Optimization of a Twistable Hovering Flapping Wing Inspired by Giant Hummingbirds Using the Unsteady Blade Element Theory

Abstract

Due to the complexity of tailoring the wing flexibility and selecting favorable kinematics, the design of flapping wings is a considerably challenging problem. Therefore, there is an urgent need to investigate methods that can be used to design wings with high energy efficiency. In this study, an optimization model was developed to improve energy efficiency by optimizing wing geometric and kinematic parameters. Then, surrogate optimization was used to solve the design optimization model. Finally, the optimal design parameters and the associated sensitivity were provided. The optimized flapping wing, inspired by hummingbirds, features large geometrical parameters, a moderate amplitude of the flapping angle, and low frequency. With the spanwise twisting deformation considered in the parameterization model, the optimization solver gave an optimized wing with a pitching amplitude of approximately 39 deg at the root and 76 deg at the tip. According to the sensitivity analysis, the length of the wing, flapping frequency, and flapping amplitude are the three critical parameters that determine both force generation and power consumption. The amplitude of the pitching motion at the wing root contributes to lowering power consumption. These results provide some guidance for the optimal design of flapping wings.

A numerical study on the aerodynamic effects of dynamic twisting on forward flight flapping wings

“…As a commonly used waveform in numerical studies, the step function is often employed to model the variation of the rotation angle during these three phases in hovering flapping wings [27]. Additionally, in earlier studies [28,29] on artificial hovering flight, the wing pitch angle approximately followed this time-varying trend. Therefore, as an exploration of the aerodynamic effect of maintaining the consistency of effective angle of attack in each spanwise section, our study aimed to utilize this waveform.…”

Aerodynamic Analysis of Hovering Flapping Wing Using Multi-Plane Method and Quasi-Steady Blade Element Theory

“…However, estimations based on this assumption omit the actual wing bending deformation and certain kinematic characteristics, leading to a model error of up to 20% in simulated aerodynamic results compared to reality [1]. In recent years, the assumption of a single rigid plane has commonly been adopted when using quasi-steady-state models for aerodynamic estimation of hovering flapping wings and analyzing the aerodynamic effects of wing morphology [46][47][48][49]. Quasi-steady-state models considering wing flexibility deformations are more accurate in calculating aerodynamic forces and loads compared to the single rigid plane assumption.…”