Editing Detonation

{{Short description |Explosion at supersonic velocity}}
{{For|detonation in spark-ignition engines|Engine knocking}}
{{Distinguish|Denotation}}
[[File:TNT detonation on Kaho'olawe Island during Operation Sailor Hat, shot Bravo, 1965.jpg |thumb |300px |Detonation of [[TNT]], and [[shock wave]]]]

'''Detonation''' ({{etymology|la|{{Wikt-lang|la|detonare}}|to thunder down/forth}})<ref>{{cite web
     |url=         https://en.oxforddictionaries.com/definition/detonate
     |archive-url=         https://web.archive.org/web/20190222042210/https://en.oxforddictionaries.com/definition/detonate
     |url-status=         dead
     |archive-date=         February 22, 2019
     |title=       detonate
     |author=      Oxford Living Dictionaries
     |author-link= Oxford Living Dictionaries
     |work=        British & World English
     |publisher=   Oxford University Press
     |access-date= 21 February 2019
    }}</ref> is a type of [[combustion]] involving a [[supersonic]] exothermic front accelerating through a medium that eventually drives a [[shock front]] propagating directly in front of it. Detonations propagate supersonically through [[shock wave]]s with speeds about 1&nbsp;km/sec and differ from [[deflagration]]s which have subsonic flame speeds about 1 m/sec.<ref>{{cite book |title=Handbook of Fire Protection Engineering |date=2016 |publisher=Society of Fire Protection Engineers |page=390 |edition=5 |url=https://www.sfpe.org/standards-guides/sfpehandbook }}</ref> Detonation may form from an [[explosion]] of fuel-oxidizer mixture. Compared with deflagration, detonation doesn't need to have an external oxidizer. Oxidizers and fuel mix when deflagration occurs. Detonation is more destructive than deflagrations. In detonation, the flame front travels through the air-fuel faster than sound; while in deflagration, the flame front travels through the air-fuel slower than sound.

Detonations occur in both conventional solid and liquid explosives,<ref>{{cite book |last1=Fickett |first1=Wildon |last2=Davis |first2=William C. |title=Detonation |publisher=University of California Press |year=1979 |isbn=978-0-486-41456-0 }}</ref> as well as in reactive gases. TNT, dynamite, and C4 are examples of high power explosives that detonate. The [[detonation velocity|velocity of detonation]] in solid and liquid explosives is much higher than that in gaseous ones, which allows the wave system to be observed with greater detail (higher [[Image resolution|resolution]]).

A very wide variety of fuels may occur as gases (e.g. [[hydrogen]]), droplet fogs, or dust suspensions. In addition to dioxygen, oxidants can include halogen compounds, ozone, hydrogen peroxide, and [[Nitrogen oxide|oxides of nitrogen]]. Gaseous detonations are often associated with a mixture of fuel and oxidant in a composition somewhat below conventional flammability ratios. They happen most often in confined systems, but they sometimes occur in large vapor clouds. Other materials, such as [[acetylene]], [[ozone]], and [[hydrogen peroxide]], are detonable in the absence of an oxidant (or reductant). In these cases the energy released results from the rearrangement of the molecular constituents of the material.<ref>{{cite book |last=Stull |first=Daniel Richard |title=Fundamentals of fire and explosion |publisher=[[American Institute of Chemical Engineers]] |series=Monograph Series |volume=10 |page=73 |year=1977 |isbn=978-0-816903-91-7 |url=https://books.google.com/books?id=zcBTAAAAMAAJ }}</ref><ref>{{cite book |title=Bretherick's Handbook of Reactive Chemical Hazards |publisher=Butterworths |location=London |year=2006 |url=https://www.sciencedirect.com/science/book/9780123725639 |isbn=978-0-123725-63-9 |first1=Peter |last1=Urben |first2=Leslie |last2=Bretherick |edition=7th }}</ref>

Detonation was discovered in 1881 by four French scientists [[Marcellin Berthelot]] and [[Paul Marie Eugène Vieille]]<ref>Berthelot, Marcellin; and Vieille, Paul Marie Eugène; « Sur la vitesse de propagation des phénomènes explosifs dans les gaz » ["On the velocity of propagation of explosive processes in gases"], Comptes rendus hebdomadaires des séances de l'Académie des sciences, vol. 93, pp. 18–22, 1881</ref> and [[Ernest-François Mallard]] and [[Henry Louis Le Chatelier]].<ref>Mallard, Ernest-François; and Le Chatelier, Henry Louis; « Sur les vitesses de propagation de l’inflammation dans les mélanges gazeux explosifs » ["On the propagation velocity of burning in gaseous explosive mixtures"], Comptes rendus hebdomadaires des séances de l'Académie des sciences, vol. 93, pp. 145–148, 1881</ref> The mathematical predictions of propagation were carried out first by [[David Chapman (chemist)|David Chapman]] in 1899<ref>Chapman, David Leonard (1899). "VI. On the rate of explosion in gases", ''The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science'', '''47'''(284), 90-104.</ref> and by [[Émile Jouguet]] in 1905,<ref name="Jouguet1905" /> 1906 and 1917.<ref>Jouguet, Jacques Charles Émile (1917). ''L'Œuvre scientifique de Pierre Duhem'', Doin.</ref> The next advance in understanding detonation was made by [[John von Neumann]]<ref name="vonNeumann" /> and [[Werner Döring]]<ref name="Döring" /> in the early 1940s and [[Yakov B. Zel'dovich]] and [[Aleksandr Solomonovich Kompaneets]] in the 1960s.<ref name="Zel'dovichKompaneets" />

== Theories ==
The simplest theory to predict the behaviour of detonations in gases is known as the [[Chapman–Jouguet condition|Chapman–Jouguet]] (CJ) condition, developed around the turn of the 20th century. This theory, described by a relatively simple set of algebraic equations, models the detonation as a propagating shock wave accompanied by exothermic heat release. Such a theory describes the chemistry and diffusive transport processes as occurring abruptly as the shock passes.

A more complex theory was advanced during World War II independently by [[Yakov B. Zel'dovich|Zel'dovich]], [[John von Neumann|von Neumann]], and [[Werner Döring|Döring]].<ref name="Zel'dovichKompaneets">{{cite book |last1=Zel'dovich |first1=Yakov B. |last2=Kompaneets |first2=Aleksandr Solomonovich |title=Theory of Detonation |publisher=Academic Press |location=New York |year=1960 |asin=B000WB4XGE |oclc=974679 }}</ref><ref name="vonNeumann">{{cite report |year=1942 |last=von Neumann |first=John |title=Progress report on "Theory of Detonation Waves" |id=OSRD Report No. 549. Ascension number ADB967734 |url=http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADB967734 |access-date=2017-12-22 |archive-date=2011-07-17 |archive-url=https://web.archive.org/web/20110717145048/http://oai.dtic.mil/oai/oai?verb=getRecord |url-status=dead }}</ref><ref name="Döring">{{cite journal |last1=Döring |first1=Werner |journal=Annalen der Physik |volume=43 |pages=421–436 |year=1943 |doi=10.1002/andp.19434350605 |title="Über den Detonationsvorgang in Gasen" |trans-title="On the detonation process in gases" |issue=6–7 |bibcode=1943AnP...435..421D }}</ref> This theory, now known as [[ZND theory]], admits finite-rate chemical reactions and thus describes a detonation as an infinitesimally thin shock wave, followed by a zone of exothermic chemical reaction. With a reference frame of a stationary shock, the following flow is subsonic, so that an acoustic reaction zone follows immediately behind the lead front, the [[Chapman–Jouguet condition]].<ref>{{cite journal |last=Chapman |first=David Leonard |title=On the rate of explosion in gases |journal=Philosophical Magazine |location=London |series=Series 5 |volume=47 |issue=284 |pages=90–104 |date=January 1899 |url=https://books.google.com/books?id=N4u8y0Kf8NQC&pg=PA90 |issn=1941-5982 |lccn=sn86025845 |doi=10.1080/14786449908621243 |url-access=subscription }}</ref><ref name="Jouguet1905">{{cite journal |last=Jouguet |first=Jacques Charles Émile |url=http://math-doc.ujf-grenoble.fr/JMPA/PDF/JMPA_1905_6_1_A9_0.pdf |title=Sur la propagation des réactions chimiques dans les gaz |journal=Journal de mathématiques pures et appliquées |series=6 |volume=1 |pages=347–425 |year=1905 |trans-title="On the propagation of chemical reactions in gases" |url-status=dead |archive-url=https://web.archive.org/web/20131019171453/http://math-doc.ujf-grenoble.fr/JMPA/PDF/JMPA_1905_6_1_A9_0.pdf |archive-date=2013-10-19 |access-date=2013-10-19 }} Continued in {{cite journal |last=Jouguet |first=Jacques Charles Émile |journal=Journal de mathématiques pures et appliquées |series=6 |volume=2 |pages=5–85 |year=1906 |url=http://sites.mathdoc.fr/JMPA/PDF/JMPA_1906_6_2_A1_0.pdf |title=Sur la propagation des réactions chimiques dans les gaz |trans-title="On the propagation of chemical reactions in gases" |url-status=dead |archive-url=https://web.archive.org/web/20151016140100/http://sites.mathdoc.fr/JMPA/PDF/JMPA_1906_6_2_A1_0.pdf |archive-date=2015-10-16 }}</ref>

There is also some evidence that the reaction zone is [[Semimetal|semi-metallic]] in some explosives.<ref>{{cite journal |doi=10.1038/nphys806 |title=A transient semimetallic layer in detonating nitromethane |year=2007 |last1=Reed |first1=Evan J. |last2=Riad Manaa |first2=M. |last3=Fried |first3=Laurence E. |last4=Glaesemann |first4=Kurt R. |last5=Joannopoulos |first5=J. D. |journal=Nature Physics |volume=4 |pages=72–76 |issue=1 |bibcode=2008NatPh...4...72R }}</ref>

Both theories describe one-dimensional and steady wavefronts. However, in the 1960s, experiments revealed that gas-phase detonations were most often characterized by unsteady, three-dimensional structures, which can only, in an averaged sense, be predicted by one-dimensional steady theories. Indeed, such waves are quenched as their structure is destroyed.<ref>{{cite journal |last1=Edwards |first1=D. H. |last2=Thomas |first2=G. O. |last3=Nettleton |first3=M. A. |name-list-style=amp |title=The Diffraction of a Planar Detonation Wave at an Abrupt Area Change |journal=Journal of Fluid Mechanics |volume=95 |issue=1 |pages=79–96 |year=1979 |doi=10.1017/S002211207900135X |bibcode=1979JFM....95...79E |s2cid=123018814 }}</ref><ref>{{cite journal |doi=10.2514/5.9781600865497.0341.0357 |volume=75 |journal=Progress in Astronautics & Aeronautics |year=1981 |title=Diffraction of a Planar Detonation in Various Fuel-Oxygen Mixtures at an Area Change |isbn=978-0-915928-46-0 |pages=341–357 |editor=A. K. Oppenheim |editor2=N. Manson |editor3=R. I. Soloukhin |editor4=J. R. Bowen |last1=Edwards |first1=D. H. |last2=Thomas |first2=G. O. |last3=Nettleton |first3=M. A. }}</ref> The Wood-Kirkwood detonation theory can correct some of these limitations.<ref>{{cite journal |doi=10.1007/s00214-007-0303-9 |title=Improved Wood–Kirkwood detonation chemical kinetics |year=2007 |last1=Glaesemann |first1=Kurt R. |last2=Fried |first2=Laurence E. |journal=Theoretical Chemistry Accounts |volume=120 |pages=37–43 |issue=1–3 |s2cid=95326309 |url=https://zenodo.org/record/1232641 }}</ref>

Experimental studies have revealed some of the conditions needed for the propagation of such fronts. In confinement, the range of composition of mixes of fuel and oxidant and self-decomposing substances with inerts are slightly below the flammability limits and, for spherically expanding fronts, well below them.<ref>{{cite journal |last=Nettleton |first=M. A. |title=Detonation and flammability limits of gases in confined and unconfined situations |journal=Fire Prevention Science and Technology |issn=0305-7844 |pages=29 |year=1980 |issue=23 }}</ref> The influence of increasing the concentration of diluent on expanding individual detonation cells has been elegantly demonstrated.<ref>{{cite journal |last1=Munday |first1=G. |last2=Ubbelohde |first2=A. R. |last3=Wood |first3=I. F. |name-list-style=amp |title=Fluctuating Detonation in Gases |journal=Proceedings of the Royal Society A |volume=306 |pages=171–178 |year=1968 |doi=10.1098/rspa.1968.0143 |issue=1485 |bibcode=1968RSPSA.306..171M |s2cid=93720416 }}</ref> Similarly, their size grows as the initial pressure falls.<ref>{{cite journal |last=Barthel |first=H. O. |title=Predicted Spacings in Hydrogen-Oxygen-Argon Detonations |journal=Physics of Fluids |volume=17 |issue=8 |pages=1547–1553 |year=1974 |doi=10.1063/1.1694932 |bibcode=1974PhFl...17.1547B }}</ref> Since cell widths must be matched with minimum dimension of containment, any wave overdriven by the initiator will be quenched.

Mathematical modeling has steadily advanced to predicting the complex flow fields behind shocks inducing reactions.<ref>{{cite book |last1=Oran |last2=Boris |title=Numerical Simulation of Reactive Flows |publisher=Elsevier Publishers |year=1987 }}</ref><ref>{{cite journal |last1=Sharpe |first1=G. J. |last2=Quirk |first2=J. J. |title=Nonlinear cellular dynamics of the idealized detonation model: Regular cells |journal=Combustion Theory and Modelling |volume=12 |issue=1 |pages=1–21 |year=2008 |doi=10.1080/13647830701335749
 |bibcode=2008CTM....12....1S |s2cid=73601951 |url=http://eprints.whiterose.ac.uk/7931/1/cells_revised.pdf |url-status=live |archive-url=https://web.archive.org/web/20170705073324/http://eprints.whiterose.ac.uk/7931/1/cells_revised.pdf |archive-date=2017-07-05}}</ref> To date, none has adequately described how the structure is formed and sustained behind unconfined waves.

== Applications ==
[[File:Iraqi Bomb Disposal Company DVIDS19881.jpg|thumb|A controlled [[bomb disposal]] in [[Iraq]], 2006; detonating the bomb causes fire and smoke to propel upward.]]
When used in explosive devices, the main cause of damage from a detonation is the supersonic blast front (a powerful [[shock wave]]) in the surrounding area. This is a significant distinction from [[deflagration]]s where the exothermic wave is subsonic and maximum pressures for non-metal specks of dust are approximately 7–10 times atmospheric pressure.<ref>{{cite book |title=Handbook of Fire Protection Engineering |date=2016 |edition=5 |publisher=Society of Fire Protection Engineers |at=Table 70.1 Explosivity Data for representative powders and dusts, page 2770 }}</ref> Therefore, detonation is a feature for destructive purposes while deflagration is favored for the acceleration of [[firearm]]s' projectiles. However, detonation waves may also be used for less destructive purposes, including deposition of coatings to a surface<ref>{{cite journal |last1=Nikolaev |first1=Yu. A. |last2=Vasil'ev |first2=A. A. |last3=Ul'yanitskii |first3=B. Yu. |name-list-style=amp |title=Gas Detonation and its Application in Engineering and Technologies (Review) |journal=Combustion, Explosion, and Shock Waves |volume=39 |issue=4 |pages=382–410 |year=2003 |doi=10.1023/A:1024726619703 |s2cid=93125699 }}</ref> or cleaning of equipment (e.g. slag removal<ref>{{cite journal |last1=Huque |first1=Z. |last2=Ali |first2=M. R. |last3=Kommalapati |first3=R. |name-list-style=amp |title=Application of pulse detonation technology for boiler slag removal |journal=Fuel Processing Technology |volume=90 |issue=4 |pages=558–569 |year=2009 |doi=10.1016/j.fuproc.2009.01.004 }}</ref>) and even [[explosive welding|explosively welding]] together metals that would otherwise fail to fuse. [[Pulse detonation engine]]s use the detonation wave for aerospace propulsion.<ref>{{cite journal |last=Kailasanath |first=K. |title=Review of Propulsion Applications of Detonation Waves |journal=AIAA Journal |volume=39 |issue=9 |pages=1698–1708 |year=2000 |doi=10.2514/2.1156 |bibcode=2000AIAAJ..38.1698K }}</ref> The first flight of an aircraft powered by a pulse detonation engine took place at the [[Mojave Airport & Spaceport|Mojave Air & Space Port]] on January 31, 2008.<ref>{{cite journal |last=Norris |first=G. |title=Pulse Power: Pulse Detonation Engine-powered Flight Demonstration Marks Milestone in Mojave |journal=Aviation Week & Space Technology |volume=168 |issue=7 |page=60 |year=2008 |url=http://archive.aviationweek.com/issue/20080218 }}</ref>

== In engines and firearms ==
Unintentional detonation when [[deflagration]] is desired is a problem in some devices. In [[Otto cycle]], or gasoline engines it is called [[engine knocking]] or pinging, and it causes a loss of power. It can also cause excessive heating, and harsh mechanical shock that can result in eventual engine failure.<ref>{{Cite web |url=https://www.hpacademy.com/technical-articles/dont-waste-your-time-listening-for-knock/ |title=Don't Waste Your Time Listening for Knock... |website=High Performance Academy |first=Andre |last=Simon }}</ref> In firearms, it may cause catastrophic and potentially lethal failure{{citation needed |date=December 2021 }}.

[[Pulse detonation engine]]s are a form of pulsed jet engine that has been experimented with on several occasions as this offers the potential for good fuel efficiency{{citation needed |date=December 2021 }}.

== See also ==
* [[Detonator]]
* [[Explosive#Detonation of an explosive charge|Detonation of an explosive charge]]
* [[Detonation diamond]]
* [[Detonation flame arrester]]
* [[Sympathetic detonation]]
* [[Nuclear testing]]
* [[Nuclear chain reaction#Predetonation|Predetonation]]
* [[Chapman–Jouguet condition]]
* [[Engine knocking]]
* [[Deflagration]]
* [[Relative effectiveness factor]]

== References ==
{{Reflist}}

== External links ==
{{Wiktionary}}
{{Commons category |Detonations}}
* [https://www.youtube.com/watch?v=TjC4SvZIARY Youtube video demonstrating physics of a blast wave]
* [http://www.galcit.caltech.edu/detn_db/html/db.html GALCIT Explosion Dynamics Laboratory Detonation Database] {{Webarchive|url=https://web.archive.org/web/20140311212147/http://www2.galcit.caltech.edu/detn_db/html/db.html |date=2014-03-11 }}

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[[Category:Explosives engineering]]
[[Category:Combustion]]