Numerical Investigation of Dynamic Flow and Turbulent Heat Transfer Performance of a Combined Solid Rocket Motor Under Thrust Regulation

For solid rocket motor, thrust regulation has been a major demand and challenge. In this study, a novel combined solid rocket motor (CSRM) with a pintle valve is proposed for thrust regulation by adjusting the mass flow rate of the high temperature inflow gas. A two-dimensional transient combustion model is developed for CSRM to capture the dynamic flow and turbulent heat transfer performance under flow regulation. Due to the formation of large recirculation regions, the high temperature and highly turbulent flow regions are formed in the pre-combustion chamber. Meanwhile, the heat release rate and the heat transfer coefficient both increase significantly. Compared with those before flow regulation, the heat release rate and the heat transfer coefficient after the flow regulation increase by 2180% and 139.47%, which leads to an increase by 175.77% for the regression rate. As the regulation ratio increases from 1.6 to 4.0, the recirculation and high-temperature zones are further intensified. Consequently, the heat release rate and heat transfer coefficient increase by up to 585% and 66.55%, while the regression rate increases by 58.97%.