The aerodynamic noise of cars at high speed greatly affects vehicle comfort. Study shows that the spoiler effect of non-smooth surface of biomimetic pits has the effect of aerodynamic noise reduction. In this study, the bionic pits and non-smooth elements are arranged on the edge of the rearview mirror. With the crosswind in the car operation condition as the research point, the perturbation of the crosswind on the aerodynamic noise reduction effect on the non-smooth surface is analyzed. Using the combined method of DES and CAA, numerical simulation is carried out to obtain the sound pressure level spectrums at the monitoring points in the crosswind condition and the condition without the crosswind respectively. By mutually comparing the airflow characteristics and pressure cloud diagrams in the region of the A pillar rearview mirror in the steady state analysis, and combining with the sound pressure level spectrum diagram of the monitoring points, the influence of the non-smooth surface on the airflow field control and aerodynamic noise reduction under the crosswind condition is detected. The results show that the crosswind has a great influence on the aerodynamic noise reduction effect of the rearview mirrors with non-smooth surface, and the noise reduction effect is the best on the non-smooth surface of the leeward side under the crosswind condition.%汽车高速行驶时的气动噪声严重影响汽车乘坐舒适性,研究表明仿生凹坑非光滑表面的扰流效应具有气动降噪的作用.通过以汽车行驶时常见的侧风工况为研究点,在后视镜边缘布置仿生凹坑非光滑单元结构,研究侧风对非光滑表面气动降噪效果的扰动.采用分离涡模拟(Detached eddy simulation,DES)与计算气动声学(Computational aeroacoutics,CAA)相结合的方法,在无侧风与侧风工况下进行数值模拟得到监测点声压级频谱.通过对比定常分析中A柱后视镜区域流动特征,压力云图,并结合侧窗区域监测点的声压级频谱图,探讨非光滑表面在侧风下对流场控制及气动降噪中的作用.研究结果表明侧风对非光滑表面后视镜气动降噪效果存在较大影响,并且在侧风下背风侧时非光滑表面的降噪效果最好.
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