Experimental investigation on wind energy harvesting by aeroelastic excitation of a semi-circular cylinder with flat side parallel to the incoming flow

Abstract

In this work, the performance of a semicircular cylinder with the flat side parallel to the incoming flow has been studied experimentally in a wind-excited energy harvester. Preliminary sectional model wind tunnel tests have allowed the identification of the reduced velocity ranges showing appreciable wind-induced oscillations. Interestingly, vortex-induced vibration-galloping interferences have been identified for both heave and pitch degrees of freedom at low reduced wind speeds, as well as coupled galloping in the higher ranges of flow velocities. The impact on the aeroelastic response caused by the attachment of a small-diameter rod at different positions has been studied, finding an enhancement in the amplitude of the oscillations and an enlargement in the vortex-induced vibration excitation range for some of them. Based on these preliminary results, an energy harvester has been designed adopting a cantilever beam supporting the semicircular cylinder. The device has showed a good performance reaching 2.5 mW of averaged harvested power for the configuration with a small-diameter rod attached at γ=85º for 8 m/s flow speed.