Taking a practical project as an example, based on the computational fluid dynamics (CFD), standard k-e model and finite element method, a mathematical model for the diffusion due to liquefied natural gas (LNG) pipeline leakage in a tunnel was established, and the diffusion process was numerically simulated for three LNG leakage cases. From the simulation results, the variation of CH4 concentration field and explosive gas cloud with time within the tunnel, and the influence of leakage location on the diffusion was analyzed for the three cases. It was shown that the variation of CH4 concentration field had a similar trend for the three cases, but the CH4 explosive gas cloud length increased rapidly with the LNG leakage intensity so that dangerous situations would occur for the medium and large leakages, and a leak location closer to air inlet would lead to a more dangerous situation. When the amount of LNG leakage in the tunnel is large, the effect of mechanical ventilation is obviously weakened. Furthermore, a nitrogen seal precaution was proposed for the situations.

中文翻译：

---

隧道LNG管道泄漏扩散过程数值模拟与分析

以实际工程为例，基于计算流体动力学（CFD）、标准ke模型和有限元方法，建立了隧道内液化天然气（LNG）管道泄漏扩散的数学模型，并在针对三种液化天然气泄漏情况对扩散过程进行了数值模拟。从模拟结果分析了三种情况下隧道内CH4浓度场和爆炸性气体云随时间的变化情况，以及泄漏位置对扩散的影响。结果表明，三种情况下CH4浓度场的变化趋势相似，但CH4爆炸性气体云团长度随着LNG泄漏强度的增加而迅速增加，导致中、大泄漏发生危险情况，靠近进气口的泄漏位置会导致更危险的情况。当隧道内LNG泄漏量较大时，机械通风效果明显减弱。此外，针对这种情况提出了氮气密封预防措施。