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Detonation
Explosion at supersonic velocity

Detonation is a form of combustion characterized by a supersonic exothermic front driving a shock front, traveling faster than sound and producing speeds around 1 km/sec. Unlike deflagrations, which are subsonic, detonations can occur in solids, liquids, and gases and do not require an external oxidizer. Examples of explosives that detonate include TNT, dynamite, and C4, with the velocity of detonation being higher in solids and liquids. Gaseous detonations can involve fuels like hydrogen and oxidants such as oxides of nitrogen. Discovered in 1881 by Marcellin Berthelot and others, the theory advanced through contributions from David Chapman and John von Neumann.

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Theories

The simplest theory to predict the behaviour of detonations in gases is known as the 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 Zel'dovich, von Neumann, and Döring.141516 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.1718

There is also some evidence that the reaction zone is semi-metallic in some explosives.19

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.2021 The Wood-Kirkwood detonation theory can correct some of these limitations.22

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.23 The influence of increasing the concentration of diluent on expanding individual detonation cells has been elegantly demonstrated.24 Similarly, their size grows as the initial pressure falls.25 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.2627 To date, none has adequately described how the structure is formed and sustained behind unconfined waves.

Applications

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 deflagrations where the exothermic wave is subsonic and maximum pressures for non-metal specks of dust are approximately 7–10 times atmospheric pressure.28 Therefore, detonation is a feature for destructive purposes while deflagration is favored for the acceleration of firearms' projectiles. However, detonation waves may also be used for less destructive purposes, including deposition of coatings to a surface29 or cleaning of equipment (e.g. slag removal30) and even explosively welding together metals that would otherwise fail to fuse. Pulse detonation engines use the detonation wave for aerospace propulsion.31 The first flight of an aircraft powered by a pulse detonation engine took place at the Mojave Air & Space Port on January 31, 2008.32

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.33 In firearms, it may cause catastrophic and potentially lethal failure.

Pulse detonation engines are a form of pulsed jet engine that has been experimented with on several occasions as this offers the potential for good fuel efficiency.

See also

Look up detonation in Wiktionary, the free dictionary. Wikimedia Commons has media related to Detonations.

References

  1. Oxford Living Dictionaries. "detonate". British & World English. Oxford University Press. Archived from the original on February 22, 2019. Retrieved 21 February 2019. /wiki/Oxford_Living_Dictionaries ↩

  2. Handbook of Fire Protection Engineering (5 ed.). Society of Fire Protection Engineers. 2016. p. 390. https://www.sfpe.org/standards-guides/sfpehandbook ↩

  3. Fickett, Wildon; Davis, William C. (1979). Detonation. University of California Press. ISBN 978-0-486-41456-0. 978-0-486-41456-0 ↩

  4. Stull, Daniel Richard (1977). Fundamentals of fire and explosion. Monograph Series. Vol. 10. American Institute of Chemical Engineers. p. 73. ISBN 978-0-816903-91-7. 978-0-816903-91-7 ↩

  5. Urben, Peter; Bretherick, Leslie (2006). Bretherick's Handbook of Reactive Chemical Hazards (7th ed.). London: Butterworths. ISBN 978-0-123725-63-9. 978-0-123725-63-9 ↩

  6. 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 ↩

  7. 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 ↩

  8. 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. ↩

  9. Jouguet, Jacques Charles Émile (1905). "Sur la propagation des réactions chimiques dans les gaz" ["On the propagation of chemical reactions in gases"] (PDF). Journal de mathématiques pures et appliquées. 6. 1: 347–425. Archived from the original (PDF) on 2013-10-19. Retrieved 2013-10-19. Continued in Jouguet, Jacques Charles Émile (1906). "Sur la propagation des réactions chimiques dans les gaz" ["On the propagation of chemical reactions in gases"] (PDF). Journal de mathématiques pures et appliquées. 6. 2: 5–85. Archived from the original (PDF) on 2015-10-16. https://web.archive.org/web/20131019171453/http://math-doc.ujf-grenoble.fr/JMPA/PDF/JMPA_1905_6_1_A9_0.pdf ↩

  10. Jouguet, Jacques Charles Émile (1917). L'Œuvre scientifique de Pierre Duhem, Doin. ↩

  11. von Neumann, John (1942). Progress report on "Theory of Detonation Waves" (Report). OSRD Report No. 549. Ascension number ADB967734. Archived from the original on 2011-07-17. Retrieved 2017-12-22. https://web.archive.org/web/20110717145048/http://oai.dtic.mil/oai/oai?verb=getRecord ↩

  12. Döring, Werner (1943). ""Über den Detonationsvorgang in Gasen"" ["On the detonation process in gases"]. Annalen der Physik. 43 (6–7): 421–436. Bibcode:1943AnP...435..421D. doi:10.1002/andp.19434350605. /wiki/Bibcode_(identifier) ↩

  13. Zel'dovich, Yakov B.; Kompaneets, Aleksandr Solomonovich (1960). Theory of Detonation. New York: Academic Press. ASIN B000WB4XGE. OCLC 974679. /wiki/ASIN_(identifier) ↩

  14. Zel'dovich, Yakov B.; Kompaneets, Aleksandr Solomonovich (1960). Theory of Detonation. New York: Academic Press. ASIN B000WB4XGE. OCLC 974679. /wiki/ASIN_(identifier) ↩

  15. von Neumann, John (1942). Progress report on "Theory of Detonation Waves" (Report). OSRD Report No. 549. Ascension number ADB967734. Archived from the original on 2011-07-17. Retrieved 2017-12-22. https://web.archive.org/web/20110717145048/http://oai.dtic.mil/oai/oai?verb=getRecord ↩

  16. Döring, Werner (1943). ""Über den Detonationsvorgang in Gasen"" ["On the detonation process in gases"]. Annalen der Physik. 43 (6–7): 421–436. Bibcode:1943AnP...435..421D. doi:10.1002/andp.19434350605. /wiki/Bibcode_(identifier) ↩

  17. Chapman, David Leonard (January 1899). "On the rate of explosion in gases". Philosophical Magazine. Series 5. 47 (284). London: 90–104. doi:10.1080/14786449908621243. ISSN 1941-5982. LCCN sn86025845. https://books.google.com/books?id=N4u8y0Kf8NQC&pg=PA90 ↩

  18. Jouguet, Jacques Charles Émile (1905). "Sur la propagation des réactions chimiques dans les gaz" ["On the propagation of chemical reactions in gases"] (PDF). Journal de mathématiques pures et appliquées. 6. 1: 347–425. Archived from the original (PDF) on 2013-10-19. Retrieved 2013-10-19. Continued in Jouguet, Jacques Charles Émile (1906). "Sur la propagation des réactions chimiques dans les gaz" ["On the propagation of chemical reactions in gases"] (PDF). Journal de mathématiques pures et appliquées. 6. 2: 5–85. Archived from the original (PDF) on 2015-10-16. https://web.archive.org/web/20131019171453/http://math-doc.ujf-grenoble.fr/JMPA/PDF/JMPA_1905_6_1_A9_0.pdf ↩

  19. Reed, Evan J.; Riad Manaa, M.; Fried, Laurence E.; Glaesemann, Kurt R.; Joannopoulos, J. D. (2007). "A transient semimetallic layer in detonating nitromethane". Nature Physics. 4 (1): 72–76. Bibcode:2008NatPh...4...72R. doi:10.1038/nphys806. /wiki/Bibcode_(identifier) ↩

  20. Edwards, D. H.; Thomas, G. O. & Nettleton, M. A. (1979). "The Diffraction of a Planar Detonation Wave at an Abrupt Area Change". Journal of Fluid Mechanics. 95 (1): 79–96. Bibcode:1979JFM....95...79E. doi:10.1017/S002211207900135X. S2CID 123018814. /wiki/Bibcode_(identifier) ↩

  21. Edwards, D. H.; Thomas, G. O.; Nettleton, M. A. (1981). A. K. Oppenheim; N. Manson; R. I. Soloukhin; J. R. Bowen (eds.). "Diffraction of a Planar Detonation in Various Fuel-Oxygen Mixtures at an Area Change". Progress in Astronautics & Aeronautics. 75: 341–357. doi:10.2514/5.9781600865497.0341.0357. ISBN 978-0-915928-46-0. 978-0-915928-46-0 ↩

  22. Glaesemann, Kurt R.; Fried, Laurence E. (2007). "Improved Wood–Kirkwood detonation chemical kinetics". Theoretical Chemistry Accounts. 120 (1–3): 37–43. doi:10.1007/s00214-007-0303-9. S2CID 95326309. https://zenodo.org/record/1232641 ↩

  23. Nettleton, M. A. (1980). "Detonation and flammability limits of gases in confined and unconfined situations". Fire Prevention Science and Technology (23): 29. ISSN 0305-7844. /wiki/ISSN_(identifier) ↩

  24. Munday, G.; Ubbelohde, A. R. & Wood, I. F. (1968). "Fluctuating Detonation in Gases". Proceedings of the Royal Society A. 306 (1485): 171–178. Bibcode:1968RSPSA.306..171M. doi:10.1098/rspa.1968.0143. S2CID 93720416. /wiki/Bibcode_(identifier) ↩

  25. Barthel, H. O. (1974). "Predicted Spacings in Hydrogen-Oxygen-Argon Detonations". Physics of Fluids. 17 (8): 1547–1553. Bibcode:1974PhFl...17.1547B. doi:10.1063/1.1694932. /wiki/Bibcode_(identifier) ↩

  26. Oran; Boris (1987). Numerical Simulation of Reactive Flows. Elsevier Publishers. ↩

  27. Sharpe, G. J.; Quirk, J. J. (2008). "Nonlinear cellular dynamics of the idealized detonation model: Regular cells" (PDF). Combustion Theory and Modelling. 12 (1): 1–21. Bibcode:2008CTM....12....1S. doi:10.1080/13647830701335749. S2CID 73601951. Archived (PDF) from the original on 2017-07-05. http://eprints.whiterose.ac.uk/7931/1/cells_revised.pdf ↩

  28. Handbook of Fire Protection Engineering (5 ed.). Society of Fire Protection Engineers. 2016. Table 70.1 Explosivity Data for representative powders and dusts, page 2770. ↩

  29. Nikolaev, Yu. A.; Vasil'ev, A. A. & Ul'yanitskii, B. Yu. (2003). "Gas Detonation and its Application in Engineering and Technologies (Review)". Combustion, Explosion, and Shock Waves. 39 (4): 382–410. doi:10.1023/A:1024726619703. S2CID 93125699. /wiki/Doi_(identifier) ↩

  30. Huque, Z.; Ali, M. R. & Kommalapati, R. (2009). "Application of pulse detonation technology for boiler slag removal". Fuel Processing Technology. 90 (4): 558–569. doi:10.1016/j.fuproc.2009.01.004. /wiki/Doi_(identifier) ↩

  31. Kailasanath, K. (2000). "Review of Propulsion Applications of Detonation Waves". AIAA Journal. 39 (9): 1698–1708. Bibcode:2000AIAAJ..38.1698K. doi:10.2514/2.1156. /wiki/Bibcode_(identifier) ↩

  32. Norris, G. (2008). "Pulse Power: Pulse Detonation Engine-powered Flight Demonstration Marks Milestone in Mojave". Aviation Week & Space Technology. 168 (7): 60. http://archive.aviationweek.com/issue/20080218 ↩

  33. Simon, Andre. "Don't Waste Your Time Listening for Knock..." High Performance Academy. https://www.hpacademy.com/technical-articles/dont-waste-your-time-listening-for-knock/ ↩