隧道内天然气埋地管道泄漏扩散特征数值模拟

To investigate the diffusion behavior of natural gas buried pipelines in the tunnel after leakage, this paper uses the Computational Fluid Dynamics (CFD) software FLUENT to conduct numerical simulation studies. This paper focuses on the spatial and temporal evolution of the natural gas buried pipeline in the tunnel after leakage and the influence of the burial depth of the pipeline on the diffusion of the leakage. The results show that the diffusion pattern changes from circular to radial after the natural gas leaks in the tunnel. After the natural gas touches the top of the pipeline, it diffuses evenly to both ends of the tunnel, mainly distributed at the top of the tunnel. In the axial cross-section, the gas volume fraction variation curves with time at each measurement point are divided into three stages, i. e., the rapid volume fraction increase stage, the relatively stable stage, and the free diffusion stage. Along the axial section of the tunnel, the volume fraction is highest near the leakage opening, the hazard range increases over time, and its growth rate slows down over time. Along the radial cross-section of the tunnel, the gas volume fraction appears to be stratified. The volume fraction gradient distribution is sparse at the top and bottom of the tunnel and dense in the middle. As the burial depth of the pipeline increases, the diffusion range of natural gas in the tunnel decreases, and the range decreases further. Once the leakage dispersion reaches a relatively stable state, the pipeline burial depth has a reduced influence on the maximum value of natural gas volume fraction at the axial monitoring points in the tunnel and the volume fraction gradient distribution in the axial direction. The hazard range in the tunnel decreases at varying levels, with a gradual increase in the rate of decrease over time.