Numerical Investigation of Inner Blade Effects on the Conventional Savonius Rotor with External Overlap
The Savonius wind turbine is considered as one of the best vertical axis wind turbines for harvesting the kinetic energy from the wind in the urban areas, due to magnificent features such as high starting torque, low construction and maintenance costs, simple design, and self-starting ability especially at low wind speed. However, the conventional style of the Savonius rotor suffers from low efficiency. Consequently, modifying the configuration of the rotor may be an appropriate solution for providing electricity to the communities with no access to the power grid. Thus, this study aims to enhance the performance of the conventional Savonius rotor with an external overlap by adding an inner blade to the rotor configuration. Hence, a comparison study between five new arrangements against the conventional rotor in terms of power coefficient (Cp) and torque coefficient (Ct) is performed through a two-dimensional simulation by using ANSYS Fluent 19.2. The k-ε/Realizable turbulence model is employed in the simulation.
Results conclude that inner blade with an angle of 120° increases the power coefficient by 41%, 39%, and 7% at tip speed ratio (TSR) = 0.7, 0.6, and 0.5, respectively.