Research On Variable Thrust Of Liquid Attitude Control Rocket Engine Based On LabVIEW

Attitude control rocket engines are an important part of modern space vehicles,mainly providing the thrust required for attitude adjustment of launch vehicles to ensure the successful completion of space missions.The engines can be divided into variable thrust and fixed thrust according to the type of thrust.The fixed thrust rocket engine works in an impulsive manner for rocket attitude adjustment,which has a low control accuracy;the output thrust of variable thrust rocket engine can change with the set thrust,which has a high accuracy.In this paper,the thrust adjustment method of the engine is discussed and modeled mathematically with an attitude controlled rocket engine as the research object.Firstly,the thrust regulation principle of liquid rocket engine,the factors affecting the thrust are explained,and various thrust regulation methods of liquid rocket engine and their advantages and disadvantages are studied.Secondly,the model of liquid rocket engine supply system is established,and the complex nonlinear supply system model is linearized by using small perturbation linearization method,and the neural network PID controller is designed to regulate the supply system.Again,the working principle and mathematical model of two throttling elements of the liquid rocket motor,adjustable vapor ventilator and pin-bolt injector.They are analyzed and controlled by two-phase hybrid stepper motors.Finally,a portable measurement and control system is designed for the needs of liquid rocket engine ground test.The software of the system is programmed by Lab VIEW with modular design.At the end of this paper,the simulation function of Lab VIEW is used to simulate the established liquid rocket engine,including the pressurization process of liquid propellant,propellant flow rate adjustment process and engine thrust change process.The simulation results are basically consistent with the actual working process of the liquid rocket engine.