Aerodynamic performance of preferred wind turbine airfoils

To investigate possible increases of the capacity factor of wind turbines, six airfoils are chosen for evaluation, three based on high Cl, low Cd/Cl, and wide operational range, and three others simply based on low Cd. Aerodynamic performance of the chosen airfoils is projected for a 45 m radius turbine using Blade Element Theory (BET) as translated in an existing computer program. Even though the airfoils do not differ significantly in shape, their performance is projected to differ in turbine performance calculations, with some generating more power than others at the same wind speed and air density. The aerodynamic performance obtained with the numerically tested airfoils is compared to that of an actual wind turbine of equal dimensions. Wind speed and directional changes can be large, and assessing their effect is complicated. Using data from the literature, a simple evaluation of the effect of wind speed can be incorporated into the power curve, and shown to be dependent on the airfoil type. Directional changes could lead to reduced output power, but they are more significant for BEs close to the hub than to the tip. The optimal incidence angle calculated with the program shows little variability with wind speed for all airfoils.