EFFECT OF BASE BLEED AND TERMINAL FAIRINGS ON THE PERFORMANCE OF EXHAUST-NOZZLE-AFTERBODY COMBINATIONS AT MACH NUMBERS OF 1.93, 2.55, AND 3.05

摘要

An investigation of four exhaust-nozzle—afterbody combinations has been conducted in the Langley 9- by 12-inch blowdown tunnel at Mach num¬bers of 1.93, 2.55, and 3.05. The models were tested on a pylon-mounted nacelle and the jet exhaust was simulated with cold air. Base bleed was varied from 0 to about 12 percent of the primary jet weight flow and was discharged into the base region through either a sonic or supersonic bleed, nozzle. The models were tested at zero degree angle of attack andnthe Reynolds number range was from 8 x 10° to 9 x 10° per foot.nThe results indicate that the base pressure and the performance of the exhaust-nozzle—afterbody combinations were little affected by the high-velocity base bleed. The efficiency of the terminal-fairing model was only slightly less than that of the convergent-divergent nozzle-afterbody combinations;this difference indicates the loss associated with improved transonic efficiency at higher Mach numbers.