Preliminary experiments with pilot burners for ram-jet combustors Page: 2 of 47
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U NACA RM E52J23 _31176 01435 6407
NATIONAL ADVISORY COMITEE FOR AERONAUTICS
PRELIMINARY EXPERIMENTS WITH PILOT BURERS FOR RAM-JET COMBUSTORS
By John M. Farley, Robert E. Smith* and John H. Povolny
As part of an over-all program to develop a high-altitude, low-drag
ram-jet combustor, a preliminary development program on can-type pilot
burners has been conducted at the Lewis laboratory. A 5-inch-diameter
circular pilot burner and an annular-segment pilot burner were developed
which gave stable operation over a satisfactory range of fuel-air ratios
with static-pressure ratios across the pilot burner from about 1.02
to 1.08 with an inlet pressure of 10 inches of mercury absolute. With
fuel injected about 12 inches upstream of the annular-segment pilot burn-
er, a combustion efficiency of 61 percent was obtained at a fuel-air
ratio of 0.06, with an inlet pressure of 10 inches of mercury absolute.
Efficiencies over 80 percent were obtained with a homogeneous fuel-air
mixture, and it is believed that with some detailed fuel-system studies
such values are attainable, when the fuel is injected within 12 inches of
the pilot-burner dome.
Recent investigations of ram-Jet engines have indicated that the
stability on low-drag ram-jet combustors operating at combustor-inlet
pressures in the order of 1/2 atmosphere and less may be improved by use
of a stable heat source or pilot flame (reference 1). In the past,
pilot-burner air flows have generally been about 1 or 2 percent of the
total air flow. However, by use of low-drag pilot configurations, pilot
air flows as high as 8 percent of the total, with a blocked area of
about 25 percent of the ram-jet combustor cross-sectional area, appear
feasible. Combustors using can-type burners of relatively low drag
have shown good stability and efficiency characteristics with inlet
pressures as low as 8 inches of mercury absolute and therefore appear
well suited to pilot applications (references 2 and 3). As part of an
over-all program to develop a high-altitude, low-drag ram-jet combustor,
an experimental investigation of some of the pertinent design features
of can-type pilot burners has been conducted at the NACA Lewis laboratory.
*Mr. Smith, of ARO Inc., is on assignment to the NACA Lewis
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Farley, John M; Smith, Robert E & Povolny, John H. Preliminary experiments with pilot burners for ram-jet combustors, report, January 2, 1953; (digital.library.unt.edu/ark:/67531/metadc59585/m1/2/: accessed February 20, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.