Energy harvesting from flow-induced vibrations enhanced by meta-surface structure under elastic interference

• The effects of meta-surface structure on energy harvesting under elastic interference are considered. • By analyzing the frequency, the ‘coupled vortex-induced vibration’ is proposed. • It is found that the optimal height is 0.6H, and the V rms that can increased by 116.3%. • "V" meta-surface has the best performance, which is 66.04% higher than 0.6H cylinder. Energy harvesting by means of flow-induced vibrations (FIVs) enables continuous supply of power to micro electromechanical systems. Furthermore, FIV is one of the most popular means of energy harvesting. Inspired by wake-induced galloping and aerodynamic changes to a meta-surface structure, a wind-energy harvester (WEH) with a simple structure and high energy density is designed based on FIV (FIV-WEH). Furthermore, the effect of the meta-surface structure on FIV enhancement under elastic interference is discussed. Four experimental models with different heights under an elastic interference are designed: 0.8H cylinder (0.20 m), 0.6H cylinder (0.15 m), 0.4H cylinder (0.10 m), and 0.2H cylinder (0.05 m). The results show that the performance of the 0.6H cylinder is the strongest. It is 116.3% stronger than that of an ordinary cylinder. Based on the experimental models, a series of grooves with different angles is designed, abbreviated as ‘Vα’, where ‘V’ indicates that the repeating units are V-shaped and α indicates the centre angle corresponding to the chord length between adjacent repeating units. The addition of a meta-surface structure significantly changes the vibration behaviour of FIV-WEHs. Moreover, the larger the meta-surface structure size, the earlier the coupling vibration region appears. Therefore, the coupling vibration region first appeared on the ‘V12’ meta-surface, then on the ‘V7.2’ meta-surface, and finally, on the ‘V3.6’ meta-surface. A ‘peak’ phenomenon is observed, and its reason is explained by analysing the frequency. This study also identified a ‘coupled vortex-induced vibration’ region. Three different shapes of meta-surface structures are designed: ‘V’, ‘T’, and ‘D’ meta-surfaces. The results show that the performance of the ‘V’ and ‘D’ meta-surfaces is significantly improved compared to that of a bare cylinder. The ‘V’ meta-surface can increase the effective wind-speed bandwidth for energy utilization and exhibits the best performance, which is 66.04% higher than that of the 0.6H cylinder. Furthermore, the reason for the enhanced energy-harvesting performance of the ‘V’ meta-surface is explained through numerical simulations. :