深海长距离垂直输送管道内固液两相流流态演化及流动保障研究

According to the major strategy on the development of deepsea mineral resources, this project focuses on the long-distance vertical hydraulic transport of deepsea ores. Based on the previous study of the solid-liquid two-phase flow transport, the flow pattern evolution and flow assurance of large particle solid-liquid two-phase flow during vertical hydraulic transport are investigated. On the basis of the mechanism of particle-fluid-wall interaction in the turbulent flow inside the vertical pipe, the particle-fluid interaction is analyzed; the models of particle-particle collision and particle-wall collision are established; the coupling simulation method of Computational Fluid Dynamics-Discrete Element Method is developed; the mathematical physics equations of the flow characteristics during long-distance and long-time transport are established. By employing analytical method, numerical simulation and experiment, the flow pattern and the evolution of solid-liquid two-phase flow in the pipeline are analyzed; the formation and evolution mechanism between the stable flow, the slug flow and the blockage are revealed; the time and position of the solid plug and the blockage are predicted; the wall shear stress of the slug flow and the blockage is analyzed; the impact of the flow on the solid plug is studied. Finally, the solutions to the slug flow and blockage are provided. The research provides the theoretical foundation and scientific basis for the design of long-distance vertical hydraulic transport in deepsea mining.

本项目围绕国家深海矿产资源开发的重大战略需求，聚焦深海矿石长距离垂直管道水力输送问题，基于申请人在博士阶段对固液两相流管道输送的研究基础，研究大颗粒固液两相流垂直管道输送的流态演化机理和流动保障特性。本项目从垂直管道湍流中颗粒-流体-壁面的相互作用机理出发，分析颗粒-流体的流固耦合作用，建立颗粒-颗粒、颗粒-壁面的碰撞模型；发展大颗粒固液两相流计算流体动力学-离散元耦合数值模拟方法；建立固液两相流长距离、长时间持续输送特性的数学物理模型。综合采用理论、数值、试验方法，分析管道内固液两相流的流态及演化规律；揭示管道内稳定流动-段塞流-堵塞的形成和相互转化机理；预报段塞流、堵塞的产生时刻和位置，分析段塞流、堵塞发生时壁面切应力和流体经过孔隙结构的冲击作用，探究段塞流、堵塞的解除方案，为深海长距离水力输送系统的设计和应用提供理论基础和科学依据。

本项目围绕国家深海矿产资源开发的重大战略需求，聚焦深海矿石长距离垂直管道水力输送，研究大颗粒固液两相流垂直管道输送的流态演化机理和流动保障特性。通过分析垂直管流中少量颗粒的动力学特性，揭示了颗粒-流体-壁面的相互作用机理；发展了大颗粒固液两相流的数值模拟方法，研究了局部流态及演化机理，并基于参数敏感性分析，探明了管内流态的主要影响因子，建立矿石输送局部特性的分析预报模型；建立了固液两相流长距离、长时间持续输送的数学物理模型，揭示了管道内稳定流动-段塞流-堵塞的形成和相互转化机理，探索了段塞流、堵塞的解除方案。研究发现，单颗粒在管流中的运动存在螺旋下落、振荡下落、竖直下落、竖直上升、振荡上升以及随机上升六种模态；斯托克斯数是影响碰撞过程的主要因素；管流中的颗粒-颗粒碰撞受到流速、管径-粒径比、粒径比影响明显。固液两相流输送过程中，颗粒局部平均浓度大多数情况下大于输送浓度；最大瞬时浓度明显高于输送浓度；输送速度和输送浓度是决定输送特性的主要参数。低流速下的颗粒局部浓度升高是导致段塞流形成的主要原因；段塞流在一定浮游高度内维持动态平衡，降低流速将导致堵塞形成，提高流速可逐渐转化为稳定输送。段塞流或少量堵塞情况下，可通过逐渐提高流速解除。项目综合采用理论分析、物理实验和数值模拟，揭示了矿石输送和堵塞发生机理，建立分析预报方法，为深海采矿长距离输送系统的设计和应用提供理论基础和科学依据。