Airfoil Optimization for Small Wind Turbines Using Multi Objective Genetic Algorithm

Abstract

Small wind turbines are gaining popularity due to their ability to meet community or domestic needs in isolated areas with relatively easier installation and lower cost than large wind turbines. This study looks at optimizing airfoils for use in small horizontal axis wind turbines. The optimization looks to maximize the lift coefficient (Cl) while minimizing or fixing the drag coefficient (Cd). To satisfy these two objectives a multi–objective genetic algorithm is used. The airfoil is parameterized using a composite Bezier curve with two Bezier segments and 11 control points. Appropriate curvature conditions are implemented at the leading and trailing edge of the airfoil and geometric constraints are applied to maintain the maximum thickness between 8% to 14% of the chord for structural reasons. An existing genetic algorithm (GA) code is modified in C++ to generate suitable airfoils using the 13 control points and pass the coordinates to a solver for analysis. As a result four new airfoils are generated for application in low Reynolds number (Re) flow. The characteristics and suitability of the four airfoils are discussed while comparing them to the popular SG6043 airfoil.

Design and Performance Analysis of Micro Wind Turbine for Fiji

“…2. These airfoils are known to have good aerodynamic characteristics [8]. Coefficient of lift to drag ratio (L/D ratio) is one of the important and useful parameters in assessing the performance of the airfoils for initial selection and modification.…”

“…Q Blade also includes extensive post processing functionally for rotor and turbine simulation and gives deep insight into all relevant blades and rotor variables [8].The blade was design with Specification of rated power of 50 watts, cut in velocity of 3m/s cut out speed of 20 m/s, blade length of 0.5 m, rotor diameter of 150 cm.…”

Improvement of aerodynamic performance of a small wind turbine

“…The rotor blades are considered the most important components, as their aerodynamic efficiency affects the overall performance of the turbine system. The blade design is determined by different parameters, and the airfoil, which defines the cross-sectional shape of the blade, is the most important one (Chen et al, 2013; Ram et al, 2008; Song and Lubitz, 2014). For small wind turbines, National Advisory Committee for Aeronautics (NACA) airfoils are not suitable, as they are not designed for low Reynolds numbers (Ram et al, 2008).…”

“…The blade design is determined by different parameters, and the airfoil, which defines the cross-sectional shape of the blade, is the most important one (Chen et al, 2013; Ram et al, 2008; Song and Lubitz, 2014). For small wind turbines, National Advisory Committee for Aeronautics (NACA) airfoils are not suitable, as they are not designed for low Reynolds numbers (Ram et al, 2008). For this reason, several airfoils have been specifically designed for use in the small wind energy industry (Giguère and Selig, 1998; Oluseyi et al, 2015).…”

“…However, the geometry of the airfoil can also be optimized. This can be done using Bezier curve (Chen et al, 2014; Ram et al, 2008; Vesel, 2009) and non-uniform rational B-spline (NURBS) method (Dahl and Fuglsang, 1998; Lépine and Guibault, 1999; Mauclère, 2009), which determine the upper and the lower surface of the airfoil. In this case, the control points are used as design variables to optimize the lift-to-drag ratio (Cl/Cd).…”