Flow feedback control based on variable area cavitating venturi and its application in hybrid rocket motors

Precise regulation of oxidizer mass flow rate is a crucial technology for hybrid rocket motors, and a flow control valve serves as a core component of an oxidizer delivery system. In this paper, we designed a variable area cavitating venturi (VACV) as a flow control valve to control oxidizer mass flow rate. Three types of experiments were carried out to investigate VACA-based flow feedback control and its application in hybrid rocket motors. Specifically, we measured flow characteristics at different pintle strokes and conducted five cold tests and one ground hot test based on flow feedback control. Test results are as follows: first, the VACA flow characteristic curve shows a wide regulation range with a flow regulation ratio of 21.8 and performs good linearity of 96.76%. Second, the mass flow rate curve measured with flow feedback control tracks the target curve. Flow feedback control effectively improves control accuracy by maintaining the steady-state error within 1.2%. Third, hot test results demonstrate that the VACA with flow feedback control can effectively maintain the accurate and consistent oxidizer mass flow rate during the firing stage of the hybrid rocket motor. The findings of this research indicate that VACA with flow feedback control can be used as an effective flow regulation component to maintain a constant and accurate oxidizer mass flow rate during the working stage of a hybrid rocket motor.