Performance enhancement of a flow-induced vibration energy harvester via combined wake interference and convergent-acceleration effect

Flow-induced vibration energy harvesting (FIVEH) is attractive due to its simple structure and scalability. To address the low power and high cut-in velocities of conventional harvesters, a novel FIVEH couples the convergent-acceleration effect with the interference plate is proposed, achieving a maximum power increase (103.78%) and cut-in velocity decrease (68.3%). Then, the effects of the gap ratio (L/D = 0.5\1.0\1.5) and the plate width (W/D = 0.5\1.0\1.5) on the vibration response are investigated. For L/D = 0.5\1.0, the plate increases the maximum voltage output (71.8%) by enhancing galloping amplitude, yet for L/D = 1.5, as the flow speed increases to 2 m/s, a desynchronization phenomenon occurs, transitioning the galloping to VIV and needs to be avoided. The vibration enhance mechanism is revealed by numerical study, founding that the harvester causes a high-pressure region behind the cylinder and changes the vortex shedding mode from 2S to P + S, increasing the pressure difference on both sides of the cylinder, which leads to enhanced vibration amplitude. Finally, the influence of the key factors (L and W) on the EH performances are revealed, the preferred design (W/D = 1.0, L/D = 1.0) is obtained by using the EWM-TOPSIS algorithm to balance the power and efficiency, and comparison with other EH validates the superiority of the novel FIVEH.