Abstract: Dispersed flow is characterized by the flow where one phase is dispersed in the other continuous phase.The force from the continuous phase, pipeline and pump can lead to drop transformation, break-up and coalescence.Drop size and distributions formed during oil-water dispersed flows have great influence on flow parameters, such as pressure drop.The study on drop size is significant in characterizing oil-water two-phase flows.A predictive model for calculating Sauter mean diameter in oil-water dispersed flows was developed, based on the study of a balance between turbulent kinetic energy and surface energy of dispersed liquid drops, approximate relationship of radial velocity fluctuation and friction velocity, and shear stress of pump.Data on drop size distributions formed during oil-water flows were obtained by using high speed camera and microscope.The experiments were carried out with both water and oil as continuous phases, in a 25.4 mm horizontal stainless-steel pipeline.Volume flow rates from 0.8 to 3.0 m³·h^-1 and oil phase volume fractions from 10% to 90% were used.An isokinetic sampling system was used in droplet sampling and size measurement.From comparison with experimental data under different flow rates, temperatures and dispersed phase volume fractions, the model predictions were accurate.Model results showed that shear and disturbance of pump made drop size smaller.Pump played a significant role in drop break-up and drop size distributions.

Key words: oil-water two-phase flow, dispersed flow, droplet, drop size, predictive model

摘要： 油水两相分散流的液滴粒径及其分布在很大程度上影响管路压降等流动参数，研究液滴粒径预测模型对揭示油水两相流的流动特性具有重要意义。通过研究湍流脉动动能与乳状液的界面能之间的平衡、管流径向速度脉动与摩擦速度之间的关系以及泵的剪切作用，建立了油水两相管流中分散相液滴粒径预测模型；在水平管道上对油水两相分散流的液滴特性进行了实验研究，采用高速摄像和显微镜拍摄获得液滴数据，探索含油率、流量和温度等因素对粒径的影响。预测模型计算结果与不同流量、温度和含油率条件下的实验数据吻合较好。根据预测模型计算了有泵和无泵情况下分散流液滴粒径，发现泵的剪切和扰动作用使得分散液滴具有更小的粒径，泵对液滴粒径及其分布起到了显著作用。

关键词: 油水两相流, 分散流, 液滴, 粒径, 预测模型