空腔流场及气动噪声数值模拟

采用带有源项的线性欧拉方程修正空腔流动的非定常流场,利用Ffowcs Williams-Hawkings方程对声源流场的声辐射及远场声信号进行求解,研究空腔辐射声场特性及阻尼截断区域中阻尼系数、控制面位置等参数对噪声信号的影响.计算结果表明,空腔内旋涡的形成和溃灭过程会引起声辐射,且具有四极子特性;在计算区域的边界处设置阻尼截断区域可以有效地控制旋涡撞击边界所产生的“假波”,为了保证较好的收敛速度,阻尼强度系数的量级为104;控制面应包围声源流场区域,以确保求解得到的远场声信号的完整性和准确性.

Numerical simulation of cavity flow field and aeroacoustic

Linear Euler equations with source terms were adopted to correct the unsteady flow of cavity. The sound radiation and signals in the far field were solved by Ffowcs Williams Hawkings equation. The characteristics of acoustic field were obtained and so were the effects of the damping coefficient of truncated region and the position of integral control surface on sound signals. Results show that the sound generated by the formation and collapse of vortex pair in cavity is revealed to be of a rotating quadrupole. A truncated region was developed at upstream of the outflow in order to effectively control the "spurious waves" produced by vortical structures. The order of damping coefficient was set to be 104 in order to ensure good computational convergence rate. The sources should be surrounded by the control surfaces in order to ensure the integrity and accuracy of the obtained sound signals in the far field．