基于比拟理论计算圆柱/翼型的气动噪声

Aerodynamic noise of the rod-airfoil computed by using acoustic analogy

采用计算流体力学(CFD)与"声比拟"相结合的方法,通过两个步骤模拟流动的声学远场。第一步,在包含所有声源的近场区域内,通过求解URANS方程获得控制面处的非定常流场参数;第二步,采用基于可穿透数据面的FW-H方法模拟声学远场。该方法与传统的半经验方法相比,计算精确,易于工程实现,并且可以计算非线性噪声。根据气动声学计算积分公式,构造了高阶的时间离散格式,采用高斯积分公式计算圆柱/翼型的气动噪声。在时域和频域上计算了观测点处的声压及声压级随时间步数的变化情况,其结果与国外实验结果对比取得了较好的一致性,此外研究了翼型尾流部分界面对计算精度的影响。

The most traditional methods about computation of the noise are half-experience. This paper is used acoustic analogy which is in combine with computational fluid dynamics. The approach is achieved by two step procedure. In the first step, the unsteady flow field is computed in a near-field domain comprising all acoustic sources via a URANS solver. In the second step, the FW-H integration approach with a permea- ble data surface is used to extend the dynamic near-field to the acoustic far-field. Compared with the tradi- tional half-experience method, this approach only has small amount of calculation, and accurate result can be obtained. The most important, it can compute nonlinear noise and be used easily. This paper calculates the noise of the rod-airfoil by the use of aeroaeoustics integral formulation, employing Gauss integral formula and constructing discrete scheme in time. In the time domain and frequency domain, this paper calculates respec tively the acoustic pressure changes and sound pressure level changes over time steps in the observation. The result agrees well with the experiment data. Furthermore, the paper researches the effect of airfoil wake flow on precision .