Research On Automobile Wind Buffeting Noise Based On Improved LRN Turbulence Model

During the high-speed driving of the car,due to the opening of the sunroof or side window,the vortex shedding at the front edge of the window occurs.The shedding vortex moves to the rear edge of the window and collides with the car body.Wind noise.With the effective control of engine noise and mechanical transmission noise,the quieter new energy vehicles have been rapidly promoted,and the problem of wind buffeting noise has become increasingly prominent,which has become one of the important evaluation indicators affecting ride comfort.However,the calculation accuracy of wind buffeting noise is still lacking.For complex engineering problems,the computer capability is not enough to support direct numerical simulation.A suitable turbulence model needs to be selected to improve calculation accuracy and save calculation resources.The research shows that the flow field around the car is relatively complicated,and there are many flow phenomena such as transitions and large-scale separation that have a large impact on the accuracy of wind buffeting noise calculation.However,many current turbulence models are not able to predict large-scale separation and cavity flow well,and rely too much on specific flows.It is considered that the fluid is incompressible,which is inconsistent with the actual flow,resulting in insufficient calculation accuracy of wind buffeting noise.Therefore,for the problem of automobile wind buffeting noise,it is necessary to develop a turbulence model suitable for it based on a deep understanding of the flow characteristics.This paper studies the wind buffeting noise problem of a car with a combination of side windows and sunroofs,develops a turbulence model suitable for it,and studies the wind buffeting noise of a car with sunroofs and side windows combined.Based on the principle of wind buffeting noise,the cause of wind buffeting noise.Based on the analysis of the influencing factors of wind buffeting noise,a wind-turbulent noise-turbulence structure of automotive sunroof based on pressure jet is proposed to effectively reduce the sound pressure intensity of automotive sunroof wind-buffeting noise.The main research contents of this article are as follows:1.Starting from the research on the mechanism of wind buffeting noise generation,an improved LRN turbulence model is proposed to simulate the steady state of wind vibration noise,and a transient DES-ILRN turbulence model is constructed for simulating wind buffeting noise of the vehicle by combining the DES method.2.The simulation results of the flow field wind tunnel test and the steady-state ILRN turbulence model are compared to verify the ability of the ILRN turbulence model to capture separated flow and cavity flow.Through the comparison of the sound field wind tunnel experiment and the transient DES-ILEN turbulence model,the simulation accuracy of the DES-ILRN turbulence model for wind buffeting noise of the simple cavity model is verified.3.Complete the real vehicle road test of wind buffeting noise and compare and analyze with the real vehicle road test.The accuracy of the improved LRN turbulence model and transient DES-ILRN turbulence model for real vehicle wind buffeting noise is further verified.4.Study the wind buffeting noise when different combinations of rear side windows and skylights are opened,and it is found that when two side windows are opened,the wind noise is smaller than that of a single side window,especially when the left and right side windows have the same opening degree.Most obviously,the reduction of wind buffeting noise is the largest.5.According to the mechanism of wind buffeting noise generation,an optimal control of wind buffeting noise of automobile sunroof based on pressure jet spoiler structure is designed,and the optimal parameter combination scheme of jet structure is determined.This structure can suppress the size of the shedding vortex,change the trajectory of the shedding vortex,reduce the probability of collision between the shedding vortex and the rear edge of the sunroof,thereby achieving the goal of optimizing the wind buffeting noise.In summary,this paper improves the ILRN turbulence model and introduces the ILRN turbulence model by introducing the separation perception model,limiting the turbulence time scale,and limiting the vortex viscosity coefficient.Wind tunnel experiments verify that the ILRN turbulence model captures vortices better than the commonly used turbulence models.Based on the ILRN turbulence model,a DES-ILRN turbulence model is constructed.Wind tunnel experiments and real vehicle experiments verify the simulation accuracy of the DES-ILRN turbulence model for vehicle wind buffeting noise.Based on the ILRN and DES-ILRN models,the wind buffeting noise of the rear side windows and sunroof of the car is studied,and it is found that the wind buffeting noise of the car can be reduced when the two rear side windows have the same opening degree.Finally,a pressure jet spoiler structure is designed to effectively control the wind buffeting noise of automobile sunroof.