Numerical modeling of the flow over wind turbine airfoils by means of Spalart-Allmaras local correlation based transition model

The aerodynamics of the blade sections constitute the core problem in the design of new-generation wind turbines. Aerodynamic theories for blade design suffer from the unavailability of aerodynamic coefficients for the airfoils involved in the blade. The aim of this work was therefore to develop an efficient and accurate tool for computing the flow parameters, reducing the need for complex and costly wind tunnel tests. Our approach is based on Computational Fluid Dynamics (CFD) and consists in the adoption of a laminar-to-turbulent transition model. For the flow regimes involved in wind energy applications, the fully turbulent or laminar flow model fails completely in the prediction of aerodynamic performance. We consequently propose a Reynolds Averaged Navier Stokes (RANS)-based approach capable of modeling transitional flows with a limited computational cost. This is a crucial aspect because standard RANS models assume a fully turbulent regime. Our proposed approach couples the well-known γ−Reθ,t˜ technique with the Spalart-Allmaras turbulence model. The effectiveness, efficiency and robustness of the computational method introduced here were tested by computing the flow over several wind turbine airfoils. © 2017 Elsevier Ltd