and air was used as oxidizer and carrier gas. Annealing process attempted in inert atmosphere at 700�C for 240 min. Numerical result showed that the increase of fuel rate caused the increase of flame temperature. Microscopic observation using Scanning Electron Microscopy (SEM) revealed that all particles have sphere and polydisperse. Increasing fuel rate caused decreasing particle size and increasing particles crystallinity. This phenomenon attributed to the flame temperature. However, all produced particles still have more amorphous phase. Therefore, annealing needed to increase particles crystallinity. Fourier Transform Infrared (FTIR) analysis showed that all particles have PO4 function group. Increasing fuel rate led to the increase of infrared spectrum absorption corresponding to the increase of particles crystallinity. This result indicated that phosphate group vibrated easily in crystalline phase. From Electrochemical Impedance Spectroscopy (EIS) analysis, annealing can cause the increase of Li{sup +} diffusivity. The diffusivity coefficient of without and with annealing particles were 6.84399�10{sup ?10} and 8.59888�10{sup ?10} cm{sup 2} s{sup ?1}, respectively.
An experimental investigation of ethylene/O{sub 2}/diluent mixtures: Laminar flame speeds with preheat and ignition delays at high pressures
Kumar, Kamal; Mittal, Gaurav; Sung, Chih-Jen [Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, OH 44106 (United States); Law, Chung K. [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States)
The atmospheric pressure laminar flame speeds of premixed ethylene/O{sub 2}/N{sub 2} mixtures were experimentally measured over equivalence ratios ranging from 0.5 to 1.4 and mixture preheat temperatures varying from 298 to 470 K in a counterflow configuration. Ignition delay measurements were also conducted for ethylene/O{sub 2}/N{sub 2}/Ar mixtures using a rapid compression machine at compressed pressures from 15 to 50 bar and in the compressed temperature range from 850 to 1050 K. The experimental laminar flame speeds and ignition delays were then compared to the computed values using two existing chemical kinetic mechanisms. Results show that while the laminar flame speeds are reasonably predicted at room temperature conditions, the discrepancy becomes larger with increasing preheat temperature. A comparison of experimental and computational ignition delay times was also conducted and discussed. Sensitivity analysis further shows that the ignition delay is highly sensitive to the reactions of the vinyl radical with molecular oxygen. The reaction of ethylene with the HO{sub 2} radical was also found to be important for autoignition under the current experimental conditions. (author)
The combustion chemistry of a fuel tracer: Measured flame speeds and ignition delays and a detailed chemical kinetic model for the oxidation of acetone
Pichon, S.; Black, G.; Simmie, J.M.; Curran, H.J.; Chaumeix, N.; Yahyaoui, M.; Donohue, R.
Acetone ignition delay and stretch-free laminar flame speed measurements have been carried out and a kinetic model has been developed to simulate these and literature data for acetone and for ketene, which was found to be an important intermediate in its oxidation. The mechanism has been based on one originally devised for dimethyl ether and modified through validation of the hydrogen, carbon monoxide and methane sub-mechanisms. Acetone oxidation in argon was studied behind reflected shock waves in the temperature range 1340-1930 K, at 1 atm and at equivalence ratios of 0.5, 1 and 2; it is also shown that the addition of up to 15% acetone to a stoichiometric n-heptane mixture has no effect on the measured ignition delay times. Flame speeds at 298 K and 1 atm of pure acetone in air were measured in a spherical bomb; a maximum flame speed of {proportional_to}35 cm s{sup -1} at {phi}=1.15 is indicated. (author)
Using powerful computers, physicists uncover mechanism that stabilizes...
U.S. Department of Energy (DOE) all webpages (Extended Search)
of the virtual plasma showing where the magnetic field lines intersect the plane. ... This gradient combines with the rotating magnetic field lines to create spinning rolls ...
Mike Bockelie; Dave Swensen; Martin Denison; Adel Sarofim; Connie Senior
In this report is described the work effort to develop and demonstrate a software framework to support advanced process simulations to evaluate the performance of advanced power systems. Integrated into the framework are a broad range of models, analysis tools, and visualization methods that can be used for the plant evaluation. The framework provides a tightly integrated problem-solving environment, with plug-and-play functionality, and includes a hierarchy of models, ranging from fast running process models to detailed reacting CFD models. The framework places no inherent limitations on the type of physics that can be modeled, numerical techniques, or programming languages used to implement the equipment models, or the type or amount of data that can be exchanged between models. Tools are provided to analyze simulation results at multiple levels of detail, ranging from simple tabular outputs to advanced solution visualization methods. All models and tools communicate in a seamless manner. The framework can be coupled to other software frameworks that provide different modeling capabilities. Three software frameworks were developed during the course of the project. The first framework focused on simulating the performance of the DOE Low Emissions Boiler System Proof of Concept facility, an advanced pulverized-coal combustion-based power plant. The second framework targeted simulating the performance of an Integrated coal Gasification Combined Cycle - Fuel Cell Turbine (IGCC-FCT) plant configuration. The coal gasifier models included both CFD and process models for the commercially dominant systems. Interfacing models to the framework was performed using VES-Open, and tests were performed to demonstrate interfacing CAPE-Open compliant models to the framework. The IGCC-FCT framework was subsequently extended to support Virtual Engineering concepts in which plant configurations can be constructed and interrogated in a three-dimensional, user-centered, interactive
A Virtual Engineering Framework for Simulating Advanced Power System
Mike Bockelie; Dave Swensen; Martin Denison; Stanislav Borodai
In this report is described the work effort performed to provide NETL with VE-Suite based Virtual Engineering software and enhanced equipment models to support NETL's Advanced Process Engineering Co-simulation (APECS) framework for advanced power generation systems. Enhancements to the software framework facilitated an important link between APECS and the virtual engineering capabilities provided by VE-Suite (e.g., equipment and process visualization, information assimilation). Model enhancements focused on improving predictions for the performance of entrained flow coal gasifiers and important auxiliary equipment (e.g., Air Separation Units) used in coal gasification systems. In addition, a Reduced Order Model generation tool and software to provide a coupling between APECS/AspenPlus and the GE GateCycle simulation system were developed. CAPE-Open model interfaces were employed where needed. The improved simulation capability is demonstrated on selected test problems. As part of the project an Advisory Panel was formed to provide guidance on the issues on which to focus the work effort. The Advisory Panel included experts from industry and academics in gasification, CO2 capture issues, process simulation and representatives from technology developers and the electric utility industry. To optimize the benefit to NETL, REI coordinated its efforts with NETL and NETL funded projects at Iowa State University, Carnegie Mellon University and ANSYS/Fluent, Inc. The improved simulation capabilities incorporated into APECS will enable researchers and engineers to better understand the interactions of different equipment components, identify weaknesses and processes needing improvement and thereby allow more efficient, less expensive plants to be developed and brought on-line faster and in a more cost-effective manner. These enhancements to APECS represent an important step toward having a fully integrated environment for performing plant simulation and engineering
Surface rheology and interface stability.
Yaklin, Melissa A.; Cote, Raymond O.; Moffat, Harry K.; Grillet, Anne Mary; Walker, Lynn; Koehler, Timothy P.; Reichert, Matthew D.; Castaneda, Jaime N.; Mondy, Lisa Ann; Brooks, Carlton, F.
We have developed a mature laboratory at Sandia to measure interfacial rheology, using a combination of home-built, commercially available, and customized commercial tools. An Interfacial Shear Rheometer (KSV ISR-400) was modified and the software improved to increase sensitivity and reliability. Another shear rheometer, a TA Instruments AR-G2, was equipped with a du Nouey ring, bicone geometry, and a double wall ring. These interfacial attachments were compared to each other and to the ISR. The best results with the AR-G2 were obtained with the du Nouey ring. A Micro-Interfacial Rheometer (MIR) was developed in house to obtain the much higher sensitivity given by a smaller probe. However, it was found to be difficult to apply this technique for highly elastic surfaces. Interfaces also exhibit dilatational rheology when the interface changes area, such as occurs when bubbles grow or shrink. To measure this rheological response we developed a Surface Dilatational Rheometer (SDR), in which changes in surface tension with surface area are measured during the oscillation of the volume of a pendant drop or bubble. All instruments were tested with various surfactant solutions to determine the limitations of each. In addition, foaming capability and foam stability were tested and compared with the rheology data. It was found that there was no clear correlation of surface rheology with foaming/defoaming with different types of surfactants, but, within a family of surfactants, rheology could predict the foam stability. Diffusion of surfactants to the interface and the behavior of polyelectrolytes were two subjects studied with the new equipment. Finally, surface rheological terms were added to a finite element Navier-Stokes solver and preliminary testing of the code completed. Recommendations for improved implementation were given. When completed we plan to use the computations to better interpret the experimental data and account for the effects of the underlying bulk
PMU Data Integrity Evaluation through Analytics on a Virtual Test-Bed
Olama, Mohammed M.; Shankar, Mallikarjun
Power systems are rapidly becoming populated by phasor measurement units (PMUs) in ever increasing numbers. PMUs are critical components of today s energy management systems, designed to enable near real-time wide area monitoring and control of the electric power system. They are able to measure highly accurate bus voltage phasors as well as branch current phasors incident to the buses at which PMUs are equipped. Synchrophasor data is used for applications varying from state estimation, islanding control, identifying outages, voltage stability detection and correction, disturbance recording, and others. However, PMU-measured readings may suffer from errors due to meter biases or drifts, incorrect configurations, or even cyber-attacks. Furthermore, the testing of early PMUs showed a large disparity between the reported values from PMUs provided by different manufacturers, particularly when frequency was off-nominal, during dynamic events, and when harmonic/inter-harmonic content was present. Detection and identification of PMU gross measurement errors are thus crucial in maintaining highly accurate phasor readings throughout the system. In this paper, we present our work in conducting analytics to determine the trustworthiness and worth of the PMU readings collected across an electric network system. By implementing the IEEE 118 bus test case on a virtual test bed (VTB) , we are able to emulate PMU readings (bus voltage and branch current phasors in addition to bus frequencies) under normal and abnormal conditions using (virtual) PMU sensors deployed across major substations in the network. We emulate a variety of failures such as bus, line, transformer, generator, and/or load failures. Data analytics on the voltage phase angles and frequencies collected from the PMUs show that specious (or compromised) PMU device(s) can be identified through abnormal behaviour by comparing the trend of its frequency and phase angle reading with the ensemble of all other PMU
Modeling the Virtual Machine Launching Overhead under Fermicloud
Garzoglio, Gabriele; Wu, Hao; Ren, Shangping; Timm, Steven; Bernabeu, Gerard; Noh, Seo-Young
FermiCloud is a private cloud developed by the Fermi National Accelerator Laboratory for scientific workflows. The Cloud Bursting module of the FermiCloud enables the FermiCloud, when more computational resources are needed, to automatically launch virtual machines to available resources such as public clouds. One of the main challenges in developing the cloud bursting module is to decide when and where to launch a VM so that all resources are most effectively and efficiently utilized and the system performance is optimized. However, based on FermiCloud's system operational data, the VM launching overhead is not a constant. It varies with physical resource (CPU, memory, I/O device) utilization at the time when a VM is launched. Hence, to make judicious decisions as to when and where a VM should be launched, a VM launch overhead reference model is needed. The paper is to develop a VM launch overhead reference model based on operational data we have obtained on FermiCloud and uses the reference model to guide the cloud bursting process.
Interactive graphical model building using telepresence and virtual reality
Cooke, C.; Stansfield, S.
This paper presents a prototype system developed at Sandia National Laboratories to create and verify computer-generated graphical models of remote physical environments. The goal of the system is to create an interface between an operator and a computer vision system so that graphical models can be created interactively. Virtual reality and telepresence are used to allow interaction between the operator, computer, and remote environment. A stereo view of the remote environment is produced by two CCD cameras. The cameras are mounted on a three degree-of-freedom platform which is slaved to a mechanically-tracked, stereoscopic viewing device. This gives the operator a sense of immersion in the physical environment. The stereo video is enhanced by overlaying the graphical model onto it. Overlay of the graphical model onto the stereo video allows visual verification of graphical models. Creation of a graphical model is accomplished by allowing the operator to assist the computer in modeling. The operator controls a 3-D cursor to mark objects to be modeled. The computer then automatically extracts positional and geometric information about the object and creates the graphical model.
Development of a new virtual diagnostic for V3FIT
Trevisan, G. L. Terranova, D.; Cianciosa, M. R.; Hanson, J. D.
The determination of plasma equilibria from diagnostic information is a fundamental issue. V3FIT is a fully three-dimensional reconstruction code capable of solving the inverse problem using both magnetic and kinetic measurements. It uses VMEC as core equilibrium solver and supports both free- and fixed-boundary reconstruction approaches. In fixed-boundary mode VMEC does not use explicit information about currents in external coils, even though it has important effects on the shape of the safety factor profile. Indeed, the edge safety factor influences the reversal position in RFP plasmas, which then determines the position of the m = 0 island chain and the edge transport properties. In order to exploit such information a new virtual diagnostic has been developed, that thanks to Ampère's law relates the external current through the center of the torus to the circulation of the toroidal magnetic field on the outermost flux surface. The reconstructions that exploit the new diagnostic are indeed found to better interpret the experimental data with respect to edge physics.
Final Report for the Virtual Reliability Realization System LDRD
Current approaches to reliability are not adequate to keep pace with the need for faster, better and cheaper products and systems. This is especially true in high consequence of failure applications. The original proposal for the LDRD was to look at this challenge and see if there was a new paradigm that could make reliability predictions, along with a quantitative estimate of the risk in that prediction, in a way that was faster, better and cheaper. Such an approach would be based on the underlying science models that are the backbone of reliability predictions. The new paradigm would be implemented in two software tools: the Virtual Reliability Realization System (VRRS) and the Reliability Expert System (REX). The three-year LDRD was funded at a reduced level for the first year ($120K vs. $250K) and not renewed. Because of the reduced funding, we concentrated on the initial development of the expertise system. We developed an interactive semiconductor calculation tool needed for reliability analyses. We also were able to generate a basic functional system using Microsoft Siteserver Commerce Edition and Microsoft Sequel Server. The base system has the capability to store Office documents from multiple authors, and has the ability to track and charge for usage. The full outline of the knowledge model has been incorporated as well as examples of various types of content.
Virtuality and transverse momentum dependence of the pion distribution amplitude
Radyushkin, Anatoly V.
We describe basics of a new approach to transverse momentum dependence in hard exclusive processes. We develop it in application to the transition process γ*γ → π0 at the handbag level. Our starting point is coordinate representation for matrix elements of operators (in the simplest case, bilocal O (0,z)) describing a hadron with momentum p. Treated as functions of (pz) and z2, they are parametrized through virtuality distribution amplitudes (VDA) Φ(x,σ), with x being Fourier-conjugate to (pz) and σ Laplace-conjugate to z2. For intervals with z+ = 0, we introduce the transverse momentum distribution amplitude (TMDA) ψ(x, k), and writemore » it in terms of VDA Φ(x,σ). The results of covariant calculations, written in terms of Φ(x, σ) are converted into expressions involving ψ(x, k). Starting with scalar toy models, we extend the analysis onto the case of spin-1/2 quarks and QCD. We propose simple models for soft VDAs/TMDAs, and use them for comparison of handbag results with experimental (BaBar and BELLE) data on the pion transition form factor. Furthermore, we discuss how one can generate high-k tails from primordial soft distributions.« less
Deeply virtual Compton Scattering cross section measured with CLAS
Guegan, Baptistse
The Generalized Parton Distributions (GPDs) provide a new description of nucleon structure in terms of its elementary constituents, the quarks and the gluons. Including and extending the information provided by the form factors and the parton distribution functions, they describe the correlation between the transverse position and the longitudinal momentum fraction of the partons in the nucleon. Deeply Virtual Compton Scattering (DVCS), the electroproduction of a real photon on a single quark in the nucleon eN --> e'N'g, is the exclusive process most directly interpretable in terms of GPDs. A dedicated experiment to study DVCS with the CLAS detector at Jefferson Lab has been carried out using a 5.9-GeV polarized electron beam and an unpolarized hydrogen target, allowing us to collect DVCS events in the widest kinematic range ever explored in the valence region : 1.0 < Q2 < 4.6 GeV2, 0.1 < xB < 0.58 and 0.09 < -t < 2.0 GeV2. In this paper, we show preliminary results of unpolarized cross sections and of polarized cross section differences for the DVCS channel.
CAD-centric Computation Management System for a Virtual TBM
Ramakanth Munipalli; K.Y. Szema; P.Y. Huang; C.M. Rowell; A.Ying; M. Abdou
HyPerComp Inc. in research collaboration with TEXCEL has set out to build a Virtual Test Blanket Module (VTBM) computational system to address the need in contemporary fusion research for simulating the integrated behavior of the blanket, divertor and plasma facing components in a fusion environment. Physical phenomena to be considered in a VTBM will include fluid flow, heat transfer, mass transfer, neutronics, structural mechanics and electromagnetics. We seek to integrate well established (third-party) simulation software in various disciplines mentioned above. The integrated modeling process will enable user groups to interoperate using a common modeling platform at various stages of the analysis. Since CAD is at the core of the simulation (as opposed to computational meshes which are different for each problem,) VTBM will have a well developed CAD interface, governing CAD model editing, cleanup, parameter extraction, model deformation (based on simulation,) CAD-based data interpolation. In Phase-I, we built the CAD-hub of the proposed VTBM and demonstrated its use in modeling a liquid breeder blanket module with coupled MHD and structural mechanics using HIMAG and ANSYS. A complete graphical user interface of the VTBM was created, which will form the foundation of any future development. Conservative data interpolation via CAD (as opposed to mesh-based transfer), the regeneration of CAD models based upon computed deflections, are among the other highlights of phase-I activity.
Array of virtual Frisch-grid detectors with common cathode and reduced length of shielding electrodes
Bolotnikov, Aleksey; James, Ralph B.; De Geronimo, Gianluigi; Vernon, Emerson
A radiation detector system that effectively solves the electron trapping problem by optimizing shielding of individual virtual Frisch-grid detectors in an array configuration with a common cathode.
Array of virtual Frisch-grid detectors with common cathode and reduced length of shielding electrodes
Bolotnikov, Aleksey E.; Yang, Ge; Camarda, Giuseppe; Cui, Yonggang; Hossain, Anwar; Kim, Ki Hyun; James, Ralph B.
A radiation detector system that solves the electron trapping problem by optimizing shielding of the individual virtual Frisch-grid detectors in an array configuration with a common cathode.
Array of virtual Frisch-grid CZT detectors with common cathode...
Office of Scientific and Technical Information (OSTI)
Citation Details In-Document Search Title: Array of virtual Frisch-grid CZT detectors with ... corrections for electron loss by reading the cathode signals to obtain depth information. ...
Students Share Experiences from First Run of BioenergizeME Virtual Science Fair
Last week concluded the beta run of the Bioenergy Technologies Office (BETO) sponsored BioenergizeME Virtual Science Fair—a high school competition that has students create and share infographics about bioenergy concepts.
SMART Wind Consortium Virtual Meeting on Installation: Reducing Electrical and Foundation Costs
This 90-minute SMART Wind Consortium virtual meeting is intended to foster dialogue on actions to improve safety and efficiency and to reduce installation costs for distributed wind turbines. Gary...
BioenergizeME Virtual Science Fair: History of Bioengineering Over the Years
This infographic was created by students from Sun Valley High School in Aston, PA, as part of the U.S. Department of Energy-BioenergizeME Virtual Science Fair.
BioenergizeME Virtual Science Fair: Is Algae the Next Big Thing
This infographic was created by students from Daniel Boone Area High School in Birdsboro, PA, as part of the U.S. Department of Energy-BioenergizeME Virtual Science Fair.
BioenergizeME Virtual Science Fair: Bio-fuels-Sustainable Transportation-
This infographic was created by students from Sun Valley High School in Aston, PA, as part of the U.S. Department of Energy-BioenergizeME Virtual Science Fair.
BioenergizeME Virtual Science Fair: The Environmental Benefit of Bioenergy
This infographic was created by students from Sun Valley High School in Aston, PA, as part of the U.S. Department of Energy-BioenergizeME Virtual Science Fair.
BioenergizeME Virtual Science Fair: Energy Production Diversity and Carreers
This infographic was created by students from Sun Valley High School in Aston, PA, as part of the U.S. Department of Energy-BioenergizeME Virtual Science Fair.
BioenergizeME Virtual Science Fair: Coal Can Be Green Too | Department...
Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)
BioenergizeME Virtual Science Fair: Coal Can Be Green Too This infographic was created by students from Belfry School in Belfry, KY, as part of the U.S. Department of Energy-Bioene...
Stability at low symmetric force levels
Canavan, G.H.
At low force levels stability indices depend primarily on the number of vulnerable missiles and the number of weapons on them. The index reduces to a product of the number of vulnerable missiles and the differences between normalized second and first strikes by vulnerable weapons. As the number of weapons per vulnerable missile decreases, the index rapidly approaches stability. Further reductions in vulnerable and survivable missiles and weapons do not affect stability, although they do reduce first and second strikes. Modest weapon reconstitution degrades stability significantly.
Structural and Evolutionary Analyses Show Unique Stabilization...
Office of Scientific and Technical Information (OSTI)
Title: Structural and Evolutionary Analyses Show Unique Stabilization Strategies in the Type IV Pili of Clostridium difficile Authors: Piepenbrink, Kurt H. ; Maldarelli, Grace A. ; ...
DNA Sequence Determinants Controlling Affinity, Stability and...
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the Nucleoid Protein Fis Citation Details In-Document Search Title: DNA Sequence Determinants Controlling Affinity, Stability and Shape of DNA Complexes Bound by the Nucleoid ...
Quench propagation velocity for highly stabilized conductors
Mints, R.G. |; Ogitsu, T. |; Devred, A.
Quench propagation velocity in conductors having a large amount of stabilizer outside the multifilamentary area is considered. It is shown that the current redistribution process between the multifilamentary area and the stabilizer can strongly effect the quench propagation. A criterion is derived determining the conditions under which the current redistribution process becomes significant, and a model of effective stabilizer area is suggested to describe its influence on the quench propagation velocity. As an illustration, the model is applied to calculate the adiabatic quench propagation velocity for a conductor geometry with a multifilamentary area embedded inside the stabilizer.
Nonlinear stability of ideal fluid equilibria
Holm, D.D.
The Lyapunov method for establishing stability is related to well- known energy principles for nondissipative dynamical systems. A development of the Lyapunov method for Hamiltonian systems due to Arnold establishes sufficient conditions for Lyapunov stability by using the energy plus other conserved quantities, together with second variations and convexity estimates. When treating the stability of ideal fluid dynamics within the Hamiltonian framework, a useful class of these conserved quantities consists of the Casimir functionals, which Poisson-commute with all functionals of the dynamical fluid variables. Such conserved quantities, when added to the energy, help to provide convexity estimates that bound the growth of perturbations. These convexity estimates, in turn, provide norms necessary for establishing Lyapunov stability under the nonlinear evolution. In contrast, the commonly used second variation or spectral stability arguments only prove linearized stability. As ideal fluid examples, in these lectures we discuss planar barotropic compressible fluid dynamics, the three-dimensional hydrostatic Boussinesq model, and a new set of shallow water equations with nonlinear dispersion due to Basdenkov, Morosov, and Pogutse(1985). Remarkably, all three of these samples have the same Hamiltonian structure and, thus, possess the same Casimir functionals upon which their stability analyses are based. We also treat stability of modified quasigeostrophic flow, a problem whose Hamiltonian structure and Casimirs closely resemble Arnold's original example. Finally, we discuss some aspects of conditional stability and the applicability of Arnold's development of the Lyapunov technique. 100 refs.
Nonlinear symmetric stability of planetary atmospheres
Bowman, J.C.; Shepherd, T.G.
The energy-Casimir method is applied to the problem of symmetric stability in the context of a compressible, hydrostatic planetary atmosphere with a general equation of state. Linear stability criteria for symmetric disturbances to a zonally symmetric baroclinic flow are obtained. In the special case of a perfect gas the results of Stevens (1983) are recovered. Nonlinear stability conditions are also obtained that, in addition to implying linear stability, provide an upper bound on a certain positive-definite measure of disturbance amplitude.
Stabilization of polyaniline solutions through additives
Wrobleski, Debra A. (Los Alamos, NM); Benicewicz, Brian C. (Los Alamos, NM)
A stabilized non-conductive polyaniline solution comprising from about 1 to bout 10 percent by weight polyaniline or a polyaniline derivative, from about 90 to about 99 percent by weight N-methylpyrrolidone, and from about 0.5 percent by weight to about 15 percent by weight of a solution stabilizing additive selected from the group consisting of hindered amine light stabilizers, polymeric amines, and dialkylamines, percent by weight of additive based on the total weight of polyaniline or polyaniline derivative is provided together with a method for stabilizing a polyaniline solution.