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NASA TN D- 1 169
TECHNICAL NOTE
D-II69
DESIGN AND CALIBRATION OF AN ARC-HEATED,
HYPERSONIC, LOW-DENSITY WIND TUNNEL
By Ruth N. Weltrnarm
Lewis Research Center
Cleveland, Ohio
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
WASHINGTON August 1962
NATiONAL AERONAUTICS AND SPACE ADMINISTRATION
TECHNICAL NOTE D-I169
DESiGN AND CALIBRATION OF ANARC-HEATED_
HYPERSONIC, LOW-DENSITY WIND TUNNEL
By Ruth N. Weltmann
SUMMARY
The design and calibration of an arc-heated gas jet that produces
a continuous flow in a wind tunnel at a Mach number of & to 5 are de-
scribed. Uniform flow conditions prevail over a central 1-inch-diameter
core at static pressures of to millimeter of mercury with en-
thalpies up to 4300 Btu per pound for nitrogen and ii00 Btu per pound
for argon. These conditions correspond to stagnation temperatures up to
9000 ° R, to altitudes of about 200_000 feet, and to velocities of about
ii,000 feet per second.
Details are given for design features that produce stability of a
confined arc over long periods of time with arc transfer efficiencies up
to 50 percent. For nitrogen, the downstream gas jet is about 5 percent
dissociated_ and the vibrational energy is in equilibrium before the gas
enters the nozzle throat.
Mass-averaged total downstream enthalpies, computed from profile
measurements made with total-pressure probes and several stagnation-
point heat-transfer probes of similar design about i/¢ inch downstream
of the nozzle exit_ agree within i0 percent with puted
from electric-power input, mass-flow rates_ and coolant temperature rise.
The enthalpies determined in the center core are about 20 percent higher.
INTRODUCTION
The theoretical and experimental study of high-energy, hypersonic,
low-density gas flow and of the interaction with solid bodies is required
for the solution of research problems in the areas of sustained flight
at high altitudes, plasma and ion propulsion, reent