Reynolds number effects on a turbulent boundary layer with separation, reattachment, and recovery
Reynolds number effects on a turbulent boundary layer with separation, reattachment, and recovery
复制标题
雷诺数对湍流边界层分离、重新附着和恢复的影响
DOI：
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
J. Eaton
中科院分区：
文献类型：
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作者：
Simon Song;Simon Song;J. Eaton
本文研究了雷诺数对具有分离、再附着和恢复的湍流边界层的影响。通过改变空气密度和风洞速度，在压力容器中封闭的风洞中，动量厚度雷诺数从1，100变化到20，100。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。实验结果表明，平均流量至多是雷诺数的一个很弱的函数，而湍流量强烈地依赖于雷诺数。在Kelvin-Helmholtz不稳定性的作用下，分离剪切层中产生了滚柱涡。提出了上游边界层、分离区和恢复区的平均速度和雷诺应力的经验雷诺数定标。折射不稳定性在分离区的标度中起着关键作用。即使外层远离平衡状态，近壁流动在再附着下游也很快恢复。结果，应力平衡层的平板边界层缩放是有效的发展在恢复区和增长向外移动下游。
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.