Abstract

Advances in wind power and tidal power have grown considerably to offer a clean and sustainable energy alternative. Nevertheless, distributed small-scale energy production from wind in urban areas has been disappointing due to very low turbine efficiencies. Hence, it is the objective of this thesis to study and analyze the performance of a novel wind turbine design, a seven bladed Savonius vertical axis wind turbine (VAWT), which is horizontally oriented inside a diffuser-shaped shroud with a flange and attached with four deflectable guide vanes, mounted on the top of a building, which is shown to have the potential to achieve higher efficiencies. The flow field over the turbine is analyzed by using Computational Fluid Dynamics (CFD) Software Package of Star CCM+, on a three-dimensional (3D) grid for multiple tip speed ratio (TSR) at four different guide vane angles of 35°, 45°, 55° and 65°, while keeping all vanes open. Another case was analyzed where selected vanes would be open while closing others. In this work, the wind flow directly facing the turbine is studied to compute the coefficient of power Cp. The coefficient of power with detachable guide vane attached was found to be 0.333 at vane angle of 55°. Finally, the most effective case is when the bottom vane is closed compared to the bottom two vanes closed. This case with only one closed vane achieves a maximum Cp value of 0.398.