Hydrodynamic performance of a vertical axis tidal current turbine with angular speed fluctuation

Abstract

ABSTRACTThe angular speed of Vertical axis tidal current turbines (VATTs) should undulate in one periodic rotation given their inherent special structure. A coupled dynamic numerical simulation method is presented to study the effect of angular speed fluctuation on the performance of a VATT. The CFX User Fortran interface is applied to simultaneously solve the fluid conservation and rigid motion equations. The angular speed and acceleration of the turbine at specific time steps are determined by solving the moment equation of the rigid blade, and the force on the blade is obtained from the dynamic integral of the fluid field. The numerical simulation and experimental results suggest that coupled numerical simulation is necessary for small moment of inertia because the amplitude of the angular speed fluctuation is approximately 28% of the average value. Undulation of the load and the moment caused by unsteady angular speeds will reduce the turbine’s energy extraction.