Implications of wing pitching and wing shape on the aerodynamics of a dragonfly. (February 2021)

• Record Type: Journal Article
• Authors: Liu, Xiaohui; Hefler, Csaba; Fu, Junjiang; Shyy, Wei; Qiu, Huihe
• Is Part Of: Journal of fluids and structures. Volume 101(2021)
• Publication Date: 2021-02
• Subjects: Wing shape -- Wing kinematics -- Pitching -- Dragonfly flight -- Aerodynamics; Fluid-structure interaction -- Periodicals; Fluid mechanics -- Periodicals; Structural dynamics -- Periodicals; Structural analysis (Engineering) -- Periodicals; 620.106
• DOI: 10.1016/j.jfluidstructs.2020.103208
• Languages: English
• ISSNs: 0889-9746

Abstract

Abstract: The forewing and the hindwing of a dragonfly have different geometry that could be an evolutionary specialization for better aerodynamic performance via sophisticated wing pitch control. Under different extent of wing pitching by the wing root musculature, the fore- and hindwings could exhibit different shape deformation and aerodynamic characteristics as a result of passive shape deformation. We measured the flow around the flapping wings using time-resolved particle image velocimetry (TR-PIV) to investigate the consequences of shape and the pitching mechanisms of the wings on the aerodynamics of dragonflies. The flow fields and pitching angle variations of the naturally actuated wing of the dragonfly were compared with that of the same wing artificially actuated only by flapping motion. We found that the trailing edge vortex dynamics and the wake were affected by the wing shape only for the in-vivo experiment with muscle induced pitching. Under the in-vivo with muscle induced pitching, the hindwing took more part in generating horizontal momentum with larger pitching magnitude, due to the larger chord length compared with forewing. Meanwhile, when there was only pitching due to the wing membrane deformation of artificially actuated flapping, a slight difference in the surrounding flow structures was found between the hindwing and the forewing, and the net flow in one period was reduced nearly to zero. These results provided quantified evidence to the extent and importance of the pitching motion of the wings in dragonfly flight. The results of this work can be useful for the design of wings, their actuation mechanism, and the in-flight kinematics control of flapping wing micro air vehicles (MAVs).