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刘应征

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期刊论文

Wall pressure fluctuations of a turbulent separated and reattaching flow affected by an unsteady wake

刘应征Sejong Chun Ying Zheng Liu Hyung Jin Sung

Experiments in Fluids 37(2004)531-546,-0001,():

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摘要/描述

The spatio-temporal characteristics of the wallpressure fluctuations in separated and reattaching flows over a backward-facing step were investigated through pressure-velocity joint measurements carried out using multiple-arrayed microphones and split-film probes. A spoke-wheel-type wake generator was installed upstream of the backward-facing step. The flow structure at the effective forcing frequency (Stf=0.2) was found to be well organized in terms of wall pressure spectrum, cross-correlation, wavenumber-frequency spectrum, and wavelet auto-correlation. Introduction of the unsteady wake (Stf=0.2) reduced the reattachment length by 10%. In addition, the unsteady wake enhanced the turbulence intensity near the separation edge and, as a consequence, enhanced the quadrupole sound sources; however, the turbulence intensity near the reattachment region was weakened and the overall flow noise was attenuated. The greater organization of the flow structure induced by the unsteady wake led to a weakening of the dipole sound sources, which are the dominant sound sources in this system. The dipole sound sources generated by wall pressure fluctuations were calculated using Curle’s integral formula.

版权说明:以下全部内容由刘应征上传于   2011年05月13日 11时16分06秒,版权归本人所有。

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