Flow separation control in a two-airfoil system by trailing edge modification and active flow control

Numerical simulations of flow past a NACA0012 airfoil with a slotted flap are conducted using steady Reynolds-averaged Navier Stokes equations at Reynolds number of 5 x 10(4) and 5(degrees) angle of attack in freestream. The ratio of chord lengths of flap to main airfoil is 0.2. The lower side of main airfoil surface is modified to incorporate a cusped trailing edge. The effects of a cusped trailing edge on flow over flap region are studied at different values of flap deflection angles, in the range 12(degrees)-25(degrees). A cusped trailing edge has a significant effect on boundary layer evolution on flap surface. The presence of cusp reduces viscous effects in slot flow, increases flow speed at the trailing edge and aligns the flow along flap suction surface. Maximum enhancement in lift coefficient of about 13% is achieved by using active flow control along with a cusped trailing edge for the main element.