Leading-edge vortices in insect flight
Leading-edge vortices in insect flight
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DOI：
10.1038/384626a0
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发表时间：
1996-12-19
期刊：
影响因子：
64.8
通讯作者：
Thomas, ALR
中科院分区：
文献类型：
--
作者：
Ellington, CP;vandenBerg, C;Thomas, ALR
根据传统的空气动力学定律，昆虫不能飞行：在拍打飞行时，它们的翅膀在相同的速度和攻角下产生的升力比稳定运动时更大(1-5)。测量的瞬时升力也显示出与传统空气动力学理论预测的力在定性和定量上的不一致(6-9)。高寿命空气动力机制的重要性现在得到了广泛的认识，但除了一些昆虫物种(1，10-13)所使用的专门的抛撒机制外，额外升力的来源仍然未知。我们现在已经看到了鹰蛾Manduca sexta机翼周围的气流和一个‘盘旋’的大型机械模型--襟翼。在下划线上发现了一个强烈的前缘涡旋，其强度足以解释高升力。漩涡是由动态失速产生的，而不是由昆虫飞行所假定的旋转升力机制造成的(14-16)。旋涡以与扑翼速度相当的展向速度向翼尖旋转，三维流动类似于三角翼上的锥形前缘旋涡，展向流动起到稳定旋涡的作用。
INSECTS cannot fly, according to the conventional laws of aero dynamics: during flapping flight, their wings produce more lift than during steady motion at the same velocities and angles of attack(1-5). Measured instantaneous lift forces also show qualitative and quantitative disagreement with the forces predicted by conventional aerodynamic theories(6-9). The importance of high-life aerodynamic mechanisms is now widely recognized but, except for the specialized fling mechanism used by some insect species(1,10-13), the source of extra lift remains unknown. We have now visualized the airflow around the wings of the hawkmoth Manduca sexta and a 'hovering' large mechanical model-the flapper. An intense leading-edge vortex was found on the downstroke, of sufficient strength to explain the high-lift forces. The vortex is created by dynamic stall, and not by the rotational lift mechanisms that have been postulated for insect flight(14-16). The vortex spirals out towards the wingtip with a spanwise velocity comparable to the flapping velocity, The three-dimensional flow is similar to the conical leading-edge vortex found on delta wings, with the spanwise flow stabilizing the vortex.