Study on the Deflagration Characteristics of Methane–Air Premixed Gas in Sudden Expansion Pipelines

Ning Zhou, Zhuohan Shi, Xue Li (), Bing Chen, Yiting Liang, Zhaoyu Li, Chunhai Yang, Xuanya Liu, Weiqiu Huang and Xiongjun Yuan
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Ning Zhou: School of Petroleum and Natural Gas Engineering, Changzhou University, Changzhou 213164, China
Zhuohan Shi: School of Petroleum and Natural Gas Engineering, Changzhou University, Changzhou 213164, China
Xue Li: School of Petroleum and Natural Gas Engineering, Changzhou University, Changzhou 213164, China
Bing Chen: Institute of Industrial Safety, China Academy of Safety Science and Technology, Beijing 100012, China
Yiting Liang: School of Petroleum and Natural Gas Engineering, Changzhou University, Changzhou 213164, China
Zhaoyu Li: School of Overseas Education, Changzhou University, Changzhou 213164, China
Chunhai Yang: School of Materials Engineering, Changshu Institute of Technology, Suzhou 215500, China
Xuanya Liu: Tianjin Fire Research Institute of MEM, Tianjin 300381, China
Weiqiu Huang: School of Petroleum and Natural Gas Engineering, Changzhou University, Changzhou 213164, China
Xiongjun Yuan: School of Petroleum and Natural Gas Engineering, Changzhou University, Changzhou 213164, China

Energies, 2025, vol. 18, issue 5, 1-21

Abstract: This study employs both experimental and numerical simulation methods to systematically investigate the influence of sudden expansion diameter ratios on methane–air premixed flame propagation, explosion overpressure, and the evolution of turbulent structures. The results show that with the increase in the diameter ratio, the flame propagation velocity and explosion overpressure present a nonlinear trend of first increasing, then decreasing, and then increasing. Specifically, when the diameter ratio is 1.5, an optimal balance between turbulence enhancement and energy dissipation is achieved, and the overpressure attenuation rate is 47.61%. However, when the diameter ratio increases to 2.0, the turbulence intensity significantly escalates, the peak flame propagation speed increases by 81%, the peak explosion overpressure increases by 69%, and the overpressure attenuation efficiency decreases, which brings greater safety challenges. Moreover, when the diameter ratio is between 1.5 and 2.0, the turbulence intensity of the premixed gas explosion flow field is significantly increased, and the stable “tulip flame” propagation velocity range is extended from 16~35 m/s to 16~42 m/s. When the diameter ratio is 2.0, a distinctive four-vortex structure is formed, with strong turbulent mixing and fast energy dissipation. The vortex structure evolves with the diameter ratio, transitioning from a symmetric and stable double-vortex form to a complex multi-vortex system. The research results provide theoretical support for the prevention of explosions.

Keywords: sudden expansion structure; diameter ratio; flame structure; peak overpressure; vortex structure (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2025
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