The effect of bend positions on premixed methane–air explosion overpressures in ducts

Bend structures in process industries can enhance gas explosions. Many researchers have studied their effects on flame propagations or overpressure evolutions with experiments or numerical simulations. In this work, three bends with different angles ranging from obtuse to acute were examined, and the effect of bend positions on gas explosions was also studied in the experiments. It was found that the peak overpressure evolutions under three different angles experienced three different stages, i.e. a slight downtrend before the bend, a sudden uptrend in and after the bend, and a following downtrend. The explosion violence was enhanced due to a reflection wave and flame tip wrinkle. The peak overpressure increased when the bend angles decreased because of stronger reflection and turbulence under a smaller bend angle. Additionally, the bend shortened the distance at which the peak overpressure reached its maximum values. However, the bend positions had little effect on the maximum overpressure in the ducts.