Component and over-all performance evaluation of an axial-flow turbojet engine over a range of engine-inlet Reynolds numbers Page: 4 of 44
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NACA RM E52B08 S 3
turbine (fig. i), was investigated. This engine was a preproduction
model of the J35-A-29 engine and had the same power section as the
J35-A-33 engine. A fixed conical exhaust nozzle having a diameter of
18.00 0.01 inches at 60 F was installed on the engine. This nozzle
is designed to produce a tail-pipe gas temperature of 1300 F (17600 R)
at rated engine speed and static sea-level conditions. At these opera-
ting conditions and when inlet screens are used, the manufacturer guar-
antees a rated thrust of 5400 pounds with a specific fuel consumption
of 1.06 pounds per hour per pound of thrust and an estimated air flow of
91 pounds per second. The rated thrust without inlet screens would be
5600 pounds. The maximum dimensions of the engine are a 37-inch diameter
and a 146-inch length. The dry engine weight without starter generator
and tachometer generator is 2305 pounds.
The automatic fuel control for the engine was replaced with an
adjustable pressure-control valve to allow a wider range of operation
and full throttle sensitivity at high altitude. An aluminum bullet-
type accessory cover and bell cowl (fig. 1) were installed at the com-
pressor inlet to obtain a smooth air flow into the compressor.,
The altitude chamber in which the engine was installed is 10 feet
in diameter and 60 feet long (fig. 2). A honeycomb is installed in the
chamber upstream of the test section to straighten and smooth the
flow of inlet air. The front bulkhead, which incorporated a labyrinth
seal around the forward end of the engine, was used to prevent the flow
of combustion air directly into the exhaust system and to provide a means
of maintaining a pressure difference across the engine. A 14-inch
butterfly valve was installed in the front bulkhead to provide cooling
air for the engine compartment. A rear bulkhead was installed to act
as a radiation shield and to prevent recirculation of exhaust gases
about the engine.
Air is supplied to the inlet section of the engine through a supply
line from the laboratory air system. Combustion air can be obtained
from this system over a range of temperatures from -700 to 850 F. Small
changes in the inlet-air temperature are obtained by the use of electric
heaters installed in a bypass line upstream of the chamber. The inlet
and exhaust pressures are controlled by means of remote-control valves
in the supply lines and the exhaust lines, respectively.
The exhaust gases from the jet nozzle are removed from the exhaust
section of the altitude chamber through a diffusing elbow and a dry-
type primary cooler. A dry-type secondary cooler downstream of the
exhaust valves further cools the hot gases before passing them into the
laboratory exhaust system.
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Walker, Curtis L.; Huntley, S. C. & Braithwaite, W. M. Component and over-all performance evaluation of an axial-flow turbojet engine over a range of engine-inlet Reynolds numbers, report, July 10, 1952; (https://digital.library.unt.edu/ark:/67531/metadc59177/m1/4/: accessed March 24, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.