Unsteady Computational Study of Novel Biologically Inspired Offshore Vertical Axis Wind Turbine at Different Tip Speed Ratios: A Two-Dimensional Study

Abstract

The aim of this paper presents an unsteady numerical investigation of a novel biologically inspired vertical axis wind turbine. The simulation was conducted in 2D using the sliding mesh technique with non-conformal mesh spatial discretisation via FLUENT. Grid sensitivity study on mesh density and turbulent transport model indicated that fine mesh and medium converged well with trivial difference. SST and k-ω model presented stable behaviour and indicated good agreement. SST were chosen for the rest of the simulation. The proposed wind turbine was simulated at five different moderate tip speed ratios under the influence of freestream velocity U_∞=8m/s. The highest moment coefficient is generated at tip speed ratio λ=1.3, which is C_m=0.1886 with a stable positive moment coefficient after 480°. The proposed turbine responded well at λ=1.3 and λ=1.7 with power coefficient result of C_p=0.245 and C_p=0.262 respectively. The effect of wake and voracity on the turbine at subjected tip speed ratios is studied. Wake regions induced by the leading edge of the aerofoil impacted the performance of the following blade. Furthermore, due to the less wake effect trailed by the leading edge at λ=1.3, it generates higher moment than λ=1.7. Since the proposed blade has a fixed 4° angle of attack, it was sensible for the turbine to experience such wake and vorticity effect.