Component and over-all performance evaluation of an axial-flow turbojet engine over a range of engine-inlet Reynolds numbers Page: 5 of 44
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NACA RM E52B08
The locations of the instrumentation stations, before and after
each of the principal components of the engine, are shown in figure 3.
The detailed arrangement of the separate temperature and pressure probes
at each station is shown in figure 4 for those stations at which data
are presented herein.
Engine-inlet pressure and temperature were set for a given run
according to the readings of the instrumentation at station 1. The tem-
peratures and pressures measured at station 2 were used in calculating
the altitude correction factors e and 8, and the compressor air-flow.
(All symbols are defined in the appendix.) Pressure and temperature
instrumentation was also installed to determine engine midframe air-
bleed. The engine-air flow was equal to the air-flow measured at sta-
tion 2 minus the air bled off at the midframe. Combustor static pres-
sure was obtained at station 4 from static-pressure taps in combustors 2
and 6. One total-pressure probe was located approximately in the center
of each of the eight transitions from the combustor to the turbine at
station 5. Pressure and temperature probes at each station, except
station 7, were so located that a mean value of temperature or pressure
could be obtained directly by averaging the individual readings. At
station 7, the average values of total temperature and pressure were
obtained from plots of the temperature and pressure profiles, and static
pressure was obtained from a mechanical average of four wall-static
orifices. These measurements at station 7 were used to calculate jet
The atmospheric pressure surrounding the jet-nozzle was measured by
two probes located near the jet-nozzle outlet in the exhaust portion of
the chamber. In order to improve the accuracy of data and the ease of
operation, two calibrated aneroid manometers (one high pressure and one
low pressure) were used to set inlet and exhaust pressures; and an elec-
trically operated strobotac was installed to assist in maintaining
constant engine-speed settings.
Fuel flow was measured by two rotameters connected in series; two
rotameters were necessary to cover the entire range of flows and to keep
the physical size at a minimum. The rotameters were calibrated with the
fuel used in the investigation (MIL-F-5624A, grade JP-3).
Reynolds number index, a function only of temperature and pressure,
is defined by the expression 82 2~ e2'. The derivation of this exprese-
sion is presented in reference 4 where 82 is the ratio of compressor-
inlet absolute total pressure to absolute total pressure of NACA
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Walker, Curtis L.; Huntley, S. C. & Braithwaite, W. M. Component and over-all performance evaluation of an axial-flow turbojet engine over a range of engine-inlet Reynolds numbers, report, July 10, 1952; (https://digital.library.unt.edu/ark:/67531/metadc59177/m1/5/: accessed April 24, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.