汽车外后视镜造型对气动和噪声影响的风洞实验研究

Wind tunnel experimental study on aerodynamics and noise based on the influence of automobile rearview mirror shapes

为降低由汽车后视镜带来的气动噪声,本文以一简化汽车外后视镜模型为基础模型,提出3个不同造型改进方案:A造型模型镜身倾斜15°;B造型模型镜身倾斜30°;C造型模型将原圆柱形底座改为椭柱形底座。对4款造型外后视镜模型进行风洞实验研究,分析流场、空气阻力和壁面脉动压力随造型改变的规律。气动特性(流场和阻力)采用粒子图像测速仪(PIV)和六分量动态天平测量,声学特性采用壁面麦克风对侧窗平板的湍流脉动进行测量。研究结果表明:3个造型改进方案均可在不同程度上改善外后视镜尾迹区域流场品质,有效降低空气阻力和气动噪声。其中B模型阻力系数较基础模型降低18.4%,壁面脉动压力总声压级在中低频段可降低4.6 dB;C模型可降低阻力系数7.5%,总声压级可降低4.3 dB。

To reduce the aerodynamic noise caused by automobile rearview mirrors,a simplified rearview mirror model was taken as the research object,and three different modeling improvement schemes were proposed:model A tilts the mirror body at 15°;model B tilts the mirror body at 30°;model C changes the cylindrical base to an elliptical base.Wind tunnel experiments were carried out on the models to analyze the variation rules of the flow field,drag,and wall pressure fluctuation with the change of the model.The particle image velocimetry(PIV)and six-component balance were used to measure the aerodynamic characteristics including the flow field and drag,and the wall microphone was applied to measure the acoustic characteristics.The results show that all three schemes can improve the flow quality in the wake area of the rearview mirror,effectively reducing the drag and the generation of aerodynamic noise.Compared to the base model,the drag coefficient and the overall sound pressure level of the wall pressure fluctuation of model B can be reduced by 18.4%and 4.6 dB in the low-mid frequency range.For model C,the corresponding results are 7.5%and 4.3 dB,respectively.The research results are beneficial for engineers in the aerodynamic and acoustic design of automobile rearview mirrors.