Experimental Study on Particle Size Distribution of Aluminum Combustion under Acoustic Oscillation

The aluminum powder combustion has a great influence on the combustion instability in the solid rocket motors (SRMs). The condensed phase products (CPPs) can effectively damp the acoustic waves of the instability, while the aluminum distributed combustion could drive the acoustic waves. Therefore, the study of the particle size distribution of aluminum combustion is essential for understanding the gain and damping factors of combustion instability. In this study, a dynamic combustion diagnosis system for measuring the particle size distribution of aluminum combustion is established, and the characteristics of particle size distribution under different oscillation were studied by the digital in-line holography (DIH). The results show that: influenced by the acoustic oscillation, the agglomeration process of aluminum particles on the burning surface will be different. Compared with the non-oscillation, the acoustic oscillation can affect the agglomeration of aluminum particles on and near the burning surface, and the mean diameter of D10, D32, D43, the agglomeration particle size (Dagg) and agglomeration fraction (fagg) all increase under acoustic oscillation.