Experimental and numerical studies on the closed and vented explosion behaviors of premixed methane-hydrogen/air mixtures

The explosion overpressure behaviors of premixed methane-hydrogen/air mixtures in a duct were evaluated by a pressure sensor, while the flame propagation behaviors in the duct and the vented explosion region were captured by a high-speed schlieren camera and a high-speed video camera, respectively. It indicated that the flame front with various concentrations had different development processes. Meanwhile, the velocity of flame front experienced three acceleration processes and explosion overpressure went up three times accordingly. The ratio of the second overpressure peak to the first one increased with the rising methane-hydrogen concentration, which signified that the second explosion severity with higher concentration of methane-hydrogen in the vented explosion region was more drastic than that with lower concentration. In addition, the simulation was applied to reveal the explosion mechanism of premixed methane-hydrogen/air mixtures. The numerical results revealed that the flame shape and pressure dynamic varying processes were corresponding to the experimental results. Besides, the numerical results also yielded several explosion parameters which were difficult to be obtained in the experiments, such as the flame temperature distribution, explosion overpressure distribution, gas-flow velocity distribution, and gas turbulent kinetic energy distribution, whose coupling effect played an important role in the explosion venting.