Aluminized Solid Propellants Burning in a Rocket Motor Flowfield
Combustion and agglomeration processes of aluminum particles emitted from the surface of an aluminized double-base propellant (NC/TMETN) were studied under rocket motor, crossflow conditions. High-speed color photographs (-2000 frames/s) were taken of burning AI/AI2O3 agglomerates forming on the surface, moving along the surface, and entering the flowfield. As an example, a propellant containing 6-^m Al burning at 7 MPa and 6 m/s crossflow produced a mean agglomerate size of about 250 ^m. Analysis of size distributions of the agglomerates leaving the surface revealed that the following parameters decrease with increasing pressure: collision frequency on the surface, the agglomerate stay time on the surface, and mean agglomerate size. Increasing the crossflow velocity decreased the mean agglomerate size. The propellants which contained the large aluminum particles (50 /*m vs 6 j*m) burned without the aluminum igniting or agglomerating on the surface.