Effect of a Tilted Obstacle on the Flame Propagation of Gas Explosion in Case of Low Initial Pressure

Obstacles are unavoidable in coalmine laneways and combustible gas pipeline. However, the obstacles may enhance the intensity of explosion, or change the propagation characteristic. The present paper deals with the flame propagation characteristic of explosion in the tube with a tilted obstacle (45 ~ 135°) under the condition of low initial pressure (0.2 ~ 0.35 kPa). Two models (a so-called modified model and a mathematical model) are adopted in order to describe the regularity of flame velocity for the first (i.e. after explosion at an edge of the tube) and third (i.e. before the flame reaches the end of the tube) stages, whereas some irregular phenomena are investigated during the second stage (i.e. in which the flame reaches the titled obstacle, and goes beyond it) of the whole process, i.e. explosion and flame propagation along the tube. A theoretical fitting model is built in order to describe the critical moments of the accident, i.e. explosion and propagation. It is shown that the initial pressure and obstacle, considered as governing factors, have specific influences on flameless zone and flame velocity. This research can provide a new basic study of the effects of obstacles on combustible gas explosion and a reference for actual explosion protection designs.