来流边界层对空腔风振噪声的影响

Effect of incoming boundary layer on cavity buffeting noise

使用计算流体力学软件STAR-CCM+,基于大涡模拟(LES)方法,采用动态Smagorinsky-Lilly亚格子模型(DSLM)和简易空腔模型研究了风振噪声机理,将仿真结果与实验数据进行对比验证了仿真方法正确性,同时,分析了不同来流边界层形态与厚度对空腔风振噪声的影响。研究结果如下:验证了空腔风振噪声的产生与空腔开口剪切层振荡和周期性涡脱有关;空腔风振噪声是声反馈机制与共振机制共同作用的结果;将来流边界层形态由层流变为湍流或者增加来流边界层厚度,均能改变开口自由剪切层振荡的稳定性及漩涡的发展与运动,从而减弱声反馈效应或者使涡脱频率远离共振频率来降低空腔风振噪声水平。

The computational fluid dynamics software STAR-CCM+ and the DSLM subgrid-scale model were used to study the mechanism of buffeting noise based on the simple cavity. The correctness of the simulation method is verified by comparing with the experimental data,and the effect of different incoming boundary layer shape and thickness on cavity buffeting noise is analyzed. The results show that the cavity buffeting noise is related to the shear layer oscillating and periodic vortex shedding of the cavity opening.The cavity buffeting noise is the result of the interaction of the acoustic feedback mechanism and the resonance mechanism. The cavity buffeting noise can be reduced through changing the boundary layer shape from laminar to turbulent or increasing the thickness of the boundary layer,which changes the stability of the free shear layer oscillation and the development and motion of the vortex of the cavity opening. These measures can weaken the acoustic feedback effect or make the vortex frequency away from the resonance frequency to reduce the cavity buffeting noise.