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Overexpanded Performance of Conical Nozzles with Area Ratios of 6 and 9 With and Without Supersonic External FlowAn investigation of the thrust characteristics and internal pressure distributions of two convergent-divergent 15 deg. half-angle exhaust nozzles having area ratios of 6 and 9 was made in the NASA Lewis 10- by 10-foot supersonic wind tunnel. The tests were conducted at free-stream Mach numbers of 0, 2.0, 2.5, 3.0, and 3.5 over a range of nozzle pressure ratios from 3 to 105. Attempts were made to induce separation of the overexpanded nozzle flow using secondary airflow and a wedge. Nozzle flow expansion under all free-stream conditions followed one-dimensional theory until separation from the nozzle wall occurred. In quiescent air the nozzle flow expanded to a pressure approximately one-half the base pressure before separation. When the nozzles were tested with supersonic external flow at the same effective pressure ratios, the nozzle flow separated with negligible expansion below the base pressure. The effect of a supersonic stream on internal nozzle flow separation characteristics was well defined only at a free-stream Mach number of 2.0. Thrust data at supersonic free-stream conditions indicate that only a small percentage of the ideal nozzle thrust will be available at nozzle pressure ratios below design. However, the overexpanded primary nozzle thrust loss was decreased by injecting large quantities of secondary air near the nozzle exit. In most cases no net gain in thrust resulted from secondary-air injection when the nozzle thrust was compared with the ideal thrust of both the primary and secondary airflows.
Document ID
20000029582
Acquisition Source
Headquarters
Document Type
Technical Memorandum (TM)
Authors
Musial, Norman T. (NASA Lewis Research Center Cleveland, OH United States)
Ward, James J. (NASA Lewis Research Center Cleveland, OH United States)
Date Acquired
September 7, 2013
Publication Date
September 1, 1959
Subject Category
Fluid Mechanics And Thermodynamics
Report/Patent Number
E-208
NASA-TM-X-83
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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