Abstract: Aiming at the problem in dynamic leakage of urban overhead gas pipeline,considering the impact of different pressure levels on leakage and diffusion, high pressure (2.0 MPa), sub high pressure (1.0 MPa) and medium pressure (0.4 MPa) three kinds of pressure grade pipe to simulate were selected.Firstly, the leakage rate of the critical flow and the sub critical flow were calculated by using the leakage rate calculation mode.Secondly, the leakage rule of different pressure pipelines was obtained.The Fluent software was used to simulate the unsteady state leakage, and the risk range of natural gas diffusion was obtained.The results showed that if the pressure in the tube was greater,the quality of residual gas in pipe and the time of leaking was higher and the risk range of natural gas was lager when the volume of pipe and the diameter of leak were fixed.With the continuous leakage of non steady state, the leakage rate was getting smaller and smaller, the risk of natural gas was also getting smaller and smaller.

Key words: Overhead pipeline, Dynamic leakage, Pressure rating, Wind speed, Numerical simulation

摘要： 针对城镇架空天然气管道动态泄漏问题,考虑不同压力等级对泄漏扩散的影响,选取高压(2.0 MPa)、次高压(1.0MPa)和中压(0.4MPa)3个压力等级管道进行模拟。先利用泄漏率计算模型分别计算临界流和亚临界流泄漏的泄漏率,得到不同压力等级管道的泄漏规律;再利用Fluent软件对动态泄漏进行数值模拟,得到天然气扩散的危险范围。结果表明,当管道体积和泄漏孔径一定时,管内压力越大,管内剩余气体质量越大,泄漏持续时间越长,天然气的危险范围也越大;随着动态泄漏的持续,泄漏率越来越小,天然气的危险范围也越来越小。天然气爆炸下限距地面高度和下风向水平距离随时间变化总体呈下降趋势,但高压(2.0MPa)管道在下风向水平方向的距离先增加再减小。

关键词: 架空管道, 动态泄漏, 压力等级, 风速, 数值模拟