Study on the ignition combustion and agglomeration mechanism of GAP/CL-20 composite propellants

Glycidyl azide polymer (GAP)/Hexanitrohexaazaisowurtzitane (CL-20) composite propellants have significant advantages, such as high energy density and low characteristic signal. However, the lack of understanding of its ignition combustion and agglomeration mechanism limits its large-scale engineering application in solid rocket motors. In this paper, the ignition, combustion and agglomeration processes of GAP/CL-20 propellants were studied in detail by using modern analytical and testing instruments, such as high-speed cameras, CO 2 laser ignition devices and laser particle size analyzers. First, the ignition and combustion process of the GAP/CL-20 composite propellant were observed with a high-speed camera, and its ignition and combustion mechanism were analyzed. On the basis of the BDP model, a multiple flame structure model suitable for the GAP/CL-20 composite propellant was proposed. Then, the agglomeration of aluminum particles in the combustion process of the GAP/CL-20 composite propellant was observed, and an agglomeration mechanism suitable for the GAP/CL-20 composite propellant was proposed based on the pocket model and skeleton layer theory. Subsequently, the particle size distribution, micromorphology and crystal structure of the condensed phase combustion products were analyzed. The particle size distribution of the condensed combustion products (CCPs) showed three modes, and the CCPs contained active aluminum, which indicated that aluminum particles were not fully oxidized during the combustion process of the propellant. Finally, several further research directions were proposed. The research results may have reference value for the engineering application of GAP/CL-20 propellants.