Study Of Ramjet Thrust Control System

The ramjet is the best power equipment of supersonic missile, and its performance mostly depends on its control system. The fuel control system is the uppermost control system of the ramjet. With the high thrust-weight ratio engine development and flight regime extended, we need the fuel system should have the characteristic such as reacting quickly, low control error and working reliability. This dissertation proposed a systematic study on the fuel control system of the ramjet. The main content contains three aspects, i.e. , modeling, simulation analysis, and control system design. The main work in this paper is as follows:Firstly, the dynamic model of turbopump is built. Based on the working principle of the turbo, we build the mathematic model of the turbo, and build the pump model by applying mechanism modeling method combined with experimental data identification. At last, introduce the one dimension dynamic system of the ramjet.Secondly, the regulation method of fuel system is introduced. With the pump control mode and valve control mode, we compare their advantages and disadvant- ages in the three indexes of efficiency, dynamic response and cavitation characters. In the aspect of efficiency, the efficiency of valve control system is lower than pump control system because of throttling loss especially when apart from the design point. But in the aspect of dynamic response, the regulation time of pump control system is longer than valve control system.Thirdly, fuel control loop of ramjet is studied. The turbopump characteristic is analyzed, and PID control system s designed according to the required performance index of control system. The simulation results demonstrate the control system performance meets the design requirement.Finally, thrust control loop of ramjet is studied. Robust controller is designed. The uncertainty of model perturbation and disturbance is analyzed. We design controller based on the method ofμ-synthesis and analysis the simulation results. The simulation proves that the controller satisfied the robust performance index.