Investigation Of Numerical Correction Based On The Porous Wall Flow Model In Transonic Wind Tunnel With Porous Wall

In order to reduce the wall interference of transonic wind tunnel and meet the requirement of aerodynamic experiment on aircraft ground,it is necessary to optimize the geometric parameters of transonic hole wall,such as the optimal open-close ratio,inclination angle and depth-diameter ratio.In this paper,based on the porous wall flow model developed by the research group,the optimization design of the optimal open-close ratio of the wall is carried out,and the wall interference correction under the non-uniform open-close ratio distribution is studied.Firstly,the DLR-F4 wing-body assembly is placed in the boundary conditions of numerical simulation of porous wall wind tunnel with variable open-close ratio on the upper and lower walls respectively and far-field boundary conditions.The CFD method is used to calculate the flow field.The open-close ratio of the wall is the optimized parameter in this paper.Then,through Latin hypercube sampling,70 sets of sample points are designed under Mach number 0.6 and Mach number 0.75 respectively.The difference between mass flow at the wall position calculated by each group of fluid and mass flow at the same location in the far field is integrated,where the integration value is the objective function of single objective optimization in this paper.On this basis,make use of Isight software,Kriging approximation model is used to reduce a large number of flow calculations,and multiisland genetic algorithm is used to optimize,and the results are obtained.Then,the optimized open-close ratio is substituted for the boundary condition of the porous wall,and the flow field is calculated again.by comparing the flow field characteristics of the optimized variable open-close ratio boundary state,far-field boundary state,uniform oblique hole wall state and uniform straight hole wall state,it can be seen that under the optimized variable open-close ratio wall boundary condition,the lift coefficient of DLR-F4 is obviously improved,the wall interference effect is obviously reduced,and the flow field quality has been significantly improved.This paper provides a simpler and more efficient method for the wall design of transonic porous wall wind tunnel,which reduces the cost of wind tunnel experiment and greatly improves the accuracy of wall interference correction.