Abstract: With the development of China's natural gas industry, the scale of natural gas pipeline transportation is also expanding, at the same time, it also brings the hidden danger of safety. The leakage accidents of urban natural gas pipeline occur frequently, which seriously affect the lives and property safety of urban residents. This paper mainly introduces the basic theory of numerical simulation and numerical simulation of the leakage of urban natural gas pipeline. Considering the influence of wind field on leakage, the variation of the wind field near the ground is analyzed, and the leakage model of the buried natural gas pipeline is established. The leakage diffusion is set in the atmospheric environment. The CFD software is selected to divide the grid and local encryption, and the steady state simulation of the wind field is carried out. After the wind field reaches the steady state, the boundary conditions of the post-processing are changed, and the leakage is simulated instantaneously. The variation law of the natural gas leakage diffusion with time is obtained, and the influence of wind speed on the leakage diffusion is analyzed quantitatively. The results show that the building has a disturbance to the wind field. During the leakage process, the gas gathers near the ground and close to the building. With the increase of wind speed, the steady-state diffusion height decreases, but the wind field has less influence on the horizontal diffusion. The greater the wind speed, the more obvious the dilution effect of the leakage gas, the smaller the dangerous area.

Key words: Natural gas pipeline, Leakage diffusion, Wind field, Numerical simulation

摘要： 随着我国天然气事业的发展，天然气管道规模也在不断扩大，与此同时也带来了安全上的隐患，城市天然气管道泄漏事故频繁发生，严重影响了城市居民的生命及财产安全。主要介绍了城市天然气管道泄漏数值仿真和数值模拟的基本理论，考虑泄漏过程中风场对泄漏的影响，分析了近地面处风场的变化，建立了埋地天然气管道泄漏模型。设定泄漏扩散发生在大气环境，选取CFD软件对网格进行划分并进行局部加密，进行了风场的稳态模拟。在风场达到稳态后，改变后处理边界条件，再对泄漏进行瞬态模拟，得出天然气泄漏扩散随时间的变化规律，定量分析了风速对泄漏扩散的影响。结果表明，建筑物对风场存在干扰，在泄漏过程中气体聚集在近地面及贴近建筑物周围，随着风速的增加，稳态扩散高度降低，但风场对水平扩散的影响较小，风速越大泄漏气体稀释效果越明显，所造成的危险区域越小。

关键词: 天然气管道, 泄漏扩散, 风场, 数值模拟