The Numerical Analysis And Controlment For The Automotive Aerodynamic Noise

With the mechanical and tire-road noise is effectively controlled and driving speeds increase.Aerodynamic noise has now become one of the main noise sources, and seriously affects the ride comfort. Therefore, in the design stage, it is necessary to prediction and analysis the aerodynamic noiseWind buffeting is an important component of aerodynamic noise. It is generated when the side-windows or sunroof open, and its frequency is low (<20Hz), but the intensity is very strong.Although it is not easy hear by human ear, the fluctuated pressure generated by it will make people irritablility and fatigue. In this paer, the Large Eddy Simulation (LES) provided by CFD software FLUENT is used to analysis the wind buffeting noise characteristics of an upscale cars when side-windows or sunroof is opened. The analysis result shows: The wind-buffeting noise closely related with the size of side-windows and sunroof, the volume of crew department, vehicle speed. According to the simulation results, some measures are used to suppress the wind buffeting noise, such as in order to suppress the rear window wind buffeting, after B pillar a groove is opened and the rear window is divied; in order to suppress the sunroof wind buffeting, the deflector is added and the sunroof opened position is optimized. Furthermore, in order to obtain a more ideal installation angle and height, the deflector relevant paramenters is optimized. In the research of the sunroof open position, an empirical formula is summed up to predict the wind buffeting frequency.According to the analysis of the external flow field and ralted literature, it found that the rearview mirror palys an important role to the wind rush noise and wind buffeting noise. In the last, the aerodynamic noise induced by mirror whichi is located on an actual car models is analysised. The local shape of the mirror is modified to reduce the aerodynamic noise. Finally a real vehicle road test is implemented, and the test velocities are from 60km/h to 120km/h. The result shows that the vehicle noise has been noticeably reduced through modifying the mirror shape, and the maximum degradation is 1.2dB (A).