Influence of geometry shape on gas explosion propagation laws in bend roadways

Based on the experiment, the important influence of the pipe with abnormal structure on gas explosion propagation characteristics is analyzed. The results show that gas explosion propagation at the turning point is a process of interaction of pressure wave, flame and complicated flow field. The overpressure of pressure wave and flame transmission velocity are rapidly accelerated and the pipe wall at the turning point is seriously destroyed. The angle of bend has a great influence on the gas explosion propagation characteristics, i.e. there is a different degree of change in both flame velocity and pressure wave overpressure value when gas explosion propagates through bend with different angles. The bend not only increases the turbulent flow of combustion area that accelerates the reaction and velocity, but also enlarges the resistance and heat transmission to the pipe wall. At the same time, the expansion wave at the turning point restrains the gas explosion propagation. The influence of bend on gas explosion propagation characteristics is determined by the combined impact of inhibitor factors and motivation factor. Experiment research and theory analysis indicate that gas explosion propagation characteristics in bend pipe are obviously different from that in straight pipe. So in the mine exploitation, the bend roadways should be decreased as few as possible, and preventive measures should be taken in order to diminish the loss caused by gas explosion. The research results will play an important role in the guidance of preventing gas explosion from occurring and alleviating the damage in coal mine.