Effect of bifurcation on premixed methane-air explosion overpressure in pipes

It is well known that bifurcation structures have a significant influence on gas explosions in pipelines or roadways. In this work, three different types of bifurcation, namely, bifurcation with two right angles (BTRAs), bifurcation with two obtuse angles (BTOAs), and bifurcation with an obtuse angle and an acute angle (BOAA), were used to study the effect of bifurcation on premixed methane-air explosion overpressure in pipes. The effect of the position of bifurcation on gas explosions was also discussed. Our results suggest that the peak overpressure evolution in pipes exhibits a downtrend before the bifurcation, a sharp increase after the bifurcation until reaching the maximum, and a downward trend when propagating into the pipe end. It was also found that gas-explosion propagation was affected by the joint action of turbulence induced by obstacles and the abrupt increase of the cross-sectional area. In addition, the bifurcation's position had only a small effect on the maximum peak overpressure in pipes.