Unique features of wind tunnel facilities at Jet Propulsion Laboratory permit variety of conventional and novel tests to be performed at supersonic and hypersonic speeds. Facilities and operations are described

Herrera, J. G.

English

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1972	 B72-10078 
NASA TECH BRIEF 
NASA Pasadena Office	 -4r 
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be directed to the Technology Utilization Office, NASA, Code KT, Washington, D. F. 20546. 
Continuous-Flow Variable-Density 
Wind Tunnel Facilities 
The unique features of the continuous-flow variable-
density wind tunnel facilities at the Jet Propulsion 
Laboratory permit a variety of conventional and 
novel tests to be performed at supersonic and hyper-
sonic speeds. Typical tests include: force and moment 
measurements; pressure measurements; temperature 
and heat-transfer measurements; free-flight model 
testing; telemetry measurements; multi-gas testing; 
low-Reynolds number studies. 
The facilities include a 20-inch supersonic wind 
tunnel and a 21-inch hypersonic wind tunnel which 
utilize two-dimensional flexible nozzles to provide 
an almost infinite choice of test section Mach num-
bers within a specified range. The hypersonic wind 
tunnel uses a pair of solid-block throats with an ad-
justable throat height in the test section; the blocks 
remain dimensionally stable for all practical purposes 
in spite of the temperature of the high-pressure air 
supplied to it. 
Moisture is removed from the air used in the tun-
nels; about 90% of the moisture content is removed 
by refrigeration, and activated-alumina beds extract 
most of the remainder. Air is supplied to both tunnels 
by a compressor plant which contains eleven centri-
fugal compressors that can be grouped into a variety 
of configurations; a twelfth (axial-flow type) is used 
to reduce tunnel supply pressure below atmospheric 
pressure. Air supplied to the hypersonic wind tunnel 
is heated by electric power so that condensation does 
not occur in the test section; an after cooler extracts 
heat from the exhaust air so that problems inherent
with the compression of hot air are minimized. 
The Mach-number range of the supersonic wind 
tunnel varies from 0.3 to 0.8 and 1.3 to 5.0 (runs at 
M = 5.6 have been made), with corresponding earth 
pressure altitude simulation from about 5 to 55 km. 
The geometric test section is 18 inches wide (46 cm) 
and nominally 20 inches high (51 cm). 
The hypersonic wind tunnel can be operated over 
a Mach-number range of 4.0 to 11.0, and will simu-
late an earth altitude pressure from 85,000 to 220,000 
feet (about 26 to 67 km). Supply air temperature 
can be varied from 88° to 730°C. The wind tunnel 
test section is 21 inches wide (about 53 cm) at the 
downstream end and height is adjustable from 15 to 
28 inches (38 to 71 cm); each side wall diverges 
approximately 0.5 degree to compensate for boun-
dary-layer thickness. 
The basic model suspension system of both wind 
tunnels features a vertical traverse and a crescent-
type support that can be pitched by remote control; 
sidewall mounts are available in the supersonic tunnel. 
A variety of test instrumentation displays quanti-
tative data in analog, digital, or visual form. The 
information is collected automatically by a computer-
controlled recording device that serves both tunnels 
and the test preparation area. The device has a total 
capability of 80 strain-gage channels, 200 thermo-
couple channels, and eighteen 36-bit data channels. 
Test programs conducted in the wind tunnel facili-
ties are usually prefaced by a test proposal which 
defines the technical objectives, indicates the required 
-	 (continued overleaf) 
This document was prepared under the sponsorship of the National 	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
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https://ntrs.nasa.gov/search.jsp?R=19720000078 2020-03-17T03:24:13+00:00Z
wind tunnel test conditions, describes the model and 
its suspension, and lists the necessary raw and re-
duced data. A project engineer is assigned to the 
test; an advanced planning conference, a model de-
sign conference, and a pretest conference are held 
to acquaint government or industry contractors and 
all project personnel with test requirements. 
Note: 
Requests for further information may be di-
rected to:
Technology Utilization Officer 
NASA Pasadena Office 
4800 Oak Grove Drive 
Pasadena, California 91103 
Reference: TSP72-10078 
Source: J
.
 Gilbert Herrera of
Caltech/JPL
under contract to 
NASA Pasadena Office 
(NPO-11287) 
Category 06


Continuous-flow variable-density wind tunnel facilities

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