Correlation of isothermal contours formed by penetration of jet of liquid ammonia directed normal to an airstream Page: 4 of 40
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NACA RM E53J08
Ammonia System
Liquid anhydrous ammonia was supplied at various temperatures and
pressures to a single-orifice spray bar which injected the ammonia nor-
mal to the air flow in the 21-inch-diameter duct. In order to maintain
the ammonia in its liquid state, the system was pressurized with helium
from tanks connected to the ammonia storage tank (fig. 2). Liquid
ammonia from the storage tank was passed through rotameters and a filter
to the heat exchanger where it was cooled by the evaporation of ammonia
surrounding the heat-exchanger coils. The temperature of the measured
ammonia flow was controlled by varying the pressure and, hence, the
evaporation rate of the surrounding .ammonia in the heat exchanger.
The pressurized ammonia from the heat exchanger was passed through
the throttle to the spray bar shown in figure 3. In order to prevent
heating of the ammonia as it flowed from the heat exchanger to the
spray orifice, the connecting lines were insulated. The temperature
of the liquid ammonia was measured by means of a thermocouple in-
stalled within the spray bar close to the orifice. The three single-
orifice spray bars investigated had orifice diameters of 0.018, 0.029,
and 0.053 inch. In addition, a two-orifice spray bar was used which
was similar to the single-orifice bars except that it had two 0.031-
inch-diameter orifices 1 inch apart.
Test Section
The spray bar was located 5 inches from the bottom of the duct
with the orifice directed upward on the vertical center line of the
duct. In order to determine the isothermal contour lines formed by
the ammonia jet, a twin-armed swinging rake equipped with aspirating
thermocouples was installed in the duct (fig. 4). The thermocouple
probes were pointed downstream to prevent droplets of liquid ammonia
from contacting the thermocouple junctions, and the rake body was
connected to the laboratory exhaust system to provide a continuous
flow of gas through the thermocouple probes. A detailed sketch of
the aspirating thermocouple probes is shown in figure 5. The mixing
distance between the spray bar and the swinging survey rake was varied
by altering the axial location of the spray bar in the duct.
Other instrumentation in the test section provided for the meas-
urement of duct static pressure by means of three wall static taps 30
inches upstream of the survey rake (fig. 4) and the measurement of
total air temperature with an 8-inch immersion thermocouple in the
8-foot straight section upstream of the survey rake.3
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Fenn, David B. Correlation of isothermal contours formed by penetration of jet of liquid ammonia directed normal to an airstream, report, February 3, 1954; (https://digital.library.unt.edu/ark:/67531/metadc59541/m1/4/: accessed April 19, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.