NUMERICAL SIMULATION OF THE EFFECTS OF VORTEX CONTROL BY USING BI-FLAP SYSTEM ON A DELTA WING
三角翼的双襟翼控涡作用的数值模拟研究

Numerical simulation of the incompressible flow past a 74 delta wing equipped with an apex flap and a leading-edge flap was conducted to investigate the effects of vortex control by using such a hi-flap system. The three-dimensional incompressible Navier-Stokes equations in curvilinear coordinates were solved by using pseudo-compressibility method. The implicit approximatelyfactorized scheme was utilized to solve the discrete equations resulting from the application of backward Euler difference for time derivative and second-order upwind TVD scheme for inviscid terms. Baldwin-Lomax turbulence model was used. Flowfields past three kinds of planform and the resulting aerodynamic characteristics were computed for 10 ~ 50 range of incidence. The comparison of numerical and previous experimental results shows that vortex breakdown can be delayed, and drag reduction, lift/drag ratio and other aerodynamic characteristics near stall can be improved by drooping the flap downward. The hi-flap system has its performance superior to NASA leading-edge flap system or a single delta wing.