الفهرس 
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Abstract
The increasing global demand for energy and environmental concerns have provoked a shift from exhaustible, fossil fuel based energy to renewable energy sources. It is clear that wind energy will play an important role in satisfying the future energy demands. Savonius rotors are low cost and simple type of vertical-axis wind turbines (VAWT). The theory of operation is based on the generated net drag. Savonius rotors may have two, three or four blades with low power coefficient. In the present study, the performance of the Savonius rotor with different modifications aiming to improve the generated power is conducted numerically and experimentally. The numerical analysis is performed using the implementation of four different turbulence models in Reynolds-Averaged Navier-Stokes (RANS) equations. The employed turbulence models are Standard k-ε, RNG k-ε, Realizable k-ε, and SST k-ω. The numerical results are compared with published and present experimental data to select the suitable turbulence model. The study is performed on the conventional, different modified blade shapes, deflector plate, twisted blades and a proposed design. The new proposed design is aimed to prevent impinging wind on the convex side of returning blade and direct it towards the concave sides of advancing and returning blades. Besides, the performance of conventional and modified rotors has been experimentally studied by measuring the generated torque and the pressure distribution on the blade surfaces at various tip speed ratios and rotor angles.