| Hydrogen exhibits high combustion reactivity and diffusivity. The addition of hydrogen can alter the combustion reaction process of the gas mixture and increase the explosion risk in pipelines. Therefore, to investigate the explosion propagation characteristics and risk evolution behavior of methane–hydrogen mixtures with different hydrogen blending ratios, this study employed theoretical analysis, medium-scale pipeline experiments, and numerical simulations to systematically investigate the effects of different hydrogen blending ratios (0%, 20%, 50%, 80%, and 100%) on the flame propagation velocity and explosion overpressure of premixed methane–hydrogen mixtures.The results show that the flame propagation velocity and explosion overpressure of methane–hydrogen mixtures generally increase with increasing hydrogen blending ratio, exhibiting nonlinear growth characteristics. When the hydrogen blending ratio increases from 0% to 50%, both flame propagation velocity and explosion overpressure gradually increase. With a further increase in hydrogen blending ratio to 80% and above, more significant enhancement in flame propagation velocity and explosion overpressure is observed. At a hydrogen blending ratio of 80%, the flame propagation velocity reaches 115.13 m/s, representing an increase of 171.53% compared with the 9.5% methane–air condition. When the hydrogen blending ratio reaches 100%, the maximum explosion overpressure increases to 1.06 MPa. Under high hydrogen blending conditions, the high reactivity and diffusivity of hydrogen promote the combustion reaction process and enhance flame propagation, resulting in further intensification of explosion severity. The findings provide theoretical support for pipeline safety design and explosion protection optimization of hydrogen-enriched natural gas systems. |
