空腔流动的大涡模拟及气动噪声控制

大涡模拟(LES)和三维的Ffowcs Williams-Hawkings声学比拟方法相结合,研究空腔过流的一种噪声控制措施.空腔的底板/后墙使用多孔壁板,因此流体可以穿透空腔壁面,多孔效果使用Darcy压力-速度关系模拟.声源流场由LES计算,声辐射和远声场由声学比拟获得.结果表明,这种措施有效地减弱了空腔内的压力脉动和远场声辐射,低频脉动Rossiter模数对应的波动幅值被有效抑制,声源中偶极子占优项大幅度减小,从而抑制了声辐射.

LARGE-EDDY SIMULATION AND CONTROLLING OF NOISE IN CAVITY

The sound controlling technique using porous inserts in an open cavity is tested numerically. Large eddy simulation(LES)combined with a three-dimensional Ffowcs Williams-Hawkings(FW-H) acoustic analogy is employed.The Darcy pressure-velocity law is applied to conceptually mimic the effect of porous media placed on the cavity floor and/or rear wall.As a result,flow in the cavity could locally move in or out through these porous walls.The numerical results show that applying the porous media on cavity floor and/or rear wall could decrease the pressure fluctuations in the cavity and the sound pressure level in the far field.The amplitudes of the Rossiter modes are suppressed while the dominant sound sources(the transverse dipole terms)are significantly reduced.As a result, the sound pressure in the far field is also suppressed.