Performance of a Short Combustor at High Altitudes Using Hydrogen Fuel Page: 2 of 21
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NACA RM E56D24
NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS
PERFORMANCE OF A SHORT COMBUSTOR AT HIGH ALTITUDES
USING HYDROGEN FUEL*
By Joseph N. Sivo and David B. Fenn
An investigation was conducted in an altitude test chamber at the
NACA Lewis laboratory to evaluate in a complete engine the performance
of a 16-inch-long combustor designed at the NACA specifically for use
with gaseous-hydrogen fuel. The investigation covered a range of com-
bustor pressures from 1260 to 420 pounds per square foot absolute ob-
tained by operating the engine over a range of simulated altitudes from
66,000 to 86,000 feet at a flight Mach number of 0.8.
Combustion efficiencies of approximately 86 percent were obtained
at a combustor pressure of 420 pounds per square foot absolute. This
was approximately the same as the efficiency obtained using hydrogen
fuel in a conventional turbojet combustor having a 25-inch length. At
a pressure level of 800 pounds per square foot absolute, the efficiency
of the short combustor was 11 percent higher than that of the standard
combustor operating with JP-4 fuel. The standard combustor using JP-4
fuel experiences blowout at approximately 65,000 feet. However, com-
bustor blowout was not experienced with hydrogen in the short combustor
at altitudes up to 86,000 feet. The minimum pressure at which ignition
was obtained was 280 pounds per square foot absolute. The combustor
pressure losses for both the standard and the short combustors were ap-
proximately the same.
The desirability of extending the range and altitude capabilities
of aircraft has created interest in high-energy fuels. One fuel which
is currently receiving a great deal of attention is hydrogen because of
its high gravimetric heating value, high flame speed, wide flammability
limits, and large heat capacity, which makes it a promising coolant.
Extension of engine operating limits to altitudes as high as 90,000 feet
at a flight Mach number of 0.8 while retaining reasonably high combus-
tion efficiency has been demonstrated in an engine using gaseous-hydrogen
fuel in a conventional combustor (ref. 1).
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Sivo, Joseph N. & Fenn, David B. Performance of a Short Combustor at High Altitudes Using Hydrogen Fuel, report, August 7, 1956; (digital.library.unt.edu/ark:/67531/metadc52921/m1/2/: accessed December 10, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.