摘要:
反射端声压级高于140dB以后驻波管中的声流结构会发生明显变化。利用流动显示和LDV(Laser Doppler Velocimetry)技术对该问题进行了实验研究。流动显示结果表明,在160dB左右的高强驻波声场中随着旋涡结构的合并、破裂等现象的出现,声致流动有明显的湍流特性。LDV测量结果显示,随着驻波管中声压级的提高,一些测点的速度频谱明显加宽,出现高频速度脉动,而另一些点的速度频谱则没有显著变化。径向湍流强度测量结果显示,此时管中流动已是复杂的三维结构,而非轴对称的二维结构。
关键词:
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驻波场 /
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声流 /
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流动显示 /
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LDV /
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湍流
Abstract:
Acoustic streaming in a standing wave field has been measured using Laser Doppler Velocimeter (LDV).If sound pressure level (SPL) of the standing wave tube is larger than 140dB,the stable and regular structure of acoustic streaming will distort apparently.As SPL improved on,vortex combining and breaking can be observed through flow visualization.Under super-high intensity of more than 160dB,it clearly changes to acoustic turbulence.The results of LDV show,following with the improvement of intensity,velocity spectra of some points broaden apparently,while others keep their original status.Results of turbulence intensity across the pressure node plane also show,the regular and symmetrical flow structures in the tube have been turned to turbulence.
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