Exhaust Plume Temperature Effects on Nozzle Afterbody Performance over the Transonic Mach Number Range
ARNOLD ENGINEERING DEVELOPMENT CENTER ARNOLD AFB TN
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Results of an experimental and analytical research investigation on nozzleafterbody drag are presented. Experimental afterbody and boattail drag coefficients and pressure distributions are discussed for an isolated, strut- mounted nozzleafterbody model for the Mach number range from 0.6 to 1.5. Some data are also given for free-stream unit Reynolds numbers from one million to approximately four million per foot. The experimental data were obtained for the basic model with an air-cooled and a water-cooled Ethyleneair combustor to provide hot-jet duplication as well as cold-jet simulation. The temperature of the nozzle exhaust gas was varied from 530R burner-off to approximately 2500R for several nozzle pressure ratios from jet-off to those corresponding to a moderately under-expanded exhaust plum. The initial series of experiments was conducted with the air-cooled combustors, and the effect of jet temperature on afterbody drag was somewhat masked by the effects of the secondary airflow from the cooling air. The general trend, however, shows a decreasing afterbody drag with increasing exhaust gas temperature and with decreasing secondary airflow at a fixed nozzle pressure ratio.
- Jet and Gas Turbine Engines