中文摘要：

为了研究天然气输送管道发生泄漏后气体的扩散规律，以长庆油田第五采气厂输送管道为研究对象，利用FLUENT软件进行数值计算。根据现场的实际情况，建立了数值模拟的物理模型，设置合理的边界条件，得到了不同风速下天然气扩散规律。结果表明：在静风条件下，气体的浓度和速度分布基本上呈对称分布。在风力的作用下，气体的浓度场向下风向发生了明显的偏斜，当风速为3m／s时，喷射气流大约在泄漏口上方50m处发生偏斜，当风速为5m／s时，喷射气流大约在泄漏口上方35m处发生偏斜，当风速为10m／s时，喷射气流大约在泄漏口上方15m处发生偏斜，而且随着风速的增大，射流偏离竖直方向角度也增大。同时风速越大，硫化氢对人体有危害的面积越小。

英文摘要：

The transportation pipe of 5th Gas Recovery Plant with Petro China Changqing（ PCOC ）was simulated using FLUENT software to study the diffusion characteristics of natural gas in the pipe after leakage. The physical model was built according to the field investigation, and the diffusion characteris- tics at various air velocities were obtained at appropriate boundary conditions. The results indicate that the distributions of gas concentrations and velocities were both symmetric at windless conditions. The gas concentration field declines downstream due to the wind. At air velocities of 3,5 and 10 m/s, the decline of the jet gas started at 50,35 and 15 m above the 1 increase of the air velocity, the decline slope became gen sulfide was smaller. eakage opening, respectively. Additionally, with the larger, and the harmful area to humans from hydro-