Research On Decoupling Control Method Of Injector Powered Half-reflux Transonic Wind Tunnel

Wind tunnel is a ductwork using powerplant to drive the controllable gas inside,in which we can get the flow needed according to the relativity and similarity principles.Wind tunnel is the essential equipment to the aerospace aircraft development,and it's regarded as the standard of a controy's aerospace aircraft development level,the study of wind tunnel is very significant to our controy's aerospace industry development.Wind tunnel is a complicated system with lots of subsystems,and it's also a system with the nature of strong nonlinear,serious coupling and time-varying,all this characteristics bring difficulties to the wind tunnel control.In the test of Mach number step changing with fixed stagnation pressure,the wind tunnel studied in this thesis encounters the difficulty brought by the coupling existing in the system.The adjustment time of Mach number is extanded by the effect of the coupling,to solve this problem decoupling control is used.Firstly,the step response test of wind tunnel is carried out and the following two aspects are analyzed.One aspect is using the RGA method to analyze the coupling in the wind tunnel,and relationships between the main variables are determined,using the Main exhaust hydraulic servo valve to control stagnation pressure while using the the choke finger input value to control Mach number.The other aspect is the mathematical model of the wind tunnel flow field identified at the working point,and the model is prepared for the decoupling design.According to the mathematical model obtained from the identification decoupling device can be designed,and two seperative controller are designed for the decoupled wind tunnel,simulation is done and the performance is compared with the single loop PID control.In the test of Mach number step changing with fixed stagnation pressure,using a single controller cannot achieve the goal in the process of Mach number changing,control effect will worse when Mach number changed for the wind tunnel is a strong nonlinear system.Therefore,in this thesis the multi model control method is introduced to solve this problem,wind tunnel models are built at different working points,corresponding controller and the decoupling devices are also built,using the soft handover we can get the outputs of the controller.The simulation results show that the method proposed in the thesis can achive the goal of Mach number control in the test of fixed stagnation pressure while step changing Mach number.