Energy harvesting performance of an elastically mounted semi-circular cylinder.

Energy extraction from ocean or wind currents through flow-induced vibration (FIV) of cylindrical structures is an important means of generating clean and renewable energy in nature. In this paper, we focus on investigating the response and energy harvesting performance of a semi-circular cylinder subjected to low- and high- Re (Reynolds number) cross-flow. Irrespective of Re , we observe six different types of FIV responses within the angle of attack (α) range of 0°–180°. Based on the characteristics of the vibration amplitudes and frequencies, these responses are categorized as typical VIV, extended VIV, narrowed VIV, galloping, combined response, and transition response. To assess the energy harvesting performance of these responses, we analyze the harvested power (P h) and efficiency (η h). Our findings indicate that in the VIV regimes, P h and η h are strongly dependent on the amplitude. However, an exception is noticed in the third branch of the extended VIV, where the amplitude is significantly large but P h and η h are small. In the galloping regime, the dependence of P h and η h on the amplitude becomes weak. Amongst all the response regimes, the galloping at α = 180° exhibits the best energy harvesting performance, with the highest η h reaching 46.5%. In the combined response, P h and η h are significantly small, regardless of whether it occurs in the VIV or galloping (or large-amplitude vibration) region. Further, we confirm the significant influences of the damping coefficient and mass ratio on the energy harvesting performance. By selecting the optimal damping coefficient and mass ratio, both P h and η h are significantly improved. [ABSTRACT FROM AUTHOR]