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Isothermal models of gas-turbine combustors

Measurements of mean axial velocity have been obtained in two perspex models which simulate important features of gas-turbine combustors and are compared with calculations based on the numerical solution of the three-dimensional equations that represent conservation of mass and momentum. The measurements show, for example, the effect of primary jet trajectory on the magnitude and proportion of total mass flow contained in the primary vortex. They also allow the value of the calculation method to be appraised and, in this context, it is shown that the local velocity values are subject to large errors in small regions of the flow but important parameters, such as the length of the primary vortex, are represented more than adequately for engineering purposes. Errors due to numerical approximations appear to be at least as important as those due to the two-equation turbulence model used to represent turbulent features of the flow.