Energy Harvesting Efficiency of Vertical Wave Flow Turbine  Power Generators Under Wave-Current Conditions

The energy harvesting characteristics of the turbine power generator set on the floater are affected by periodic motion under wave-current conditions significantly. In this paper, a new type of vertical wave flow turbine (VWFT) is developed, which could drive the mechanism to rotate and capture the energy by using the current force and part of the wave force together acting on the blades. Firstly, a series of sea trials were conducted to investigate the hydrodynamic and energy capture performance of VWFT. The maximum average impeller rotation power is approximately 460W and the optimal energy harvesting coefficient is approximately 21% for the designed turbine. The agreement between the comparison of experiments and numerical results illustrates the accuracy and reliability of the established CFD model. Furthermore, the time domain motion of the platform and turbine under the wave-current conditions are obtained with 3D potential flow theory, and the study showed that the sway and pitch motions had more influence on the energy harvesting efficiency. Finally, in the data processing of the user-defined function, the actual nonlinear motion is used to instead of the traditional simple harmonic input, which is more suitable for the actual working environment.