Unsteady aerodynamic mechanisms of wing flexibility in dragonfly flapping flight

This study investigates the effect of flexible wings on the aerodynamic performance of dragonfly flapping flight through both experimental and numerical simulations. The model experiment employed an isotropic flexible wing, and the results showed that the flexible deformation of the dragonfly wing led to a 12% increase in average lift. On the numerical side, an anisotropic flexible wing model replicating the mechanical properties of the dragonfly wing is constructed, and fluid–structure interaction (FSI) simulations are conducted. The simulation results show that the cycle-averaged lift coefficient of the flexible wing increases by 7.86% compared to its rigid counterpart. Comparative analysis of the flow field reveals three key unsteady aerodynamic mechanisms associated with wing flexibility: the chordwise camber mechanism, which stabilizes the attachment of the leading-edge vortex (LEV) to the upper surface of the wing, generating stable lift; the accelerated rotation mechanism, which increases the amplitude and speed of wing rotation and facilitates vortex accumulation; and the spanwise bending mechanism, which increases the flapping angle range and enhances lift.