Underexpanded jet-free stream interactions on an axisymmetric afterbody configuration

The exhaust jet-freestream interactions of an axisymmetric afterbody configuration have been studied experimentally, using an equivalent body-of-revolution representative of an actual combat aircraft configuration. Attention is given to the effects of jet pressure ratio and freestream Mach number on boattail, base, and afterbody pressure drag, for Mach numbers of 0.6-1.1 and Reynolds numbers from 20 million/m to 35 million/m, at zero-deg incidence. Jet pressure ratio was varied over 1-6. The underexpanded jet plume primarily affects the afterbody pressure distribution, and therefore the afterbody pressure drag. (O.C.