Experimental Investigation on Ablative Characteristics of EPDM Insulation in SRJ Combustion Chamber

The ablative characteristics of the insulation in the combustion chamber are an essential part of the research on solid rocket ramjet thermal protection. However, the research on ablative characteristics under long working times is quite limited. In this paper, the ground direct connection test of the solid rocket ramjet with EPDM as insulation is carried out, and the actual working time of the ramjet exceeds 400 s. Insulation ablation properties of the combustion chamber are analyzed by 3D scanning technology and SEM. The experimental results show that the insulation behind the inlet of the combustion chamber is completely carbonized. The ablation rate in the smooth area of the inlet outlet downstream and the gully region of the combustion chamber is larger. However, the negative ablation rate is generated at the junction with the nozzle due to the deposition of molten particles. Analysis of ablative products shows that the erosion and deposition of particles affect the compactness of the insulation layer surface structure.