Observations of the frequencies in a sphere wake and of drag increase by acoustic excitation
Observations of the frequencies in a sphere wake and of drag increase by acoustic excitation
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DOI：
10.1063/1.866937
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发表时间：
1988-11
影响因子：
4.6
通讯作者：
H. J. Kim;P. Durbin
中科院分区：
文献类型：
--
作者：
H. J. Kim;P. Durbin
在雷诺数为500<；Re<；60000的球体尾迹中，测量到了旋涡脱落和不稳定波的频率。考察了声激励的影响，发现在较低雷诺数时，两种频率模式之间存在相互作用，通过这种相互作用，失稳频率处的外力可以改变涡旋脱落频率。平均尾迹的发展是通过强迫接近剪切层的主要不稳定频率来控制的。在这种强迫作用下，分离的剪切层向球体表面移动，尾迹的逆流区变短。随之而来的是，底部压力降低，阻力增加。
Vortex shedding and instability wave frequencies have been measured in the wakes of spheres in the Reynolds number range 500<Re<60 000. The effect of acoustic excitation was examined and an interaction between the two frequency modes was found at the lower Reynolds numbers; through this interaction, external forcing at the instability frequency could change the vortex shedding frequency. The development of the mean wake was manipulated by forcing near to the dominant shear layer instability frequency. With this forcing, the separated shear layer moved closer to the surface of the sphere and the reversed flow region of the wake was shortened. Concomitantly, the base pressure decreased and drag increased.