Experimental study of methane explosion containing coal dust in flame instability and pressure variation process

It is important to understand the evolution process of an explosion flow field for accident prevention. This study investigated the effects of low coal dust concentrations on gas explosion characteristics by incorporating coal dust into air-methane gas mixtures (the volume fraction of methane is 12.5%, 9.5% and 6.5%, respectively) in a cylindrical combustion chamber for conducting explosion experiments. Pressure measurement and laser schlieren technology were used to record explosion pressure variations and to capture flame schlieren images. The results revealed that the flame radius shrank with elevated coal dust concentration at the initial stage of explosion. At a methane concentration of 6.5%, the flame appeared to float up, and the explosion reaction intensity increased with higher coal dust content. The flame spread out in a spherical morphology was observed at 9.5% and 12.5% methane concentrations. With elevated coal dust concentration, increased the maximum explosion pressure and pressure rise rate first, then decreased it. The dynamic coupling of flame instability propagation and pressure had a limited effect on the rising explosion pressure. In addition to providing experimental data for validating and enhancing the kinetic mechanism of gas-dust chemical reactions, these findings provide in-depth insight into prevention and management of coal-mine catastrophes.