Two-dimensional shape of a wind turbine blade was optimized by means of Particle Swarm Optimization. By following blade element theory, lift coefficient Cl and drag coefficient Cd were used as objective functions. In order to compute the objective functions, flow field around airfoils were calculated by Re-Normalization Group (RNG) k-ε model. Shapes of airfoils were defined by modified PARSEC method with 10 parameters.
Two optimization cases were conducted with maximum thickness limited to 10% and 20% of the chord length respectively. In both cases, Reynolds number was set at 2.0×106, which is the design condition of S809 airfoil. S809 airfoil is a well known airfoil used in wind turbines and many experimental data are available. The angle of attack for the optimization was set at 5.13 deg., the mount angle of S809. Non-dominated solutions obtained by this research were compared with the performance of S809 at several angles of attack.
The results of optimization showed that 1) there is a strong influence of maximum thickness of airfoil to its performance, 2) non-dominated solutions constitute a gradual relationship which implies that there are many airfoil shapes that could be considered as an optimum. The resulting shape along this Pareto front showed higher performance than the existing blade section (i.e. NREL S809) in certain conditions.