Wall-shear stress measurements in an adverse pressure gradient turbulent boundary layer
Wall-shear stress measurements in an adverse pressure gradient turbulent boundary layer
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DOI：
10.2514/6.2014-2098
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发表时间：
2014-06
期刊：
影响因子：
2.5
通讯作者：
B. Nottebrock;K. Geurts;W. Schröder
中科院分区：
文献类型：
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作者：
B. Nottebrock;K. Geurts;W. Schröder
建立了逆压梯度湍流边界层模型，表明微柱剪应力传感器可用于非定常自由流测量壁面剪应力分布。通过额外的测量，如压力和PIV测量以及大涡模拟，确保了参考的质量。基于动量的雷诺数为Reθ = 4420，表征压力梯度的Clauser参数为β = 1.77。对微柱剪切应力传感器的灵敏度的介绍性讨论揭示了压力梯度对壁面剪切应力结果的影响很小，因为阻力对速度分布的依赖性是阻尼的。因此，传感器对由于正压力梯度而导致的与壁的线性定律的差异仅是很小的敏感性。介绍了用MPS测量APG TBL中壁面剪应力的方法。使用统计矩分析传感器的行为和精度。这与数值模拟的结果是一致的。此外，它们揭示了压力梯度对壁面剪应力的影响。与零压力梯度湍流边界层相比，湍流强度、偏度和峰度都较小。这证实了APG TBL中近壁高速条纹的数量和强度的减少，这与Harun等人的研究结果非常一致。
An adverse pressure gradient turbulent boundary layer has been established to show that the micro-pillar shear-stress sensor can be used in non-constant free-stream flows to measure the wall-shear stress distribution. The quality of the reference has been ensured by additional measurements such as pressure and PIV measurements, and large-eddy simulations. The momentum based Reynolds number is Reθ = 4420 and the Clauser parameter characterizing the pressure gradient is β = 1.77. An introductory discussion on the sensitivity of the micro-pillar shear-stress sensor reveals only little effect of a pressure gradient on the wall-shear stress results since the dependence of the drag force on the velocity distribution is damped. Hence, the sensor is only little sensitive to discrepancies from the linear law of the wall due to a positive pressure gradient. Measurements of wall-shear stress in an APG TBL using MPS are presented. The behavior and accuracy of the sensor is analyzed using the statistical moments. They coincide with the results of the numerical simulation. Furthermore, they reveal an effect of the pressure gradient on the wall-shear stress. Turbulence intensity, skewness and kurtosis are smaller compared to the zero-pressure gradient turbulent boundary layer. This confirms the decrease in number and strength of the near-wall high-speed streaks in the APG TBL which is in good agreement with the findings of Harun et al.