The explosion venting characteristics of hydrogen/methane/air mixtures under the congestion of obstacles

To investigate the characteristics of vented explosions in stoichiometric hydrogen/methane/air mixtures in the presence of obstacles, experiments were conducted within a cylindrical duct, taking into account the effects of hydrogen concentration, blockage ratio (BR), and the number of obstacles. The results indicate that internal and external peak overpressures generally increase with a higher hydrogen fraction. A higher propensity for transitioning from deflagration to detonation is observed under conditions of elevated hydrogen concentration and higher BRs. The rupture shock overpressure increases with the hydrogen fraction, peaking with five obstacles, and then decreases as the BR further increases. This pattern is also observed in the overpressure of external explosions and the maximum temperature of external flames. Given the impact of blast overpressure on human safety and structural integrity, the minimum safe distance required for equipment is notably greater than that for personnel. These results contribute to the safe and efficient use of hydrogen/methane blended gases.