SHI F C, WANG X, PEI B,et al.Effects of confinement on explosion characteristics of biogas/air premixed gas in a duct[J].Journal of Henan Polytechnic University(Natural Science) ,2026,45(3):115-122.

doi:10.16186/j.cnki.1673-9787.2025060049

Received:2025/06/30

Revised:2025/12/31

Published:2026/04/28

Effects of confinement on explosion characteristics of biogas/air premixed gas in a duct

Shi Fengchao1, Wang Xi1, Pei Bei1,2

1.School of Safety Science and Engineering， Henan Polytechnic University， Jiaozuo  454003， Henan， China；2.Collaborative Innovation Center of Coal Work Safety and Clean High Efficiency Utilization， Jiaozuo  454003， Henan， China

Abstract: Objectives To provide a theoretical basis for the safe utilization of biogas， the effects of confinement conditions on the explosion characteristics of biogas with different compositions were systematically investigated， and the flame propagation behavior and pressure evolution mechanism after venting were clarified.  Methods Focusing on a typical long pipeline with a large length-to-diameter ratio in biogas storage and transportation， experiments were conducted using a self-developed apparatus. The left end of the pipeline was sealed with PVC films of different layers， while the right end was closed. By varying the number of film layers and the methane concentration， the variation of explosion parameters was systematically analyzed.  Results The results show that the number of PVC film layers has a significantly greater effect on the  peak overpressure than the methane volume fraction. As the number of layers increases from 1 to 9， the pressure waveform gradually transitions from bimodal to unimodal， with three layers identified as the critical threshold. Increasing the number of film layers is more effective in enhancing the maximum pressure rise rate than increasing the methane concentration. The methane volume fraction plays a dominant role in flame propagation time and flame front velocity. At a fixed number of film layers， the maximum instantaneous flame velocity increases linearly with methane concentration， while the propagation time decreases accordingly. During the explosion process， the dynamic evolution of flame front velocity， spatial position， and pressure is strongly coupled with the turbulent development of the flame structure.  Conclusions The results reveal the regulatory mechanisms of confinement strength and biogas composition on explosion characteristics， providing theoretical support and technical guidance for the safety design of biogas storage and transportation systems， optimization of venting devices，  and risk control in engineering applications.

Key words:biogas;explosion characteristic;tulip flame;confinement;overpressure