Experimental Investigations on the Wake-Induced Vibration of an Electromagnetic Energy-Harvesting System

The wake energy of an electromagnetic harvesting device is derived from the phenomena of wake-induced vibration (WIV). Experiments were conducted to determine the effects of the Reynolds number, the resistance of the circuit, and the distance between two concentric circular cylinders on the wake energy of the flow. The mechanism of the diaphragm energy harvester (DEH) consists of a single and tandem circular cylinders, which were examined separately. An elastic diaphragm with a magnet was also mounted in the wake of the cylinders. The Reynolds number varies between 2000 and 5000. The converter transforms the wake energy of the flow into electricity due to the vibration of the cylinder in a magnetic field. This research fills a critical gap in the literature by investigating the energy performance of a DEH under the wake-induced vibration of two fixed circular bluff bodies, demonstrating for the first time the feasibility of capturing vortex energy through the wake in the presence of a diaphragm. This unique approach distinguishes our work in the field of electromagnetic energy-harvesting devices, showcasing the potential for practical applications in renewable energy generation. The test results indicate that increasing the Reynolds number enhances the converter's power output. Additionally, it has been observed that two critical distances are significant for the output voltage: the gap between the tandem cylinders (CL∗) and the distance between the edge of the diaphragm and the center of the cylinder (CX∗). The voltage output of tandem cylinders suggests that an optimal cylinder spacing falls within the range of C4≤L∗<5.