First stages of the transition to turbulence and control in the incompressible detached flow around a NACA0012 wing

The present study analyses the successive transition steps in the flow around a high-lift wing configuration, as the Reynolds number increases in the low and moderate range (800–10,000), by the Navier–Stokes approach. The flow system is mainly governed by two kinds of organised modes appearing successively as the Reynolds number increases: the von Kàrmàn and the shear layer mode. A period-doubling scenario characterises the first 2D stages of the von Kàrmàn mode up to Reynolds number 2000, where the shear-layer mode becomes predominant. The successive stages of the 3D transition are also analysed in detail. In a second step, the effect of wall suction has been studied both in 2D and 3D flows around the NACA0012 airfoil at 20° of incidence and a Reynolds number of 800. This study has the objective to optimise the aerodynamic coefficients and to attenuate the mentioned 3D transition effects in the near wake. The receptivity of the flow to the suction is clearly shown and the suction position on the wall has been optimised according to the improvement of the aerodynamics coefficients.