Abstract: Interaction of synthetic jet and low-speed high-lift flow past a YISG 107 airfoil is simulated and stall control of high-lift airfoil is investigated. A cell-centered finite-volume scheme is used to discrete unsteady Reynolds-Averaged Navier-Stokes equations in integral form. An AUSM^± up upwind scheme and a fully implicit dual-time step method are utilized for spatial discretization and time stepping, respectively. Implicit preconditioning method and geometric multigrid method are employed to remove stiffness encountered in simulation of low-speed flows and to accelerate convergence of computation. Influence of synthetic jet on main flow is modeled with a generalized unsteady blowing/suction boundary condition. Computational results with a synthetic jet located at 17.5% c from leading edge agree weU with low-speed wind tunnel experiment. With a momentum coefficient of 0.005, nondimensional frequency of 2.75 and jet angle of 20°, critical stall angle is delayed by 2°, and the maximum lift is increased by 8.7%. Influence of momentum coefficient and jet angle on stall performance is studied. It is shown that two key reasons lead to small improvement in previous wind tunnel experiments: One is due to low momentum coefficient. Only as momentum coefficient is larger than 0.001 can relatively evident improvement of stall characteristic be obtained. Another is due to unsuitable normal jet in tall control of a high-lift thick airfoil. Near tangent jet is better than normal jet.

Key words: active flow control, synthetic jet, stall, Navier-Stokes equations, high-lift airfoil