Aerodynamic Performance Enhancement of a NACA 66-206 Airfoil Using Supersonic Channel Airfoil Design

Supersonic channel airfoil design techniques have been shown to significantly reduce drag in high-speed flows over diamond shaped airfoils by Ruffin and colleagues. The effect of applying these techniques to a NACA 66-206 airfoil is presented. The design domain entails channel heights of 8-16.6% thickness-to-chord and speeds from Mach 1.5-3.0. Numerical simulations show an increase in the lift-to-drag ratio for airfoils at Mach 2.5 at a 35,000-ft altitude with a 12% channel height geometry showing a benefit of 17.2% at 6-deg angle of attack and a sharp channel leading edge. Wave drag is significantly reduced while viscous forces are slightly increased because of greater wetted area. Lift forces compared to clean airfoil solutions were also decreased, due mainly to the reduction in the length of the lifting surfaces. A tensile yield failure structural analysis of a typical beam found an 11.4% channel height could be implemented over 50% of the span between two typical ribs. A three dimensional wing was designed with the determined slot geometry and two dimensional flow analyses. An overall increase in L/D of 9% was realized at Mach 2.5 at a 35,000-ft altitude and 6-deg angle of attack.