Numerical simulation and analysis of nozzle mechanical erosion in hybrid rocket motors under overload conditions

Hybrid rocket motors (HRMs) are gaining widespread application due to their advantages, including high safety, ease of thrust control, and multiple restart capability. However, nozzle ablation remains a critical technical bottleneck limiting their development. This study presents a numerical investigation of nozzle mechanical erosion in HRMs under overload conditions. The mechanical erosion of nozzles for four propellant grain configurations tube, star, single-channel wheel, and multi-channel wheel were computationally analyzed. The results reveal a strong correlation between nozzle mechanical erosion and the propellant-grain type, as well as a significant dependence on motor overload conditions. Under certain operating scenarios, the peak erosion rate increases by more than threefold compared with that under non-overload conditions. As overload increases, the peak erosion rate initially rises and then stabilizes. For the motor configurations studied, when the overload exceeds 10 g, the maximum erosion rate remains nearly constant. Furthermore, the magnitude of the overload effect on erosion and particle distribution varies with grain type. Overall, the influence of overload is more pronounced for single-channel grains than for multi-channel grain. Within the single-channel grains, the degree of influence decreases in the following order: cylindrical, star, and wheel grain. It is worth noting that this study focuses on the mechanical erosion of HRMs nozzle under overload conditions and does not consider the effect of overload on the combustion state.