Supersonic inlet study using the Navier-Stokes equations

Abstract

The three-dimensional, unsteady, compressible Navier-Stokes equations were numerically solved for the flowfield about three external-compression inlet configurations. Configuration 1 was a generic Mach 2.2 variable-geometry, two-ramp inlet with a bleed slot. Configuration 2 was an F-16/79 inlet at Mach 2.0 with porous-ramp and slot bleed. For these configurations, two different approaches were used to model the bleed. Configurations 1 and 2 were modeled by using three lateral planes in the three-dimensional code with symmetry around the center plane, which provides an equivalent two-dimensional solution. Configuration 3 was an axisymmetric spike inlet at Mach 2.2 at 0 deg angle of attack. A full three-dimensional solution was obtained for this configuration. For configurations 2 and 3, the computed surface pressures are in good agreement with the experimental data for cases with and without bleed. The computed pressure recovery at the throat for the threedimensional spike inlet at AQ/Af = 0.84 was 2% higher than the compressor-face data. In all the configurations, a computational flow plug was used for the duct outflow boundary. This flow plug eliminates the need to specify a back pressure, particularly at angles of incidence, where the back pressure varies circumferentially. Due to limited computer resources, the analysis was limited to the shock system plus 25-45% of the subsonic diffuser length. Numerical results are given in terms of Mach number and static pressure plots and are compared with experimental data.