Altitude-Wind-Tunnel Investigation of Turbine Performance in J47 Turbojet Engine Page: 3 of 41
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NACA IRM EK0
a J47 turbojet engine. The investigation was conducted over a
wide range of simulated altitudes and flight Mach numbers through-
out the operable range of engine speeds. The use of three exhaust
nozzles of different outlet area extended the range of engine
operation over which the components could be investigated. Over-
all engine performance, compressor performance, and engine oper-
ational characteristics are presented in references 1, 2, and 3,
respectively.
Performance data are presented in this report to show the
characteristics of the turbine operating as an integral part
of the engine. Typical results are graphically presented to show
the effects of changes in altitude, flight Mach number, and exhaust-
nozzle-outlet area on turbine performance. All turbine-performance
data obtained are given in tabular form.
ENGINE AND INSTALLATION
The J47 turbojet engine (fig. 1) used in this investigation has a
static sea-level thrust rating of 5000 pounds at an engine speed
of 7900 rpm and a turbine-outlet temperature of 12750 F. At this
rating, the air flow is 94 pounds per second. The principal com-
ponents of the engine are a 12-stage axial-flow compressor,
eight cylindrical direct-flow-type combustion chambers, a single-
stage impluse turbine, a tail pipe, and an exhaust nozzle. The
standard exhaust-nozzle-outlet area for the engine investigated
was 280 square inches, which was the area with which the limiting
turbine-outlet temperature, 12750 F, could be obtained at rated
engine speed and approximately static sea-level conditions.
Exhaust nozzles having outlet areas of 302 and 342 square inches
were also used.
The single-stage impulse turbine (fig. 2) used in this
engine delivers approximately 12,000 horsepower at rated sea-
level conditions. The turbine drives the compressor di-
rectly by means of a hollow shaft. Air is extracted from
the compressor for turbine cooling.
The engine was mounted on a wing section that spanned the
20-foot-diameter test section of the altitude wind tunnel
(fig. 1). Dry refrigerated air was supplied to the engine in-
let through a duct from the tunnel make-up air system.2
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Thorman, H. Carl & McAulay, John E. Altitude-Wind-Tunnel Investigation of Turbine Performance in J47 Turbojet Engine, report, September 21, 1950; (https://digital.library.unt.edu/ark:/67531/metadc58352/m1/3/: accessed April 17, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.