Passive wing pitch reversal in insect flight
Passive wing pitch reversal in insect flight
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DOI：
10.1017/s0022112007008440
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发表时间：
2007-11-25
影响因子：
3.7
通讯作者：
Wang, Z. Jane
中科院分区：
文献类型：
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作者：
Bergou, Attila J.;Xu, Sheng;Wang, Z. Jane
机翼俯仰反转，即在冲程过渡附近迎角的快速变化，代表了扑翼悬停和连续旋转桨叶悬停（例如直升机飞行）之间的差异。虽然昆虫有肌肉组织来控制飞行过程中的翅膀俯仰，我们在这里表明，空气动力学和翅膀惯性力是足够的俯仰翅膀没有肌肉的帮助。我们研究了被动性质的机翼俯仰在几个观察到的机翼运动学，包括机翼运动的系留的蜻蜓，Libellula pulchella，悬停果蝇，悬停天蛾和简化的滑翔机悬停运动。为了确定俯仰是否是被动的，我们计算了由于气动力和机翼惯性力引起的绕扭转轴的旋转功率。这是使用直接数值模拟和准稳态流体力模型。我们发现，在这里研究的所有情况下，净旋转功率是负的，这意味着流体力协助而不是抵制机翼俯仰。为了进一步理解这些结果的一般性，我们使用准定常力模型来分析俯仰反转时流体力分量的影响，并预测机翼俯仰反转是被动的条件。这些结果表明，昆虫飞行中翅膀的俯仰运动可能是被动的。
Wing pitch reversal, the rapid change of angle of attack near stroke transition, represents a difference between hovering with flapping wings and with a continuously rotating blade (e.g. helicopter flight). Although insects have the musculature to control the wing pitch during flight, we show here that aerodynamic and wing inertia forces are sufficient to pitch the wing without the aid of the muscles. We study the passive nature of wing pitching in several observed wing kinematics, including the wing motion of a tethered dragonfly, Libellula pulchella, hovering fruitfly, hovering hawkmoth and simplified dragonfly hovering kinematics. To determine whether the pitching is passive, we calculate rotational power about the torsion axis owing to aerodynamic and wing inertial forces. This is done using both direct numerical simulations and quasi-steady fluid force models. We find that, in all the cases studied here, the net rotational power is negative, signifying that the fluid force assists rather than resists the wing pitching. To further understand the generality of these results, we use the quasi-steady force model to analyse the effect of the components of the fluid forces at pitch reversal, and predict the conditions under which the wing pitch reversal is passive. These results suggest the pitching motion of the wings can be passive in insect flight.