Design of a slotted, natural-laminar-flow airfoil for commercial transport applications

Slotted, natural-laminar-flow (SNLF) airfoils are a novel aerodynamic concept that enable significant performance improvements over conventional, single-element NLF airfoils. The 5207, SNLF airfoil has been designed using requirements derived from a transonic, truss-braced wing commercial aircraft configuration. The airfoil is designed for a cruise Reynolds number of 13.2 x 10(6) and it exhibits a drag divergence Mach number exceeding 0.71. At these conditions, low drag is predicted to occur between lift coefficients of 0.40 and 0.79. The 5207 airfoil exhibits a range-based figure of merit nearly triple that of a turbulent airfoil representative of modern commercial transport aircraft. Slotted configurations also have benefits for low-speed, high-lift conditions representative of approach. The S207 airfoil exhibits a low-speed, maximum lift coefficient in excess of 2.1, and is limited by compressibility effects around the leading edge. Incorporation of this airfoil onto a transonic, truss-braced wing configuration shows strong potential for meeting mid- and far-term goals for reducing aircraft fuel/energy consumption. (C) 2020 Elsevier Masson SAS. All rights reserved.