Table Of ContentFlames
Their structure, radiation
and temperature
Flames
Their structure, radiation
and temperature
A. G. GAYDON, D.Sc., F.R.S.
Emeritus Professor of Molecular Spectroscopy
Imperial College, London
and formerly Warren Research Fellow
of the Royal Society
AND
H. G. WOLFHARD, Dr. rer. nat.
Institute for Defense Analyses, Arlington, Va.
FOURTH EDITION
@
LONDON
CHAPMAN AND HALL
A Halsted Press Book
John Wiley & Sons, New York
First published 1953
Second edition (revised) 1960
by Chapman and Hall Ltd
11 New Fetter Lane, London EC4P 4EE
Third edition (revised) 1970
Fourth edition (revised) 1979
© 1979 A. G. Gaydon and H. G. Wolfhard
Typeset by Fletcher & Son Ltd, Norwich
and printed in Great Britain by
Richard Clay (The Chaucer Press) Ltd
Bungay, Suffolk
ISBN 0 412 15390 4
All rights reserved. No part of this book may be
reprinted, or reproduced or utilized in any form or
by any electronic, mechanical or other means, now
known or hereafter invented, including photo-
copying and recording, or in any information
storage or retrieval system, without permission in
writing from the publisher.
Library of Congress Cataloging in Publication Data
Gaydon, Alfred Gordon.
Flames, their structure, radiation, and
temperature.
“A Halsted Press Book.”
Bibliography: p.
Includes indexes.
1. Flame. I. Wolfhard, Hans G., joint author.
Il. Title.
QDS516.G28 1978 541'.361 78-16087
ISBN 0-470-26481-0
Distributed in the U.S.A. by Halsted Press,
a Division of John Wiley & Sons, Inc., New York
Preface to First Edition
The science of combustion has now become so large, and embraces so
many other aspects of science that it is no longer practical adequately to
cover the whole field in a single book, or indeed for two authors to deal
with all sides of the subject. The aim here is to give a fairly advanced dis-
cussion of a part of the field, that concerned with stationary flames, with
the emphasis on the physical rather than the chemical viewpoint.
Bone & Townend’s Flame and Combustion in Gases (1927) gives a clear
account of many aspects of flame structure, and is valuable historically, but
is now out of date. More recent books, Explosion and Combustion Processes
by Jost, and the revised edition of Combustion Flames and Explosions by
Lewis & von Elbe give a very good general introduction to the subject
of combustion, especially the chemical aspects. There are, however, many
parts of the subject which are not completely covered for various reasons.
Among the subjects on which we have especially concentrated are the
measurement of flame velocity, the theories of flame propagation, the
method of carbon formation in flames, flame radiation, the measurement
of high flame temperatures and ionisation in flames. Many of these topics
were considered by Lewis & von Elbe to be in too fluid a state or too
controversial, and this is indeed to some extent true, but nevertheless they
are among the most interesting. Some fields, such as the chemical kinetics
of combustion processes, cool flames, minimum ignition energies, quench-
ing distances and flame stability which have been very ably discussed in the
books mentioned are not fully dealt with here, only sufficient mention
being made of them to preserve the continuity of this book. Rather sur-
prisingly there is little overlap with Spectroscopy and Combustion Theory
(Gaydon, 1948) although our recent spectroscopic work on low-pressure
flames and on the structure of flat diffusion flames is included here. The
new book by Thring The Science of Flames and Furnaces gives a good
account of the heating of furnaces by large industrial flames, but has little
in common with the problems of laboratory flames discussed here.
Our aim is to present as clearly as possible the underlying physical pro-
cesses occurring in flames. We fully realise, of course, the need for quanti-
tative measurements, but have avoided purely mathematical discussion;
vi FLAMES
indeed we have little enthusiasm for abstract mathematical treatments of
combustion, these usually involving many unknown and often unknowable
parameters.
We should like to express our sincere thanks to Sir Alfred Egerton,
F.R.S. for his encouragement and stimulation. We are also grateful to a
number of persons for helpful discussion on various parts of the subject
and for co-operation in obtaining photographs and diagrams. We should
like especially to thank Drs. J. Barr (Glasgow), H. P. Broida (U.S. Bureau
of Standards), J. H. Burgoyne (Imperial College), H. Behrens (Weil a/R.
Germany), J. E. Garside (Leeds), W. Gohrbandt and B. P. Mullins
(National Gas Turbine Est.), H. Hahnemann, W. G. Parker (Royal Air-
craft Est.), B. Lewis and G. von Elbe (U.S. Bureau of Mines), W. A.
Simmonds (Gas Research Board) and K. Wohl (Delaware). One of us
(A.G.G.) is indebted to the Royal Society for the award of a Warren Re-
search Fellowship, and the other (H.G.W.) to the Chief Scientist, Ministry
of Supply, for permission to publish. We also wish to thank the Editor of
Endeavour for help in supplying the blocks for the colour plates.
Chemical Engineering Department, A.G.G.
Imperial College,
London, S.W.7.
Royal Aircraft Establishment, H.G.W.
Farnborough,
Hants.
May 1952
vii
Preface to Fourth Edition
The first edition of this book appeared in 1953 and it was revised in 1960
and 1970. This further revision has been prompted by the steady demand.
Although the lay-out and chapter headings have remained practically un-
changed for all editions, revision in each case has been thorough. In the
preface to the third edition we said that knowledge of flames was then
more certain and quantitative so that the book was in more definitive
form; this has been partly true, but the development of new techniques,
such as laser-Doppler anemometry, laser-Raman spectroscopy and com-
puter handling of data, have led to appreciable advances in our detailed
knowledge of flames. This fourth edition appears deceptively similar to
the third. The problem has been to bring the book up to date without losing
the basic clarity and emphasis on a simple physical understanding of flame
processes. To this end we have added over 200 new references, deleting
over 60 old ones, and have also inserted 17 new figures and two plates,
with some extra sections on new techniques and a more thorough revision
of some parts, such as flame propagation, structure of turbulent flames and
soot formation. We have still endeavoured to keep the emphasis on the
basic physical principles, avoiding detailed chemical processes or too much
formal mathematics, but we have been able to include some extra numeri-
cal data, e.g. for reaction rates.
There are some fairly recent books on various aspects of combustion
such as Flame Structure (Fristrom & Westenberg, 1965), Fundamentals of
Combustion (Strehlow, 1968), Electrical Aspects of Combustion (Lawton
& Weinberg, 1969), Industrial Flames. I. Measurements in Flames (Chedaille
& Braud, 1972), Combustion Technology (Palmer & Beer, 1974), Spectro-
scopy of Flames (Gaydon, 1974) and Introduction to Combustion Pheno-
mena (Kanury, 1975), but the emphasis in all these is different and they do
not cover in any detail the subjects discussed here.
A minor problem has been the recent change to International System
(S.I.) units. Most of the work on flames so far published has been in c.g.s.
or more practical units. While a change here to S.I. would appear desir-
able, there are difficulties in making a simple conversion. Thus if a measure-
ment is made at 10 torr pressure, using an actual mercury manometer, is it
viii FLAMES
realistic to say it was made at 1-333 KN m-?? Should work at 1 atm. be
described as at 101-3 KN m-?? We have also left most thermochemical
data in kcal/mole (1 kcal = 4-184 J) and flame speeds in cm/sec rather than
m/s, but have changed temperatures from °k to K and inches to mm.
The revision for this edition has been done by one of us (A.G.G.) as the
other (H.G.W.) has been unable to spare the time.
We are grateful to Dr D. R. Ballal and Dr P. A. Marsh for providing
prints for the new Plates 21 and 22.
Chemical Engineering Department, A.G.G.
Imperial College,
London, S.W.7.
Institute for Defense Analyses, H.G.W.
Arlington,
Virginia.
ix
Contents
Preface to First Edition pagev
Preface to Fourth Edition vii
INTRODUCTION
Flame - Stationary flames — Propagating flames —- Physics or
chemistry?
II PREMIXED FLAMES
The Bunsen burner - The Méker burner - Laminar premixed
flames - The Smithells separator —- Turbulent flames — Flame
stability - Quenching - Low-pressure flames and their struc-
ture - Spontaneous ignition and cool flames - Ignition by
external means- Limits of flame propagation — The position of
luminous zones — Polyhedral and cellular flames — The transi-
tion between premixed fiames and diffusion flames.
lil FLOW VISUALISATION AND FLAME
PHOTOGRAPHY
The gas flow from a burner — The measurement of the gas flow
~ Laser-Doppler anemometry - The photography of the
flame cone - Particle-track photography - Schlieren photo-
graphy — Interferometry — Lasers and holography — The flame
thrust, and its effect on cone shape — The tip of the flame.
IV MEASUREMENTS OF BURNING VELOCITY 58
The burning velocity - Gouy’s flame-area method - Modified
flame-area and cone-angle methods - The nozzle method -
The particle-track method — Methods of locating the flame
front — Rectified flat-flame methods — The flame-thrust method
- The soap-bubble method - The spherical-bomb method -
x FLAMES
Page
The revised tube method - Comparison of burning velocity
Measurements - The temperature dependence of burning
velocity - The pressure dependence of burning velocity —- The
influence of hydrocarbon structure on burning velocity - The
influence of mixture strength, diluents and additives - The
burning velocity of turbulent flames.
V THE STRUCTURE OF THE REACTION ZONE
AND ITS RELATION TO FLAME
PROPAGATION 92
Introduction - The preheating zone - The ignition point - The
reaction zone; radical concentrations — The reaction zone; its
thickness in relation to burning veloci—- tThye relation between
burning velocity, temperature and radical concentration - The
effect of additives on burning velocity, flammability limits and
spontaneous thermal ignition — Early thermal and diffusion
theories of flame propagation - Combined thermal and
diffusion theories - The concept of excess enthalpy - The
concept of flame stretch ~ Reaction rates - The formation of
oxides of nitrogen — Flame propagation in turbulent gases.
VI DIFFUSION FLAMES 146
The height and shape of small flames — The candle flame - The
Wolfhard-Parker flat diffusion flame — Spectroscopic study
of structure — Counter-flow diffusion flames - Comparison of
diffusion with premixed flames - Turbulent flames - Thin
flames — The Coanda burner — Furnace flames — Combustion
of droplets and dusts - Flames on wicks; mixed fuels - Com-
bustion of liquids at a free surface.
VII FLAME NOISE AND FLAME OSCILLATIONS 177
Flame noise — Jet noise - Singing flames - Combustion cham-
ber oscillations - Flame flicker and other instabilities -
Sensitive flames — The influence of sound on premixed flames.
VIII SOLID CARBON IN FLAMES 195
Introduction — Diffusion flames — Premixed flames — The effect
of pressure — The effect of temperature - Explosion flames —
The effect of non-metallic additives - The effect of metallic
additives - Electrical effects - The nature of carbon particles
and deposits - The equilibrium between carbon and the
burnt gases - Detection of intermediate products — Isotope
