The spatial-temporal effects of wing flexibility on aerodynamic performance of the flapping wing

In this paper, three-dimensional fluid–structure interaction simulation of flapping of a flexible wing is carried out. The aerodynamic effect of the flexible wing can be explained by analyzing the spatial and temporal effects of wing flexibility on aerodynamic performance. It is concluded that the flexible wing can increase the average lift and the aerodynamic efficiency. The spatial influence of flexible deformation mainly comes from the contribution of camber. In the mid-downstroke, wing flexibility results in significant camber near the wingtip, which is conducive to the attachment of the leading-edge vortex to the wing surface, thus enhancing the ability of the wingtip to generate lift. The temporal influence of flexible deformation mainly comes from the contribution of twist and bend. The fast pitching-down rotation due to the wing twist in the early downstroke is conducive to the accumulation of vorticity. The spanwise bend of the flexible wing due to the aerodynamic force and inertia can increase the flapping amplitude, which accounts for the lift increase. The above spatial-temporal effects make the flexible wing have better performance in generating lift and aerodynamic efficiency. The results are beneficial to systematically understand the aerodynamic effects of insect wing deformation and can provide guidance for the wing design of micro aerial vehicles.