Effects of Micro-Blowing and Vortex Generators on the Boundary Layer Separation Control of a NACA 0015 Airfoil

The flow on the upper surface of an airfoil is subject to an adverse pressure gradient when the incidence increases. This leads to boundary layer separation, causing losses in aerodynamic performance by decreasing lift and increasing drag. Various techniques, both passive and active, exist for boundary layer control to delay or eliminate fluid separation. Vortex generators (VGs) are simple use and among the most effective passive flow control solutions. They bring momentum from the external flow to the boundary layer, making it more resistant to separation. Active control methods, such as blowing through micro-holes, are also very effective but more challenging to implement. In the present work, a comparative experimental study of the flow control around a NACA 0015 airfoil is conducted in a subsonic wind tunnel using the two types of control strategies. The used VGs are the Lin’s counter –rotating configuration. They are triangular shape, placed on the suction face at 10% of the airfoil chord. The active control solution proposed relates to a steady blowing carried out with an angle of 45° relative to chord line, through a series of micro-holes of 0.6 mm in diameter uniformly arranged also at 10% from the leading edge. An improvement in aerodynamic performance was achieved with both strategies, with a more significant increase of approximately 49% in lift and a reduction of about 69% in drag in the case of micro-blowing.