The Research of Main Injector Pressure Control Strategy for Intermittent Transonic Wind Tunnel

Wind tunnel is an important platform for ground aerodynamic simulation test of aerospace vehicles, and its flow field control accuracy directly affects the reliability of aerodynamic data and technical performance of aircraft. As a intermittent wind tunnel, the main injector is the key component to provide driving power for the wind tunnel, and the accuracy of its pressure control directly determines the accuracy and noise level of flow field control. Due to the large time-delays of pressure closed-loop control and the time-varying disturbance caused by the continuous drop of air storage tank pressure, the traditional PID control strategy has poor effect, which makes the pressure fluctuate greatly and deviate from the expected value. In view of the existing problems, a feedforward + feedback control strategy of main injector pressure is proposed in this paper, and the control parameters in the initial charging stage are optimized based on the flow field control parameter library. In the initial stage, the flow field control parameter library based on CBR can generate accurate initial control parameters. In the test stage, a pressure feedforward model based on BP neural network is constructed, and the time-varying disturbance caused by the decreasing pressure of the air storage tank is effectively compensated by the compound control method. Simulation results show that the initial control parameter deviation is small and the pressure can quickly reach the steady-state position. The compound control method can better overcome disturbance, reduce the fluctuation of the main injection pressure control, and improve the control accuracy and stability.