Chordwise wing flexibility may passively stabilize hovering insects
Chordwise wing flexibility may passively stabilize hovering insects
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DOI：
10.1098/rsif.2018.0409
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发表时间：
2018-10-01
影响因子：
3.9
通讯作者：
Kang, Chang-kwon
中科院分区：
文献类型：
--
作者：
Bluman, James E.;Sridhar, Madhu K.;Kang, Chang-kwon
昆虫的翅膀是柔性的，并且动态变形的翅膀形状影响所产生的空气动力学和功率消耗。然而，翅膀的灵活性对昆虫飞行动力学的影响是未知的。文献中的大多数稳定性研究考虑刚性机翼，并得出悬停平衡条件是不稳定的结论。刚性机翼具有不稳定的振荡模式，这主要是由于它们对水平速度扰动的俯仰敏感性。在这里，我们表明，一个扑翼飞行器与灵活的翅膀表现出稳定的悬停平衡。在果蝇尺度上模拟了纵向平面内自由飞行昆虫的飞行动力学。弦向机翼的灵活性被建模为线性梁。二维Navier-Stokes方程采用流固耦合方法求解。对于一系列类似于活昆虫的机翼柔性，悬停平衡的系统矩阵的所有特征值具有负的真实的部分。柔性机翼似乎通过在存在扰动的情况下被动地使其机翼形状变形来稳定不稳定模态，从而产生显著更多的水平速度阻尼和俯仰速率阻尼。这些结果表明，昆虫可以被动地稳定他们的悬停飞行通过翅膀的灵活性，这可以通知合成扑翼机器人的设计。
Insect wings are flexible, and the dynamically deforming wing shape influences the resulting aerodynamics and power consumption. However, the influence of wing flexibility on the flight dynamics of insects is unknown. Most stability studies in the literature consider rigid wings and conclude that the hover equilibrium condition is unstable. The rigid wings possess an unstable oscillatory mode mainly due to their pitch sensitivity to horizontal velocity perturbations. Here, we show that a flapping wing flyer with flexible wings exhibits stable hover equilibria. The free-flight insect flight dynamics are simulated at the fruit fly scale in the longitudinal plane. The chordwise wing flexibility is modelled as a linear beam. The two-dimensional Navier-Stokes equations are solved in a tight fluid-structure integration scheme. For a range of wing flexibilities similar to live insects, all eigenvalues of the system matrix about the hover equilibrium have negative real parts. Flexible wings appear to stabilize the unstable mode by passively deforming their wing shape in the presence of perturbations, generating significantly more horizontal velocity damping and pitch rate damping. These results suggest that insects may passively stabilize their hover flight via wing flexibility, which can inform designs of synthetic flapping wing robots.