垂直管中双尺寸颗粒群的混合及分离规律研究  

THE MIXING AND SEGREGATION OF BINARY PARTICLES TRANSPORTATION IN VERTICAL PIPE

作　　者：张岩[1] 任万龙 张旭辉[1,2] 鲁晓兵 Zhang Yan;Ren Wanlong;Zhang Xuhui;Lu Xiaobing(Key Laboratory for Mechanics in Fluid Solid Coupling Systems,Institute of Mechanics,Chinese Academy of Sciences,Beijing 100190,China;School of Engineering Science,University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院力学研究所流固耦合系统力学重点实验室,北京100190 [2]中国科学院大学工程科学学院,北京100049

出　　处：《力学学报》2023年第7期1582-1592,共11页Chinese Journal of Theoretical and Applied Mechanics

基　　金：国家自然科学基金(12132018);中科院先导A(XDA22000000)和中科院青促会(2017027)资助项目。

摘　　要：深海能源的开发利用近年来受到各国关注,而深海矿石是深海能源的重要组成部分.文章以深海采矿的垂直管水力输送为研究背景,其管道内流的典型特征是颗粒级配宽且颗粒浓度高.宽级配特征下,管道内存在粗细颗粒混合及分离的现象,可能导致颗粒局部浓度增加,危害输送安全.因此,文章研究垂直管内双尺寸颗粒群的混合及分离机理.采用计算流体力学-离散元方法 (CFD-DEM)开展数值模拟,针对粗细颗粒尺寸差异大导致体积浓度计算不准确的问题,提出颗粒群体积浓度计算修正模型以及欧拉场到拉格朗日场的数据映射模型,并进行程序实现及模型验证.研究发现粗细颗粒混合及分离过程会造成颗粒群前后出现间断,并且增加颗粒群局部体积浓度及颗粒碰撞频率.还定义无量纲颗粒碰撞应力和流固相互作用应力,表征颗粒碰撞强度和流固相互作用强度.颗粒群混合到分离过程中颗粒碰撞应力显著增加,因此可通过颗粒碰撞应力曲线确定初始混合到完全分离的时刻.此外,流固相互作用的差异是引起粗细颗粒分离的根本原因.The development of deep-sea resources has attracted the attention of various countries in recent years where the mineral resources is an important part.This paper considers the internal flow in hydraulic conveying during the deep-sea mining,which is characterized by wide particle gradation and high particle volume concentration.The wide particle gradation will lead to the particle mixing and segregation,which may result in high local particle concentration.The mixing and segregation of binary particles transportation in vertical pipe is investigated based on the computational fluid dynamics-discrete element method(CFD-DEM).A virtual mass distribution function method is proposed for calculating the coarse particle volume fraction field.In addition,a weighted function method relating the particle size is given for the interpolation between the Eulerian and Lagrangian field.The two models are implanted in the open source code CFDEM based on the based on the C++programming language.Then,the numerical method is verified by comparing the pressure drop and the minimum fluidization velocity of a fluidized bed case between the simulation results and analytical results.The study found that the mixing and segregation of binary particles will cause a gap between the front mixing area and the no-mixing area at the rear.The local particle concentration and the particle collision frequency increase also increased significantly.The particle collision stress and fluid-particle interaction stress are given,which are the ratios of unit particle collision force and unit fluid drag force to unit particle buoyant force,respectively,to explain the particle segregation mechanism.The particle mixing stage makes the particle collision stress increasing.Therefore,the moment from initial mixing to complete separation can be determined by the particle collision stress curve.In addition,the difference of fluid-particle interaction stress between the binary particle results the particle segregation because the fluid-solid interaction stress of

关 键 词：垂直管道 粗颗粒 颗粒分离 CFD-DEM 

分 类 号：O359[理学—流体力学]