山脚地形下天然气管道泄漏扩散的特性分析

Study on the influence of natural gas pipeline leakage and diffusion at the foot of a mountain

为了研究山地天然气管道泄漏扩散的影响情况,掌握山地管道泄漏扩散的规律,以西南山地天然气管道沿线高后果区为工程背景,建立山脚地形下管道泄漏扩散模型,采用计算流体动力学(CFD)软件Fluent研究不同泄漏孔径、不同风速对山脚地形下泄漏扩散的影响情况。结果表明:随泄漏孔径增大天然气射流核变粗、变长,射流初始截面和初始速度变大,射流的高度和幅度也变大,泄漏的影响区域变大;随泄漏孔径增加山脚地形下射流中心线的偏转程度变大,山脚处聚集的甲烷质量分数越来越高;在有风条件下,风速作用使甲烷在山脚处产生了聚集,且聚集的甲烷质量分数超过使人窒息的甲烷质量分数10%,随风速增大山脚处甲烷聚集的质量分数先增加后减小,且沿山坡向上扩散的甲烷质量分数先增加后减小。

The purpose of the paper is to study the influence and laws of mountain natural gas pipeline leakage and diffusion. Taking the high-consequence area along the natural gas pipeline in the southwest mountainous area as the engineering background, the paper establishes the model of leakage and diffusion of a natural gas pipeline at the foot of the mountain and uses Computational Fluid Dynamics(CFD) to study the influence of the leakage and diffusion of methane at the foot of the mountain under the different leakage aperture and different wind speeds. The results indicate that under the static wind condition, the core of the natural gas jet becomes coarser and longer with the increase of the leakage aperture, and the initial cross-section and velocity of the jet become larger. The height and amplitude of the jet also increase, and the decreasing trend of jet velocity and methane mass fraction slows down, and the mixing area of methane and air becomes larger with increasing the height of the jet. Under the static wind condition, the jet center-line will deflect to the mountain slope position, and methane accumulates at the foot of the mountain. With the increase of leakage aperture, the deflection degree of the jet center-line also increases, and the mass fraction of methane at the foot of the mountain increases. Under windy conditions, the methane gathers at the foot of the mountain because of the impact of wind, and the mass fraction of methane exceeds the methane mass fraction that causes suffocation by 10%. As the wind speed increases, the mass fraction of methane at the foot of the mountain increases first and then decreases, and the mass fraction of methane flowing upwards the hillside also increases first and then decreases continuously.