Airfoil Control of Small Wind Turbines

Although the latest technologies have achieved outstanding improvements in the energy capture efficiency of wind power turbines, lack of cost effectiveness remains a major disadvantage. The problem lies in the limitation of operating effectively over a wide range of wind speeds. A variety of wind turbines have implemented variable control systems such as pitch control to extend the range of wind speeds at which the turbines can operate efficiently. These systems, however, have negatively impacted on the cost of wind energy. This paper investigates the possibility of achieving variable speed control performance by means of airfoil design for an uncontrolled wind turbine. Using computational fluid dynamics (CFD), this study optimizes the maximum thickness location of the S809 airfoil profile implemented in the National Renewable Energy Laboratory (NREL) Phase VI wind turbine blades to verify the design parameter most relevant to the objective of this research. The aerodynamic characteristics of the resulting design are compared to those of the baseline model. The results do indeed indicate the ability of the airfoil design to improve the power curve without the use of control systems.