A new structure of energy harvesting from vortex-induced vibrations (VIV) is proposed by Dr. Li and An. In the structure, the bimorph piezoelectric cantilever is inside the flexible circular tube, the circular tube stands in the fluid, the axial direction is perpendicular to the incoming flow direction, and the neutral plane of the cantilever beam in the cylinder is parallel to the flow direction. When it is in water current perpendicular to its axis, the water current exerts a transverse force on the cylinder due to asymmetric vortex shedding, which drives the cylinder into flexural vibrations. The cyclical vibration of the flexible tube caused by the flow-induced vibration drives the piezoelectric cantilever inside the tube to vibrate and generate electric energy. It is shown in Fig.1. At present, the structure has not been found in the world report. Piezoelectric harvestor from vortex-induced is able to run in slow water stream. It will supply persistent power for underwater wireless equipment.
The project has been supported by the National Natural Science Foundation of China, the Natural Science Foundation of Liaoning Province and the Science and Technology Foundation of the Provincial Department of Education. It has published many papers on SCI and EI in international journals and conferences. It has applied for many national invention patents and has been granted one.
At present, a breakthrough has been made in the theoretical and experimental study of the energy harvesting structure by Li Li and An Ran Ran’s research team. The one-dimensional FSI (fluid-structure coupling) vibration equation of the structure has been derived, and the vibration frequency and displacement of the structure have been obtained. A three-dimensional FSI finite element computer simulation model of the structure is established, and the relationship between fluid velocity, structural parameters and vibration performance of the energy harvesting structure is analyzed (See Fig.2). A small and medium-sized water cycling device has been set up, and an energy harvesting structure prototype has been developed. In the near future, the vibration mechanism of energy harvesting structures will be studied through experiments; the effects of different experimental conditions on the vortex-induced vibration performance of structures will be analyzed; large-scale experimental devices will be built to develop a mass-produced energy collection device.
The energy harvesting structure can provide sustained and stable electric energy for wireless devices in the seabed environment. You can also increase the energy by placing one or more rows of arrays along the water bottom in the direction of the incoming flow, as shown in Fig.3. It will solve the problem of sustainable energy supply about underwater wireless sensor networks and other national strategic technology.
Fig.1. The principle of piezoelectricity energy harvesting structure from VIV
Fig.2 Three dimensional FSI finite element simulation of vortex induced vibration
Fig. 3 Vortex induced vibration energy harvesting structure array