Research On Predictive Control Application To Wind Tunnel Flow Field

Developing large aircrafts puts forward almost harsh requirements for wind tunnel flow field precision,but existing control methods cannot meet the high-precision requirements in flow field.Predictive Control is able to realize high-precision control because it optimizes control law based on predictive future control deviation.Therefore,this thesis takes an intermittent transonic wind tunnel as the plant,and researches predictive control application to realize high-precision wind tunnel flow field.Based on the analysis of the characteristics of the wind tunnel system,and taken disturbance caused by attack angle variation into consideration,a predictive controller for the flow field of the wind tunnel is designed,and the corresponding controller parameter tuning method is given.To figure out problems in predictive control application to wind tunnel flow field,this thesis proposes following solutions respectively.In the process of establishing prediction model in a new working condition,the step response experiment requires a lot of time,energy and cost.To solve this problem,an estimation method based on case-based reasoning is proposed in this paper,to estimate prediction model under a new condition,with existing ones accumulated under different typical working conditions.If the control effect of the estimated prediction is unsatisfactory,the estimated prediction model is calibrated according to data acquired in the blowing test under this new condition.Since the attack angle step response experiment under a working condition with high Mach number is strictly forbidden for safety reasons,it is difficult to determine the attack angle compensation model precisely.To solve this problem,this thesis uses pre-acquired attack angle compensation model,to regulate the flow field and iteratively revises the compensation model according the corresponding control effect.The wind tunnel predictive controller based on Lab VIEW software is put into use in the actual blowing tests.The control effect of the actual blowing tests verifies effectiveness of the predictive control method as well as the feasibility of proposed solutions.Application results shows that the flow field controller designed by the predictive control method can control the Maher number to the required precision,thus effectively improve the flow field quality.