Leading-edge vortex improves lift in slow-flying bats
Leading-edge vortex improves lift in slow-flying bats
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DOI：
10.1126/science.1153019
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发表时间：
2008-02-29
期刊：
影响因子：
56.9
通讯作者：
Hedenstrom, A.
中科院分区：
文献类型：
--
作者：
Muijres, F. T.;Johansson, L. C.;Hedenstrom, A.
在悬停和缓慢飞行时保持在高空是很有要求的。根据准稳态空气动力学理论，飞行缓慢的脊椎动物应该不能产生足够的升力保持在高空。因此，人们提出了非定常气动力机制来增强升力产生。使用数字粒子图像测速仪，我们表明，一个小的花蜜喂养蝙蝠能够增加升力高达40%，使用附加的前缘涡流（LEV）在缓慢向前飞行，导致最大升力系数为4.8。经过LEV的气流在LEV后面平滑地重新附着到机翼上，尽管局部迎角和机翼外倾角非常大。我们的研究结果表明，在扑翼飞行中使用非定常空气动力学机制不仅限于昆虫，但也用于较大和较重的动物。
Staying aloft when hovering and flying slowly is demanding. According to quasi - steady- state aerodynamic theory, slow- flying vertebrates should not be able to generate enough lift to remain aloft. Therefore, unsteady aerodynamic mechanisms to enhance lift production have been proposed. Using digital particle image velocimetry, we showed that a small nectar- feeding bat is able to increase lift by as much as 40% using attached leading- edge vortices ( LEVs) during slow forward flight, resulting in a maximum lift coefficient of 4.8. The airflow passing over the LEV reattaches behind the LEV smoothly to the wing, despite the exceptionally large local angles of attack and wing camber. Our results show that the use of unsteady aerodynamic mechanisms in flapping flight is not limited to insects but is also used by larger and heavier animals.