The filling process and its effect on the start-up of electric pump in hybrid rocket motor

The electric pump integrated into propellant supply system boasts the expansive capacity for swift thrust adjustments, making it an indispensable asset for optimizing the performance of a hybrid rocket motor. Although previous studies have explored the efficacy and practicability of hydrogen peroxide electric pumps in hybrid rocket motors, the implications of their filling process on start-up have remained elusive. In this study, the filling process and its effect on the start-up of the electric pump were numerically and experimentally investigated. The experimental and simulation results show that the electric pump cannot be completely filled by opening only the valve upstream of the pump and that there are still areas of air in the pump after the filling process. The results of the start-up process of the electric pump with different filling conditions indicate that the air, filling and acceleration process increase the pressure and axial force fluctuation, decrease the efficiency and compromise the operational stability of the pump after start-up. The results of the filling process of the electric pump at 2000 rpm demonstrate that filling the pump after starting it further reduces its efficiency and operational stability. This study provides practical guidance for filling electric pump supply systems and starting electric pumps of the rocket engines, which ensures the stable operation of rocket engines.