Parameters influencing vortex growth and detachment on unsteady aerodynamic profiles
Parameters influencing vortex growth and detachment on unsteady aerodynamic profiles
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DOI：
10.1017/jfm.2015.259
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发表时间：
2015-05
影响因子：
3.7
通讯作者：
Alexander Widmann;Cameron Tropea
中科院分区：
文献类型：
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作者：
Alexander Widmann;Cameron Tropea
为了研究前缘涡 (LEV) 形成和分离的机制，进行了俯仰和俯冲翼型实验。弦长从 90 到 180 mm 变化，保持所有其他无量纲参数恒定，特别是雷诺数 (17 000)、斯特劳哈尔数 (0.25)、折减频率 (0.5) 和有效攻角历史记录。结果表明，涡流脱离的机制随着弦长的变化而变化，这在流拓扑的相应变化中很明显。一种机制与弦长成比例，另一种机制归因于边界层中的粘性效应。对于后一种机制，引入了 LEV 循环的新缩放。第二个实验研究了频率降低对 LEV 循环和分离机制的影响，再次保持所有其他无量纲参数恒定。
Experiments with a pitching and plunging airfoil are conducted in order to investigate the mechanisms responsible for the formation and detachment of leading edge vortices (LEVs). The chord length is varied from 90 to 180 mm, keeping all other non-dimensional parameters constant, specifically the Reynolds number (17 000), the Strouhal number (0.25), the reduced frequency (0.5) and the effective angle of attack history. It is shown that the mechanism of vortex detachment changes with chord length, evident in a corresponding change in flow topology. One mechanism scales with chord length, the other is attributed to viscous effects in the boundary layer. For the latter mechanism a new scaling of the LEV circulation is introduced. A second experiment investigates the influence of the reduced frequency on the LEV circulation and detachment mechanisms, again keeping all other non-dimensional parameters constant.