非紧致边界气动噪声数值预测方法

通过寻找满足非紧致边界的精确格林函数,发展了一种基于声模拟理论的非紧致边界气动噪声数值预测方法。该方法首先采用边界积分方法计算满足相应边界条件的精确格林函数,然后采用精确格林函数求解FW-H方程,进行远场气动噪声预测。考虑了非紧致边界对声波传播的散射作用,适用于尺寸较大且几何外形复杂的边界与非定常流动相互作用诱发的气动噪声的数值预测。以雷诺数90 000、马赫数0.2的圆柱绕流诱发的气动噪声为例,数值预测了非紧致边界条件下的气动噪声,并与采用自由空间格林函数求解FW-H的计算结果进行了对比,对该方法进行了验证。

Computational Method of Aerodynamic Noise Induced by Airflow over Non-compact Boundary

A general computational method is proposed to evaluate aerodynamic noise generated by unsteady flows interacting with non-compact boundary. Firstly, a boundary element method is applied to compute the exact/tailored Green’s Function that satisfied the specific boundary conditions. Then, the numerical results of exact/tailored Green’s Function are used to solve FW-H equation to predict the far field noise. This numerical method can predict not only the radiating noise from the aerodynamic sources, but also the scattering noise from non-compact surfaces. Especially, the approach is suitable for boundary which has large and complex geometric shape. The present method is applied to predict aerodynamic noise generated by turbulent flows at Reynolds number of 90000 over a circular cylinder with non-compact boundary conditions.