Study of ram-air heat exchangers for reducing turbine cooling-air temperature of a supersonic aircraft turbojet engine Page: 2 of 35
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NACA RM E56E17 L
. e; . "_3 1176 01435 8569
NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS
STUDY OF RAM-AIR HEAT EXCHANGERS FOR REDUCING TURBINE COOLING-AIR
TEMPERATURE OF A SUPERSONIC AIRCRAFT TURBOJET ENGINE
By Anthony J. Diaguila, John N. B. Livingood,
and Ernst R. G. Eckert
An analytical investigation was made to determine the sizes and
weights of the cores of crossflow finned-tube heat exchangers for re-
ducing the temperature of turbine cooling air for an engine designed
for operation at a flight Mach number of 2.5 and an altitude of 70,000
feet. A compressor-bleed-air weight flow of 2.70 pounds per second was
assumed for the turbine coolant; ram air was considered for reducing
the compressor-bleed-air temperature. The available pressure drops of
the two fluids and the inlet states of each fluid were prescribed. Re-
ductions in ccnpressor-bleed-air temperature of 1000, 2000, 000, and
4000 F and values of the ratio of compressor-bleed-air to ram-air
weight flow of 1.00, 0.75, 0.50, and 0.25 were considered. The calcu-
lations were made with the use of prepared charts.
For a compressor-bleed-air temperature reduction of 3000 F, the
heat-exchanger core weight was reduced from about 49 to 19 pounds as the
ratio of compressor-bleed-air to ram-air weight flow was decreased from
1.00 to 0.25. For heat exchangers of moderate weight (30 to 60 pounds),
the compressor-bleed-air temperature reduction can be increased by about
1000 F if the weight-flow ratio is reduced from 1.00 to 0.25. Reductions
in weight-flow ratio for a fixed compressor-bleed-air temperature drop
result in increased frontal area in the primary-fluid direction. In all
calculations, only core weight was considered; duct weight was not
For the conditions of this investigation the heat-exchanger core
weight was less than 60 pounds in most cases. If a sea-level static
specific engine weight of 0.300 without a heat exchanger is assumed, the
core weight would increase the specific engine weight to only 0.305 for
the engine size considered (12,000-pound sea-level static dry thrust).
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Diaguila, Anthony J.; Livingood, John N. B. & Eckert, Ernst R. G. Study of ram-air heat exchangers for reducing turbine cooling-air temperature of a supersonic aircraft turbojet engine, report, August 3, 1956; (digital.library.unt.edu/ark:/67531/metadc62770/m1/2/: accessed January 17, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.