Effect of length and attack angle of the splitter plates on circular cylinder piezoelectric water energy harvester

With the micro-miniaturization of offshore wireless sensors, signal lights, and other devices and the emergence of the problem of self-powering in the distant sea, how to harvest energy from low-speed currents has become a hot spot of research nowadays. To improve the energy output power and conversion efficiency of low-speed water flow, we propose a vertical cantilever beam circular cylinders fitted with a rigid splitter plate piezoelectric energy harvester (CSPPEH). In this paper, the influence of the length and the attack angle of the splitter plate on CSPPEH has been experimentally investigated. The vibration response mechanism involving the mutual transition between vortex-induced vibration and galloping was analyzed through particle image velocimetry flow field visualization. The experimental results indicate that the vibration and piezoelectric characteristics of the CSPPEH increase initially and then decrease with the length of the splitter plates (L/D = 0–2.4) at the attack angle of 0°, which can be explained by the theoretical model of the energy harvester. It is found that the optimal vibration and piezoelectric characteristics occur at a rigid splitter plate length of 1.40D with an attack angle of 90°. The maximum values for amplitude, vibration swing angle, voltage, power, and power density are 4.96D, 21.7°, 42.68 V, 910.81 μW, and 1.94 mW/cm3, respectively. Efficiency was up to 2.2% at 0.4D length and 90° attack angle of the splitter plate. Compared to the bare circular cylinder energy harvester, the output power and efficiency are significantly improved. The demonstration of continuous charging and discharging of capacitors and light emitting diode lights is performed to show the practicability of the designed CSPPEH. Overall, the present study enables the applications of CSPPEH for realizing self-powered wireless sensing and signal lights under low-water-speed environments.