Asymmetric arc-shaped vortex-induced electromagnetic generator for harvesting energy from low-velocity flowing water

In this study, a novel small-scale electromagnetic energy harvester is designed and optimised, which aims at addressing the limitations of existing approaches in output power scavenged from low-velocity flowing water. Instead of conventional cantilever beams, an asymmetric arc-shaped elastic beam is implemented to disrupt flow, leading to its oscillation in the induced unsteady flow field. An electromagnetic transducer is utilised to convert kinetic energy into electrical energy. Furthermore, the effects of the structure asymmetry and curvature on the electrical outputs are investigated to optimise the scavenging energy capability. A prototype with the volume of 152.4 cm3 is fabricated and tested. A maximum open-circuit voltage of 1440 mV is obtained at 0.409 m/s, and the harvester generates an output power of 0.503 mW when it is connected to an external load of 110 Ω. The small-scale harvester shows great potential for applying in wireless sensor networks.