Abstract:

Oil-water two-phase flow in horizontal pipelines exhibits complex and diverse dynamics, with intricate fluid structures and uncertain mechanisms of flow regime transitions. To facilitate the visualization of the oil-water two-phase flow process, a multiphase flow ultrasonic testing simulation platform was established to study the complex interfacial effects and relative motion between phases. Utilizing finite volume method (FVM) based three-dimensional fluid simulation software, a dynamic flow model for oil-water mixed inputs was developed. By extracting the coordinates of the multiphase interface cross-section, a two-dimensional geometric partition model of the test field was constructed using finite element method (FEM) within a multiphysics coupled simulation software, establishing a coupled FVM-FEM visualization simulation platform for multiphase flow. The mechanisms of interaction between oil-water two-phase flow and ultrasound were investigated under ultrasonic excitation. The research findings indicated that in the dynamic water-in-oil and oil-in-water flow regimes within the horizontal pipeline, the number of discrete phases increased within a certain range, but decreased due to coalescence, with the ultrasonic attenuation coefficient positively correlating with the number of discrete oil or water droplets. An in-depth exploration of the transition process from water-in-oil to oil-in-water reverse regimes was conducted, where both phases existed in a non-discrete form and the ultrasonic attenuation coefficient increased with the number of layers.

Key words: oil-water two-phase flow, phase inversion process, transitional flow regime, phase content, finite volume method-finite element method (FVM-FEM), ultrasonic attenuation

摘要：

油水两相流在水平管道中流动过程复杂多样，流体结构复杂多变，流态转化机理尚不明确。为实现油水两相流动过程可视化检测，本文建立了研究油水两相流动过程复杂相间界面效应及相间相对运动的多相流超声测试仿真平台，利用有限体积法（FVM）的三维流体仿真软件，构建油水混合输入的动态流动过程模型。通过提取多相界面横截面坐标，在多物理场耦合仿真软件中基于有限元法（FEM）构建被测场二维几何剖分模型，建立FVM-FEM耦合的多相流可视化仿真平台。在超声波激励作用下研究油水两相流与超声相互作用的机理。研究结果表明：水平管道动态水包油与油包水流型中，离散相数量在一定范围内增大，但由于聚拢作用离散相数量会有所减少，超声衰减系数与离散油泡或水泡数量为正相关。最后，对水包油向油包水流型反相的过渡过程进行了深入探究，油水两相均以非离散形式存在，超声衰减系数随分层数量的增加而增大。

关键词: 油水两相流, 反相过程, 过渡流型, 相含率, 有限体积法-有限元法, 超声衰减