Cooling of ram jets and tail-pipe burners: analytical method for determining temperatures of combustion chamber having annular cooling passage Page: 2 of 53
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NACA RM E9LO9 AnAmThm
3 1176 01434 9089
NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS
RESEARCH MEMORANDUM
COOLING OF RAM JETS AND TAIL-PIPE BURNERS - ANALYTICAL
METHOD FOR IERMINING TEMPERATURES OF COMBUSTION
CHAMBER HAVING ANNULAR COOLING PASSAGE
By William K. Koffel, Eugene Stamper
and Newell D. Sanders
SUMMARY
An analytical method is given for calculating the maximum wall
temperature of a tail-pipe burner or a ram-jet combustion chamber
cooled by air or gas flowing through a surrounding annular passage.
Data from step-by-step integrations of the heat flow from the com-
bustion gas to the cooling gas, which take into consideration the
longitudinal temperature distribution cf the combustion gases, the
variation of heat-transfer coefficients along the burner length,
and radiation from combustion gases to the combustion-chamber wall,
are used to develop an empirical equation expressing the outlet
temperature of the cooling gas in terms of known conditions of flow
and geometry. When the outlet cooling-gas temperature is known,
two parameters can be evaluated. that make possible the determina-
tion of the maximum temperature of the inside wall from a working
chart, which is a solution of the heat balance across the inside
wall at the outlet.
Extensive combinations and ranges of the independent variables
(mass velocity of combustion gas, mass velocity of cooling gas,
inlet cooling-air temperature, final combustion-gas temperature,
burner diameter, cooling-passage height, burner length, and fins)
have been generalized by the empirical equation, which greatly
reduces the labor of calculating the inside-wall temperature.
Temperatures calculated by this method. show satisfactory
agreement with corresponding temperatures measured on several exper-
imental tail-pipe burners. Corresponding temperatures calculated
at a station 0.7 of the distance from the flame holder to the nozzle
outlet are within +150 of the measured cooling-gas temperature and
within approximately 250 of the measured inside-wall temperature.
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Koffel, William K.; Stamper, Eugene & Sanders, Newell D. Cooling of ram jets and tail-pipe burners: analytical method for determining temperatures of combustion chamber having annular cooling passage, report, March 21, 1950; (https://digital.library.unt.edu/ark:/67531/metadc58451/m1/2/: accessed May 7, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.