Experimental and numerical evaluations on characteristics of vented methane explosion

Abstract

To research the characteristics of vented explosion of methane-air mixture in the pipeline, coal mine tunnel or other closed space, the experiments and numerical simulations were carried out. In this work, explosion characteristics and flame propagation characteristics of methane in pipeline and coal mine tunnel are studied by using an explosion test system, combined with FLACS software, under different vented conditions. The numerical simulation results of methane explosion are basically consistent with the physical experiment results, which indicates that the numerical simulation for methane explosion is reliable to be applied to the practice. The results show that explosion parameters (pressure, temperature and product concentration) of methane at five volume fractions have the same change trend. Nevertheless, the explosion intension of 10.0% methane is the largest and that of 9.5% methane is relatively weak, followed by 11.0% methane, 8.0% methane and 7.0% methane respectively. Under different vented conditions, the pressure and temperature of methane explosion are the highest in the pipeline without a vent, followed by the pipeline where ignition or vent position is in each end, and those are the lowest in the pipeline with ignition and vent at the same end. There is no significant effect on final product concentration of methane explosion under three vented conditions. For coal mine tunnel, it is indicated that the maximum explosion pressure at the airproof wall in return airway with the branch roadway at 50 m from goaf is significantly decreased while that in intake airway does not change overwhelmingly. In addition, when the branch roadway is longer or its section is larger, the peak pressure of airproof wall reduces slightly.