Aerodynamic Drag Reduction Effect Analysis Of An SUV Based On Concept A Surface

In order to promote the high-quality development of domestic economy and the construction of ecological civilization,Our country put forward the goal of peak carbon dioxide emissions and carbon neutrality.For the automobile industry,it is facing increasingly stringent emission regulations.Industry consensus holds that reducing the aerodynamic drag of automobiles is an effective measure to reduce fuel consumption and improve fuel economy.Generally,the wind resistance performance optimization of automobile exterior styling can be divided into three stages,namely,CAS surface,A surface and whole vehicle.Among them,CAS surface is the initial stage of modeling development and plays a decisive role in modeling style.In engineering practice,the optimization of CAS surface model usually adopts traditional iterative optimization,which is not only time-consuming and labor-intensive,but also exists in order to meet the requirements of wind resistance performance.Great changes have been made to some parts of the car body,sacrificing the original styling style.In addition,in engineering practice,it is found that the scheme with no drag reduction effect on the CAS surface model is effective when loaded on the whole vehicle model,and this difference is enough to influence the engineers’ judgment on the effective scheme.Based on the above-mentioned problems,combined with the existing project development experience,this paper analyzes the aerodynamic drag reduction effect of an SUV by CFD(Computational Fluid Dynamics)method,and the main research contents are as follows:(1)Through CFD simulation analysis of CAS surface model of this SUV,nine optimized parts are selected,and the significance of each part on aerodynamic drag coefficients is explored by using P＿B experimental design,and Class A variables with less influence on aerodynamic drag coefficients and Class B variables with greater influence on aerodynamic drag coefficients are screened out.(2)For class B variables,Kriging proxy model is established based on automatic calculation flow platform and DOE sampling method.Multi-island genetic algorithm is used to optimize with the lowest aerodynamic drag coefficient and minor changes to the original shape.The results show that only small changes to two parts can reduce drag by 8Count,and the error between the optimized value and the simulated value is 0.35%.The validity and accuracy of this method are fully illustrated.(3)Based on the chassis structure of this SUV,build the whole model of this SUV and introduce AGS(Active Air Intake Grill).By comparing the CFD calculation results of the whole vehicle model with or without AGS,the reasons for the difference of aerodynamic drag coefficients between them are analyzed from the aspect of air flow,and the special contribution of AGS to aerodynamic drag reduction is studied.Secondly,the CFD calculation results of CAS surface model and AGS vehicle model are compared,Explore the influence of engine compartment and chassis system on aerodynamic drag when the exterior surface of the car body is the same.(4)Select three levels of high,medium and low for each parameter variable in Class A variables,and calculate the aerodynamic drag coefficient on CAS surface model and AGS vehicle model under the same scheme.According to the calculation results,comparative analysis is carried out,and the reasons of different drag reduction effects of the same scheme on CAS surface model and AGS vehicle model are studied respectively,which can provide reference for practical engineering development.In this paper,the aerodynamic drag reduction of a certain SUV is studied,and the P＿B experimental design is used to screen the variables that have great influence on the aerodynamic drag,and then based on this kind of variables combined with the established automatic calculation process platform,the proxy model is constructed,and the algorithm is used to optimize it.The results show that this method can not only greatly improve the optimization efficiency,Moreover,while obtaining a lower aerodynamic drag coefficient,the original modeling style can be retained to the greatest extent.It provides a high engineering reference for the optimization of wind resistance performance in CAS surface stage.Secondly,by comparing and analyzing the similarities and differences of the same scheme on CAS surface model and AGS vehicle model,the results can provide useful reference for the subsequent engineering development of wind resistance performance.