Aerodynamic Properties Identification for Small-Size Wind Turbine Blade Airfoil Sections Using the CFD Method

Abstract

In this paper, three airfoil sections at the root, middle, and tip of the blade of the Sunforce 400 W conventional wind turbine were investigated at different angles of attack using Computational Fluid Dynamics (CFD) to identify the stall occurrence correlated with the maximum of the lift coefficient. To verify the CFD models, firstly, simulation results of the NACA 4412 airfoil were calculated using the XFOIL code and the CFD method, and compared against available experimental data when using a k-ω SST turbulence model. Then, lift coefficients for the three airfoil sections of the small-size wind turbine blade obtained from the CFD simulations and k-ω SST turbulence model, were calculated and compared with each other. The simulations were performed at three flow speeds, V = 3, 5 and 7m/s, while the angle of attack was varied between -2 and 15 degrees until stall occurred. Flow separation occurred close to the leading edge of the airfoil at the middle and tip of the blade at lower angles of attack, while the airfoil section at the root of the blade was more successful in keeping the flow attached to the surface.