Erosion Mechanisms of Baffle Plates at Stagnation Point in Hybrid Rockets

To use hybrid rockets as kick motors, it is essential to address their inherently low combustion efficiency issue. Although baffle plates are employed to improve combustion efficiency, their structural failure due to erosion phenomena caused by combustion gases becomes a serious concern. This study aims to identify the dominant parameters governing the erosion rate at the stagnation point of an impingement flow and to establish a predictive numerical model. Experiments were conducted using a high-density polyethylene/[Formula: see text] hybrid rocket, varying the impinging jet velocity gradient and chamber pressure. A predictive model for the baffle plate erosion in hybrid rocket environments was developed by modifying the heterogeneous reaction mechanism in a preexisting theoretical model established in the field of carbon combustion. The experimental results revealed that the velocity gradient exponent was lower than the theoretical value under diffusion-limited conditions. Also, a dependence of the baffle plate erosion rate on the surface temperature was observed, indicating the erosion rate is not diffusion limited. The application of the theoretical model demonstrates good alignment between predicted and experimental results with an average error of about 33% without any corrections. This confirms the applicability of the theoretical model for predicting baffle plate erosion in hybrid rockets.