Peculiarities are considered related to the numerical integration of the diffusion equations for describing the formation and motion (drift) of explosive clouds formed on the territories of industrial facilities as a result of the accidental releases of combustible substances. The relevance of the study is associated with the fact that when the contents of an emergency release are mixed with an air, an explosive and flammable mixture is formed. The process of its combustion is determined by the volumetric concentration of the combustible substance. At concentrations below the lower concentration limit of ignition, combustion or explosion of the mixture is completely excluded. If the concentration of the mixture is between the lower and upper concentration limits of ignition, then there is an explosion. When the concentration of the mixture is above the upper concentration limit of ignition, a flash fire or a fireball occurs. Thus, the information is required on the parameters of the explosive mixture that may form due to the accidental release.
Accidental releases can occur under the most adverse atmospheric environment and weather conditions. As a result, the focus of the article is on determining the parameters of an explosive cloud in the conditions of drift under the influence of a slight movement of the atmosphere (the most unfavorable scenario for the development of an accident). The results of numerical calculations of the diffusion equation with allowance for the mobility of the atmosphere are presented. The presence of a weak wind is the most unfavorable situation in terms of the drift of an explosive cloud. The methods and criteria are substantiated that allow obtaining the most correct results of calculating its motion.
2. Komarov A.A., Bazhina E.V. Determining the dynamic load caused by accidental explosions affecting buildings and structures of hazardous areas. Vestnik MGSU = Bulletin of MGSU. 2013. № 12. pp. 14–19. (In Russ.).
3. 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
4. Anh Ph., Komarov A. Parameter calculation of accident explosions at outdoor installations of power-intensive facilities// IOP Conference Series: Materials Science and Engineering. 2018. Vol. 365. Iss. 4. P. 042041. DOI: 10.1088/1757-899X/365/4/042041
5. Liu W., Li Y., Zhang L., Shen S., Yang M., Zhao J., Song Y. Modeling gas hydrate formation from ice powders based on diffusion theory. Theoretical Foundations of Chemical Engineering. 2019. Vol. 53. Iss. 2. pp. 305–317. DOI: 10.1134/S0040579519020106
6. Adushkin V.V., Kogarko S.M., Lyamin A.G. Calculation of safe distances in case of gas explosion in the atmosphere. Vzryvnoe delo = Explosion Technology. 1975. № 32. pp. 82–94. (In Russ.).
7. Munin A.G., Kvitka V.E. Aviation acoustics. Moscow: Mashinostroenie, 1973. 448 p. (In Russ.).
8. Baker W.E., Cox P.A., Westine P.S., Kulesz J.J., Strehlow R.A. Explosive events. Assessment and consequences. In 2 books. Bk. 1. Moscow: Mir, 1986. 319 p. (In Russ.).
9. Baker W.E., Cox P.A., Westine P.S., Kulesz J.J., Strehlow R.A. Explosive events. Assessment and consequences. In 2 books. Bk. 2. Moscow: Mir, 1986. 384 p. (In Russ.).
10. Bradley D., Mitcheson A. The venting of gaseous explosion in spherical vessels. I — Theory. Combustion and Flame. 1978. Vol. 32. pp. 221–236.
11. Buzaev E.V. Formation of explosion and fire hazardous clouds of heavy and light hydrocarbon compounds on the example of an explosive accident. Pozharotushenie: problemy, tekhnologii, innovatsii: sb. materialov Mezhdunar. nauch.-prakt. konf. (Fire-fighting: problems, technologies, innovations: Collection of Materials of the International Scientific-Practical Conference). Moscow: Akademiya GPS MChS Rossii, 2012. pp. 282–284. (In Russ.).
12. Johnson D.M. The potential for vapour cloud explosions — Lessons from the Buncefield accident. Journal of Loss Prevention in The Process Industries. 2010. Vol. 23. Iss. 6. pp. 921–927. DOI: 10.1016/J.JLP.2010.06.011
13. Godunov S.K. Numerical solution of gas dynamics multidimensional problems. Moscow: Nauka, 1976. 400 p. (In Russ.).
14. Buzaev E.V. Calculation of the formation of explosive clouds taking into account the air flows, buildings and diffusion processes. Pozharotushenie: problemy, tekhnologii, innovatsii: sb. tez. dokl. IV Mezhdunar. nauch.-prakt. konf. (Fire-fighting: problems, technologies, innovations: Abstracts of the IV International scientific-practical conference). Moscow: Akademiya GPS MChS Rossii, 2015. pp. 23–25. (In Russ.).
15. 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
16. Zagumennikov R.A., Buzaev E.V. Experimental determination of the value of excess pressure during the combustion of partially mixed gas-air mixtures. Problemy tekhnosfernoy bezopasnosti — 2014: sb. materialov III Mezhdunar. nauch.-prakt. konf. molodykh uchenykh i spetsialistov (Problems of technosphere safety — 2014: Collection of Materials of the III International Scientific-Practical Conference of young scientists and specialists). Moscow: Akademiya GPS MChS Rossii, 2014. pp. 19–21. (In Russ.).
17. Buzaev E.V., Zagumennikov R.A. An indirect method for determining the coefficient of turbulent diffusion during formation of the explosive clouds. Pozharotushenie: problemy, tekhnologii, innovatsii: sb. materialov III Mezhdunar. nauch.-prakt. konf. (Fire-fighting: problems, technologies, innovations: Collection of Materials of the III International Scientific-Practical Conference). In 2 parts. Pt. 1. Moscow: Akademiya GPS MChS Rossii, 2014. pp. 133–135. (In Russ.).
18. NPB 105—03. Fire safety norms. Determination of categories of rooms, buildings and external installations of explosion and fire hazard. Moscow: FGU VNIIPO MChS Rossii, 2003. pp. 19–20. (In Russ).