Wear And Resistance Characteristics Analysis Of Ice-water Pipe Flow On Pipe Segment At Low Temperature

Ice particles enter the pipeline with the seawater when polar ships sail into the ice area.Then the ice particles will cause sea pipeline erosion and increase the pipe resistance.High flow rate of the water will increase energy consumption,while plugging phenomenon occurs at low flow rate.The paper does research on the wear characteristics and resistance characteristics of ice-water two-phase flow pipeline aiming to analyze the impact of various factors on pipes and wear resistance properties.In this way,pipeline leaks and the plugging can be prevented.It will improve the safety of ships and the manufacture and maintenance of the polar ship.The main work is as follows:1.The wear characteristics of the part ice-water two-phase flow pipe in low temperature are studied.The erosion characteristics on horizontal straight and 90° elbow are analyzed when the phase change is ignored.Then the lagrangian model and erosion model are set up through Fluent.According to the numerical results,the wear of ice-water two-phase flow pipe in low temperature occurred mainly on the curved portion and the straight upper portion of the pipeline.The wear of sediment-laden flow pipe appeared on the curved portion and the straight lower portion of the pipeline.The increase of flow rate,particle diameter,particle volume concentration,impact angle will increase the erosion of pipelines.The erosion influence of various factors on the sediment flow and ice-water two-phase flow pipelines are approximately the same,but the impact on the pipeline of ice water two-phase flow is relatively small.The check on wall thickness of the curved portion and the straight upper portion of the pipeline should be enhanced.2.The frictional resistance of the part ice-water two-phase flow pipe in low temperature is studied.The Lagrange discrete model is established through Fluent when the phase change is ignored,and the friction coefficient of the horizontal pipe is calculated.The calculation results show that the energy consumption caused by inelastic collision between solid particles and pipeline wall had a great influence on loss of pipeline resistance.Within a certain range,with the increase of flow velocity,the friction coefficient of ice water two-phase flow decreased.With the increase of ice particles concentration scores and wall roughness,friction coefficient increased.The influence of these factors on ice-water two-phase flow pipe and the sediment flow pipes roughly the same.But the friction coefficient of sediment flow is higher than that of ice-water two-phase flow.3.The critical velocity of the part ice-water two-phase flow pipe in low temperature is studied.The research was carried out from the Lagrange discrete model and the Euler-Euler model.The frictional resistance is calculated by using the Lagrange method.Pipe friction at minimum speed is defined as the critical velocity of flow.Due to the inconspicuous friction variation,the critical velocity can't be calculated.By using Euler-Euler model for research,the effectiveness of the Euler-Euler model for calculating pipeline two-phase flow is verified.The critical velocity is studied by observing the regime change of two-phase flow.We observed phase flow state change between the suspension streams,moving bed flow,static bed of the stream,and determine the range of critical flow rate.And the range of the critical velocity is very similar to the experimental data in the literature.