Enhancing piezoelectric energy harvesting from the flow-induced vibration of a circular cylinder using dual splitters

Ambient energy harvesting from the vortex-induced vibration (VIV) of circular cylinders has been extensively studied in recent years. However, the effect of multiple splitters attached to the cylinder surface in different configurations on the energy harvesting performance is not well understood to date. This study is focused on enhancing the piezoelectric energy harvesting from the flow-induced vibration of a circular cylinder by using two symmetric splitters in different relative angular positions with respect to the oncoming uniform flow. Both wind tunnel experiments and numerical simulations are carried out to study the effect of seven different installation angles (α = 0°, 30°, 60°, 90°, 120°, 150°, and 180°) of the dual splitters on the energy harvesting efficiency with the increasing flow velocity. It is observed that, in the absence of any splitter, the energy harvesting performance is constricted to the lock-in regime for the VIV of the circular cylinder. When the dual splitters are introduced at the positions of 0° and 120°, energy harvesting is completely suppressed, and no voltage is generated. The transition from VIV to galloping is observed for the positions of 30°, 60°, 150°, and 180°. Among them, 60° is the optimal position, where the maximum output voltage increases up to 188.61% of that obtained from the harvester without any splitters. VIV with a reduced maximum output voltage is observed at the position of 90°. The underlying vortex interactions behind the transitional dynamics are investigated by analyzing the flow-field. It is observed that the vortex formation length increases with the increase in the splitter angle, and the secondary vortices also play a key role behind the VIV to galloping transition. This study systematically carries out the performance analysis of the VIV-based energy harvester with multiple splitters for the first time in the literature and directly contributes to the optimized design of an innovative wind energy harvester with multiple splitter configuration.