Experimental and numerical study on slag deposition in solid rocket motor

In solid rocket motor the slag deposition may cause severe ablation of insulation and size change in throat area. Thus, the prediction of slag accumulation is of great significance to improve the safety of solid rocket motor. This study aims to explore the characteristics of slag deposition and its influencing factors by experiments and numerical simulation. As the input of the simulation, the size of the initial agglomerate was obtained firstly. Meanwhile, the size distribution of the particles in plume and the deposition mass in solid rocket motor were measured by ground firing test to validate the numerical model. Thereafter, a deposition prediction model coupling the combustion of aluminum particles was developed, in which the detailed effects of burning surface regression, particle size, detaching position and nozzle structure on slag deposition were explored. The results indicated that these parameters exert great influences on slag accumulation. As burning surface regresses, the slag deposition on nozzle decreases and its distribution becomes more uniform. With increasing initial particle size, the deposition rate increases obviously until 170 μm. Most of the deposition was caused by the aft segment of burning surface. For the effects of nozzle structure, the deposition mass drops with the decrease of convergence angle. And it is feasible to reduce the deposition by designing the profile of nozzle convergence to improve the engine safety.