Investigation utilizes static and fluctuating pressure measurements and oil flow visualization techniques to analyze perturbed flow environments of three-dimensional protuberances and the surrounding structure. Significant findings are given

Robertson, J. E.

English

NASA Technical Reports Server

July 1971	 Brief 71-10254 
NASA TECH BRIEF 
Marshall Space Flight Center 
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 National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the. Tech Brief program may 
be directed to the Technology. Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Wind Tunnel Investigations at Transonic Mach Numbers 
is
The flow field induced in a wind tunnel by 
three-dimensional protuberances at transonic 
Mach numbers was investigated. The perturbed 
flow environments of both the protuberances and 
the surrounding structure were analyzed using 
static- and fluctuating-pressure measurements and 
oil-flow visualization techniques. Test results for 
the generalized configuratins, which consisted of 
three different sized diameter cylindrical protuberances 
(of the ratio d, d 2l, and, d 3 , where d = diameter of 
smallest protuberance) were derived for a range of 
test variables consisting of protuberance heights 
from zero to twice the protuberance diameter, free-
stream Mach numbers from 0.60 to 1.60, and Reynolds 
numbers from 1.5 to 4.5 million per 0.30 rn of cyl-
inder length. 
The static pressure results are presented in 
coefficient form to show the axial pressure dis-
tributions associated with the protuberance induced 
flow field, as well as the distribution of surface 
pressures over the wall of the protuberances. 
Fluctuating pressure measurements are presented 
in the form of overall rms fluctuating pressure 
coefficients, power spectra, cross-power spectra, 
and narrow band convection velocities. 
From the static- and fluctuating-pressure measure- 
ments and the oil-flow patterns, the structure of 
the perturbed flow field is defined. One of the most 
significant findings is that the upstream separated
flow field induced by three-dimensional protuberances 
consists of a complex, multiple vortex system which 
generates fluctuating pressures that are an order 
of magnitude greater than those observed in 
two-dimensional separated flows. The extreme 
fluctuating pressures encountered within the three-
dimensional separated flow field are attributed to 
the shear interaction of two major vortices within 
the separated region. 
Notes: 
1. The experimental data can be used by aircraft 
designers for estimating the structural loading 
in a full-scale vehicle. 
2. No additional documentation is available. Specific 
questions, however, may be directed to: 
Technology Utilization Officer 
Code A&TS-TU 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: B71-10254 
Patent status: 
No patent action is contempated by NASA. 
Source: J. E. Robertson of

Wyle Laboratories
under contract to

Marshall Space Flight Center

(M FS-20895) 
Category 06 
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 
Government nor any person acting on behalf of the United States 	 will be free from privately owned.rights.
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Wind tunnel investigations at transonic Mach numbers

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