Effect of a circular cylinder in front of advancing blade on the savonius water turbine by using transient simulation

The paper has investigated the effect of a circular cylinder diameter on the performance of the vertical axis savonius water turbine. The free stream velocity over the cylinder will increase the velocity in the upper side and lower side. The phenomena will increase the flow momentum when the fluid-flow through between Savonius turbine and a circular cylinder. The cylinder can improve positive torque at the advancing blade and will improve the turbine performance. The flow investigation has been studied numerically to the Savonius turbine by placing a circular cylinder as passive control in the front of the advancing blade side. The paper has seen the influence of the cylinder diametervariations to the performance andtheflow characteristics of the turbine.The numerical simulation has been conducted on the Savonius turbine by without and with a circular cylinder. The numerical of 2D simulation has been conducted by using a sliding mesh to solve the rotation equipment in the transient conditionand the turbulence model used is the realizable k-ε (RKE). The firstly, the numerical has been verified and has validated with respect to experimental data. The data used in verification and validation is the torque coefficient using air fluid. Secondly, after the validation has attained, the next simulation has changed the working fluid to be water by placing a circular cylinder in front of advancing blade with varying ds/D of 0.1, 0.3 and0.5for each stagger angle (γ) of 0°, 30°, and 60 of or S/D of 0.95.The results have shown that the bestperformance of Savonius turbine occurs at the ds/Dof 0.5, γ of 30°, and TSR of 0.9.The turbine performance has increased by41.18% higher than conventional Savoniusat γ of 30oand TSR of 0.9. The ds/D variations have lowest turbine performance at γ of 0°.