Applications of divergent trailing edge airfoil in wide-body airliner wing design

Computational fluid dynamics (CFD) method is used to evaluate the benefits of divergent trailing edge (DTE) modification in the wing design of a wide-body airliner. A power function is proposed to describe the disturbance for DTE, and effects of the power number and the trailing-edge thickness on the aerodynamic performance of a supercritical airfoil are studied, with comparison of the difference in the lift force and momentum between two Reynolds numbers, i.e. Re = 4×10⁶ and 2×10⁷. It shows that the trailing-edge thickness is a key parameter of the DTE airfoil. For the same trailing-edge thickness, the drag reduction at Re = 2×10⁷ is less than that at Re = 4×10⁶. By taking into account the transonic drag reduction, subsonic drag and nose-down pitching moment increment at Re = 2×10⁷, it is more reasonable to take the trailing-edge thickness around 3‰c. Two applications of the DTE design have been explored, i.e. exchanging for airfoil thickness increment, and adjusting the wing load distribution. With the DTE modification of a supercritical airfoil, a 2‰c increment of the trailing-edge thickness leads to the maximum relative thickness of the airfoil increased from 10.2% to 11.5%, while the lift-drag performance is still kept at the same level of the original one. When a trailing-edge thickness increment of 1‰c at inboard and 2‰c at outboard is applied to the wing of a wide-body airliner, a drag reduction of more than 2 counts (1 count = drag coefficient 0.0001) can be achieved in the wing-fuselage-nacelle-pylon configuration, without any penalty of wing thickness and drag divergence performance loss.