Numerical Analysis of Aerated Drag Reduction in Dredging Pipelines Based on CFD-PBM Model
The energy loss caused by the delivery of mud in the process of dredging pipelines has significant impact on the spacing of pipelines.Eulerian model of particle dynamic theory and PBM model was used to carry out the numerical simulation analysis of three-phase flow delivery of the dredged pipelines.After the grid and model were verified independent and effective respectively,the analysis was made for the changes in slurry flow characteristics and pipeline pressure loss gradient caused by pipeline aerated delivery.The results showed that the pipeline aerated delivery could reduce the sedimentation of solid particles,narrow the low concentration area at the top of the pipeline,which was much more obvious with the increase of aerated volume based on lower air concentration,but the above effect tended to be stable subject to a certain air volume being reached.An aerated pipeline ensured more regular flow of the slurry inside the pipeline,enlarged high-speed-flow area,and the decreased flow velocity at the centre of the pipeline.The aerated pipeline also led to better drag reduction effect.The pressure loss gradient of the pipeline decreases with the increase of aerated volume,and then gradually became stable,especially for the delivery of medium coarse sand.The suitable aerated volume should range from 3%to 4%.The research results could serve as a reference for the design of pipeline delivery and the related engineering application.
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