TURBULENT FLOW CONTROL WITH VORTEX GENERATORS AROUND A SYMMETRICAL AIRFOIL AT HIGH ATTACK ANGLES

The flow on the upper surface of NACA 0015 airfoil is subject to an adverse pressure gradient when the incidence increases. This leads to the boundary layer separation which causes losses in the aerodynamic performances. Control using Vortex Generators (VGs) is a simple passive mean used to delay or eliminate the flow separation from the wall. The two main objectives of the experimental work performed consist in the optimization by experimental design method "DoE" of a new VGs configuration, inspired by Lin's one, by varying its different geometrical parameters. A comparative efficiency study of the two VGs configurations (Lin's VGs, modified VGs) on aerodynamic performances was then undertaken at different Reynolds numbers. In addition to the significant improvement in lift around 22%, the study resulted in a drag reduction of approximately 16% and a stall delay of two degrees. The results were also compared to a three-dimensional numerical simulation (3D-RANS) and showed good agreement. The CFD results highlighted a clear improvement in the momentum thickness along the airfoil's upper face, particularly a rate of 44.44% at 40% of the chord length.