Numerical Investigation of Ultra-High Lift Coefficient Co-Flow Jet Wing Without Flaps

摘要

Recent advances in 2D Co-Flow Jet (CFJ) flow control airfoil has achieved the super-lift coefficient that exceeds theoretical lift coefficient limit [1]. The super lift coefficient of the 3D finite-span CFJ wing has not yet been investigated. To understand the aerodynamic performance of the finite-span CFJ wing, numerical simulations were conducted at high angles of attack for the takeoff/landing conditions in this paper. This paper applies the Super-Lift 2D CFJ airfoil to 3D finite span wings to investigate the flapless wing performance and the capability of ultra-high lift coefficient generation for takeoff and landing performance. The 3D wings with aspect ratio of 20, 10 and 5 are studied. The Reynolds averaged Navier-Stokcs equations (RANS) are solved with the Spalart-Allmaras (S-A) turbulence model. The fifth-order WENO scheme is used to reconstruct the iuviscid fluxes and a fourth-order central differencing scheme is used to reconstruct the viscous fluxes. The simulations are performed at .Vlarh number of 0.063 and Reynolds number of 3.03 x 10~6. The CFJ wing is generated by the CFJ6421-SST01C-SUC053-INJ009 airfoil, which is designed for the super-lift coefficient. The aspect ratio of CFJ wing of 20, 10, and 5 is studied. The simulations are conducted at the AoA of 25°, 45°, and 70° with the CFJ jet momentum coefficient C_μ of 0.15, 0.2, 0.25 and 0.3. The maximum lift coefficient of C_l = 7.81 is achieved at AoA = 70°, C_μ=0.3 , and aspect ratio of 20. The lift coefficient of CFJ wing is reduced compared to that, of a 2D airfoil, while the drag is increased due to lift induced wingtip vortex. The Oswald efficiency of 3D CFJ wing is much higher than that of the conventional wing with no flow control. It indicates that the penalty of induced drag for 3D CFJ wing is small with decreased aspect ratio even though very high lift coefficient is obtained.