Objective Currently, hydrogen-blended natural gas transportation is the primary method for hydrogen delivery. The inclusion of hydrogen reduces the viscosity of the fluid in natural gas pipelines, leading to more complex turbulence formation and development.

Methods To accurately predict the flow characteristics of hydrogen-blended natural gas, a LES-Schumann model was developed by integrating the Large Eddy Simulation (LES) model with the Schumann model. This model employs the LES to analyze large-scale eddy characteristics, while the Schumann model captures small-scale turbulence changes resulting from flow instability, thereby addressing the limitations of LES in small-scale turbulence modeling. The LES-Schumann model was utilized to investigate the flow characteristics of gas mixtures in pipelines with varying hydrogen blending ratios. The analysis focused on changes in density, volume fraction, turbulent viscosity, pressure, and other parameters, discussing the impact of hydrogen blending ratios on gas flow, turbulence characteristics, and hydrogen embrittlement sensitivity.

Results The LES-Schumann model accurately predicted the flow characteristics of hydrogen-blended natural gas, with an average error of just 3.422％ between simulation results and experimental data, demonstrating the model’s high reliability for this application. As the hydrogen blending ratio increased, the density of the gas mixture in the pipeline gradually decreased, while the volume fraction of hydrogen increased and pipeline pressure rose significantly. Notably, at the initial mixing point of hydrogen and natural gas, turbulent viscosity peaked, resulting in the most intense turbulence. The effects of the hydrogen blending ratio on mixing uniformity and the hydrogen embrittlement sensitivity coefficient were nonlinear. At a hydrogen blending ratio of 20％, gas mixing uniformity was optimal, and the hydrogen embrittlement sensitivity coefficient increased by only 0.41％ compared to the 10％ blending ratio, indicating a low risk of hydrogen embrittlement. However, when the blending ratio rose to 30％, gas mixing uniformity declined, resulting in an increased risk of hydrogen embrittlement.

Conclusion The LES-Schumann model can predict the flow characteristics of hydrogen-blended natural gas at various blending ratios and assess the risk of hydrogen embrittlement. A blending ratio of 20％ achieves optimal mixing uniformity between hydrogen and natural gas while effectively mitigating potential issues such as pressure rise, turbulent viscosity increase, and hydrogen embrittlement risks associated with the mixture. The research findings offer a crucial theoretical foundation for the optimal design and operation of hydrogen-blended natural gas pipelines.