Abstract: One of the most common oil-water flow patterns in a pipeline is dispersion flow formed by one phase dispersed into another in the form of droplets. The flow characteristics of oil-water dispersion are affected by the sizes and distribution of the droplets，thus the study on droplet formation is the basis in oil-water dispersion flow research. This paper studied oil-water dispersion flows formed by two different mineral oils and tap water in a 25.4mm nominal bore stainless pipeline. The droplet pictures were obtained using a high speed video recording technique in an isokinetic sampling system. The results showed that the breaking up and coalescence of droplets occurred at the same time until a dynamic balance was obtained with the dispersed flow parameters achieving a stable state. The time and characteristics of droplets breaking up，coalescence and forming a stable state were obtained，as well as the influence of pump on the time of stable flow formation. The results showed that pump had a strong influence on the characteristics of oil-water dispersion flows.

Key words: two-phase flow, dispersion, droplets, collision, coalescence

摘要： 油水两相流在管道中流动时会形成多种流型，其中一相形成液滴分散到另一相中是常见的流型之一，液滴粒径及其分布会影响油水两相流的流动特性，因此液滴的形成是研究油水两相流的基础。本文研究了两种白油和水在内径25.4 mm的不锈钢管道内形成的油水两相分散流，通过高速摄像系统拍摄等动量取样装置上有机玻璃样槽中流动状态下的分散流来获取液滴的图像，捕捉有代表性的过程。研究发现，液滴形成过程中剪切破碎和碰撞聚结现象同时发生，并最终达到动态平衡，宏观表现为两相流系统流动参数达到稳定，得到了液滴剪切破碎、碰撞聚结和形成稳定液滴的时间以及各过程中的液滴特性和泵对形成稳定液滴时间的影响。实验结果表明，泵的存在对油水两相分散流的特性有较大影响。

关键词: 两相流, 分散, 液滴, 碰撞, 聚结