Micro-energy harvesting based on vortex-induced vibration of cross-flow hydroturbine with various cantilever beam configurations

Abstract

The cross-flow hydroturbine is a water impulse turbine with a low efficiency relatively, but it is easy to maintain and can adjust to a wide range of flow rates. Also, vortex fields are formed downstream of the cross-flow hydroturbine when the working fluid passes through an impeller, and these vortex fields can cause vibrations during electrical energy production. However, these vortex fields could gradually disappear and become a wasted, unused energy source. Therefore, amplifying and causing vortex fields continuously could result in vortex-induced vibration (VIV), which can be used as an energy source to enhance the performance of micro-energy harvesting (MEH) system. The vibration is typically converted into piezoelectric energy using a piezoelectric energy harvester, such as cantilever beam, membrane or other structure. In this study, the downstream of the cross-flow hydroturbine was equipped with a cantilever beam to harvest the vibration energy of the vortex fields. Numerical analysis was conducted using the commercial CFD code, ANSYS CFX 17.1 with a shear stress transport (SST) turbulence model. A 2-way fluid-structure interaction (FSI) analysis was also used to investigate the motion of the cantilever beam for the feasibility of using it in piezoelectric energy harvesting. As a result, the velocity vector and deformation of the cantilever beam were graphically depicted.