Passive control on the NACA 4412 airfoil and effects on the lift

Abstract

The boundary layer separation on the upper surface of airfoils results in a decrease of the aerodynamic performances accompanied by vibrations and noise. Passive flow control with vortex generators (VGs) is a simple solution to delay or eliminate the flow separation. Lin’s generators V-shaped are among the most efficient and allow a significant increase in lift associated with a drag reduction when their height is less than the boundary layer thickness. The present work concerns the effectiveness of a new VGs configuration, delta wing shape, placed on line on the suction surface of a curved profile (NACA 4412). The experimental study conducted in a wind tunnel at Reynolds number equals to 2. 5 105 shows improved lift with an increase of 20% and one degree delay of the stall incidence. The study also highlights the VGs geometrical parameters influence such as their height, their position from the leading edge, their spacing and their apex angle.