汽车气动噪声特性的随机声学法分析

Characteristics of Automobile Aerodynamic Noise Based on Random Acoustics Theory

为分析某款汽车高速行驶时车内气动噪声特性,采用流体力学(CFD)软件与专业声学仿真软件进行联合仿真,并进行了实车道路试验。通过分离涡模拟(DES)方法,计算车外涡流场,得到车身表面脉动压力,并将其视为随机载荷,利用随机声学法计算车内声场。结果表明:气动噪声为宽频噪声,主要能量集中在2500 Hz以下,且无明显主频率,噪声频谱变化趋势与脉动压力频谱变化趋势基本一致。随机声学法较好地模拟了脉动压力能量向车内的传播过程,且捕捉了湍流场相互叠加所致的声压级波动。

Interior aerodynamic noise characteristics of high speed automobile were explored with CFD combined with professional acoustic analysis programma and the road experiments were conducted. The flow fields were generated using detached eddy simulation（DES）. The fluctuating pressure on carbody was obtained and viewed as random loads. Interior sound fields were calculated with random acoustics methods. The results show that： aerodynamic noise is a kind of wide frequency noise, and main energy of which exists below the frequeney of 2 500 Hz without prominent frequeneies. The trends of niose frequency speetrum are consistent with that of fluetuating pressure frequency speetrum. Random acoustic methods display the capacity to simulate the energy propagations and eapture fluctuations of sound pressure level caused by vortex superpositions.