Design And Research Of Control Scheme Of Variable Thrust Liquid Rocket Engine

Liquid rocket engines are the main power devices for space transportation systems and spacecraft propulsion and control.It could provide controllable power for the spacecraft and also an essential propulsion system for space flight and exploration missions,such as aircraft orbital maneuver control,space rendezvous and docking,soft landing of the planet and maneuvering of the planet without air.At present,a lot of research achievements have been obtained for the supercharging scheme and control scheme of variable thrust liquid-rocket engine at home and abroad.But most of supercharging schemes adopt the squeeze or turbo pump system,and only a few researches on the new electric-pump system.In this paper,the variable thrust liquid rocket engine is taken as the research object,and the motor pump supercharged fuel supply system of liquid rocket engine is designed.The structure,control scheme and control characteristics of the fuel supply system are discussed in depth.Firstly,research on the design and working characteristics of the working components are carried out.According to the basic working principle of the variable thrust engine,the system scheme of motor pump boosting is proposed,which can reduce the structural quality of the system and improve the controllability of the engine.And the simulation models of DC motor driven centrifugal pump,DC motor driven gear pump,controllable cavitating Venturi and pintle injector of the electric supercharged fuel supply and control system are established in AMESim software,researching on the dynamic characteristics of the working units,and lay the foundation for the design and research of the electric supercharging system.Secondly,the control requirements of variable thrust liquid-propellant rocket engine were analyzed,four different structures of electric supercharging propellant supply and control system are proposed,the simulations were carried out by combing AMESim and Simulink.According to the simulation results,the system control performance parameters and the feasibility of the control scheme for each scheme are comprehensively compared to determine an optimal fuel supply system structure scheme.And then,further control characteristics research for the electric supercharging propellant supply and control scheme is carried out.On the basis of fully understanding of the working principle and characteristics of the system components,the PID controller is used to design the control loops for different control objects,and the control characteristics of the system under different control loops are obtained through simulation in the combination of AMESim and Simulink.Finally,a control scheme based on neural network PID control is proposed.According to the optimal fuel supply system structure scheme,a neural network adaptive controller was designed.The simulation results show that the algorithm can effectively reduce the parameter error,overshoot and oscillation of the control process,which improves the performance of the control system,and meets the control requirements better.