不同离散格式下埋地穿越段天然气管道泄漏扩散数值研究

为了掌握埋地穿越段天然气管道泄漏扩散特性、防止因管道泄漏引起的火灾爆炸等事故发生,研究了埋地穿越段天然气管道泄漏扩散的机理。针对埋地穿越段天然气管道泄漏扩散问题,运用多孔介质模型,结合三大守恒方程,构建了基于计算流体力学的数值模型,探讨了大小孔隙率特性下,对非线性对流项和压力梯度项分别采用4种不同离散格式组合方式时的天然气体积分数分布,并与试验进行对比分析。以泰州至戴南的埋地穿越段天然气管道泄漏进行实例研究。结果表明:大孔隙率特性下,一阶standard格式在精度和计算速度上要优于其他离散格式,与试验结果更加接近;小孔隙率特性下,二阶presto!格式相比其他几种压力离散方式具有更高的求解精度。

Numerical study on the leakage and diffusion of the natural gas pipeline in the buried cross-transfer section in different discrete schemes

This paper is engaged in an investigation of the leakage and diffusion characteristics of natural gas pipeline in the buried cross-sections in hoping to increase its tightness and permanent effects in preventing from the likely accidents,such as fire and explosion risks caused by the pipeline leakage.The paper has also proposed a numerical simulated model for the leakage and diffusion of the pipeline in crossing the prairie area based on the calculation fluid dynamics,which also include a porous medium model and the three conservation equations to be used.In addition,the paper has not only included the four different discrete schemes in different groups,but also consists of nonlinear convection terms and pressure gradients.What is more,the paper has also discussed the volume fractions distribution of the natural gas under the different discrete schemes in the condition of different porosities.Furthermore,we have also made a comparison between the results we have gained through the simulated study with the experimental data we have gained from the research institute who is usually regarded as authoritative institutions in the research area.And,finally,we have made a case study sample by taking the buried crossing section from Taizhou to Dainan in the paper,whose total length is about 10 km,with the pipeline diameter being 600 mm,and its pipe thickness-12.9 mm and its material texture being directly made with the spiral-welding steel.The results of our simulated study show that:(1) in the conditions of large porosity,the first-order standard scheme can be realized in a much higher accuracy and higher calculation speed than in the other discrete schemes.The results we have gained through the simulated study from the first-order standard scheme prove to be much closer to the experimental data;(2) in the small porosity conditions,the second-order presto! scheme turns out to be of higher accuracy than in the other discrete schemes of the pressure item and the nonlinear convection one.