This paper discusses new boundary constraints

This paper reports the results of a computational study that was conducted to explore the effect of various Variable Camber Continuous Trailing Edge Flap (VCCTEF) configurations on the lift and drag of a NASA Generic Transport Model (GTM) wing section at a span-wise location called the break station that marks a sharp change in the wing trailing edge slope. The OVERFLOW solver with the the one-equation Spalart-Allmaras (SA) turbulence model 1 and the two-equation (k − ω) Shear Stress Transport (SST) turbulence model 2 was first applied to a NACA0021 airfoil case and the results were compared with experimental data of Harris 3 and ARC2D results 4 . The comparison showed good agreement between earlier results 3,4 and the SA model. Therefore, SA model was used for all the simulations in this study. Design cruise condition at 36,000 feet at free stream Mach number of 0.797 and Reynolds number of 30.734x10 6 was simulated for an angle of attack (AoA) sweep from -3 deg. to 10 deg. Five VCCTEF configurations with varying camber in the flap region were considered along with an unmodified (no flap deflection) airfoil as the baseline case. Comparison of lift and drag corresponding to these configurations with baseline configuration (retracted flaps) showed a definite trend in the results. Although the baseline configuration produced the lowest lift at a given AoA among the set under investigation, it produces stall after about 5 deg AoA, whereas with the VCCTEF settings, stall occurs earlier between 3 and 4 deg AoA. The lift enhancement was significant with the extended flaps, but it was accompanied with a drag penalty, as expected. But, the lift versus drag L/D results showed that at the design cruise lift coefficient of 0.51, the L/D characteristics improved from the baseline to four of the five VCCTEF configurations. Among these four configurations, the configuration which reflects a parabolic-like camber is more optimal than the other three configurations in terms of improved L/D and well-behaved C p distribution. The lift prediction is compared against theoretical lift prediction from potential flow theory. Excellent agreement between computed and theoretical incremental lift is shown.

This paper summarizes the recent development of an adaptive aeroelastic wing shaping control technology called variable camber continuous trailing edge flap (VCCTEF). As wing flexibility increases, aeroelastic interactions with aerodynamic forces and moments become an increasingly important consideration in aircraft design and aerodynamic performance. Furthermore, aeroelastic interactions with flight dynamics can result in issues with vehicle stability and control. The initial VCCTEF concept was developed in 2010 by NASA under a NASA Innovation Fund study entitled "Elastically Shaped Future Air Vehicle Concept," which showed that highly flexible wing aerodynamic surfaces can be elastically shaped in-flight by active control of wing twist and bending deflection in order to optimize the spanwise lift distribution for drag reduction. A collaboration between NASA and Boeing Research & Technology was subsequently funded by NASA from 2012 to 2014 to further develop the VC-CTEF concept.This paper summarizes some of the key research areas conducted by NASA during the collaboration with Boeing Research and Technology. These research areas include VCCTEF design concepts, aerodynamic analysis of VCCTEF camber shapes, aerodynamic optimization of lift distribution for drag minimization, wind tunnel test results for cruise and highlift configurations, flutter analysis and suppression control of flexible wing aircraft, and multi-objective flight control for adaptive aeroelastic wing shaping control.

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