Short-duration test facility obtains extremely high Reynolds number flows in subsonic, transonic, and supersonic speed ranges, and aids in solving Reynolds number-dependent aerodynamic and thermodynamic problems in design and testing of large, high speed vehicles. The modified blowdown wind tunnel avoids data confusion and aerodynamic noise

Davis, J. W.

Hill, O. E.

English

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Scpemhcr 1970	 Brief 70 1026 
.
NASA TECH BRIEF 
:â 15 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage commercial 
application. Tech Briefs are available on a subscription basis from the Clearinghouse for Federal Scientific and Technical 
Information, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Division, NASA, Code UT, Washington, D.C. 20546. 
Short-Duration, Transonic Flow, Variable-Porosity Test Section 
A relatively inexpensive short-duration test facility 
has been constructed in which extremely high Reynolds 
number flows are obtained in the subsonic, transonic, 
and supersonic speed ranges. This device, a section of 
which is illustrated, has been found useful in solving 
a number of Reynolds number-dependent aerodynamic 
and thermodynamic problems in the design and test-
ing of large, high speed vehicles. 
Basically, the method employs a type of blowdown 
Hid tunnel in which the usual air storage vessels have
been replaced by a long tube filled with highly pres-
surized gas. Upon bursting of a diaphragm, a short-
duration steady flow on the order of 500 ms is achieved 
behind a centered rarefaction fan, which propagates 
into the gas supply tube. Useful testing has been ac-
complished during this period by expanding the gas to 
the desired test condition. 
Action of the rarefaction fan sets the gas in motion 
and results in a reduction of its pressure and tem-
perature. The lowered pressure causes flow to pass 
(wniunued oserical) 
This document was prepared under the sponsorship of the National	 Governmãnt 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 
Government nor any person acting on behalf of the United States	 will be free from privately owned rights.
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through the inclined holes in the sleeve assembly, 
through the plenum chamber, and out the covering. 
In conventional chambers, at any given mach num-
ber larger then 1, shock and expansion waves, orginat-
ing at the test model, travel to the chamber wall, re-
flect back to the model and confuse the data. This 
design, employing a sleeve assembly composed of an 
inner and an outer wall, each with an identical inclined 
hole pattern with a maximum of 10 percent open area, 
avoids this problem. By translating the outer wall 
with respect to the inner wall, the percent open area 
can be changed from zero to 10 percent, allowing 
optimum transient wave cancellation at any mach 
number in the range of interest. Inclined holes restrict 
outflow from the plenum chamber back to the free 
stream and a plenum flow optimization liner main-
tains uniform flow conditions at all points in the test 
region. 
Notes: 
1. This equipment has produced Reynolds number 
flows 4 to 6 times larger than existing long-du-
ration facilities. It also avoids the aerodynamic 
noise associated with conventional valve diffusers 
and turbines.
2. The following documentation may be obtained 
from:
Clearinghouse for Federal Scientific 
and Technical Information 
Springfield, Virginia 22151 
Single document price $3.00 
(or microfiche $0.65) 
Reference: 
NASA-TM-X-53571 (N68-18190) 
Feasibility Studies of a Short 
Duration High Reynolds Number 
Tube Wind Tunnel 
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA, Code 
GP, Washington, D.C. 20546. 
Source: John W. Davis and

Olen E. Hill
Marshall Space Flight Center

(MFS-20509) 
Brief 70-10256	 Category 03


Short-duration, transonic flow, variable-porosity test section

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