Supersonic Axisymmetric Flow over Boattails Containing a Centered Propulsive Jet

Abstract

The influence of underexpanded jets on a supersonic afterbody flowfield is investigated using computational techniques. The thin-shear-layer formulation of the compressible, Reynolds-averaged, Navier-Stokes equations is solved using a time-dependent, implicit numerical algorithm. Solutions are obtained for supersonic flow over an axisymmetric conical afterbody containing a centered propulsive jet where the freestream Mach number is 2.0 and the jet exit Mach number is 2.5. Exhaust-jet static pressures are considered in the range of 2 to 9 times the freestream static pressure and with nozzle-exit half-angles from 15 to 43 deg. Comparisons are made with experimental results for base pressure, separation distance, afterbody pressure distribution, and flowfield structure. Although good quantitative agreement with experimental separation distance and base pressure level is not observed, the parametric trends induced by exhaust-jet pressure level and nozzle-exit angle are well predicted, as well as the flowfield details in the vicinity of the afterbody and in the exhaust plume.