Vortex generators are widely used passive flow-control devices to improve the aerodynamic perfor-mance of large wind turbines. In this paper, the aerodynamic performance of the airfoil S809 without and with vortex generators was investigated using a computational fluid dynamic method of simulation. In this paper, the vortex generators in order to control the flow within the boundary layer of the S809 airfoil with the momentum transferring and the vortex trajectory was discussed. The results were obtained with three-dimensional incompressible Reynolds-averaged Navier-Stokes equations, and the turbulence was simulated with the shear stress transport k-omega turbulence model. It is shown that the vortex gen-erators can effectively improve the aerodynamic performance of the airfoil S809 and decrease the thickness of the boundary layer. The stall phenomenon is delayed. Double vortex generator arrangements show better performance in the control of flow separation and further improve the aerodynamic per-formance of the airfoil S809. According to the results of the vortex generators, the vortex generators can effectively enhance the lift coefficient of the airfoil and control the flow separation. It can provide some instructional meaning to the application of vortex generators on the wind turbine blade, which benefits to the utilization of wind power. (C) 2016 Elsevier Ltd. All rights reserved.