Wind energy has been usually harvested through large-scale propeller-type horizontal-axis wind turbines (HAWTs) in open spaces such as suburban or offshore areas, while the enormous potential for wind energy harvesting in urban environments has not been widely exploited. A through-building channel is beneficial for wind speed enhancement and wind power generation, due to the channeling effect. In this study, the performance of a Savonius wind turbine in a long channel is investigated based on computational fluid dynamics (CFD) simulations. Two-dimensional simulations were conducted using ANSYS Fluent 16.1, employing the shear-stress transport (SST) k-ω turbulence model. The incoming wind velocity at the channel inlet was U_o = 4.05 m/s, corresponding to a Reynolds number Re = 1.0 x 10⁵,...[ Read more ]

Wind energy has been usually harvested through large-scale propeller-type horizontal-axis wind turbines (HAWTs) in open spaces such as suburban or offshore areas, while the enormous potential for wind energy harvesting in urban environments has not been widely exploited. A through-building channel is beneficial for wind speed enhancement and wind power generation, due to the channeling effect. In this study, the performance of a Savonius wind turbine in a long channel is investigated based on computational fluid dynamics (CFD) simulations. Two-dimensional simulations were conducted using ANSYS Fluent 16.1, employing the shear-stress transport (SST) k-ω turbulence model. The incoming wind velocity at the channel inlet was U_o = 4.05 m/s, corresponding to a Reynolds number Re = 1.0 x 10⁵, based on U_o and the projected width (W) of the turbine. Three different widths of the channel were considered, i.e., 2W, 3W and 4W, with a channel length of 45W. The performance of the Savonius turbine in the channel is discussed, considering the contribution of pressure difference across the turbine to the power generation, and compared with that in open space. A comprehensive comparison is made between the Savonius turbine in the channel and that in the open space, in terms of force characteristics, flow structure and power output. The results show that the power output (P_out) of the Savonius wind turbine can be greatly improved, and this improvement increases with reducing channel width. In addition, shortening the distance between the advancing blade and the boundary wall is favorable to the turbine performance enhancement, but this eccentric placement effect is not as significant as the effect of channel width. Furthermore, the optimum tip speed ratio (TSR) becomes higher for a Savonius turbine located in a channel than in the open space. Finally, a correction of the power coefficient is discussed based on the performance of a Savonius turbine in a channel.