Establishment And Numerical Study On Fully Coupled Population Balance Model In Oil-Water Two-Phase Flow

In the process of offshore oil exploitation and transportation,the accident of pipeline corrosion and leakage as well as oil spill can lead to amount of economic loss and serious ecological environment problem.Pipeline corrosion rate is closely related to phase distribution of oil and water in pipeline.In addition,droplet motion characteristics of two phase flow in the process of oil spill has significant effects on the ranges of polluted offshore areas.Consequently,it is necessary to study the motion characteristics of oil-water two-phase flow in horizontal pipeline and to determine diffusion law of oil droplet in the process of oil spill.In this paper,a fully coupled population balance model(PBM),based on the two fluid model and turbulence model by combing the overall interfacial forces,was established.Flow pattern distribution of oil-water two-phase flow in horizontal pipeline and oil droplets distribution regulation in the process of oil spill are numerically studied.The presented results could provide a theoretical guideline to prevent pipeline leakage and dispose pollution in time.The main contributions of this work were listed as follows:Numerical simulations of oil-water two-phase flow in horizontal pipeline were conducted and compared based on various interfacial forces.Results demonstrates that the fully coupled PBM model,including Frank wall lubrication force,Saffman lift force,Symmetric drag force and LdB turbulent dispersion force,can efficiently predict the phase distribution characteristics in low water-cut flow.However,for high water cut flow,the fully coupled PBM model,with Frank wall lubrication force,Saffman lift force,Schiller-Naumann drag force and LdB turbulent dispersion force,is more favorable in predicting phase distribution.The turbulent dispersion force and the turbulence intensity increase with the increase of inlet velocity,leading to a higher level dispersion of oil/water droplet and a lower water cut near the tube wall,which is helpful to prevent the corrosion of pipeline.Additionally,with the increasing of water cut or oil cut,the trend of oil/water droplet coalescence enhances and the droplet size increases,along with an increased water cut near the tube wall,as a result,the pipeline is easy to be corroded.The multi-fully coupled PBM models including the two fluid model and the Mixture model were employed to investigate the two phase flow in oil spill.It indicates that the multi-fully coupled PBM model,with the consideration of Simonin turbulent dispersion force,Saffman lift force and Grace drag force,can reasonably predict the jet turbulent stage,diffusion phenomena in the buoyant plume stage and droplet size distribution column.It also reveals that the disintegrating trend is relatively higher and the column tended to the smaller bins with the increasing of jetting velocity or decreasing of nozzle size.