Energy Harvesting of Flow Induced Vibration Enhanced by Bionic Non-Smooth Surfaces

Abstract Current research on wind energy piezoelectric energy harvesters (PEHs) mainly focuses on tandem smooth cylinder energy harvesters; however, the traditional tandem smooth cylinder energy harvester has low voltage output and narrow energy harvest bandwidth. In this study, a D-type bionic fin is designed and installed on a smooth cylindrical surface to improve its performance. The influence of the spacing ratio on the amplitude and voltage of PEHs with D-type bionic fins added under elastic interference was investigated through wind tunnel tests. Three installation positions were designed: only installed upstream, only installed downstream, and not installed upstream and downstream (BARE). It was found that the maximum displacement of the upstream PEH (UPEH) was not apparently affected by the D-type bionic fin. Contrastingly, the fin changed the maximum amplitude from a small to a large spacing ratio for the downstream PEH (DPEH). D-type bionic fin can enhance energy harvest performance by coupling “coupled vortex-induced vibration” and wake induced galloping, increasing the surface velocity of PEHs and expanding the bandwidth of the voltage harvested by the PEHs. Analysis of the power under the experimental wind speed showed that installing D-type fins in the PEHs can increase the output power of the upstream and downstream PEHs by 392.28% and 13%, respectively, compared with that of the BARE-PEH. Additionally, computational fluid dynamics was used to analyze the flow pattern, wake structure, and lift coefficient of the PEHs, and to explain why the upstream D-type bionic fin installation has an impact on the harvest performance of the upstream and downstream PEHs at a spacing ratio of 1.5. This study provides an efficient and simple scheme for designing wind PEHs.