Enhancing energy harvesting through hybrid bluff body at a predefined angle of attack coupling vortex-induced vibration and galloping

This paper introduces a novel approach to enhance energy harvesting efficiency by coupling vortex-induced vibration and galloping through the use of a D-shaped hybrid bluff body with a predefined angle of attack. By adjusting the angle of attack, the aerodynamic interaction with the bluff body is improved, significantly increasing the vibration amplitude. Wind tunnel experiments are conducted to explore the effects of the predefined angle of attack and the rectangular height of the bluff body cross-section on the energy harvester's efficiency. The analysis identifies several optimal configurations that utilize the coupled vortex-induced vibration and galloping to enhance energy harvesting at low wind speeds while maintaining significant vibration amplitudes at high wind speeds. The proposed structure could achieve an RMS output voltage of 38.76 V, representing a 153.5% improvement compared to the traditional galloping piezoelectric energy harvesters. Additionally, the cut-in wind speed is reduced by 37.5%, allowing vibrations to begin at a low wind speed of 1.5 m/s, exhibiting a superior wind energy harvesting efficiency. Two-dimensional computational fluid dynamics simulations are employed to explain the underlying mechanisms of fluid-structure interaction, demonstrating the characteristics of the flow field, vortex shedding, and the transition in vibration modes.