Effects of porous materials and powders of varying explosibility on gas explosion characteristics in confined channels

To investigate the effects of porous materials and powders of varying explosibility on gas explosions, a custom-built explosion duct system was designed. Using four porosities (10, 20, 30, 40 PPI) and three powders (sand, sand-laden coal dust, coal dust) at 0, 10, and 20 mL, the system systematically examined flame structure, propagation velocity, and overpressure for 9.5 % methane-air premixed mixtures. Results show that with decreasing pore size, porous materials gradually transition from enhancing to suppressing explosions: 10 PPI exhibits a pronounced enhancing effect, while 40 PPI completely extinguishes the downstream flame, achieving an overpressure attenuation rate of up to 90 %. Among the powders, coal dust significantly intensifies the explosion; sand plays a predominantly suppressive role; and sand-laden coal dust shows a moderating effect due to the presence of sand. Moreover, powder addition level nonlinearly influences explosion intensity: increasing from 0 to 10 mL enhances the explosion, whereas further increase to 20 mL suppresses it, with powders and large-pore porous materials coupling to exacerbate downstream development. This study reveals the mechanism by which the combined action of porous materials and different powders of varying explosibility affects combustible gas explosion propagation, thereby providing a theoretical basis for industrial explosion prevention technologies and safe production.