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Comparison on Laser Ignition and Combustion Characteristics of Nano- and Micron-Sized Aluminum

ABSTRACT This paper presents a comparative study on the laser-induced ignition and combustion characteristics between nanometer-sized aluminum (nano-Al) and micron-sized aluminum (micro-Al) powder stacks. Six different sizes of Al powders (56.0 nm, 74.4 nm, 93.4 nm for nano-Al and 2.9 μm, 6.1 μm, 10.8 μm for micro-Al) were selected to conduct ignition and combustion experiments, at the same operation conditions in the static air flow with atmospheric temperature and pressure and 55% relative humidity. The results demonstrated that ignition delay time of nano-Al is much lower than that of micro-Al. The size of nano-Al has a weak effect on ignition delay time. Whereas, the size of micro-Al has an exponential effect on ignition delay time. The combustion of nano-Al is more intense and the self-maintenance performance is better than micro-Al. Finally, a comparative model on the ignition and combustion difference between nano-Al and micro-Al was built, which comprehensively considers the influences of particle core size, oxide shell thickness and porosity. This study will be helpful to recognize the difference of ignition and combustion characteristics between nano-Al and micro-Al and promote the application in solid rockets.