Science：蝙蝠慢飞模式类似昆虫

在2月29日的《科学》（Science）杂志上，研究人员报道说，蝙蝠用的是与昆虫相同的空气动力学技巧在高空中逗留。当蝙蝠的翼翅向下扇动时，这一动作产生了一种叫做“前缘涡流”的细微气旋，蝙蝠籍此使其身体向上提拉。人们已知昆虫在飞行时会运用这种涡流，但是研究人员不知道这种机制是否也适用于较大、较重的动物如蝙蝠，特别是当其缓慢飞行或在空中盘旋滑翔的时候。

Florian Muijres及其瑞典和美国的同僚对小体型的在风道中飞行的吸蜜蝙蝠进行了研究。在烟雾机的帮助下，研究人员对飞过风道的蝙蝠尾流中的烟雾粒子的运动进行了记录。结果显示，这些涡流可以提供帮助该类动物在空中停留的高达40%的提升力。（来源：EurekAlert!中文版）

生物谷推荐原始出处：

（Science），Vol. 319. no. 5867, pp. 1250 - 1253，F. T. Muijres，A. Hedenstr

Leading-Edge Vortex Improves Lift in Slow-Flying Bats

F. T. Muijres, L. C. Johansson, R. Barfield, M. Wolf, G. R. Spedding, A. Hedenstr

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.