The Performance Augmentation of Savonius Wind Turbine Using Staggered Cylinder Circular as Passive Flow Control

Abstract

AbstractThere are two flow control methods for reducing drag force on the cylinder: active and passive control. The passive control method regulated the airflow by varying the body shape or installing additional rods or surface roughness. This airflow control procedure is applied to the returning blade of the Savonius wind turbine by installing a circular cylinder to reduce pressure drag and improve its performance. A circular cylinder varies with a stagger angle −10° ≤ α ≤ 90° and within the center to a center distance fixed at S/D = 1.4 were investigated numerically. The transient numerical calculation was performed with Ansys Fluent 19.1 to identify the dynamic nature of the 2D modeled turbine. The numerical calculation set with constant freestream velocity (U∞) 5 m/s at Reynolds number Re = 105.000. The two-equation URANS and k-ε enhance wall function turbulence models are used in this simulation. The simulation was also verified with experimental data and showed healthy agreement so that the boundary conditions, grid, turbulent model, and solver setup settings can be maintained for further consideration. The analysis is carried out on the power coefficient and moment coefficient compared between conventional cylinders and cylinders with staggered cylinders. The result shows that staggering cylinder circular enhances the conventional turbine performance by 9% higher. The optimum staggered angle was founded at α = 70° within TSR = 0.8.KeywordsSavonius wind turbineCylinder circularCFDPressure dragCoefficient of power