匀速及加速行驶直背式轿车气动噪声

Aerodynamic noise of a fastback car in uniform and accelerated motion

应用计算流体力学软件FLUENT对简化直背式轿车外部流场及车外某接收点处气动噪声进行了数值计算和分析.脉动流场计算采用大涡模拟湍流模型,动量方程的离散格式采用有限中心差分格式.分别对两种匀速运动情况和一种加速运动进行了计算,由此研究不同车速、匀速和加速运动对接收点处脉动流场和气动噪声的影响.对于匀速运动,车速越大,接收点处流速越大,压力越小,在每个频率上所对应的声压级基本上越大,总声压级也越大;在同一行驶速度下,加速运动比匀速运动在接收点处的流速要大,压力要小,在每个频率上所对应的声压级基本上要大,总声压级要大,声压级随频率的变化情况与匀速运动一样.

Numerical simulation and analysis of flow field around a simplified fastback car and aerodynamic noise at some receiving point were conducted using CFD software FLUENT. The pulsating flow field was simulated by the large eddy turbulence model and the momentum equations were discretized with the unbounded central difference scheme. The calculations were performed under three conditions： uniform motion with two running speeds and accelerated motion. The influences of pulsating flow field and aerodynamic noise by uniform motion speed, uniform and accelerated motions were investigated. The results show that with the increase of uniform motion speed, the velocity, sound pressure level corresponding to each frequency and total sound pressure level at the receiving point become bigger, the pressure becomes smaller; At the same motion speed, the velocity, sound pressure level corresponding to each frequency and total sound pressure level in accelerated motion are greater than those in uniform motion, the pressure is smaller.