气液混输管线与立管系统严重段塞流数值研究

针对气液混输管线与立管系统严重段塞流问题, 采用严重段塞流形成条件一致的等效原则, 发展了一种将三维管道系统等效为二维管道系统的计算流体力学(CFD)数值模拟方法. 以文献中某下倾管与立管组合系统为对象, 结合其实验工况, 对严重段塞流气液流动过程进行了数值模拟, 获得了其周期、压力波动幅值及喷发时间等关键参数的变化规律, 数值模拟与文献所述实验结果符合. 在此基础上, 建立了立管入口气液折算速度、立管含气率以及立管出口平均速度的理论模型, 获得了这些关键参数随时间的变化规律, 并给出了确定立管内气液流型变化的理论方法, 理论结果与CFD数值模拟结果一致. 建立的CFD方法大幅缩减了严重段塞流数值模拟所需的时间和资源, 推导的理论模型揭示了严重段塞流特性参数之间的关联, 可以对严重段塞流所引发的危害进行快速评估及预测,具有一定的工程应用价值.

Numerical investigation on the gas-liquid severe slugging in a pipeline-riser system

Based on the consistence principle for the severe slugging formation condition, a computational fluid dynamics (CFD) method is proposed for numerically simulating the gas-liquid severe slugging in a pipeline-riser system by converting the three-dimensional pipeline-riser system into a two-dimensional equivalent one. Numerical simulation is conducted for the gas-liquid flow patterns of the severe slugging in a declination pipeline-riser system according to the experimental cases presented in the reference, and variations of characteristics of the flow parameters with gas-liquid superficial velocity due to such a severe slugging are obtained, including period, pressure fluctuation and blowout time, the numerical results are in good agreement with the experimental results. Moreover, the theoretical methods are obtained of determining the gas superficial velocity at the riser inlet, the gas volume fraction in the riser and the average velocity at the riser outlet during the severe slugging blowout stage, and the variations of characteristics of these flow parameters with time are presented. Besides, a theoretical predicting method of determining the flow patterns in the riser during the severe slugging blowout stage is further proposed, and the theoretical results are consistent with the CFD numerical results. The CFD method could save much time and computing resource, and the theoretical methods could be used to predict the damage of severe slugging quickly.