Research on leakage and diffusion characteristics of buried hydrogen-blended natural gas pipelines based on CFD

Hydrogen plays a crucial role in addressing fossil energy shortages and advancing new energy transitions. However, its storage and transportation present significant challenges. This paper employs computational fluid dynamics(CFD)simulations to compare leakage flow field distributions in buried natural gas pipelines before and after hydrogen blending. Using orthogonal experimental design, simulation schemes considering multiple interacting factors were developed. Based on the simulation results, a prediction model for gas concentration at the highest-risk ground point was established via least-squares and multiple nonlinear regression methods. Findings indicate that hydrogen blending expands the gas pressure, velocity, and concentration distribution ranges in soil. Increasing the hydrogen blending ratio from 0% to 30% enlarges the explosion-hazard radius from 1.523 m to 1.612 m, a 5.8% increase. The prediction model 's maximum and average errors are 8.359% and 5.744%, respectively. This study supports risk assessment and secondary explosion prevention for buried hydrogen-blended natural gas pipelines.