Combustion of Large Aluminum Agglomerate Particles in Air. III. Particle Fragmentation

The combustion of aluminum agglomerate particles with a diameter of 215–840 μm in free fall in air at atmospheric pressure has been studied. The main events of the combustion of particles after their release from the sample into air—the transition from symmetric to asymmetric combustion, fragmentation, and the end of combustion—are characterized by corresponding times. Approximating dependences on the particle diameter were obtained for the characteristic times of symmetric combustion, the beginning of fragmentation, the end of fragmentation, and the end of combustion. The characteristics of particle fragmentation were determined. Data are presented on the relative number of mother agglomerate particles ejecting a given number of fragments and on the dependence of the number of fragments on the burning particle diameter. For larger particles, fragmentation begins later, but proceeds more intensely. In general, the observed spontaneous fragmentation of aluminum agglomerates is insignificant; therefore, to reduce their burning time, it is necessary to enhance the fragmentation process.