CFD investigation of flatback airfoils and swallow tail for wind turbine blades

Modern wind turbines use longer blades to improve annual energy production. Longer blades require thicker airfoils for structural integrity. Thicker airfoils are susceptible to issues like erosion, abrupt stalls, and early boundary layer transition, leading to increased drag and decreased lift, affecting overall performance. Flatback airfoils offer structural and aerodynamic advantages, being stiffer, less sensitive to surface roughness. However, this comes with a drag penalty, mainly due to the increase in base drag. Swallow tail add-on has been proposed to overcome these challenges. URANS simulations are used to analyze the aerodynamic performance of the different airfoils and hybrid RANS/LES simulations are used to study the flow features in more detail. The swallow tail airfoil was found to maintain many of the advantages of the flatback airfoils while reducing the drag penalty.