Use of flame-immersed blades to improve combustion limits and efficiency of a 5-inch diameter connected-pipe, ram-jet combustor Page: 4 of 38
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NACA RM E53B16
In order to obtain realistic ram-jet operating conditions, sonic
flow was maintained with a two-dimensional variable-area exhaust nozzle
(fig. 2). A metered water spray was introduced at the nozzle exit to
quench the reaction and to permit determination of combustion efficiency
by calorimetric methods.
Clear gasoline or isopentane metered by a rotameter was injected
C124 inches upstream of a V-gutter flame holder l inches wide by
1- inches high and was ignited by a momentary hydrogen-oxygen pilot in
one end of the gutter.
The fuel injector consisted of two concentric tubes with two rows
of 0.055-inch holes,drilled 1800 apart,through both tubes. Fuel was
supplied to the center tube and air to the annulus to atomize the spray.
The fuel injector was mounted at the inlet of the diffuser perpendicular
to the stream and oriented so that the fuel sprayed normal to the
stream (fig. 2). For part of the investigation, a low fuel-injection
pressure of about 10 pounds per square inch gage was used and, for the
remainder of the investigation, a high pressure of 45 pounds per square
inch gage was used.
Two types of blade were used (fig. 3); uncooled molybdenum blades
protected from oxidation by a coating of molybdenum disilicide, and
Inconel blades protected from melting by internal water cooling. Unless
otherwise specified, the blades were uncooled. A maximum of 12 blades,
-by 3 by g inches, were cantilever-mounted in the water-cooled com-
bustor in various arrangements (fig. 4).
The combustion efficiency was determined by operating the combustor
at equilibrium at a given condition with the quench water rate adjusted
so that the temperature of the exhaust gases was 6000 F. Efficiency
calculations were based on the ratio of the total enthalpy rise over the
theoretical enthalpy rise possible if all the fuel were completely
Efficiency calculations were made according to the following
(~a,+ e + tHj)
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Male, Donald W. Use of flame-immersed blades to improve combustion limits and efficiency of a 5-inch diameter connected-pipe, ram-jet combustor, report, April 9, 1953; (digital.library.unt.edu/ark:/67531/metadc59576/m1/4/: accessed April 22, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.