Effects of blade shape and its corresponding moment of inertia on self-starting and power extraction performance of the novel bowl-shaped floating straight-bladed vertical axis wind turbine

Abstract

In this paper, the effects of the blade shape and its corresponding moment of inertia on the performance of a novel bowl-shaped floating straight bladed vertical axis wind turbine (VAWT) have been investigated. A numerical method was developed and validated to accurately simulate the interaction between the wind and VAWT. Three inferential parameters, the starting time, mean power coefficient, and standard deviation of the aerodynamic force, were employed to evaluate the performance of the turbine with different blade shapes. Performance indicators including the self-starting capability, power extraction efficiency, and fatigue characteristics, were assessed. The results indicated that the VAWT with S-1046 blade had better overall performance as compared to the one with NACA0018 blade, where the reduced self-starting time, slight more or identical mean power coefficient, and minor standard deviation of Ft and Fn were observed. Further, the flow structure around the blade was also analyzed, it was found that at low wind speed (less than 6.0 m/s) separated vortex around the turbine is observed, whereas at high wind speed, attached vortex is observed. Fluctuation curves of power coefficient variation with tip speed ratio ‘λ’ were also noted for the wind induced rotation of VAWT. At low wind speed, the highest power coefficient amplitude was obtained when the turbine was at maximum tip speed ratio, whereas at high wind speed, the highest power coefficient amplitude was obtained when the tip speed ratio of the turbine was slight less than the maximum value. Based on these results, it is strongly recommended to apply thinner symmetry (S-1046) blade for designing VAWT.