Data from absorption coefficients and fine-structure parameters measured for water vapor have been incorporated in an analytic program useful in evaluating heating by radiation from the exhaust plume of a large rocket

Ludwig, C. B.

English

NASA Technical Reports Server

September 1969
	
Brief 69-10371 
NASA TECH!BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information-,Springfield, Virginia 22151. 
Prediction of Thermal Radiation from a Rocket's Exhaust Plume 
.
The absorption coefficients and fine-structure 
parameters have been measured for water vapor at 
wavelengths between 1 and 10 tLm at temperatures 
between 1,200° and 3,000°K. The resultant data 
have been incorporated in a practical analytic pro-
cedure that can be used for evaluation of heating 
by radiation from the exhaust plume of the base 
of a large rocket. 
A uniform volume of high-temperature water 
vapor was produced above the combustion zone of a 
specially constructed long, 3-inch-wide, flat burner. 
Emission and absorption were measured, with path 
lengths of 2, 5, and 10 feet, at temperatures between 
1,200° and 3,000°K. From these measurements 
mean absorption coefficients and fine-structure param-
eters (averaged over 25-cm- 1 intervals) were de-
duced for the spectral interval between 1,000 and 
9,000 cm- 1 . The resultant data are presented in 
both graphic and tabular forms, with polynomial 
representations also. 
Combination of these results with earlier data has 
generated tables of water-vapor absorption coeffi-
cients covering the spectral region between 50 and 
9,300 cm-' and the temperature range between 
300° and 3,000°K; the representation of the fine-
structure parameters covers the ranges between 
1,150 and 9,300 cm-1 and 1,250° and 2,750°K. 
Several nonisothermal measurements, with two 5-
foot sections at different temperatures, were made
to test the nonisothermal-radiance calculation pro-
cedure. The following analytic studies were made: 
(1) extension of the high-pressure-limit calculation 
for the total engineering emissivity to self-broadened 
and nitrogen-broadened water vapor, with use of 
published absorption coefficients and band-averaged 
fine-structure parameters; (2) study of band models 
for randomly distributed Doppler lines; (3) an error 
and sensitivity analysis of the inhomogeneous-radi-
ance calculation technique; and (4) study of an al-
ternative expression for the collision-broadened line 
width. 
Notes: 
1. This information may interest personnel con-
cerned with thermal radiation from gases. 
2. Documentation is available from: 
Clearinghouse for Federal Scientific 
and Technical Information 
Springfield, Virginia 22151 
Price $3.00 
Reference: TSP69-1 0371 
Patent status: 
No patent action is contemplated by NASA. 
Source: C. B. Ludwig et al. of
General Dynamics Corporation
under contract to
Marshall Space Flight Center
(MFS-204 14) 
Category 02 
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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Prediction of thermal radiation from a rocket's exhaust plume

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