Research On Closed-loop Control System Of Gas Flow Dynamic Regulation Of Solid Rocket Ramjets

Solid rocket engine is a kind of aspirated power unit.Compared with the traditional solid rocket motor,solid rocket ramjets have the advantages of large specific impulse and long range,which has broad application prospects in tactical missiles.The gas flow regulating technique is the key to ensure that the rich gas and air can be fully mixed and combusted in the after burning chamber.It is of great significance to improve the performance of solid fueled ramjet engine.In the current research,the choked-type gas flow controlling method is utilized to investigate the principle of gas flow regulation,the characteristics of gas flow regulation system and the design of control system.Firstly,a control scheme of indirect gas flow controlling method based on the pressure of the gas generator is proposed by using the relevant theory of choked-type gas flow regulation.The gas flow regulating valve,brushless DC motor drive system and gas generator pressure control board of the gas flow regulating system are designed and manufactured.The effectiveness of data communication and valve actuation is verified.Secondly,the choked-type gas generator is analyzed,and the dynamic and static models of gas generator pressure and gas flow are established.The simulation results indicate that the gas generator has the characteristics of nonlinearity and variable parameters.The linearized model proves that the gas flow control model is a non minimum phase system,and the flow undershoot will appear in the process of gas flow regulation.In addition,the effects of gas generator volume,pressure and throat change rate on the dynamic response of gas generator are closely investigated.Thirdly,for the position control of brushless DC motor,the "three loops" control,i.e.,current loop,speed loop and position loop,are employed.And the proportional–integral–derivative(PID)control algorithm is applied to achieve the accurate control of motor position.There are some problems in the gas flow regulation system,such as mathematical model modeling error,parameter perturbation and environmental high-frequency disturbance.Therefore,in order to ensure the good robust stability and robust performance of the control system,the gain scheduling method and synthesis control method are used to study the closed-loop control system of gas flow dynamic regulation of gas generator.For the undershoot phenomenon during the gas flow regulation,transition process is added to the target signal to suppress it.The first-order inertial link,(tracking differentiator)TD and modified arctangent-based tracking differentiator(MATD)are used to add the transition process to the signal respectively.The simulation results show that the MATD has the best effect of suppressing undershoot.Finally,the designed closed-loop control system for dynamic regulation of gas flow is studied via experimental approach.The reliability of the system under the condition of high pressure is validated.The experiment gas flow regulation is conducted.It is found that the control system can perform a better gas flow regulation ability.