汽车后视镜气动噪声的影响参数

Influence Parameters of Aerodynamic Noise for Automotive Rear View Mirror

选取普通后视镜外形作为基础模型,分别挑选可能影响后视镜气动噪声的3个形状参数和2个角度参数,使用大涡模拟和FW-H方程预测后视镜的气动噪声并分析其影响因素.整车风洞普通后视镜气动噪声试验结果与数值计算结果吻合,表明采用混合方法预测后视镜气动噪声的可行性.分析各种参数的后视镜气动噪声可以发现,声源强度在支撑面比后视镜表面大;它在普通后视镜支撑面的分布呈现梯形形状,且不随后视镜前后脸的变化而变化,但支架的存在却使之成为矩形形状.除旋转角度外,增加其他4种参数均有利于降低后视镜产生的气动噪声.

The profile of generic rear view mirror is taken as the basic model,and three shape parameters and two angle parameters,the possible parameters that affect the noise characteristics of rear view mirror,are chosen respectively.The aerodynamic noise generated by mirror is predicted by using large eddy simulation and FW-H equation and the influence parameters are analyzed.The agreement of aerodynamic noise generated by generic rear view mirror between full scale automotive wind tunnel test results and numerical computation results indicates that hybrid method is feasible to predict the aerodynamic noise generated by mirror.When aerodynamic noise generated by all kinds of mirrors was analyzed,it is found that the sound source intensity radiated from the support surface of the mirror is stronger than it is at mirror surfaces.A trapezium region based on high sound pressure level is found at the support surface of generic rear view mirror and it is independent of the shape of front face and rear face,but it becomes the rectangular region when a root is mounted at the bottom of mirror.The increase of all parameters except rotate angle can be applied to reduce aerodynamic noise generated by mirror.