隧道内天然气埋地管道泄漏扩散特征数值模拟

Numerical simulation of natural gas leakage dispersion characteristics of the buried pipeline in a tunnel

天然气输送管道会经过山区,隧道穿越技术被广泛采用,而隧道内天然气埋地管道由于腐蚀等因素有泄漏的风险。运用计算流体动力学(Computational Fluid Dynamics,CFD)软件FLUENT模拟研究隧道内天然气埋地管道泄漏后的时空演化规律及管道埋深对泄漏扩散的影响。结果表明:隧道中天然气泄漏后扩散形态由圆形变为放射状,向隧道两端均匀扩散,主要分布在隧道顶部;沿隧道轴向截面,危险范围随时间延长而增加,其增长速度随时间延长而减缓;沿隧道径向截面,天然气体积分数出现明显分层现象;随着管道埋深增加,隧道内的天然气扩散范围减小,且扩散范围减小幅度较大;隧道内不同等级的危险范围都减小,且减小幅度越来越大。研究结果对预防事故发生和应急救援有指导意义。

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.