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Journal of Zhejiang University SCIENCE A
ISSN 1673-565X(Print), 1862-1775(Online), Monthly
2017 Vol.18 No.7 P.545-552
Experimental investigation of vortex-ring cavitation
Abstract: Vortex-ring cavitation occurs when the pressure inside a torus-shaped core of a vortex ring falls below the vapor pressure of the ambient liquid. By generating a vapor bubble in a rigid tube, a toroidal cavity can be produced outside the tube. The pulsation and propagation behaviors of vortex-ring cavitation are studied using a high-speed video camera and a hydrophone. The experimental results show that the cavity continues to oscillate with a period that depends heavily on the maximal cross-section radius of the cavity and circulation of the vortex flow, under the influence of the surrounding vortex flow field. It is also shown that the cross-radial oscillation of the toroidal cavity can be measured both by a high-speed camera and hydrophone. Moreover, three different methods for estimating the circulation are compared to propose an accurate model of toroidal cavity oscillation. The phenomenon of a toroidal cavity impinging on a fixed wall is also investigated.
Key words: Cavitation; Toroidal cavity; Oscillation period; Impinging on wall
创新点：1. 通过实验方法，比较几种不同的速度环量计算模型在环状空泡振荡控制方程中的适用性。2. 通过声学方法，得到环状空泡在撞击壁面溃灭过程中的频谱特征。
方法：1. 通过管内空泡膨胀产生高速射流；高速射流在管口处形成涡环并发生涡环空化。2. 基于高速摄像进行流体分析。
结论：1. 在管内空泡溃灭后,环状空泡以恒定速度沿管的轴向运动,且其振荡周期几乎保持不变。2. 环状空泡的振荡周期基本上满足规律:τ~R0(ρ/ΔP)0.5[ln(8/ε)]0.5。3. 在空泡振荡的最小直径为特征直径;根据空心涡核模型,可以计算得到最接近实验结果的速度环量值。4. 当空泡冲击壁面时,空泡的环向直径将变大。5. 环向直径的最大扩张比α与其截面直径与环向直径的比ε相关:α~ε0.25。
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DOI:
10.1631/jzus.A1600537
CLC number:
TH161.12
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On-line Access:
2017-07-04
Received:
2016-07-29
Revision Accepted:
2016-10-09
Crosschecked:
2017-06-12