A simulation-based study on longitudinal gust response of flexible flapping wings
A simulation-based study on longitudinal gust response of flexible flapping wings
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DOI：
10.1007/s10409-018-0789-5
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发表时间：
2018-12-01
影响因子：
3.5
通讯作者：
Liu, Hao
中科院分区：
文献类型：
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作者：
Nakata, Toshiyuki;Noda, Ryusuke;Liu, Hao
昆虫等有翅膀的动物能够在不稳定且不可预测的空中环境中飞行和生存。它们通过拍动灵活的机翼来产生和控制空气动力。虽然众所周知，扑翼的动态形状变化可以提高飞行效率，但它们也会通过响应机翼上空气动力的突然变化，影响扑翼飞行器在不可预测的干扰下的稳定性。为了验证这一假设，对柔性扑翼的阵风响应进行了数值研究，特别关注机翼柔性对空气动力的被动维持。该计算模型基于动态飞行模拟器，可以结合悬停天蛾的真实形态、运动学、结构动力学、空气动力学和流体结构相互作用。纵向阵风是针对具有灵活拍动翅膀的盘旋天蛾的系留模型施加的。研究发现，由于相对翼尖速度或运动攻角的增加或减少，扑翼上的空气动力受到阵风的影响。然而，柔性机翼的被动形状变化可以减少除向下阵风以外的各个方向的阵风对气动力大小和方向的变化。柔性结构稳定姿态的自适应响应可以归类为机械反馈，它以最小的延迟被动工作，对于微型飞行器仿生扑翼的设计具有重要意义。
Winged animals such as insects are capable of flying and surviving in an unsteady and unpredictable aerial environment. They generate and control aerodynamic forces by flapping their flexible wings. While the dynamic shape changes of their flapping wings are known to enhance the efficiency of their flight, they can also affect the stability of a flapping wing flyer under unpredictable disturbances by responding to the sudden changes of aerodynamic forces on the wing. In order to test the hypothesis, the gust response of flexible flapping wings is investigated numerically with a specific focus on the passive maintenance of aerodynamic forces by the wing flexibility. The computational model is based on a dynamic flight simulator that can incorporate the realistic morphology, the kinematics, the structural dynamics, the aerodynamics and the fluid-structure interactions of a hovering hawkmoth. The longitudinal gusts are imposed against the tethered model of a hovering hawkmoth with flexible flapping wings. It is found that the aerodynamic forces on the flapping wings are affected by the gust, because of the increase or decrease in relative wingtip velocity or kinematic angle of attack. The passive shape change of flexible wings can, however, reduce the changes in the magnitude and direction of aerodynamic forces by the gusts from various directions, except for the downward gust. Such adaptive response of the flexible structure to stabilise the attitude can be classified into the mechanical feedback, which works passively with minimal delay, and is of great importance to the design of bio-inspired flapping wings for micro-air vehicles.