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Characteristics of overpressure and thermal effects of methane–air explosions in tunnels.

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Title: Characteristics of overpressure and thermal effects of methane–air explosions in tunnels.
Authors: Gu, Linlin1 (AUTHOR), Nie, Zhenjing1 (AUTHOR), Li, Yi1,2 (AUTHOR) yilisafety@163.com, Wang, Zhen3 (AUTHOR), Huang, Chuyuan4 (AUTHOR), Chen, Xianfeng4 (AUTHOR)
Source: Fuel (0016-2361). Oct2026, Vol. 421, pN.PAG-N.PAG. 1p.
Subjects: Gas explosions, Shock waves, Combustion, Acoustic wave propagation, Temperature effect, Computer simulation, Temperature distribution
Abstract: [Display omitted] • Tests of methane-air explosion in a scale-down tunnel were conducted. • Numerical model of methane-air explosions in the full-scale tunnel was developed. • Effects of methane concentration and gas volume on gas explosion were discussed. • The laws of overpressure propagation and temperature field evolution were revealed. Five sets of combustion and explosion tests using premixed methane–air mixture were conducted in a 1:10 scaled-down tunnel to explore the characteristics of overpressure and thermal effects inside the tunnel. A three-dimensional numerical model was developed and simulations were performed using the space–time conservation element and solution element (CESE) method. In the model test, as the methane concentration increased from 6.5% to 12.5%, the reaction intensity progressively intensified. Surprisingly, the 12.5% volume concentration premixed gas exhibited more pronounced combustion and explosion phenomena due to the dilution of the methane/air caused by the ruptured gas bag. With the gas volume increased from 100 to 300 L, the peak temperature, reaction rate, and residual temperature increased. For a volume of 300 L and concentration of 9.5%, the peak overpressure and peak strain decreased with distance. The amplitude of strain at the arch waist was greater and the dynamic change was more intense than that at the bottom. The results of CESE numerical simulations and tests were highly consistent, verifying the feasibility of the method, they all revealed the characteristics of gas combustion and explosion inside a tunnel. The propagation of shock waves in a full-scale tunnel revealed that the overpressure variations in the axial direction of the tunnel could be divided into free propagation, reflection dissipation, wall acceleration and Mach propagation. In the radial direction, they were characterized by periodic reflection propagation along the wall, with the intensity decreasing gradually with methane consumption. The temperature distribution exhibited symmetrical characteristics along the axial direction from the explosion center toward both ends of the tunnel, with peak temperatures decreasing rapidly. As the heat flow diffused toward the tunnel floor, the cross-sectional temperature slowly decreased over time, eventually becoming uniform. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
Description
Abstract:[Display omitted] • Tests of methane-air explosion in a scale-down tunnel were conducted. • Numerical model of methane-air explosions in the full-scale tunnel was developed. • Effects of methane concentration and gas volume on gas explosion were discussed. • The laws of overpressure propagation and temperature field evolution were revealed. Five sets of combustion and explosion tests using premixed methane–air mixture were conducted in a 1:10 scaled-down tunnel to explore the characteristics of overpressure and thermal effects inside the tunnel. A three-dimensional numerical model was developed and simulations were performed using the space–time conservation element and solution element (CESE) method. In the model test, as the methane concentration increased from 6.5% to 12.5%, the reaction intensity progressively intensified. Surprisingly, the 12.5% volume concentration premixed gas exhibited more pronounced combustion and explosion phenomena due to the dilution of the methane/air caused by the ruptured gas bag. With the gas volume increased from 100 to 300 L, the peak temperature, reaction rate, and residual temperature increased. For a volume of 300 L and concentration of 9.5%, the peak overpressure and peak strain decreased with distance. The amplitude of strain at the arch waist was greater and the dynamic change was more intense than that at the bottom. The results of CESE numerical simulations and tests were highly consistent, verifying the feasibility of the method, they all revealed the characteristics of gas combustion and explosion inside a tunnel. The propagation of shock waves in a full-scale tunnel revealed that the overpressure variations in the axial direction of the tunnel could be divided into free propagation, reflection dissipation, wall acceleration and Mach propagation. In the radial direction, they were characterized by periodic reflection propagation along the wall, with the intensity decreasing gradually with methane consumption. The temperature distribution exhibited symmetrical characteristics along the axial direction from the explosion center toward both ends of the tunnel, with peak temperatures decreasing rapidly. As the heat flow diffused toward the tunnel floor, the cross-sectional temperature slowly decreased over time, eventually becoming uniform. [ABSTRACT FROM AUTHOR]
ISSN:00162361
DOI:10.1016/j.fuel.2026.139036