Hydrodynamic energy collection using a cylinder with different cross sections based on macro-fiber composite

Abstract

With the rapid development of small and microelectronic devices, energy utilization from the surrounding environment has been paid significant attention. This study aims to enhance the performance of energy harvesting devices utilizing a macro-fiber composite (MFC) attached to a cantilever beam with a cylinder attached at the free end with three different cross sections, namely circular, square, and triangular. Experiments were conducted in a low-speed circulating water flume at Reynolds numbers ranging within 770–8800. Three oscillation modes based on different cross sections can be observed: (1) vortex-induced vibration (VIV) for the circular cylinder water energy harvester (CWEH); (2) combined VIV-galloping for the triangular cylinder water energy harvester (TWEH); and (3) separated weak vortex-induced vibration-galloping for the square cylinder water energy harvester. The characteristics of the MFC water energy harvester are revealed through the vibration mechanism analysis. The effects of flow velocity, resistance, and cross section on the energy harvester were studied, and the flow field was analyzed. The energy harvesting results indicate that the TWEH exhibits the highest voltage, power, power density, and efficiency among the three devices; the maximum voltage, power, power density, and efficiency achieved are 28.9 V, 241.1 μW, 512.6 μW/cm3, and 0.23%, respectively. Despite the TWEH exhibiting a maximum efficiency that is 0.68 times that of the CWEH, it is noteworthy that the TWEH presents a superior performance in terms of maximum voltage, power, and power density by factors of 2.77, 7.37, and 7.38, respectively, compared to the CWEH. Hence, the research suggests that the TWEH is the most suitable device for energy collection under low-speed water flow conditions.