Study on the influence of obstacle on the flame behaviors of methane/air in a semi-confined pipe with wire mesh installed

Abstract

Studying the coupling effect of obstacle and fire-resistant structure on the propagation of premixed flame is an effective measure to improve the flame quenching theory and the prevention measures for gas explosion. To evaluate the coupling effect of the obstacle and the fire-resistant structure, this article focuses on the influence of the characteristics of the methane/air flame in a semi-confined pipe when the wire mesh and the obstacle are coexisting. In this study, an experimental system and a geometric model with multi-holes obstacle and wire mesh were constructed, and the methods of experiment and numerical simulation were adopted. The results show that the installation of obstacle will promote the flame propagation process, and the wire mesh will be ineffective under severe combustion conditions. When the obstacle is installed, the flame front position will be raised, and the velocity of flame propagation will increase. In the process of the flame propagating to the bottom of the obstacle, the reflux stage and the “turbulent vortex” flame in this stage vanish under the influence of the obstacle. In addition, the changes of flow field in the pipe are mainly influenced by the upward propagation of unburned gas and reflected waves, and the turbulent vortexes in the flow field are symmetrical in cross section. In the process of flame passing through obstacle, under the coupling effects of Rayleigh-Taylor instability, entrainment and wrinkled flame, the flow field becomes turbulent and the process of flame propagation ends earlier.