Shock Wave Science and Technology Reference Library, Vol. 5: Non-Shock Initiation of Explosives

630 Pages·2010·16.213 MB·English

by  Blaine W. Asay (auth.), B. W. Asay (eds.)

ShockWaveScienceandTechnology Reference Library
The new Springer collection, Shock Wave Science and Technology Reference Library,
conceived in the style of the famous Handbuch der Physik has as its principal motivation
toassembleauthoritative,state-of-the-art,archivalreferencearticlesbyleadingscientistsand
engineersinthefieldofshockwaveresearchanditsapplications.Anumberedandbounded
collection, this reference library will consist of specifically commissioned volumes with
internationallyrenownedexpertsaseditorsandcontributingauthors.Eachvolumeconsistsof
asmallcollectionofextensive,topicalandindependentsurveysandreviews.Typicalarticles
start at an elementary level that is accessible to non-specialists and beginners. The main
part of the articles deals with the most recent advances in the field with focus on experi-
ment, instrumentation, theory, and modeling. Finally, prospects and opportunities for new
developmentsareexamined.Lastbutnotleast,theauthorsofferexpertadviceandcautions
thatarevaluableforboththenoviceandthewell-seasonedspecialist.
ShockWaveScienceandTechnology Reference Library
CollectionEditors
HansGro¨nig
Hans Gro¨nig is Professor emeritus at the Shock Wave Laboratory of
RWTHAachenUniversity,Germany.HeobtainedhisDr.rer.nat.degree
in Mechanical Engineering and then worked as postdoctoral fellow at
GALCIT, Pasadena, for one year. For more than 50 years he has been
engaged in many aspects of mainly experimental shock wave research
including hypersonics, gaseous and dust detonations. For about 10 years
hewasEditor-in-ChiefofthejournalShockWaves.
YasuyukiHorie
Professor Yasuyuki (Yuki) Horie is internationally recognized for his
contributionsinhigh-pressure shockcompression ofsolidsandenergetic
materialsmodeling.Heisaco-chiefeditoroftheSpringerseriesonShock
Wave and High Pressure Phenomena and the Shock Wave Science and
Technology ReferenceLibrary,andaLiaisoneditorofthejournalShock
Waves. He is a Fellow of the American Physical Society, and Secretary
of the International Instituteof Shock WaveResearch. Hiscurrent inter-
ests include fundamental understanding of (a) the impact sensitivity of
energeticsolidsanditsrelationtomicrostructureattributessuchasparticle
size distribution and interface morphology, and (b) heterogeneous and
nonequilibriumeffectsinshockcompressionofsolidsatthemesoscale.
KazuyoshiTakayama
ProfessorKazuyoshiTakayamaobtainedhisdoctoraldegreefromTohoku
Universityin1970andwasthenappointedlecturerattheInstituteofHigh
SpeedMechanics, Tohoku University,promoted toassociateprofessor in
1975 and to professor in 1986. He was appointed director of the Shock
WaveResearchCenterattheInstituteofHighSpeedMechanicsin1988.
TheInstituteofHighSpeedMechanicswasrestructuredastheInstituteof
FluidSciencein1989.Heretiredin2004andbecameemeritusprofessor
ofTohokuUniversity.In1990helaunchedShockWaves,aninternational
journal,takingontheroleofmanagingeditorandin2002becameeditor-
in-chief. He was elected president of the Japan Society for Aeronautical
andSpaceSciencesforoneyearin2000andwaschairmanoftheJapanese
SocietyofShockWaveResearchin2000.Hewasappointedpresidentof
theInternationalShockWaveInstitutein2005.Hisresearchinterestsrange
fromfundamental shockwavestudiestotheinterdisciplinaryapplication
ofshockwaveresearch.
B.W. Asay (Ed.)
Shock Wave
Science and Technology
Reference Library, Vol. 5
Non-Shock Initiation of Explosives
With298 Figures and 31 Tables
123
BlaineW.Asay
LosAlamosNationalLaboratory
ExplosivesApplicationsandSpecialProjects
LosAlamosNM87545
USA
Email:[email protected]
BlaineW.Asay
BlaineW.AsayisaResearchScientistandGroupLeaderintheExplosive
Applications and Special Projects group at Los Alamos National Labo-
ratory. His research interests include hypervelocity jet initiation, DDT,
novel energetic materials,thermobarics, abnormal initiation,and thermal
response. He has published over 50 papers in the refereed literature and
presented numerous papers at international conferences, and also holds
several patents. Dr. Asay received the Ph.D. in Chemical Engineering
forhisworkincombustionfromBrighamYoungUniversityin1982and
workedatKodakResearchLaboratoriesbeforejoiningLANLin1984.
ISBN978-3-540-87952-7 ISBN978-3-540-87953-4 (eBook)
DOI10.1007/978-3-540-87953-4
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Preface
Los Alamos National Laboratory is an incredible place. It was conceived and
born amidst the most desperate of circumstances. It attracted some of the
most brilliant minds, the most innovative entrepreneurs, and the most cre-
ative tinkerers of that generation. Out of that milieu emerged physics and
engineering that beforehand was either unimagined, or thought to be fan-
tasy. One of the fields essentially invented during those years was the science
of precision high explosives. Before 1942, explosives were used in munitions
and commercial pursuits that demanded proper chemistry and confinement
for the necessary effect, but little else. The needs and requirements of the
Manhattan project were of a much more precise and specific nature. Spatial
and temporal specifications were reduced from centimeters and milliseconds
to micrometers and nanoseconds. New theory and computational tools were
required along with a raft of new experimental techniques and novel ways of
interpreting the results. Over the next 40 years, the emphasis was on higher
energy in smaller packages, more precise initiation schemes, better and safer
formulations, and greater accuracy in forecasting performance. Researchers
from many institutions began working in the emerging and expanding field.
In the midst of all of the work and progress in precision initiation and
scientific study, in the early 1960s, papers began to appear detailing the first
quantitative studies of the transition from deflagration to detonation (DDT),
first in cast, then in pressed explosives, and finally in propellants. Clearly
this phenomenon had been observed before, and was undoubtedly the cause
of many accidents, but with the improved diagnostic techniques (e.g., image-
intensifiedcameras,rapidoscilloscopes,etc.)workerswerefinallyabletobegin
toprobethisverydifficultareaofreactivematerialbehavior.Theseformedthe
initial studies of what has come to be known as nonshock initiation. This be-
haviorandthereasonsitissodifficulttounderstandareexploredinChap.1.
If an explosive is going to react violently, an ignition event must oc-
cur at some location within the volume. That ignition will be at a single
point, perhaps in asmall portion of acrystal. Whatever its size, to propagate
VI Preface
the reaction, mass, momentum, and energy must be conveyed (conducted,
convected, radiated, or advected) to other locations on a timescale that pro-
motes growth of temperature and pressure. Transport phenomena have been
studied for hundreds of years, but in the context of nonshock initiation, we
felt that a complete presentation was required to place the common terms
into context. This forms the substance of Chap. 2 by Perry.
Explosives are metastable molecules – they are always reacting, but the
rate is extremely temperature sensitive. Depending on the material and tem-
perature, the reaction rate can double with an increase of only a few degrees
centigrade. The physics and chemistry governing this behavior are extremely
complex. For example, the decomposition of HMX has been described with
over 500 elementary kinetic steps, and it is known that this is not a complete
treatment. Trying to use that kind of description to understand the behav-
ior of a reactive system is impossible, even with the latest state-of-the-art
computational capabilities. We require a more global approach to the entire
decomposition process. The ability to do that requires enormous insight, a
fundamental understanding of chemistry, and the capability of reducing pro-
cesses to their most simple, yet complete, level. But no further. Henson has
done just that in Chap. 3.
Onceinitiated,anexplosivegrain,orhotspot,caneitherfail,survivefora
shortamountoftime,orprogressandgrow.Thisistheproblemofcriticality,
and without knowing how this process occurs, it is impossible to understand
or predict the outcome of an initiation event. In Chap. 4, Hill discusses in
detail the important issues surrounding the topic of criticality, upon what it
depends and how it affects the outcome of an event.
If a hotspot survives, the reaction may then proceed through the body of
material. This process is called combustion, and involves the conversion of a
solid material having chemical energy into gas at much higher temperature
and pressure. The rate at which this occurs is governed by the kinetics, but
the process is controlled by how the mass, momentum, and energy move.
Combustion wavescanprogressatveryslowspeeds(fractionsofacentimeter
per second) or up to supersonic speeds in cracks. Clearly, the mechanism of
combustion is central to the concept of nonshock initiation and is covered by
Jackson in Chap. 5.
HMX is a very powerful explosive, but at atmospheric pressure and no
confinement, it burns very slowly and in a laminar fashion. However, allow
thepressuretoincreasesomewhat,andprovidesurfaceareaandconfinement,
and that lazy laminar combustion wave can easily convert into a detonation
wave with pressures of thousands of atmospheres. In Chap. 6, Parker and
Rae discuss the damage mechanisms that create the surface area without
whichthetransitiontodetonationcannotoccurinsecondaryexplosives.This
is an area of study of relatively recent vintage and which some have been
slowtoacknowledge.However,ourabilitytodirectlyobservereactingsystems
beingdamagedhasincreasedsubstantiallyinthepast10years,enablingthese
conclusions to be considered incontrovertible.
Preface VII
Chapter7discussesthetopicofcookoff,whichcompriseseachofthetopics
discussed before. It is a general term that includes explosion as well as det-
onation. The chapter discusses the small and large-scale tests used to study
the field of nonshock initiation and some of its important elements.
Thedeflagrationtodetonationtransitionwasalludedtoinanearlierpara-
graphandisdiscussedinotherportionsofthetext,butitneededachapterof
its own to be elucidated more fully. The earliest papers accurately described
the overall behavior of explosives, but in many cases missed the quantitative
response. In Chap. 8 McAfee provides a complete treatment of the DDT pro-
cessincorporatingalloftheadvancesthathaverecentlyoccurred,andunifies
many of the observations that have been made over the past 50 years.
Itispossibletodroparelativelylargepieceofexplosivefromasubstantial
distance onto a very hard surface and have no reaction. However, take that
same explosive part, and the same hard surface and add a few grains of sand,
andanentirelydifferentoutcomeobtains.Thestudyoffrictionalinitiationhas
alonghistorywithmanyelegantexperimentshavingbeenconducted.Dickson
provides a well-reasoned and complete analysis of the topic in Chap. 9.
Finally, in Chaps. 10 and 11, Kennedy covers the areas of initiation by
shear and impact, followed by spark and laser. These topics are sometimes
overlooked because they are not very well characterized, but the first three
constitute primary sources of accidental nonshock initiation, and the last is a
current topic of study for purposeful ignition of explosives.
We hope that readers will see the organization of the text as a natural
progression in the study of nonshock initiation. It is by no means an easy
field of study, nor one in which all of the major questions have been worked
out. Each of the authors of this volume is not only an expert in the field,
but someone who has thought deeply about the topic. It took several years
to formulate the concepts, reduce them to the written word, and then finally
producesomethingworthyofpublication.Eachhasbeenagreatresourceand
animportantandtrustedcolleagueformanyyears.Iamindebtedtoeachone
for his contribution to my understanding of the field. I also acknowledge the
workofPhilHowe,withoutwhosetirelessandpersistentsupportmanyofthe
experiments and analyses discussed in this text would not have occurred. He
is an integral and crucial member of the team.
I have been incredibly fortunate to have known some of the most influen-
tial men and women in the field of explosives research. At Los Alamos, I was
instructed in DDT by Wayne Campbell, shock physics by Mac Walsh, det-
onation physics by Bill Davis and John Bdzil, detonation chemistry by Ray
Engelke, propellant behavior and explosives safety by John Ramsay, shaped
charge design by Bill Mautz, and the list goes on. I have also had the privi-
lege of meeting pioneer researchers from throughout the world ranging from
Kondrikov and Dremin from Russia to Price and Jacobs from White Oak.
As funding and support for the kind of work we do erodes, the community
is becoming ever smaller. I am grateful to have been involved during some of
the high points.
VIII Preface
I want to thank my closest coworkers of many years, Laura Smilowitz,
Bryan Henson, Steve Son, John McAfee, and Peter Dickson. The thousands
ofhoursspentindiscussion,writing,somearguing,andwaitingforthatelusive
exotherm have been joyous.
Finally, I acknowledge the inestimable influence of my four children who
have each exceeded every expectation of which I could have ever conceived,
and my wife and eternal companion, Patrice, who completes me.
Los Alamos, NM, October 2009 Blaine W. Asay
Contents
1 Introduction
Blaine W. Asay.................................................. 1
1.1 Background................................................ 3
1.2 What Are We Able to Predict?............................... 5
1.3 What Are We Unable to Predict? ............................ 7
1.4 Numerical Approaches ...................................... 9
1.5 Motivation for This Text .................................... 11
1.6 Purpose of This Book....................................... 11
1.7 Final Word of Caution ...................................... 13
References ...................................................... 14
2 Transport Phenomena for Nonshock Initiation Processes
W. Lee Perry.................................................... 15
2.1 An Overview of Transport Theory in Explosives Problems ....... 15
2.2 The Origins of Transport Theory in the Field on Nonshock
Initiation.................................................. 19
2.3 Physical Properties Used in Transport Theory Analysis ......... 22
2.4 Transport Theory Equations ................................. 27
2.5 Selected Examples of Transport Theory Applied to Explosive
Problems.................................................. 30
2.6 Summary.................................................. 41
References ...................................................... 42
3 The Chemical Kinetics of Solid Thermal Explosions
Bryan F. Henson and Laura B. Smilowitz ........................... 45
3.1 Introduction ............................................... 45
3.2 General Considerations...................................... 49
3.2.1 Chemical Kinetics and Explosives Modeling ............ 49
3.2.2 Types of Models .................................... 73
3.2.3 Modeling Objectives ................................. 76