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This paper describes the influence of grid resolution and turbulence modeling for a 3D transport aircraft in high lift configuration with massive flap separation. The flap is equipped with spanwise slotted active flow control (AFC) devices to allow studies on active separation control. The effects of constant slotted blowing on the high lift performance are highlighted. Oil flow pictures from a mid-scale experiment in the low speed wind tunnel of Airbus in Bremen (B-LSWT) serve as a validation database for the baseline CFD results. RANS calculations are carried out with and without constant blowing boundary conditions. The baseline flow is also investigated with a time-accurate URANS approach. One of the major outcomes of the AFC study is the demonstration of the feasibility to simulate AFC concepts on a 3D configuration. Constant blowing shows the beneficial effect that separation can largely be suppressed because of the energy added to the flow on the suction side of the flap. This study serves as a preceding validation for the subsequent pulsed blowing approach treated in Part 2.

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This contribution discusses the implementation of fluidic actuators that produce a pulsed outlet flow on a three dimensional model of the outer wing of a long-range transport aircraft at take-off, by high-fidelity numerical simulations. The leading-edge high-lift unprotected wing extension, including a wingtip device, designed for high performance at cruise flight, is subject to local flow separation at high angles of attack and low speed flight conditions. Active flow control (AFC) applied at the outer wing can prevent the formation of large turbulent flow separation and increase the aircraft lift to drag ratio (L/D), decrease the drag (D), and increase the angle of attack (AoA) for maximum lift (C Lmax ). The performed unsteady Reynolds-averaged Navier-Stokes (URANS) simulations prove the flow changes by the local AFC application and include a variation of the actuator's geometrical setup. The results suggest a successful implementation on a transport aircraft and with an acceptable blowing momentum coefficient. Nomenclature α = angle of attack α jet = blowing angle A = wing reference area A/C = aircraft AFC = active flow control AoA = angle of attack c = reference model chord CFL = Courant-Friedrichs-Lewy number C L = lift coefficient C Lmax = maximu m lift coefficient C D = drag coefficient C my = pitching moment coefficient C µ = blowing momentum coefficient D = drag force DC = actuation duty cycle f = actuation frequency F + = reduced actuation frequency γ = climb gradient λ 2 = second negative eigenvalue of the symmetric gradient tensor of the velocity field l = actuator-slit's length l i = distance between two slits of one actuator-pair l o = distance between two slits of two neighbour's actuator-pairs L = lift force LE = leading edge L/D = lift to drag ratio = actuation mass flow 2 M = Mach number OEI = one engine inoperative Re = Reynolds number T/W = thrust to weight ratio TE = trailing edge URANS = unsteady Reynolds-averaged Navier-Stokes U ∞ = inflow velocity U jet = actuation peak velocity r * = non-dimensional rotation parameter w = actuator-slit's width ω x = x-vorticity