Thrust and Pumping Characteristics of a Series of Ejector-type Exhaust Nozzles at Subsonic and Supersonic Flight Speeds Page: 2 of 37
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NATIONAL ADVISORY COMMIAITEE FOR AERONAUTICS
RESEARCH MEMORANDUM
THRUST AND PUMPING CHARACTERISTICS OF A SERIES OF EJECTOR-TYPE
EXHAUST NOZZLES AT SUBSONIC AND SUPERSONTTC FTLIGHTFP SPEEDS
By Donald P. Hearth and Alfred S. Valerino (
SUMMARY
An investigation was conducted in the 8- by 6-foot supersonic wind
tunnel to determine the thrust and pumping characteristics of a series
of ejector exhaust nozzles. Data were obtained for various ejector diam-
eter and spacing ratios at free-stream Mach numbers of 0.10, 0.63, 1.50,
and 1.90 over a pressure-ratio range of 1 to 10 and secondary-primary
weight-flow ratios to 0.36.
Results of this investigation indicated that free-stream Mach number
had no effect on the pumping and jet-thrust characteristics of the ejec-
tors in the range for which the secondary flow was choked. The mass-flow
discharge coefficient of the primary nozzle was reduced as secondary
weight flow was increased for some of the shroud configurations. How-
ever, the flow coefficient was not affected by primary pressure ratio or
free-stream Mach number.
INTRODUCTION
It has been shown (refs. 1 and 2) that increases in the basic thrust
of a conventional convergent nozzle may be obtained when cooling air is
pumped through an ejector surrounding the primary nozzle. These ejector-
type exhaust nozzles also represent a form of variable-geometry jet exit
(ref. 2) which is desirable for engine operation over a wide range of
pressure ratios. Numerous investigations (refs. 3 and 4, for example)
have been made in quiescent air to determine the thrust and pumping char-
acteristics of various types of ejector nozzles.
In order to fully evaluate such exhaust systems, determination of
the interferences between the internal and external flows are required.
Investigation of this problem has been initiated; results concerning the
external flow influence on ejector pumping performance and the external
drag characteristics are reported in references 5 and 6 However, t.he
external flow effect on measured internal thrust for ejector configura-
tions has not been reported.
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Hearth, Donald P. & Valerino, Alfred S. Thrust and Pumping Characteristics of a Series of Ejector-type Exhaust Nozzles at Subsonic and Supersonic Flight Speeds, report, November 17, 1954; (https://digital.library.unt.edu/ark:/67531/metadc52835/m1/2/: accessed April 19, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.