考虑对流效应的圆柱绕流气动噪声的预测

Numerical Prediction of Noise Induced by Flow Around a Cylinder Considering the Convection Effect

采用非稳态雷诺时均(URANS)方程求解圆柱绕流获得近场声源信息,同时运用考虑对流效应的频域声比拟方法,研究了圆柱绕流的气动噪声问题,并考察了不同来流马赫数对辐射声压的影响。结果表明:卡门涡的脱落导致圆柱阻力系数频率为升力系数频率的两倍;较大的升力系数脉动幅值产生了偶极子源,偶极子源在远场辐射声压中占主导作用,最大辐射声压垂直于来流方向;随着马赫数的增大,对流效应显著增强且辐射声压正比于马赫数的三次方。

Noise induced by flow around a cylinder has been investigated numerically using a hybrid scheme.The acoustic source information in the near field is obtained using unsteady Reynolds averaged Navier-Stokes equations（URANS）.The noise radiated to the far field is predicted with acoustic analogy taking convection effect into account.The influences of different Mach numbers on acoustic pressure are also addressed.The results show that the frequency of drag coefficient is twice the frequency of lift coefficient due to Karman vortex shedding.The dipole source produced by large magnitude of lift coefficient plays a significant role in radiated pressure and the direction of maximum acoustic pressure is perpendicular to the incoming flow.As the Mach number increases,the convection effect increases significantly and the acoustic pressure is proportional to the third power of Mach number.