Numerical simulation of circulation control airfoil using RANS solver

In this paper, the experimental results of the flow around RAE-104 circulation control (CC) airfoil are benchmarked by Reynolds averaged Navier-Stokes (RANS) solver for explanation of underlying physics of circulation control airfoils. The airfoil used in simulations has a circular trailing edge with a slot on its upper surface at about 95% of the chord length. The free stream Reynolds number and Mach number are about 5.51×10⁵ and 0.090 respectively. In simulations, twenty-five cases (by varying the angle of attack and jet velocity) are studied. Good agreement is observed between the experimental and simulation results. Simulations showed that the secondary jet at the trailing edge of airfoil changes the Kutta condition and the associated circulation around the airfoil. The new circulation around the airfoil increases the difference in pressure on the high and low pressure side of airfoil. It is due of this altered circulation and difference in pressures that the lift coefficient of airfoil is increased. At the end of paper, the optimal range of secondary jet velocity and angle of attack of airfoil is studied by calculating the ratio of lift to drag force acting on airfoil.