Abstract The effect of Reynolds number on the flow development upstream of a rigid, non-porous, static fence is investigated experimentally. The flow field is measured using time-resolved, two-component particle image velocimetry at Reynolds numbers based on fence height of 18000, 36000, and 54000. The results show that a laminar separation bubble forms upstream of the junction vortex at the base of the fence. The mean extent of the bubble decreases with increasing Reynolds number, with mean separation moving downstream and mean reattachment moving upstream. In the aft portion of the bubble, shear layer vortices form and are shed at scaled frequencies and wavelengths that are comparable to laminar separation bubble shedding in low Reynolds number airfoils and flat plates with an imposed adverse pressure gradient. The strong periodicity of the associated coherent structures and the proximity of shear layer roll-up relative to the fence should be taken into consideration in the relevant designs due to potential implications to structural loading. A simple flow separation prediction model combining inviscid fence flow solution with Thwaites’ method is introduced and shows good agreement with the experimental results for the Reynolds number range considered.

中文翻译：

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围栏上游的流动发展

摘要 通过实验研究了雷诺数对刚性、无孔、静态围栏上游流动发展的影响。流场使用基于 18000、36000 和 54000 围栏高度的雷诺数的时间分辨、双分量粒子图像测速法进行测量。结果表明，层流分离气泡在连接涡流的上游形成，位于围栏底部栅栏。气泡的平均范围随着雷诺数的增加而减小，平均分离向下游移动，平均再附着向上游移动。在气泡的后部，剪切层涡流形成并以与低雷诺数翼型和平板中的层流分离气泡脱落相媲美的缩放频率和波长脱落，并施加不利的压力梯度。由于对结构载荷的潜在影响，相关设计中应考虑相关连贯结构的强周期性和剪切层卷起相对于围栏的接近程度。介绍了一种结合无粘性围栏流动解决方案与 Thwaites 方法的简单流动分离预测模型，该模型与所考虑的雷诺数范围的实验结果具有良好的一致性。