Experimental and Numerical Study of Installed Circular and I-65° Type Cylinders Toward Returning-Blade Savonius Turbine for Augmented Aerodynamic Performance

In this essential investigation, the center point returning turbine blade of a Savonius has been positioned in a staggered alignment with a cylinder type I-65°. The conventional circular cylinder has been cut at an angle of 65° on both sides. This kind of cylinder, known as a cylinder, I-65° type, is made to reduce the aerodynamic drag force on the returning blade. The investigation has been performed under two scenarios, conventional and tandem turbine with installing a Cylinder I-65°. The staggered angle has been set within-20°≤α≤90° relative to the center point of the returning turbine blade. Experimental and numerical approaches based on those scenarios have examined the wind turbine performance. Based on a wind speed (U_∞) of 5 m/s, the study has used a width L=2D-b, where D refers to the turbine blade outside diameter, and b is the turbine e-gap. The 0.5D-diameter cylinder I-65° type is positioned 1.4D upstream of the returning turbine blade. In the CFD study, a 2D numerical computation has been iterated by using ANSYS Fluent® 19.1 in order to investigate the Savonius turbine flow. The experiment results indicate that positioning Cylinder I-65° upstream of the returning blade can raise the Savonius turbine power. Furthermore, adding a Cylinder I-65° has enhanced the maximum Cp of the Savonius turbines by about 12%. The peak C_P is obtained at a tips-speed ratio λ=0.8 and staggered angle α=0°. Numerical analysis has been carried out to analyze the airflow phenomenon around the turbine more deeply, and the results have showed good agreement to reveal and strengthen experimental quantitative data.