Enhancing energy harvesting ability of a flapping wing with a coupled leading-edge rotating cylinder and trailing-edge oscillating flap

Bio-inspired flapping-wing motion represents a promising approach for renewable energy conversion. To enhance energy harvesting efficiency, this study proposes a composite flapping-wing design featuring a leading-edge rotating cylinder (LRC) and a trailing-edge oscillating flap (TOF). This configuration leverages the Magnus effect and variable-camber airfoil principles to cooperatively regulate unsteady aerodynamic responses across different frequency conditions. Transient numerical simulations were conducted using an overlapping grid method within a relative heaving coordinate system, enabling a systematic investigation into the effects of LRC, TOF, and their combined control strategy on heaving force and energy harvesting efficiency. Results indicate that the LRC effectively suppresses vortex shedding, enhancing heaving force amplitude and energy conversion efficiency in the low-frequency regime (f*=0.04–0.10). In contrast, the TOF dynamically adjusts airfoil camber and strengthens circulation, thereby improving harvesting performance at mid-to-high frequencies (f*=0.10–0.20). The composite configuration, integrating the advantages of both control strategies, demonstrates superior performance across the full operational frequency range. Practical recommendations derived from this study suggest employing the LRC configuration in low-frequency applications, while the TOF is better suited for higher frequency conditions.