Evaluation of Savonius rotor performance: Static and dynamic studies

• Using Savonius rotor for capturing, wind energy is presented in non-rotating and rotating statuses.
• Experimental and numerical studies are performed on Savonius rotor with the two mentioned statuses at different geometrical and inflow parameters.
• The results showed that SST k–ω turbulence model is suitable for simulating the flow pattern around Savonius rotor than other models.
• The presence of overlap enhanced the performance of the rotor.
• Generally, the best performance is achieved with overlap ratio of 0.15, which gives an averaged power coefficient of 0.21 at speed ratio of 0.9.

An aerodynamic performance of stationary and rotating Savonius rotor for various overlap ratios is numerically analyzed using four turbulence models. The simulation is compared with the present and published experimental results to determine the suitable turbulence model. The computations are statically and dynamically performed at different rotor angles ranging from 0° to 180°. Five rotors, having two semicircular blades, but with different overlap ratios; reading 0, 0.15, 0.2, 0.3 and 0.5 are considered. The results indicate that the SST k–ω turbulence model gives more accurate results compared with the other studied turbulence models. In addition the static torque coefficient is improved by increasing the overlap ratio especially on the returning blade, which is due to the pressure recovery effect by the flow through the overlap. Furthermore the results of the rotating rotor show that the maximum device performance can be satisfied with overlap ratio value of 0.15.