Airfoil type and blade size effects on the aerodynamic performance of small-scale wind turbines: Computational fluid dynamics investigation

Abstract A comprehensive study was conducted to explore the effect of the blade airfoil section as well as the rotor diameter size on the power output of a small-scale wind turbine using finite elements method-based computational fluid dynamics. In the recent years, the large-scale wind turbines have been subject to copious advancements thanks to which many efficient and powerful designs have emerged improving the large-scale wind energy industry. However, small-scale wind turbines have not been subject to as much extensive study, and the literature regarding these latter still suffers from noticeable scarcity compared to their large-scale counterparts. Consequently, this study aims at providing a comprehensive computational fluid dynamics investigation of the airfoil type and blade size effects on the aerodynamic performance of a small-scale wind turbine, where the full three-dimensional Navier-Stokes equations are solved. A combination of four airfoils, namely, NACA 0012, NACA 4412, NACA 0015, and NACA 4415 and three rotor diameter sizes of 50 cm, 75 cm, and 100 cm are investigated, and the power generated from each configuration is estimated. The aim is to evaluate the airfoil and rotor diameter size effect on the aerodynamic performance of small-scale wind turbines and eventually select the optimal performing combination out of the studied ones. The two-dimensional analysis shows that at a freestream velocity of 4 m/s, NACA 4412 outperforms the other airfoils yielding the highest lift to drag ratio. The three dimensional analysis shows that this latter remains the optimal performing airfoil reaching a power density of 2.465 W / m 2 for a 50 cm rotor diameter, 5.935 W / m 2 for a 75 cm rotor diameter, and 11.011 W / m 2 when the rotor diameter size reached 100 cm.