Numerical Analysis of Vertical Axis Tidal Turbine: A Comparison of Darrieus and Gorlov Type

Tidal current energy is a natural resource which can replace fossil energy. A vertical-axis tidal turbine is a device that can be used to extract tidal current energy. However, the influence of the vertical axis tidal turbine is not fully understood. Under the actual condition, the vertical axis tidal turbine produces a high torque fluctuation, making the turbine power coefficient low. This study aims to numerically analyze the performance of vertical axis tidal turbine straight blade (Darrieus type) and helical blade (Gorlov type) and the blade inclination angle effect to improve the power coefficient of vertical axis tidal turbines. 3D CFD models of vertical axis tidal turbines developed using OpenFOAM software—the blade profile using NACA 0012 with a given tip speed ratio (TSR) 2.2. The simulation result of a turbine with a straight blade and helical blades 55°, 65° is compared. The results show the advantages of the helical blade over the straight blade, including the significantly reduced torque fluctuations: where the TRF is reduced from 1.288 up to 0.6204. The power coefficient increases from 23% to 25%. Therefore, a vertical-axis tidal turbine with a helical blade has a smoother torque fluctuation and a better power coefficient. The uniqueness of this research is compared to previous studies where the turbine was analyzed at a flow rate corresponding to ocean in Indonesian with a flow velocity of 2 m/s. In this study, a variation of the angle of inclination of the blades was carried out on the Gorlov-type turbine so that it could determine the inclination angle Optimal blade for the Gorlov-type turbine.