VORTEX INTENSIFICATION OF A TRIBOELECTRIC NANOGENERATOR ARRAY FOR WATER ENERGY HARVESTING

As a promising renewable energy source in nature, water wave energy in oceans is abundant but hard to scavenge. Toward harvesting water wave energy efficiently, this paper reports a cylinder array structure with triboelectric nanogenerators for any position. Each array element is composed of a cylinder, a cantilever beam, and an energy conversion unit. When the cylinder is in water flow field, the vortex shedding occurs, leading to vibration of the cylinder. The vibration is amplified by the cantilever and transferred to the energy conversion unit. The relative motion of a sliding block along a guide rail to the frame of a case in the energy conversion unit achieves energy harvesting via triboelectric effect. With an appropriate arrangement of the array, vortex resonance occurs in the device and the vortex intensification effect shredded from the upstream cylinder elicits the resonance of the downstream cylinders to a higher degree. The finite element analysis is conducted to explain the vortex resonance and vortex intensification effect for the device. Besides, the influence diameters of the cylinder, the array arrangement and water flow speed on the displacement response and converted power for the structure is elaborately elucidated. Compared to the single cylinder, the upstream wake flow intensification effect increases the converted power of downstream cylinder in 6-2 array up to 2.6 W (163% higher) at the flow speed of 0.6 m/s. This work provides a novel angle for vortex-induced vibration energy harvesting based on array-type triboelectric nanogenerators.