Effects of Ammonium Perchlorate Particle Size on the Aluminum Agglomeration in Primary Combustion of the Ammonium Perchlorate/Aluminum Binary Mixture with a High Aluminum Content

Effects of ammonium perchlorate (AP) particle size on the aluminum (Al) agglomeration in primary combustion of AP/Al binary mixture with a high Al content were investigated experimentally using a CO2 laser ignition apparatus. The combustion of AP/Al binary mixture and Al agglomeration were observed by a high-speed camera. In addition, the particle size distributions and chemical compositions of the condensed combustion products were analyzed by a laser particle size analyzer, X-ray diffraction, and other experimental techniques. Results show that the increase in AP particle size can decrease the size of Al agglomeration, the combustion efficiency of Al powder, the brightness of oxide cap, and the distance from the flame front to the Al droplet but can increase the flame radius. The Al particle burns in evaporation mode, and the rotation phenomenon occurs in the Al droplet. The rotational velocity of the Al droplet decreases with increasing AP particle size. The Al agglomeration can be formed by two ways in the flame zone. For larger Al agglomerations, the spherical molten Al particles first aggregate, then some small aggregates detach from the surface of the big aggregates, and last, the remaining irregular aggregates become regular bigger spherical agglomerations. For small Al agglomerations, the agglomerates directly separate small agglomerations.