Ignition of Aluminum Particle Clouds Behind Reflected Shock Waves

Extending on a companion paper in this colloquium, the dispersion, ignition and combustion characteristics of aluminum particle clouds is investigated numerically behind reflected shock waves. It is observed that a higher proportion of the Al cloud by mass burns for a higher initial cloud concentration. Vorticity from the cloud wake and from that deposited by the reflected shock cause the particle cloud to convolute, and this effect is particularly very significant for higher concentration clouds. Faster ignition delay times and higher overall Al burning by mass are observed for stronger incident shock Mach numbers due to the consequent hotter gas temperatures behind the reflected shock wave. A mass-weighted ignition parameter is introduced in this study and is identified to be particularly useful to determine overall cloud ignition trends.