Abstract: Hydrogen-blended natural gas has already been implemented in industrial and residential sectors, and the strategy of transporting hydrogen by integrating it at low volume fractions into natural gas pipelines is feasible. However, due to the reactive properties of hydrogen, introducing hydrogen into natural gas pipelines may increase the likelihood of jet fire incidents, with temperature being a key factor in these accidents. Therefore, an experimental study was conducted on the axial temperature of non-premixed jet flames of natural gas at various hydrogen blending ratios, flow rates, and leak sizes. The experimental results indicate that the axial temperature generally exhibits an upward trend followed by a decrease with increasing height. As the flow rate increases, the range of flame temperatures also expands. Additionally, as the hydrogen blending ratio increases, the peak temperature of the flame rises. The flame height was adjusted using a virtual origin model, and a dimensionless relationship for the axial temperature of hydrogen-blended natural gas based on this model was derived, providing a basis for assessing the risk of jet combustion fires of hydrogen-blended natural gas.

Key words: hydrogen-blended natural gas, non-premixed combustion flame, hydrogen blending ratio, temperature profile, virtual origin