虚拟激励法的汽车气动噪声研究
Study on Automobile Aerodynamic Noise based on Pseudo-excitation Method

采用分离涡模拟（DES）方法对车外流场进行瞬态计算得到车身表面脉动压力，将虚拟激励法应用于求解汽车内部的气动噪声场，利用声振耦合法得到车内场点的声压级频谱。对不同车速不同位置的噪声特性进行了对比分析和道路实验验证。结果表明：汽车气动噪声为宽频谱，在某一特征频率处达到峰值后呈指数型下降；噪声截止频率和峰值频率随着车速的提高向高频移动；声压级大小与脉动压力强度以及辐射面积有关；将虚拟激励法应用于气动噪声求解是可行的。
The transient exterior flow fields were calculated with a turbulence model: detached eddy simulation (DES) method to get the fluctuating pressure on car body. Pseudo-excitation method (PEM) was used to calculate the interior acoustic fields and the sound pressure level spectrum was got by acoustic-vibration coupling method. Noise characteristics at different field points were compared under different vehicle velocity conditions. Road experiments were implemented to verify the effects of simulations. Results show that the aeroacoustic noise is a kind of noise with wide frequency bands, which decreases in the form of exponential function when reaching the peak value. Both the frequencies of zero value and peak value become higher when the vehicle velocity increases. The amplitudes of sound pressure level are relative to the intensity of fluctuating pressure and the radiation surface areas, and the application of PEM on aerodynamic noise simulations is feasible