Analysis of aerodynamic characteristics of flexible flapping flap with bidirectional fluid–structure interaction

Birds in nature adjust the shape of their wings in time according to the change in wind resistance to achieve the purpose of increasing lift and reducing drag, thereby achieving higher flight efficiency. Aiming at the aerodynamic change caused by the flexible deformation of the flapping wing, an analysis model of the flexible wing is established. The two-way fluid–solid coupling method is used to construct the control equations in an arbitrary Lagrange–Euler coordinate system and analyze the overall aerodynamic changes in the flapping process of the flexible flapping wing and the deformation of the wing surface and skeleton. The simulation results show the following: The larger lift force and forward thrust can be obtained from the flapping of the flexible wing, but the larger flexible deformation will lead to the increase in resistance, which leads to the decline of the overall aerodynamic efficiency. Therefore, the flexible wing structure should be designed to ensure that the wing has a certain degree of flexibility and improve the stiffness of the wing.