基于主动射流的汽车后视镜区域气动噪声控制

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

使用大涡模拟和声扰动方程求解后视镜区域气动噪声的非定常流场和声场.通过比较前侧窗19个测点能量平均总压力级的仿真和试验结果发现,两者仅相差2.3 dB(A),它们频谱变化趋势相同,量值差异较小.在此基础上,建立了主动射流模型,并改变射流位置、方向和速度等参数,采用子域仿真方法得到最优射流方案.将最优射流方案置于整车气动噪声仿真模型中,通过与原始模型对比发现,主动射流增大了后视镜尾部的时均压力,减小了压力梯度,降低了后视镜区域涡流强度,使整车气动阻力系数减少0.002,前侧窗网格节点能量平均的总声功率级降低1.8 dB(A),湍流脉动总功率级降低0.3 dB(A).

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).