Research On Rearview Mirror Modeling Factors Based On Aerodynamic Noise Of Front Side Window

As the vehicle speed increases,the noise of the car increases exponentially,which reduces the passenger's riding comfort.Related research shows that,the rearview mirror area is one of the main parts of the aerodynamic noise source of outside vehicle,and the shape of the rearview mirror plays a key role in the production of aerodynamic noise.At present,there are few researches on the influencing factors of the aerodynamic noise of rearview mirrors modeling at home and abroad,and there is no support for a large amount of experimental data.Therefore,this part of content needs to be studied.This project is based on a school-enterprise cooperation project,based on aerodynamic and aeroacoustic theory,from two aspects of the wind tunnel experiment and numerical simulation,the rearview mirror modeling factors based on the aerodynamic noise of the front side window were studied.This subject is based on the 5 types of rear view mirrors of a series of cars,3D models of 5 car rearview mirrors were established through reverse engineering.the aerodynamic noise of the rearview mirror is numerically simulated through the commercial software star ccm+.Combining the rearview mirror-flat wind tunnel experiment to explore the numerical simulation method suitable for the aerodynamic noise of rearview mirror,based on this method,the exterior rearview mirror modeling factors affecting the aerodynamic noise of the front side window are explored.Firstly,the SST k-? model and the Realizable k-? model were selected for steady-state numerical simulation.By comparing and analyzing the corresponding residual and other parameters of the two models,the Realizable k-? model is finally determined as the steady-state numerical simulation model.Transient numerical simulation selects LES based on DSSL model,DES based on Realizable k-? model,and DES based on SST k-? model,and analyzes multiple pairs of noise data obtained through rearview mirror-flat wind tunnel experiments,it is concluded that DES based on Realizable k-model is the most reasonable model for transient numerical simulation,so as to determine the research method suitable for this subject.In addition,the effect of the rear view mirror on the aerodynamic noise of the front side wind window is determined from a quantitative point of view.Secondly,according to the reasonable numerical simulation method,we compare and analyze the 3D velocity streamline and surface acoustic power distribution form the wake flow of all kinds of rear view mirrors,and analyze the influence of different rear view mirrors on the aerodynamic noise of the front side windows qualitatively,and verified the accuracy of the numerical simulation method.Thirdly,the streamline and pressure cloud images of the rearview mirrors on 5 planes,such as X,Y and Z,are compared and analyzed.Based on the structure of the swirling motion and the distribution of the low pressure center,the modeling factors that affect the aerodynamic noise of each rear view mirror are deduced.Finally,we compare and analyze the surface acoustic power and surface pressure nephogram of all kinds of rear view mirrors.According to the size of the acoustic power and the pressure gradient of the whole rear view mirror,we can verify the influence factors of the aerodynamic noise of the rear view mirror.And summarizing and adjusting these factors reduces the influence of the rearview mirror on the aerodynamic noise of the front side window.The study shows that the adjustment of the following rearview mirror modeling factors can reduce the aerodynamic noise of the front window: the lower edge of the rearview mirror cover is away from the body,the direction of the rear rim of the rearview mirror is far away from the body,the outer edge of the mirror base and the rearview mirror cover transition smoothly,the outline of the rearview mirror cover is far away from the base,the ratio of the width and the length of the rearview mirror cover is larger,the outline of the base of the rearview mirror is streamlined with curvature decreasing,and the mounting angle of the rearview mirror is increased properly.This research not only has practical significance,but also on the rearview mirror aerodynamic wind tunnel experiments and numerical simulation of noise has certain guiding significance,in addition,it has certain reference significance for the rear-view mirror of low-pneumatic noise and the development of vehicle NVH.