Detached-eddy simulation of three airfoils with different stall onset mechanisms

The detached-edd}-simulation (DES) method is applied to calculate prestall and poststall aerodynamic characteristics of three airfoils that have different flow separation patterns at the stall regime. The DES method combines strong points of two turbulent models that are based on time-averaged and space-filtered Navier-Stokes equations, respectively. Specifically, we employ the Spalart-Allmaras DES approach, which has a Reynolds-averaged Navier-Stokes formulation near wall and reduces to a subgrid turbulence model, if we go away from the wall. The comparison between experimental data and numerical results is presented, which shows that the stall angle and prestall and poststall aerodynamic characteristics can be predicted by the present method accurately for two airfoils: NACA63₁-012 and NACA63₃,-018. However, a discrepancy between numerical and experimental data is observed for the third airfoil: NACA644_A-006. The reason for this discrepancy and also possible improvements of the numerical model are discussed.