Energy harvesting of flow induced vibration enhanced by bionic non-smooth surfaces

Abstract

Inspired by the shield scale on the shark surface, a D-type bionic fin with non-smooth surface is proposed and used in tandem cylinders piezoelectric energy harvesters (PEHs) for the utilization of wind energy on the roof of buildings. The repeating unit of D-type bionic fin is semicircle, and the corresponding center angle of each repeating unit is 7.2°. PEHs consist of a piezoelectric cantilever beam and a wind-interference cylinder connected to the beam tip. The influence of the spacing ratio on the amplitude of PEHs with D-type bionic fins added under elastic interference is studied through wind tunnel tests and three installation positions are designed: only installed upstream, only installed downstream, and not installed upstream and downstream (bare). It is found that the maximum amplitude response law of the upstream piezoelectric energy harvester (UPEH) is not affected by the D-type bionic fins, and the D-type bionic fins can make the downstream piezoelectric energy harvester (DPEH) realize the change of the maximum amplitude from small spacing ratio to large spacing ratio. In addition, the influence of the installation position of D-type bionic fins on the output voltage of upstream and downstream PEHs is also studied. The research shows that the addition of D-type bionic fins significantly changes the vibration behavior of PEHs. D-type bionic fins can enhance the energy harvest performance by coupling "coupled vortex-induced vibration" and wake induced galloping (WIG), and increasing the surface velocity of PEHs. D-type bionic fins can also expand the bandwidth of the voltage harvested by the PEHs. The analysis of the power under the experimental wind speed shows that the installation of D-type fins in PEHs can increase the output power of the upstream and downstream PEH by 392.28% and 13% respectively compared with the bare piezoelectric energy piezoelectric energy harvester (BARE-PEH). In addition, the computational fluid dynamics is used to analyze the flow pattern, wake structure and lift coefficient of PEHs, and the reason why the installation of D-type bionic fins in the upstream has an impact on the harvest performance of upstream and downstream PEHs at 1.5 spacing ratio is explained.