A Study of the Radiation From Laminar and Turbulent Open Propane-Air Flames as a Function of Flame Area, Equivalence Ratio, and Fuel Flow Rate Page: 3 of 42
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NACA RM E54F29
NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS
RESEARCH MEMORANDUM
A STUDY OF THE RADIATION FROM LAMINAR AND TURBULENT OPEN
PROPANE-AIR FLAMES AS A FUNCTION OF FLAME AREA,
EQUIVALENCE RATIO, AND FUEL FLOW RATE
By Thomas P. Clark and David A. Bittker
SUMMARY
Radiation measurements have been made on open propane-air flames
to find the extent to which radiant flux intensity can be used to
measure the surface area of such flames. For laminar flames of a given
equivalence ratio, intensity changes linearly with both fuel flow rate
and photographically measured surface area. Moreover, the intensity per
unit area of the flame depends on only the equivalence ratio.
Turbulent flame intensity is also proportional to fuel flow rate.
Laminar and turbulent flames at identical conditions of flow rate, equiv-
alence ratio, and burner diameter have approximately the same radiation
intensities. Furthermore, the spectral intensity distributions appear
to be the same for both types of flames, which suggests that the
kinetics may also be the same. These results are entirely compatible
with the current "extended surface" concept of turbulent flame structure;
they do not, however, rule out other theories of the structure of
turbulent flames.
INTRODUCTION
Much of the theoretical and experimental work on hydrocarbon
flames has revolved around the concept of a fundamental burning velocity.
This burning velocity or "flame speed" is defined as the rate of advance
of a reaction zone into a nonturbulent gas stream. In most practical
combustion systems such as furnaces, combustion chambers, and aircraft
power plants, however, the burning gases are highly turbulent. The need
thus arises for a study of the burning velocities of flames in turbulent
gas mixtures.
One common way of expressing the fundamental burning velocity of a
laminar flame is as the quotient of the gas volume flow divided by the
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Clark, Thomas P. & Bittker, David A. A Study of the Radiation From Laminar and Turbulent Open Propane-Air Flames as a Function of Flame Area, Equivalence Ratio, and Fuel Flow Rate, report, August 24, 1954; (https://digital.library.unt.edu/ark:/67531/metadc64986/m1/3/: accessed April 18, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.