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.

An LU-SGS based Choi-Merkle matrix preconditioning method is implemented within the framework of dual-time stepping and geometric multigrid method.An efficient method for steady and unsteady flows past aircraft configurations with Mach numbers from incompressible to transonic regime is developed.LU-SGS time stepping method is modified according to the preconditioned system.An efficient and robust splitting method for Jacobian matrix is presented.In simulation of viscous flows past NACA0012 airfoil ONERA M6 wing and DLR F4 wing/body configuration,the method obtains nearly Mach number-independent convergence at low-Mach numbers and improves efficiency slightly for transonic flows.Compared with Runge-Kutta based preconditioning method,LU-SGS based preconditioning method is more efficient.In simulation of unsteady viscous flow past an oscillating NACA 0012 airfoil convergence of sub iteration of dual time stepping is improved slightly.