Fluid-structure analysis of flapping-wing rotorcraft considering stiffness influence

As a novel aerial vehicle, flapping-wing rotorcrafts (FWRs) leverage both aerodynamic advantages of flapping and rotary wings, which can enhance the lift by using the passive rotational effect generated by the flexible deformation of their center symmetrical flapping wings. Due to FWRs' unique wing kinematics, considering the aeroelastic deformation of wings is essential for the aerodynamic optimization of FWRs. In this paper, we propose a computational method of fluid-structure interaction for FWRs based on a simplified structural model. Such a method guarantees accurate results and works with high computational efficiency. To experimentally validate the proposed computational method, motion capture testing is constructed to simultaneously measure FWR wing deformation and aerodynamic forces during flapping. By comparing the experimental and computational results, the proposed method is capable of predicting the flapping lift effectively. Moreover, it can interpret the wing rotation and twist of the tested FWR. The computational efficiency in this paper is extremely close to that of the CFD calculation without considering the fluid-structure interaction. Based on this proposed computational method, the lift force of the test FWR platform is increased by 36.2 % by changing wing stiffness.