Research On Flow Field Control System Based On Adjustable Opening-closing Ratio Panel

With the development of aerospace technology,the development of all kinds of aircraft is more and more dependent on the wind tunnel test.How to improve the control performance index of wind tunnel flow field and obtain high-precision blowing data is not only the main task of wind tunnel control,but also the basis of aircraft development and design,especially in the transonic phase will directly affect the quality of aircraft design.There is a serious problem of wall interference in transonic wind tunnel.the opening-closing ratio of the panel in different areas of the test section directly affects the acceleration characteristics of the entrance of the test section and the wave dissipation characteristics of the model zone.Selecting an appropriate opening-closing ratio can reduce the wall interference and improve the quality of the flow field.However,at present,the opening-closing ratio of different areas of the panel in the test section of the transonic wind tunnel is usually controlled manually according to experience,which can not be automatically adjusted according to the flow field performance parameters,and a large number of experiments are needed to obtain the best flow field performance parameters.Therefore,the design of a flow field control system which can automatically adjust the opening-closing ratio of different regions of the test panel according to the flow field performance parameters is of great significance to improve the quality of the flow field.First of all,taking a transonic wind tunnel as the object,this paper analyzes the overall structure of the wind tunnel,the main parameters of the wind tunnel experiment and the performance requirements of the flow field,and designs a kind of open-close ratio adjustable panel used in the transonic wind tunnel.the adjustment of the opening-closing ratio in different regions of the test section is realized.On this basis,the structure of the three-input and twooutput flow field control system is determined,in which the opening-closing ratio of the panel acceleration zone,model zone and support area of the test section is taken as the input,and the average Mach number and the root mean square deviation of Mach number as the output.Secondly,through the ANSYS Fluent simulation software,combined with the opening wall boundary numerical model,the wind tunnel flow field is numerically simulated and analyzed,and the input and output data of the flow field are obtained.According to the obtained data,the system model parameters of three inputs and two outputs are identified by the recursive least square method,and the mathematical model of the flow field is established.Then,according to the flow field characteristics of transonic wind tunnel,the current mainstream predictive control algorithms are compared and analyzed,and the generalized predictive control algorithm is selected to design the flow field predictive controller.According to the generalized predictive control theory,the generalized predictive control model of the wind tunnel flow field is established,and the objective function is used to solve the incremental expressions of the optimal control rate and control quantity.The feasibility of the control system scheme is verified by simulation.Finally,the hardware of the flow field control system is designed,including the main control circuit design,communication circuit design and drive circuit design.The upper computer software and the lower computer software of the flow field control system are designed,the automatic adjustment of the opening and closing ratio of the panel in the wind tunnel test section is realized,and the physical manufacture of the control system is completed.The system is put into the actual wind tunnel,and the related experiments are carried out at Mach 0.95,and a good control effect is obtained.