Low Reynolds number airfoil optimization for wind turbine applications using genetic algorithm

Optimization of a low Reynolds number airfoil for use in small wind turbines is carried out using a Genetic Algorithm (GA) optimization technique. With the aim of creating a roughness insensitive airfoil for the tip region of turbine blades, a multi-objective genetic algorithm code is developed. A review of existing parameterization and optimization methods is presented along with the strategies applied to optimize the airfoil in this study. A composite Bezier curve is used to parameterize the airfoil. The resulting airfoil, the USPT2 has a maximum thickness of 10% and shows insensitivity to roughness at the optimized angles and at other angles of attack as well. The characteristics of USPT2 are studies by comparing it against the popular SG6043 airfoil. While a slight loss in lift is noticed for both airfoils, the drag increments due to early transition are noticeable as well. The airfoil is also studied using computational fluid dynamics (CFD) and wind tunnel experiments during free and forced transition. The USPT2 airfoil will be useful in small wind turbines for locations where blade soiling is likely or where other flow phenomena may cause early transition of the boundary layer.