Effect of hydrogen addition on the explosion characteristics of methane-hydrogen-air mixture in T-shaped bifurcation pipe

Adding a certain proportion of hydrogen into the natural gas pipeline network is an effective way to solve the economical transportation problem of hydrogen. However, due to the special physical and chemical properties of hydrogen, there will be great potential safety hazards in the process of hydrogen transportation in the pipe network. In this paper, we studied the effect of adding hydrogen into T-tube on the explosion characteristics of methane hydrogen air premixed gas through experiments and numerical simulation. The results showed that hydrogen addition has an obvious effect on the explosion characteristics of the mixed gas. When the volume content of hydrogen exceeds 10%, the strengthening effect of the T-shaped bifurcation structure on the explosion reaction was more significant. The explosion characteristics in the upstream of the T-shaped bifurcation structure pipeline are consistent with those in the straight pipe, but it has a great impact on the downstream of the T-shaped bifurcation structure. When the flame passed through the bifurcation, the turbulence intensity in the pipe increased rapidly, which resulted the flame propagation velocity and explosion overpressure rising rapidly and exceeding the level before the bifurcation. The dynamic strain occurred on the thin wall of the pipe under the dynamic impact of gas cloud explosion, and the response of thin-wall strain had a good consistency with the explosion overpressure. In the experiment, the maximum strain at the bifurcation structure reached 1.02719×10−5 when the volume fraction of hydrogen was 20%.