Underexpanded jet-freestream interactions on an axisymmetric afterbody configuration

Experimental investigations are carried out in the 0.3 m trisonic wind tunnel at NAL to study exhaust jet-freestream interactions on an axisymmetric afterbody configuration. The model chosen for these studies is an equivalent body of revolution of a representative combat aircraft configuration. The effects of jet pressure ratio and freestream Mach number on boattail, base, and afterbody pressure drag are studied along with color Schlieren flow visualization of the afterbody flowfield. Experiments are carried out in the freestream Mach number range of 0.6 to 1.1 at Reynolds number from 20 amp;times; 10lt;supgt;6lt;/supgt;/m to 35 amp;times; 10lt;supgt;6lt;/supgt;/m keeping model at zero degree of incidence. Jet pressure ratio is varied from 1 to 6 during this investigation. The jet at nozzle exit is sonic throughout these tests.