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.