An insight on the calculation of aerodynamic polars for stall-controlled wind turbines using CFD: the case of S8XX airfoils

To ensure that stall control performs correctly in wind turbines making use of this logic, having accurate airfoil data near and post the stall limit is crucial. Due to the scarcity of experimental data, Computational Fluid Dynamics (CFD) simulations are increasingly used to this end, although modelling stall is critical due to the impact of turbulence that often impacts on transition; therefore, various numerical methods have been proposed for use within a Reynolds-Averaged Navier-Stokes approach. In this study, a critical analysis has been carried out to define some best practice in the simulation of airfoils designed for stall control. Commonly adopted transitional models, i.e., the k-ω SST and the γ-Reθ ones, have been compared with the novel GEKO model by Ansys, and deriving CFD results are benchmarked against ubiquitous panel methods (XFoil and RFOIL), which still often represent an industry standard. Key performance factors have been critically compared, providing some case-specific indications on the benefits and drawback of the different models.