Numerical Study on Aerodynamic Performance of the Wrinkled Flexible Dragonfly Forewing in Gliding Flying

Dragonflies are highly skilled flyers in the natural world, capable of performing flight maneuvers such as lateral flight, hovering, and backward flight—many of which are difficult for human aircraft to achieve. The exceptional flight abilities of dragonflies are closely related to their wings. The wrinkled and venous structures on their wings provide aerodynamic advantages that flat wings with equal thickness, equal projected area, and identical shape profiles do not possess. At the same time, dragonfly wings have a certain degree of flexibility, which causes deformation under aerodynamic forces during flight. This deformation, in turn, affects the aerodynamic characteristics of the wings. To reveal the impact of the wing wrinkling and flexibility on the aerodynamic properties, this study established a three-dimensional CFD model and CSD model of the dragonfly’s wrinkled forewing based on previous measurements and research results using 3D modeling software. Modal analysis was performed to verify the model’s accuracy. Using the CFD method and a CFD/CSD bidirectional fluid-structure coupling calculation method, numerical simulations were conducted on the aerodynamic characteristics of both rigid and flexible wrinkled forewings, as well as flat forewings with equal thickness, equal projected area, and identical shape profiles during gliding flight. The results showed that the stronger leading-edge vortex and the attached vortices within the wrinkled structure improve the aerodynamic performance of the dragonfly’s forewings. Additionally, for the wrinkled forewings, the flexibility factor causes the wing veins and membrane to deform under aerodynamic loads. The pressure difference between the upper and lower surfaces of the flexible forewing is reduced compared to the rigid forewing, leading to a decrease in both lift and drag. However, in terms of the final result, the aerodynamic performance of the dragonfly’s forewings is enhanced.