Analysis Of External Flow Field And Aerodynamic Noise Of Vehicle With Wheel Rolling

In recent years,with the growth of the economy,the car ownership is increasing,the noise of the vehicle at high speed is gradually coming out.Vehicle noise not only affects people's normal life and work,but also affects the ride comfort of the car.The automobile external flow field is a kind of complicated turbulent flow,the rolling of the wheels makes the flow field more complicated,and the result will affect the aerodynamic noise.Therefore,from the perspective of protecting the environment and improving the ride comfort of the car,it is significant to study the flow field and aerodynamic noise of the vehicle.With the rapid development of CFD technology,the computation of aerodynamic acoustics has opened up a new way for the research of vehicle aerodynamic noise.By using the numerical method to solve the corresponding equations,the noise characteristics of the car,near field and far field are obtained.It provides the basis for the automobile noise reduction.Vehicle aerodynamic noise is mainly due to the pressure fluctuation of the vehicle exterior surface.Therefore,the study of the external flow field and the fluctuating pressure on the surface of the vehicle body is the basis of the research of the aerodynamic noise.In this paper,based on the theory of aerodynamics and aerodynamic acoustics,used the method of acoustic analogy to simulate the flow field and aerodynamic noise characteristics of the vehicle.Firstly,based on a certain type of car,the flow field analysis model including the rear view mirror and the wheel structure is established,and the simulation calculation of the vehicle flow field is carried out by Fluent software.In the calculation process,the steady state calculation is carried out,the contour of pressure and the velocity vector diagram are obtained,and the directional analysis is conducted.Here compared to the wheel in rolling and the stationary of the automobile external flow field characteristics and wheel cavity noise,The simulation results show that the rolling of the wheel makes the aerodynamic noise of the automobile increase,and the external flow field characteristics of the wheel cavity,the tail of the body and the bottom of the vehicle body are also affected,and calculation of steady state results provide the basis for the noise source analysis of the vehicle body.Then using the large eddy simulation method for transient simulation,taking into account the importance of wheel rolling here will wheels are arranged for rolling,Then,the monitoring points are set at the rear view mirror,the side window,the wheel cavity and the vehicle outside,the time domain diagram and the noise spectrum of the pulse pressure of each monitoring point under different vehicle speed are obtained.According to the distribution of flow field,explains the noise mechanism of the rearview mirror and the side window of gas,where the vortex motion,the fluctuating pressure greatly due to aerodynamic noise.It also analyzes the monitoring points of the sound pressure level size,obtained in the rapid flow,local vortex motion intensity,the sound pressure level is larger.