汽车外表面气动噪声特性分析

Analysis of aerodynamic noise of vehicle's external surface

以荣威750为研究对象,通过声学风洞实验手段对车辆后视镜表面、侧窗表面及其附近流场,以及外场的气动噪声特性进行测试分析;在对数值计算结果验证分析之后,通过数值计算手段以流场脉动压力标准差为评价指标并结合速度场特征,分析车辆表面的压力脉动特性及其产生的原因,在此基础上对车辆表面的噪声大小和分布以及频率特性进行计算分析。研究表明车辆的气动噪声主要能量集中在中低频,频带较宽,不同部位特性差异较大;表面压力脉动是表面气动噪声产生的根本原因,压力脉动大的地方气动噪声亦大;气动噪声大的位置是发生气流分离,湍流运动比较剧烈的区域。就该款车而言,气动噪声主要出现在汽车头部上方、前后挡风玻璃边沿、车顶、A柱、侧窗、后视镜以及车尾和轮胎部分位置处。

The analysis shown in this paper is based on the car of Roewe 750. Aerodynamic noise characteristics of vehicle’s rearview mirror surface, side window surface and the fluid field are tested and analyzed by acoustic wind tunnel experiments. Compared computation results to the experimental results, the magnitude and distribution, as well as the frequency characteristics of the aerodynamic noise on the vehicle surface are calculated and analyzed on the basis that the fluctuation pressure characteristics of the vehicle’s surface and the causes are analyzed by the means of numerical computation taking fluctuation pressure RSM as the evaluation index and referring to characteristics of the velocity field. Studies show that the energy of the vehicle aerodynamic noise is mainly concentrated in the rather broad low-middle frequency band. And the characteristics of aerodynamic noise differ largely from part to part. The pressure fluctuation is the root cause of surface aerodynamic noise. Where the pressure fluctuation is large the aerodynamic noise is also large. The places generating aerodynamic noise are where flow separation and intense turbulent flew occur. For this car, the major aerodynamic noise is generated in the head of the car, the edge of the front and rear windshields, roof, A-pillars, side windows, rearview mirrors, rear of the vehicle and tires.