海底管道泄漏天然气扩散规律数值模拟

Numerical simulation on the gas diffusion law due to leakage of submarine pipeline

李新宏;  朱红卫;  陈国明;  孟祥坤

中国石油大学(华东)海洋油气装备与安全技术研究中心

LI Xinhong;  ZHU Hongwei;  CHEN Guoming;  MENG Xiangkun

Center for Offshore Equipment and Safety Technology, China University of Petroleum (Huadong)

海底管道; 泄漏; 天然气; 扩散规律; 数值仿真; 计算流体动力学

submarine pipeline; leakage; natural gas; diffusion law; numerical simulation; computational fluid dynamics (CFD)

为研究浅水区域海底管道泄漏天然气扩散规律,减少重大事故的发生,基于计算流体动力学(CFD)理论,建立海底天然气管道泄漏事故后果预测和评估模型.通过用户自定义函数(UDF)给出海流流速分布情况,结合VOF 模型和κ-ε湍流模型,实现对泄漏天然气扩散行为的模拟,研究不同泄漏速率、泄漏孔径及海流流速对天然气在海水中扩散行为的影响.结果表明:海底天然气泄漏扩散大致经历气云团→大气泡→小气泡3 种形态的变化过程;泄漏速率越大,扩散气体气泡半径越大,与海水掺混比例越小,抵达海面的时间越短;泄漏孔径变化对天然气扩散的影响与泄漏速率变化影响相同,但泄漏孔径变化对天然气扩散形态的影响更为明显;海流流速越大,气体扩散轨迹与海底的夹角越小,沿海流方向的扩散距离越大.

In order to study the diffusion law of natural gas due to leakage of submarine pipeline in shallow waters and thereby reduce the possibility of major accidents, this paper proposes a consequence prediction and evaluation model for the submarine natural gas pipeline leakage based on the computational fluid dynamics (CFD) theory. The user-defined function (UDF) is used to define the distribution of ocean current velocity, and then combined with VOF model and k-ε turbulence model, the diffusion behavior of leaking natural gas is simulated to identify the influence of different leaking rates, leaking hole diameter and ocean current velocity on the diffusion behavior. The results show that the diffusion of natural gas due to leakage of submarine pipeline usually experiences three forms of changes from gas cloud to big bubbles and then to small bubbles. The larger the leaking rate is, the larger the diameter of gas bubbles is, the smaller the mixing proportion with sea water and the quicker to reach the surface of ocean. The changes of leaking hole diameter have similar influences on the diffusion of natural gas and the leaking rate changes, but the changes of leaking hole diameter have more obvious influences on the diffusion form of natural gas. The larger the ocean current velocity is, the smaller the included angle between the track of gas diffusion and seabed and the larger the diffusion distance alongside the ocean current.