Influence of flow path modification on oscillation of cavity shear layer
Influence of flow path modification on oscillation of cavity shear layer
复制标题
流路改造对空腔剪切层振动的影响
DOI：
10.1007/s003480100270
复制
发表时间：
2001
影响因子：
2.4
通讯作者：
Shr
中科院分区：
文献类型：
--
作者：
C. Kuo;Shr
本研究通过在腔体底部引入倾斜底部或流路调节器来研究对腔体剪切层振荡特性的影响。所有实验均在循环水通道中进行。激光多普勒测速系统和激光片技术分别用于执行定量速度测量和定性流动可视化。基于腔上游边缘处的动量厚度，雷诺数保持在大约Reθ0=194 ± 3.4。研究发现，除了反馈作用外，腔内循环流的上游运动部分对于改变不稳定剪切层的振荡特性也起着重要作用。由于空腔底部的倾斜度为负或正，空腔剪切层的振荡特性会发生不同程度的改变。发现腔体内的振荡幅度显着减小，而底部斜率增加到d/L=± 2/5。随着底部斜率进一步增加到d/L=± 1/2，自激振荡被完全抑制。此外，负底部斜率抑制自激振荡的能力优于正底部斜率的情况。根据围栏位置，再循环流的上游移动部分将扰动不同 x/L 位置处的不稳定剪切层，导致不同的振荡幅度。正角度倾斜的栅栏比负角度倾斜的栅栏促进不稳定剪切层振荡幅度扩大的能力更好。
This study investigates the influence on the oscillating characteristics of a cavity shear layer by introducing either a sloped bottom or a flow path modifier at the bottom of the cavity. All the experiments are performed in a recirculating water channel. The laser Doppler velocimetry system and the laser sheet technique are employed to perform the quantitative velocity measurements and the qualitative flow visualization, respectively. The Reynolds number, based on the momentum thickness at the upstream edge of the cavity, is kept at aboutReθ0=194 ± 3.4. It is found that, in addition to the feedback effect, the upstream moving part of the recirculating flow inside the cavity also plays an important role in changing the oscillating characteristics of the unstable shear layer. As the bottom of the cavity is either negatively or positively sloped, the oscillating characteristics of the cavity shear layer are modified to different extents. Significant reduction of the oscillating amplitude within the cavity is found while the bottom slope increases up tod/L=± 2/5. As the bottom slope further increases up tod/L=± 1/2, the self-excited oscillation is completely suppressed. In addition, the ability to suppress the self-excited oscillation by the negative bottom slopes is superior to that in the case of a positive bottom slope. Depending upon the fence locations, the upstream moving part of the recirculating flow will perturb the unstable shear layer at differentx/Llocations, leading to different oscillating amplitudes. The ability to promote the enlarged oscillating amplitude of the unstable shear layer is better for a fence inclined at a positive angle than for one at a negative angle.