Flow separation on flapping and rotating profiles with spanwise gradients
Flow separation on flapping and rotating profiles with spanwise gradients
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具有展向梯度的扑动和旋转轮廓上的流动分离
DOI：
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发表时间：
2017
影响因子：
3.4
通讯作者：
D. Rival
中科院分区：
文献类型：
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作者：
J. Wong;B. laBastide;D. Rival
已经通过实验研究了类似扑动和旋转轮廓上前缘涡流 (LEV) 的增长。考虑了三种时变情况：具有翼展方向均匀迎角变化 α 的二维参考情况； α 朝向轮廓尖端增加的情况（类似于扑动的传单）；以及α朝向轮廓根部增加的情况（类似于经历轴向阵风的转子叶片）。研究表明，时变翼展方向攻角梯度会产生涡度梯度，该涡度梯度与翼展方向流动相结合，导致环流沿剖面重新分布。具体而言，当复制经历轴向阵风的转子的迎角梯度特性时，翼展方向涡度梯度被对齐，使得测量域内的环流增加。这反过来又增加了局部 LEV 增长率，这表明叶片上的力增大。研究发现，反转展向涡度梯度和展向流的相对排列，从而复制扑动飞行器中发现的这种排列，可以减少局部循环。由此，我们可以得出结论，可以通过安排展向流来改变 LEV 增长，以延长升力增强并减少循环载荷的不稳定性。
The growth of leading-edge vortices (LEV) on analogous flapping and rotating profiles has been investigated experimentally. Three time-varying cases were considered: a two-dimensional reference case with a spanwise-uniform angle-of-attack variation α; a case with increasing α towards the profile tip (similar to flapping flyers); and a case with increasing α towards the profile root (similar to rotor blades experiencing an axial gust). It has been shown that the time-varying spanwise angle-of-attack gradient produces a vorticity gradient, which, in combination with spanwise flow, results in a redistribution of circulation along the profile. Specifically, when replicating the angle-of-attack gradient characteristic of a rotor experiencing an axial gust, the spanwise-vorticity gradient is aligned such that circulation increases within the measurement domain. This in turn increases the local LEV growth rate, which is suggestive of force augmentation on the blade. Reversing the relative alignment of the spanwise-vorticity gradient and spanwise flow, thereby replicating that arrangement found in a flapping flyer, was found to reduce local circulation. From this, we can conclude that spanwise flow can be arranged to vary LEV growth to prolong lift augmentation and reduce the unsteadiness of cyclic loads.
影响因子：
2.4
作者：
Rival, David E.;Kriegseis, Jochen;Tropea, Cameron
通讯作者：
Tropea, Cameron