Modes of Explosive Combustion during Emergency Explosions of the Gas Clouds in the Open Space


Annotation:

Emergency explosions of steam clouds in the open space occur in the deflagration combustion mode. Destructive force of the explosive waves is mainly determined by the rate of combustion in the steam cloud. Therefore, the issue of explosive combustion rate is the key one for predicting explosion parameters. To form the waves of destructive force, it is required that the combustion rate of the substance in the cloud increase by 30 or more times compared to laminar.
The main and generally recognized mechanism of combustion intensification is turbulization of the process as a result of interaction of the gas flow field with various obstacles located in the area of the exploding cloud. 
In the work, the analysis focuses on the combustion processes in the obstacles with continuously changing blocking of space. Under such conditions, the combustion is not structured, it smoothly changes its characteristics, and not jerks at the locations of blocking barriers. That is, explosive combustion can be considered as a classic turbulent combustion of a homogeneous mixed mixture.
The work gives preference to the analysis of works, in which the turbulent combustion rate is presented as allowing a change in the scale of turbulence. The results of these works are presented in the form of functions ff(U¢/Sl, l/d) of the ratio of the pulsation component of turbulence to the laminar combustion rate, and the ratio of the integral scale of turbulence to the thickness of the laminar flame.
The work gives a comparison of the turbulent combustion velocity depending on the U¢/SL  ratio for three values l/d = 100, 1000, 10 000.
On the basis of the turbulent combustion modes diagram, the zones of applicability of various methods for determining the turbulent combustion rate are shown. The paper expresses preference for the Peters theory as the most universal and giving a realistic value of the turbulent combustion rate at l/d >> 1.

References:
1. Gorev V.A. Comparison of the air blast waves from different sources. Fizika goreniya i vzryva = Combustion, Explosion, and Shock Waves. 1982. № 1. С. 94–101. (In Russ.).
2. Agapov A.A., Safonov V.S., Sumskoy S.I., Shvyryaev A.A. On Some Differences in the Methodological Approaches when Modeling the Parameters of Pressure Waves from Combustion and Detonation of Fuel-Air Mixtures Clouds. Bezopasnost Truda v Promyshlennosti = Occupational Safety in Industry. 2020. № 5. pp. 36–42. (In Russ.). DOI: 10.24000/0409-2961-2020-5-36-42
3. Sumskoy S.I., Efremov K.V., Lisanov M.V., Sofyin A.S. Comparing Results of Hazardous Substances Emission Simulation and Facts of the Accidents. Bezopasnost Truda v Promyshlennosti = Occupational Safety in Industry. 2008. № 10. pp. 42–50. (In Russ.).
4. Agapova E.A., Degtyarev D.V., Lisanov M.V., Kryukov A.S., Kulberg S.B., Sumskoy S.I. Comparative Analysis of the Russian and Foreign Methods and Computer Programs on Modeling Emergency Releases and Risk Assessment. Bezopasnost Truda v Promyshlennosti = Occupational Safety in Industry. 2015. № 9. pp. 71–78. (In Russ.).
5. Gorev V.A., Fedotov V.N. Experimental study of the influence of cluttered space on the rate of gas combustion. Fizika goreniya i vzryva = Combustion, Explosion, and Shock Waves. 1986. № 6. pp. 79–83. (In Russ.).
6. Moen I.O., Donato M., Knystautas R., Lee J.H. Flame acceleration due to turbulence produced by obstacles. Combustion and Flame. 1980. Vol. 39. Iss. 1. pp. 21–32. DOI: 10.1016/0010-2180(80)90003-6
7. Gorev V.A. The role of the scale effect in the mechanism of flame acceleration by barriers. Khimicheskaya fizika = Chemical physics. 1990. № 12. pp. 1602–1605. (In Russ.).
8. Masri A.R., Alharbi A., Meares S., Ibrahim S.S. A Comparative Study of Turbulent Premixed Flames Propagating Past Repeated Obstacles. Industrial & Engineering Chemistry Research. 2012. Vol. 51. pp. 7690−7703. DOI: 10.1021/ie201928g
9. Kim S.E. Large Eddy Simulation Using an Unstructured Mesh Based Finite-Volume Solver. Available at: http://courses.washington.edu/mengr544/handouts-08/AIAA-2004-kim.pdf (accessed: June 1, 2022).
10. Poinsot T., Veynante D., Candel S. Quenching processes and premixed turbulent combustion diagrams. Journal of Fluid Mechanics. 1991. Vol. 228. pp. 561–606. DOI: 10.1017/S0022112091002823
11. Williams F.A. Turbulent combustion. The Mathematics of Combustion. Philadelphia: SIAM, 1985. pp. 97–131. DOI: 10.1137/1.9781611971064.ch3
12. Bradley D., Lau A.K.C., Lawes M., Smith F.T. Flame stretch rate as a determinant of turbulent burning velocity. Philosophical Transactions of the Royal Society of London. Series A: Physical and Engineering Sciences. 1992. Vol. 338. Iss. 1650. pp. 359–387. DOI: 10.1098/rsta.1992.0012
13. Bradley D. How fast can we burn? Symposium (International) on Combustion. 1992. Vol. 24. Iss. 1. pp. 247–262. DOI: 10.1016/S0082-0784(06)80034-2
14. Zimont V.L. Gas premixed combustion at high turbulence. Turbulent flame closure combustion mode. Experimental Thermal and Fluid Science. 2000. Vol. 21. Iss. 1–3. pp. 179–186. DOI: 10.1016/S0894-1777(99)00069-2
15. Peters N. The turbulent burning velocity for large-scale and small-scale turbulence. Journal of Fluid Mechanics. 1999. Vol. 384. pp. 107–132. DOI: 10.1017/S0022112098004212
DOI: 10.24000/0409-2961-2022-8-7-12
Year: 2022
Issue num: August
Keywords : detonation emergency explosions deflagration explosion turbulent combustion turbulence scale laminar combustion
Authors:
  • Gorev V.A.
    Gorev V.A.
    Dr. Sci. (Phys.–Math.), Prof., va.gorev@yandex.ru Moscow State University of Civil Engineering, Moscow, Russia