Research On Flow Control Of Solid Rocket Ramjet Binary Inlet

Solid rocket ramjet has the advantages of high specific impulse,simple structure,reliable performance and so on.In order to make solid rocket ramjet travel efficiently in wide Mach number range,it is necessary to adjust the flow rate of inlet to optimize the comprehensive working performance of solid rocket jet.The inlet flow regulation is mainly carried out by variable geometry.Based on the design of variable geometry inlet,the aerodynamic characteristics analysis was carried out,and the modeling of variable geometry inlet flow regulation system and the motor control algorithm were studied.The main research contents and achievements are as follows:(1)Structure design and operation characteristic analysis of variable geometry inlet.The numerical simulation of a certain base inlet under different flow conditions was carried out.On this basis,a fixed geometry inlet with a discharge cavity is designed to improve the comprehensive performance of the inlet.In order to keep the inlet with spillway cavity in the optimal working state within the Mach number of 2.6～3.6,the inlet flow regulation was achieved by adjusting the inlet’s contraction section and expansion section wedge to generate sealing shock waves.The results show that when the variable geometry inlet is lower than the designed Mach number,the inlet outlet flow is about 10% higher than the fixed geometry inlet,which is conducive to expanding the working range of the inlet and optimizing the aerodynamic characteristics of the inlet.(2)Variable geometry variable geometry inlet flow control system design.According to the inlet flow regulation rule obtained by numerical simulation,the relation between inlet Mach number and inlet outlet flow and the relation between inlet Mach number and wedge Angle are obtained.Combined with the regulation law of inlet flow,the process of inlet flow regulation was analyzed,and the control model of inlet flow regulation system was constructed by studying the control system of mechanical actuator and brushless DC motor respectively.(3)The mathematical model of brushless DC motor(BLDCM)used for inlet flow regulation is studied and different control algorithms are designed.The PID controller and sliding mode controller are introduced.PI controller is designed for motor current loop and speed loop of flow control system.The PID controller,the fixed gain superscrew sliding mode controller based on the extended state observer,and the adaptive variable gain superscrew sliding mode controller based on the extended state observer were designed to optimize the motor position loop.The response performance and tracking performance of the three controllers are analyzed through simulation experiments.The results show that the variable gain super spiral sliding mode controller based on the extended state observer can make the motor work better.