Influence of blockage ratio and length-to-diameter ratio on explosion dynamics of DME/H2 blended gas in semi-open space

This study systematically investigates the influence of obstacle blockage ratio (BR = 0–0.75) and pipeline length-to-diameter (L/D = 45–90) ratio on explosion dynamics in dimethyl ether/hydrogen (DME/H₂) blended gas. The results indicate that increasing BR enhances flame turbulence, which intensifies combustion reactions and accelerates flame propagation. Consequently, there is a significant rise in the maximum explosion overpressure (P_max) and a reduction in the time to reach P_max. Specifically, P_max increases the most at BR = 0.55 with 204 % and the time to reach P_max shortens the most at BR = 0.35 with 13.3 % compared to unobstructed condition. However, at the higher blockage ratio of BR = 0.75, the throttling effect becomes dominant, resulting in a decrease in P_max and an extended time to reach P_max. Additionally, increasing the L/D ratio enhances the turbulence effect generated during the flame propagation, resulting in the formation of more small-scale vortex structures at the flame front. This promotes the mixing of unburned gas with the flame front, thereby increasing the combustion rate and peak overpressure, while shortening the time to reach P_max by 7.95–41.4 %. Notably, neither BR nor L/D ratio significantly affected peak flame temperatures.