arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 2602.09052physics.flu-dyn
收藏

机翼上滞止细胞。第一部分:三维流动组织与涡量动力学

Stall cells over an airfoil. Part 1: Three-dimensional flow organisation and vorticity dynamics

LHEEA lab. - CNRS - Nantes Université, Centrale Nantes(南特大学、中央南特学院);FLOW, Department of Engineering Mechanics, KTH Royal Institute of Technology(瑞典皇家理工学院)

Rishabh Mishra, Emmanuel Guilmineau, Ingrid Neunaber, Caroline Braud

AI总结:

本研究采用混合RANS/LES方法分析机翼上滞止细胞的三维流动组织与涡量动力学,揭示了展向速度结构的旋转特性及分离涡管的不稳定性。

摘要:

本研究调查了机翼上分离流区域中滞止细胞的三维组织和演变。采用基于DDES-SST湍流模型的混合RANS/LES方法,我们表征了这些结构的形成和发展,这些结构在实验上仍然具有挑战性。初步验证确认了与实验数据和RANS模拟相比,全局载荷的准确再现。通过研究涡量,分析了复杂的三维流动组织,发现沿机翼展向分离位置的展向变化导致了机翼展向上的非均匀载荷分布。中展处由于流动分叉而发生早分离,而±1弦长处的流动吸引成功在弦长进一步延伸处维持附着流动。分离流产生一个剪切层,最终形成分离涡管,当与反向旋转的尾涡管相互作用时,该不稳定现象会表现出Crow型不稳定性。这种不稳定性会诱导涡管和剪切层的波浪状弯曲,产生显著的垂直涡量(y-涡量),驱动展向流动。我们识别出一种此前未报告的现象,即展向速度结构的最大值围绕固定展向轴旋转,旋转角度根据ζ=14.5(x/c) - 0.8线性地随下游距离变化。本研究提供了关于滞止细胞形成机制的新见解,并突显了分离流中三维效应的重要性,这对气动载荷预测和控制策略具有影响。

英文摘要:

This study investigates the three-dimensional organisation and evolution of stall cells in the separated flow region over an airfoil. Using a hybrid RANS/LES approach based on the DDES-SST turbulence model, we characterise the formation and development of these structures, which remain challenging to capture experimentally. Initial validation confirms accurate reproduction of global loads when comparing with both experimental data and RANS simulations. The complex three-dimensional flow organisation is analysed through investigating the vorticity, revealing that spanwise variation of the separation location leads to non-uniform load distribution along the airfoil span. The mid-span experiences premature separation due to flow bifurcation, while flow attraction at $\pm1$ chord length successfully sustains attached flow further along the chord. The separated flow generates a shear layer culminating in a separation vortex tube, which exhibits a Crow-type instability when interacting with the counter-rotating trailing edge vortex tube. This instability induces a wave-like bending of the vortex tubes and shear layer, generating significant vertical vorticity (y-vorticity) that drives spanwise flow. We identify a previously unreported phenomenon where the maxima of spanwise velocity structures exhibit rotation around fixed spanwise axes, with the rotation angle evolving linearly with downstream distance according to $ζ= 14.5(x/c) - 0.8$. This study provides new insights into the mechanisms underlying stall cell formation and highlights the importance of three-dimensional effects in separated flows, which has implications for aerodynamic load prediction and control strategies.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑