Correlation for the Estimation of Afterbody Drag with Hot Jet Exhaust

MODERN turbojet and turbofan engines of combat aircraft operating over a wide range of power settings experience jet exhaust temperature typically varying from 1000-2000 K, whereas much of afterbody-nozzle testing is conducted with a cold jet near 300 K.1-5 Thus there remains a problem to determine the extent to which jet total temperature (and its associated gas constants) affects the afterbody drag of a combat aircraft under various operating conditions of its nozzle during the flight operations-$ Physical modeling of jet freestream interactions with temperature effects is quite difficult_ and, calculations of afterbody drag with hot jet exhaust are computationally intensive. Efforts made earlier for the estimation of afterbody drag with hot jet exhaust had limited success. In the present analysis, a simple correlation is proposed that can be used in the subsonic and transonic Mach number range for the estimation of afterbody pressure drag with jet temperature effects.