Explosion venting of hydrogen-air mixture in an obstructed rectangular tube

A series of experiments was performed in an obstructed rectangular tube to investigate the effect of the blockage ratio of obstacle on vented hydrogen-air explosion. Internal and external pressure evolutions were monitored by pressure sensors while internal and external flow fields were recorded by high-speed schlieren photography. The overpressure histories, dynamic characteristics of external combustible cloud and flame behavior inside and outside the tube were discussed. The results show that the obstacle blockage ratio has a significant effect on the peak overpressure induced by the obstacle, but it has an ignorable effect on the peak overpressure resulting from the vent rupture. The peak overpressure induced by the obstacle increases with the blockage ratio. For the relatively lower blockage ratio of 7.14% and 21.43%, the peak overpressure is mainly induced by the enhancement of turbulence and burning rate caused by the obstacle. For the higher blockage ratio of 35.71%, 50% and 64.29%, the peak overpressure results from the combined effect of the flame acceleration and external explosion.

Automated summary

Experiments conducted in an obstructed rectangular tube revealed that the blockage ratio of the obstacle has a significant impact on the peak overpressure induced by the obstacle, but a negligible effect on the peak overpressure resulting from vent rupture. Lower blockage ratios mainly increase peak overpressure through enhanced turbulence and burning rate, while higher blockage ratios result in peak overpressure from the combined effect of flame acceleration and external explosion.