基于LBM-LES拟流体分析的细颗粒固液离心泵内流特性研究

With the wide application of solid-liquid two phase centrifugal pump, wear damage caused by particle movement inside pump is increasingly serious, which threats the security and stable operation of the equipment and piping system. Therefore, it's desiderated to systematically study the two-phase flow mechanism and particles movement, of which the key issue is how to accurately depict the coupling effects of two phase and particle collisions, to establish close to the real fluid property and flow model and realize the accurate numerical solution..This project focuses on fine particles, low concentration two-phase flow in centrifugal pump, the research work combines theoretical analysis, numerical simulation and experimental research. Lattice-Boltzmann method is adopted to explore the microscopic characteristic of two phase flow, and the equivalent single quasi-fluid phase is modeled on the basis of the exact solution of the interfacial force and particle collision, of which the constitutive model by viscosity correction and flow model by turbulent model correction are built. With the aid of large eddy simulation, the precise simulation can be succeeded on flow structure of two-phase flow pump, and by the reverse decomposition technique the liquid and solid flow profile can be deduced by the quasi-fluid flow field. Relying on the combination of the macroscopic and mesoscopic view into together, this project reveals the micro two-phase characteristics of particle movement on one hand, the macro internal flow and wears mechanism on the other hand. The whole research approaches and conclusions can provide theoretical guide for researching and engineering application of two phase flow pump.

两相流泵内颗粒运动对磨损影响较大，严重影响着泵和管线的安全稳定运行。因此亟需系统地研究泵内两相作用机理及颗粒运动规律，常见的两相数值求解基于宏观控制方程，相间关系表达模糊，计算过程复杂且通用性较差。这其中的关键问题是准确描述两相的耦合作用和颗粒的碰撞，构建贴近真实介质属性的两相模型。.本项目将针对泵内细颗粒低浓两相流，采用理论分析、数值模拟和实验相结合的方式开展研究。借助格子-玻尔兹曼方法研究两相微观特征参数，在准确求解相间作用力和粒子碰撞的基础上，将两相流体等效为拟流体均一相，构建基于粘度和湍流模型修正的拟流体的本构模型和流动模型，借助大涡模拟实现对泵内拟流体的数值求解，通过拟流场反向分解获得固相颗粒的流场特征。项目将宏观与介观相结合，揭示两相粒子微观运动特征，掌握两相宏观运动规律和固相磨损机理，整体研究思路和结论对于相关研究和两相流泵的工程应用有较大的推动作用。

本项目从理论分析、数值模拟和实验三方面对细颗粒固液两相泵内颗粒与流体及壁面之间的复杂作用进行了基础研究。首先通过理论分析颗粒的受力，结合颗粒在泵流道内的宏观迁移轨迹，建立了颗粒在泵内运动模型，在此基础之上改进了CFD-DEM计算方法；通过颗粒在静止喷管和圆管内的高精度数值计算，还原了颗粒的运动特征和与流场的关联，揭示了细颗粒数量巨大情形下颗粒群的宏观分布、速度滑移和迁移轨迹，量化获得了壁面位置处的法向力和切向力，以及颗粒群的碰撞次数等，为未来统计学量化壁面磨损奠定了基础；进一步将上述研究工作拓展至混输泵内，项目通过离散元颗粒计算模型，获得了全尺度的颗粒时空分布和运动参数，将其空间位置与运动参数关联，用统计学的观点呈现了众多颗粒的宏观运移趋势。在试验方面，本项目构建了细颗粒两相和粗颗粒泵管测试试验台，定量地研究了不同粒径、不同浓度和不同流动工况下泵管的输运性能，试验与计算吻合较好，表明项目整体的分析计算有效。这些工作的开展，颗粒运动、流场结构到整体的输运性能，从内到外的拓展，为颗粒两相流整体输运和泵管设计提供了较好了理论支撑。.通过研究共发表论文4篇，其中 SCI 检索论文4 篇，申请发明专利11项，授权发明专利2项；培养毕业硕士研究生2名。