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National Advisory Committe for Aeronautics, Research Memorandum - Investigation of Shock Diffusers at Mach Number 1.85 - II - Projecting Double Shock Cones

An investigation of a heated Jet was conducted in conJunction
with tests of an axialaflcw'Jetvpropulsion engine in the Cleveland
altitude wind tunnel. Pressure and temperature surveys were made
across the Jet 10 and 15 feet behind the Jet-nozzle cutlet of the
engine. Surveys were obtained at pressure altitudes of 10, 000,

20, 000, 30, 000, and 40, 000 feet with test-section velocities from
30 to 110 feet per second and test-section temperatures from 60°
to -50°F rom,measurements taken throughout the operable range
of engine speeds, tail-pipe outlet temperatures from 500° to lESOOF
and Jet velocities from 400 to 2200 feet per second were obtained.
The Jet-survey data presented extend the work previously done with
low—velocity and low-temperature Jets to the region_of high veloc-
ities and high temperatures.

The results obtained agree with previously determined experi—
mental data and with predicted theoretical expressions for the
dimensionless transverse velocity and temperature profiles across
a Jet. The spread of both the temperature and the velocity pro-
files was very nearly linear. Dimensionless plots of temperature
and velocity along the axis of a heated Jet agree with experi-
mental results of tests with a cold Jet.

The characteristics of the spread of a Jet have been theo—
retically investigated (references 1 and 2) and experiments were
conducted with small slightly heated Jets (reference 5) and with
a large Jet at roam temperature (reference 1, p. 599). This work
was done at approximately sea-level pressure with the air surrounding
the Jet at very nearly static conditions. Some work has also been
reported on small oblique Jets discharging into a high-velocity stream

No results are generally available on characteristics of
high-temperature, high—velocity Jets of the size encountered in Jet—
propulsion engines.

In conjunction with tests of a Jet—propulsion engine equipped
with an axial-flow compressor in the Cleveland altitude wind tunnel,
a survey of the Jet was made to provide information by which an
engine could_he so located in an airplane that no external surface
was overheated by the Jet. Data were obtained at altitudes from
10,000 to 40,000 feet by varying the temperature and pressure in the
tunnel.

The temperature_and the velOcity on the axis of the Jet and the
diameter of the Jet are presented nondimensionally as functions of
the axial distance from the Jet—nozzle outlet and the diameter of the
Jet at the vena contracts. Nondimensional transverse profiles of
velocity and temperature across the Jet are presented as functions
of the distance from the Jet axis and the radius of the Jet boundary.
Comparisons are made between these data and previously published
theoretical predictions by Prandtl (reference 2) and experimental
data reported by Corrsin (reference 5.)