Enhancing wind energy harvesting performance by leveraging the synergy of rotational and transverse wake galloping mechanisms

This study introduces a novel, high-efficiency wake-induced tri-body hybrid wind energy harvester. The proposed system comprises a front-mounted wake-modifying interference bluff body, a central rotational bluff body, and a rear transversal bluff body connected to a piezoelectric cantilever. The asymmetric wake generated by the frontal body induces self-excited rotation of the central body, which, in turn, drives strong transverse vibrations in the rear body. This arrangement enables a coupled rotational–transversal vibration mechanism. In terms of transduction, the system integrates dual energy-harvesting channels, piezoelectric and electromagnetic, which jointly enhance sensitivity under low-wind-velocity conditions and alleviate power saturation at high wind velocities. Parametric optimization is conducted for three key geometric factors: the length of the downstream cantilever beams, the diameter of the wake-modifying fixed bluff body, and the angular placement of the external magnets. A two-degree-of-freedom aerodynamic model incorporating time-delay effects is developed to characterize the unsteady excitation process induced by the wake interactions; it accurately captures the coupling behavior between the wake field and the structural response. The model's predictions agree closely with experimentally determined vibration frequencies, amplitude trends, and critical wind velocity thresholds. Based on experimental validation, the proposed system achieves a peak power density of 183.61 W/m3 at 10 m/s, while maintaining stable, high-amplitude vibrations over a wide range of wind velocities. The proposed structural and theoretical framework provides a robust foundation for designing high-efficiency, low-threshold, and adaptive microscale wind energy harvesters, facilitating the development of sustainable and distributed power systems.