Arresting underground tunnel explosions—a computational fluid dynamics study

Abstract

Traditional methods of arresting underground mine explosions have employed water and/or stone-dust barriers. The first barriers used in underground coal mines operated passively, using the blast wave as the mechanism for discharging the inert material into the path of the flame front. Further research led to the introduction of active barriers, which used pressure as the primary method of detecting an explosion and subsequently arresting the flame. These methods have been in use for a number of years, but to achieve greatest success they require precise placement of the sensing mechanism as well as precise timing of the ejection of the inert material into the path of the flame.

To eliminate this reliance on positioning and dispersal rates a novel method for arresting underground tunnel explosions is proposed–an active explosion door, placed much further from the source of the explosion, to function as a final barrier should the primary water and stone-dust barriers fail. The barrier is designed to minimize the attenuation of the blast wave and then be structurally intact to extinguish the flame. To ascertain the performance requirements of the explosion door a computational fluid dynamics code was used to model the flow through the permeable section of the door material. The simulations were conducted by modelling a section of a 3 m long (55-mm diameter) shock tube in which obstructions were placed. The results from the computational simulations are presented in the forms of pressure drop across the permeable region and change in velocity for a number of blockage ratios.