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首页> 外文期刊>Experiments in Fluids: Experimental Methods and Their Applications to Fluid Flow >Reynolds number effects on a turbulent boundary layer with separation, reattachment, and recovery
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Reynolds number effects on a turbulent boundary layer with separation, reattachment, and recovery

机译：雷诺数对湍流边界层的影响，包括分离，重新附着和恢复

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摘要

The present paper addresses experimental studies of Reynolds number effects on a turbulent boundary layer with separation, reattachment, and recovery. A momentum thickness Reynolds number varies from 1,100 to 20,100 with a wind tunnel enclosed in a pressure vessel by varying the air density and wind tunnel speed. A custom-built, high-resolution laser Doppler anemometer provides fully resolved turbulence measurements over the full Reynolds number range. The experiments show that the mean flow is at most a very weak function of Reynolds number while turbulence quantities strongly depend on Reynolds number. Roller vortices are generated in the separated shear layer caused by the Kelvin-Helmholtz instability. Empirical Reynolds number scalings for the mean velocity and Reynolds stresses are proposed for the upstream boundary layer, the separated region, and the recovery region. The inflectional instability plays a critical role in the scaling in the separated region. The near-wall flow recovers quickly downstream of reattachment even if the outer layer is far from an equilibrium state. As a result, a stress equilibrium layer where a flat-plate boundary layer scaling is valid develops in the recovery region and grows outward moving downstream. [References: 31]
机译：本文讨论了雷诺数对湍流边界层分离，重新附着和恢复的影响的实验研究。通过改变空气密度和风洞速度，将风洞封闭在压力容器中，使动量厚度雷诺数在1100至20100之间变化。定制的高分辨率激光多普勒风速计可在整个雷诺数范围内提供完全解析的湍流测量。实验表明，平均流量至多是雷诺数的非常弱的函数，而湍流量强烈取决于雷诺数。由开尔文-海姆霍兹（Kelvin-Helmholtz）不稳定性在分离的剪切层中产生滚子涡旋。针对上游边界层，分离区和恢复区，提出了平均速度和雷诺应力的经验雷诺数标度。弯曲的不稳定性在分离区域的缩放中起关键作用。即使外层远离平衡状态，近壁流也能在重新连接的下游迅速恢复。结果，平板边界层缩放有效的应力平衡层在恢复区内发展，并向下游移动而向外生长。 [参考：31]

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