Numerical simulation on improvement of a Savonius vertical axis water turbine performance to advancing blade side with a circular cylinder diameter variations

The use of fossil fuel will generate particulate gas in the atmosphere and forming the greenhouse effect. One of the ways to reducing greenhouse effect is used renewable energy as hydropower without generating particulate gas impacted in human life. The present study uses hydropower as the renewable energy by using a Savonius turbine. The main objective investigates the performance of Savonius water turbine numerically due to the installation of a circular cylinder beside of the advancing blade with circular cylinder diameter variations. The method used is numerically toward Savonius turbine disturbed a circular cylinder. The numerical simulation using two-dimensional (2D) analysis of Computational Fluid Dynamics (CFD) simulation by using ANSYS 17.0-Fluent and sliding Mesh technique used is to solve the incompressible Unsteady Reynolds Averaged Navier-Stokes (URANS) equations. The turbulence model uses Realizable k-epsilon (RKE) and transport equation uses the finite volume discretization method with the second-order upwind scheme and the SIMPLE algorithm. Firstly, the numerical model has been validated by the published experimental data toward the torque coefficient by using air fluid at Reynolds of 4.32.10⁵. Then the fluid is changed the water fluid at the same Reynolds. The circular cylinder diameter relative to the turbine diameter (ds/D) is varied of 0.1, 0.3, 0.5, 0.7 and 0.9 at X/D of 0.5 and Y/D of 0.7 kept constant with TSR of 0.5, 0.7, 0.9, 1.1 and 1.3. The numerical simulation uses the transient and two dimensional (2D) simulations. The results show that the increase of disturbance diameter (ds/D) will improve the performance of the conventional Savonius turbine and the maximum power coefficient increase about 18.04% at ds/D of 0.7 with TSR of 0.7.