Experimental Investigation and Modeling of the Formation of Explosive Concentrations


Excess pressure is the main indicator characterizing the magnitude of explosive loads during emergency gas explosions. The value of this parameter and the entire accident scenario as a whole directly depend on the concentration of gas entering the room. 

Any typical room is characterized by the presence of two processes: laminar and turbulent diffusion. The laminar diffusion coefficient depends on the main characteristics of the gas (pressure, temperature). The laminar diffusion coefficient depends on the main characteristics of the gas (pressure, temperature). The coefficient of turbulent diffusion is determined only by the turbulent structure of the considered medium. 

It is established that the incomplete vortex mixing of gas with air is sufficient for flame propagation. This indicates the importance of studying the process of turbulent diffusion from the point of view of the formation of explosive gas-air mixtures.

The purpose of the study is the experimental and computational determination of the coefficient of methane turbulent diffusion. This characteristic is required to assess the state of the gas-air environment in the room. It can be used in the development of explosion prevention measures, for example, in the design of a ventilation system.

The study of the process of formation of explosive concentrations was carried out on the basis of an experiment and subsequent comparison of its results with a calculation model.

In the course of the studies, it was established that the coefficient of turbulent diffusion, due to which explosive mixtures are formed, exceeds the coefficient of molecular diffusion by two orders of magnitude or more and is at least 4∙10–3 m2/s. The applied mathematical model and calculation scheme adequately describe the course of the experiments. Determination of the turbulent diffusion coefficient will allow assessing the state of the gas-air environment in the room and determining the required measures to prevent a possible emergency explosion.

1. Timokhin V.V. Peculiarities of the physical picture of the crash explosions development in isolated room. Pozhary i chrezvychaynye situatsii: predotvrashchenie, likvidatsiya = Fires and Emergencies: Prevention, Liquidation. 2022. № 2. pp. 60–66. (In Russ.). DOI 10.25257/FE.2022.2.60-66
2. Timokhin V.V., Grokhotov M.A., Komarova E.A. Causes and determining factors of the formation of explosive loads during internal emergency explosions. Problemy tekhnosfernoy bezopasnosti: materialy Mezhdunarodnoy nauchno-prakticheskoy konferentsii molodykh uchenykh i spetsialistov = Problems of Technosphere Safety: Proceedings of the International Scientific and Practical Conference of Young Scientists and Specialists. 2022. № 11. pp. 242–247. (In Russ.).
3. Komarov A.A., Buzaev E.V., Vasyukov G.V., Zagumennikov R.A. Simulation of accidental emissions of explosive substances in premises. Vestnik MGSU = Bulletin of MGSU. 2014. № 10. pp. 132–140. (In Russ.).
4. Komarov A.A., Vasyukov G.V., Zagumennikov R.A., Buzaev E.V. Experimental study and numerical simulation of methane-air mixture formation process in premises. Pozharovzryvobezopasnost = Fire and Explosion Safety. 2015. Vol. 24. № 4. pp. 30–38. (In Russ.).
5. Komarov A.A. Conditions for the formation of explosive clouds in the gasified residential premises. Pozharovzryvobezopasnost = Fire and Explosion Safety. 2002. Vol. 11. № 4. pp. 24–28. (In Russ.).
6. Buzaev E.V., Zagumennikov R.A. Experimental study of the formation process of an explosive methane-air mixture in a closed volume. Evraziyskiy soyuz uchenykh = Eurasian Union of Scientists. 2014. № 5-3(5). pp. 15–19. (In Russ.).
7. Clavin P., Williams F.A. Analytical studies of the dynamics of gaseous detonations. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 2012. Vol. 370. Iss. 1960. pp. 597–624. DOI:10.1098/rsta.2011.0345
8. Coelho P.J. A theoretical analysis of the influence of turbulence on radiative emission in turbulent diffusion flames of methane.Combustion and Flame. 2013. Vol. 160. Iss. 3. pp. 610–617. DOI: 10.1016/j.combustflame.2012.11.009
9. Xiaoping W., Minggao Y., Zhichao L., Wence S. Large eddy simulation of methane-air deflagration in an obstructed chamber using different combustion models. Journal of Loss Prevention in the Process Industries. 2012. Vol. 25. Iss. 4. pp. 730–738. DOI: 10.1016/j.jlp.2012.04.008
10. Sochet I., Gillard P., Guelon F. Effect of the concentration distribution on the gaseous deflagration propagation in the case of H2/O2 mixture. Journal of Loss Prevention in the Process Industries. 2006. Vol. 19. Iss. 2–3. pp. 250–262. DOI: 10.1016/j.jlp.2005.02.006
11. DeHaan J.D., Crowhurst D., Hoare D., Bensilum M., Shipp M.P. Deflagrations involving stratified heavier-than-air vapor/air mixtures. Fire Safety Journal. 2001. Vol. 36. Iss. 7. pp. 693–710. DOI: 10.1016/S0379-7112(01)00011-X
12. Adushkin V.V., Kogarko S.M., Lyamin A.G. Calculation of safe distances in case of gas explosion in the atmosphere. Vzryvnoe delo: sb. № 75/32. Svoystva vzryvchatykh materialov i ikh sovershenstvovanie (Explosive business: collection No. 75/32. Properties of explosive materials and their improvement). Moscow: Nedra, 1975. pp. 82–94. (In Russ.).
13. Timokhin V.V. Existing measures to ensure the explosion safety of residential buildings. Pozharnaya i avariynaya bezopasnost: sb. materialov XVI Mezhdunar. nauch.-prakt. konferentsii, posvyashchennoy provedeniyu v Ros. Federatsii Goda nauki i tekhnologiy v 2021 g. i 55-letiyu uchebnogo zavedeniya (Fire and Emergency Safety: Collection of Materials XVI International Theoretical-Practical Conference, Dedicated to the Year of Science and Technology in the Russian Federation in 2021 amd the 55th Anniversary of the Academy). Ivanovo: IFRA of SFS of EMERCOM of Russia, 2021. pp. 191–194. (In Russ.).
DOI: 10.24000/0409-2961-2023-1-84-88
Year: 2023
Issue num: January
Keywords : modeling accident explosion methane explosion safety gas-air mixture turbulent diffusion explosive concentrations
  • Komarov A.A.
    Komarov A.A.
    Dr. Sci. (Eng.), Prof., Head of the Explosion Safety Research Center NRU MGSU, Moscow, Russia
  • Timokhin V.V.
    Timokhin V.V.
    Student of the Post-Graduate Course, timokhin.vv@mail.ru State Fire Academy of EMERCOM of Russia, Moscow, Russia