Aerodynamic Noise Control of Automobile Rear View Mirror Based on Active Jet

Abstract:

The aerodynamic noise in the rear view mirror region has an important influence on the vehicle interior noise. Therefore, large eddy simulation and acoustic perturbation equations were used to solve its unsteady flow field and sound field. A comparison of the results between simulation and experiment of the energy averaged total pressure level of the 19 measuring points of the front side window indicates that the difference between them is only 2.3 dB(A). The trend of frequency spectrum is similar and the difference in magnitude is small. Based on this, the active jet model is established and the parameters such as jet position, direction, and speed are changed. Besides, the subdomain simulation method was used to find the optimal jet scheme. Moreover, the optimal jet scheme was put into the vehicle aerodynamic noise simulation model. A comparison with the original model shows that the active jet increases the time-averaged pressure at the wake of the mirror, and reduces the pressure gradient and the vortex intensity of the mirror region. The vehicle aerodynamic drag coefficient is reduced by 0.002 while the energy averaged overall sound power of the front side window is reduced by 1.8 dB(A), and the overall turbulent fluctuation power is reduced by 0.3 dB(A).