Characterization of the initial agglomerates of aluminized composite propellants

The size distribution and morphology evolution of the initial agglomerates on the burning surface of aluminized composite propellants have a strong influence on the agglomeration mechanism and size of condensed products. However, most previous research has focused on the establishment of size prediction models, and research on other characteristics of initial agglomerates is still lacking. The characteristics of the size distribution and evolution of the morphology of the initial agglomerates are investigated in this study. Analysis of the size distribution of the initial agglomerates shows that the distribution is regular in the stable combustion stage, and the agglomerates in this stage show weak agglomeration. The morphologies of the initial agglomerates are found to comprise coral-like structures composed of small alumina particles with strong fluidity in Stage (a), in which the effect of accumulation is dominant. In Stage (b), the initial agglomerates exhibit a relatively stable form of a ‘spherical structure + coral-like bond’, and the effects of accumulation and combustion are in dynamic equilibrium. In Stage (c), the initial agglomerates are spherical with an oxidation cap, and this stage is dominated by combustion. Through analysis of the characteristics of the size distribution and morphology evolution of the initial agglomerates, the agglomeration mechanism of aluminum particles on the burning surface is further clarified, which provides the foundation for further research.