Research On High Precision Control Method Of Wind Tunnel Flow Field For The Experiment Of Variable Angle Of Attack

With the development and progress of science and technology of aviation and aerospace,the requirement of aerodynamics test is higher and higher.Through the comparative analysis of various advanced control methods,ModelPredictive Control is able to realize high-precision control because it optimizes control law based on predictive future control deviation.Therefore,this thesis takes an 2.4m intermittent transonic wind tunnel as the plant,finally,The Model Predictive Control is used to realize the high precision control of the wind tunnel flow field.This thesis analyzes the hardware structure and characteristics of 2.4m wind tunnel,andwind tunnel control system was simplified and transformed.According to the time-varying characteristics of flow field,a new parameter variable—main induced pressureis introduced.According to the characteristics of the system nonlinearity and coupling,changethe original control of the total pressure and the Mach number into the total pressure and static pressure,the Mach number iscalculated by the formula.The original wind tunnel control system is transformed into a single input and single output main control system and a 2 input and 2 output wind tunnel flow field control system.The control system adopts PID control method to design the controller,which realizes the constant control of the main pressure.According to the characteristics of the wind tunnel flow field control system with time varying,delay,variable coupling,nonlinear and the same condition,the model predictive control method is designed.In addition,according to the analysis of attack angle on the disturbance of wind tunnel flow field,the angle perturbation belongs to the measurable disturbance,so the use of feedforward way of compensation can be more reasonable and effective to resist the disturbance of attack angle brings to the wind tunnel.Finally,a multivariable feedforward model predictive controller is designed.The approximate model of the flow field,the approximate model of the angle of attack and the engineering experience are used to make the parameters of the controller.The designed wind tunnel predictive controller is realized by LabVIEW software.It is verified that the controller can effectively regulate the wind tunnel flow field and ensure wind tunnel tests reach the requiredprecision.Furthermore,the extension capacity of working conditionsof the controller is verified by experiments.