Influence of Cavity Width and Powder Filling in a Cavity on Overpressure Evolution Laws and Flame Propagation Characteristics of Methane/Air Explosion

[Image: see text] Passive explosion suppression remains an indispensable auxiliary method for gas explosion suppression due to its low cost. To explore a new type of explosion passive suppression technology, three rectangular cavities with different width–diameter ratios were designed and laid in a large-scale methane/air explosion experiment system, and its explosion suppression performance was evaluated by measuring the changes in the explosion flame and shock wave before and after passing through the cavity. The results show that the suppression effect of the cavity is affected by its width. The larger the width–diameter ratio, the faster the attenuation of the flame and shock wave. The cavity-combined aluminum hydroxide powder effectively improves the suppression effect. When the filling amount of the powder is 140 g, the flame is quenched. However, there is an optimal powder filling degree for the suppression of the shock wave in the limited space of the cavity. In the test range, the maximum decay rate of the overpressure and impulse are 49.4 and 39.4%, respectively. This study can provide theoretical guidelines for the suppression of gas explosion.