Model can be tested directly, which eliminates costly, time-consuming, and inaccurate method of making test models solely for purpose of determining thermophysical properties. Method is adaptable to numerous modifications and variations

Jones, R. A.

English

NASA Technical Reports Server

-	 February 1974
	 UPDATED COPY	 B73-10447 
Updated July 1975 
.
	 NASA TECH BRIEF	
'-Langley Research 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. 
New Method for Determining Thermophysical Properties

of Test Specimens 
A new method has been developed for determining 
the thermophysical properties of test specimens 
where p is the density, c is the specific heat, and k is the 
thermal conductivity) directly from a specimen such as a 
wind tunnel model. The illustration shows one example 
of use, but the method is adaptable to numerous 
modifications and variations. A model can be tested 
directly, which eliminates the costly, time-consuming, 
and inaccurate method of making test models solely for 
the purpose of determining thermophysical properties. 
The apparatus used includes the following: 
a. A heat source, 
b. The means for locating a test specimen and a 
reference specimen at a given distance from the 
heat source, 
c. The means for exposing the test and reference 
specimens to the heat source (a shutter),
d. The equipment for determining the time required to 
heat the specimens to a given temperature (a motion 
picture camera), and 
e. The equipment for measuring the temperature of the 
reference specimen as a function of time (a thermo-
couple and a recorder). 
The test specimen and the reference specimen of 
known specific heat are positioned a given distance from 
the heat source. A coating, such as a phase-change 
coating, is placed on the specimens to give a visual 
indication that a given temperature has been reached. 
The coating also ensures that both specimens have the 
same absorbtivity and receive the same heat rate. A 
motion picture camera is used to provide a record of 
the time from the beginning of the heating step (the 
opening of the shutter) to the melt of the phase-change 
coating. 
Shutter 
Heat Source	
'N1 
Motion Picture Camera
Test Specimen 
Tempilaq Coating
Reference Specimen 
Thermocouple Leads 
Thermocouple 
Recorder 
.
Apparatus for Determining Thermophysical Properties 
of Test Specimens
(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 
Government nor any person acting on behalf of the United States
	 will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19730000447 2020-03-17T07:29:40+00:00Z
After the heat source (a lamp bank) has reached its 
operating temperature, the camera is started; and 
then the shutter, which is interposed between the heat 
source and the specimens, is opened. The tempera-
ture of the reference specimen is recorded as a 
function of time. The heat rate to which the reference 
specimen has been subjected is determined from the 
temperature-time response of the reference specimen 
(as measured by the thermocouple), using the con-
ventional thin-skin calorimeter equation. This heat 
rate, together with the measured time required to melt 
the phase-change coating, then is used to determine 
the thermophysical properties of the test specimen 
from the transient, one-dimensional, heat-conduction 
equation for a semi-infinite solid subjected to a 
step-heat input at a constant heat rate. 
Notes: 
1. The following documentation may be obtained 
from: 
National Technical Information Service 
Springfield, Virginia 22151 
Single document price $5.75 
(or microfiche $2.25)
Reference: NASA CR-2434 (N75-10104/LK), 
Development of an Apparatus To Measure 
Thermophysical Properties of Wind Tunnel 
Heat Transfer Models 
2. Technical questions may be directed to:
Technical Utilization Officer 
Langley Research Center 
Mail Stop 139-A 
Hampton, Virginia 23665 
Patent status: 
This invention has been patented by NASA (U.S. 
Patent No. 3,789,654). Inquiries concerning non-
exclusive or exclusive license for its commercial 
development should be addressed to: 
Patent Counsel 
Langley Research Center 
Mail Stop 313 
Hampton, Virginia 23665 
Source: Robert A. Jones
Langley Research Center and
R. F. Romanowski and I. H. Steinberg of 
Grumman Aerospace Corp. 
under contract to
Langley Research Center 
(LAR- 11053) 
B73-10447	
Categories: 03 (Physical Sciences) 
04 (Materials)


New method for determining thermophysical properties of test specimens

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