海豹胡须柱杆件周围流场与气动噪声特性

Behaviour of Flow and Aerodynamic Noise Around Seal-vibrissa-shaped Cylinder

摘要:

基于海豹胡须能有效抑制涡激振动的特殊结构，数值分析了海豹胡须柱杆件周围流场与气动噪声特性。在声学风洞中进行了气动噪声测试，并与具有相同特征长度的圆柱以及椭圆柱杆件进行对比。结果表明，海豹胡须柱鞍面与节点面交错排列的几何结构引发流体三维分离，剪切层之间的相互作用减弱，导致尾迹中没有明显的拟序结构、尾迹稳定性显著提升、几何体表面升力脉动被抑制；海豹胡须柱破坏了圆柱尾流规律性脱落的卡门涡街，抑制了所产生气动噪声的谐频峰值，多数频段内声压级幅值降低。气动噪声风洞测试结果验证了数值模拟的准确性。

Abstract:

Based on the special structure of seal vibrissa with its ability to effectively inhibit vortex-induced vibrations， the behaviour of flow and aerodynamic noise around a seal-vibrissa-shaped cylinder was numerically simulated. Aerodynamic noise was measured in an anechoic wind tunnel， and the seal-vibrissa-shaped cylinder case was compared with the cases of cylindrical and elliptical bars in same characteristic dimensions. Results show that the alternative arrangement of the saddle and nodal planes of the seal-vibrissa-shaped cylinder leads to three-dimensional flow separations and suppresses the shear layer interactions， which improves the flow stability with no dominant coherent structures developed in the wake and thus suppresses the lift fluctuations on solid wall surfaces. The morphology of the seal-vibrissa-shaped cylinder inhibits the regular vortex shedding of Karman vortex street which occurs in a cylinder wake， and consequently eliminates the tonal peak of flow-induced noises. Thereby， the sound pressure level is reduced at main frequencies. The experimental results verify the accuracy of numerical simulations.