Comparative study of boundary layer control around an ordinary airfoil and a high lift airfoil with secondary blowing

Boundary layer separation over an airfoil causes large energy losses and strong adverse pressure gradients. This in turn leads to a reduction in the lift force and an increase in the drag force. Therefore delaying or if possible, eliminating the flow separation is mandatory. The elimination of flow separation would permit higher angles of attack for many practical applications. Steady blowing on the suction side of the airfoil is found to be effective in controlling the boundary layer separation. Flow around NACA0012 and LA203A airfoils are analysed in the present study, with the position of the secondary blowing jet at 60 percent of the chord length and angles of attack ranging from 2 to 18° for NACA0012 and 2 to 20° for LA203A. The secondary blowing velocity is varied from 0 percent to 40 percent of the free stream velocity. The lift curves of all the cases studied are plotted. The results show that the secondary blowing helps to control flow separation and cause an increase in the lift and delay the stalling of airfoils in both cases.