（1. 江苏省食品先进制造装备技术重点实验室，江苏 无锡 214122；2. 江南大学 机械工程学院，江苏 无锡 214122；3. 江苏创新包装科技有限公司，江苏 扬州 225600）
蔡文源，王利强，徐立敏. 基于CFD-DEM的超细碳酸钙螺旋输送仿真分析［J］. 中国粉体技术，2024，30（3）：100-111.
CAI W Y， WANG L Q， XU L M. Simulation analysis of ultrafine calcium carbonate spiral transportation based on CFD-DEM［J］. China Powder Science and Technology，2024，30（3）：100−111.
DOI：10.13732/j.issn.1008-5548.2024.03.009
收稿日期：2024-03-05，修回日期：2024-04-12，上线日期：2024-04-25。
基金项目：中央高校基本科研业务费专项资金项目，编号：JUSRP21115；江苏省食品先进制造装备技术重点实验室自主研究课题资助项目，编号：FMZ202304。
第一作者简介：蔡文源（1999—），男，硕士生，研究方向为包装工艺与机械。E-mail：c2752096870@163. com。
通信作者简介：王利强（1977—），男，教授，博士，江苏省“双创博士”人才计划计划、江苏省“企业创新岗”特聘专家，主要从事食品包装技术研究。E-mail： liqiang-wang@jiangnan. edu. cn
摘要：【目的】 为提高螺旋输送机的输送效率，降低输送机的功耗与磨损，探究在不同进料速率、螺旋轴转速与几何体摩擦系数下，超细碳酸钙在水平变径变距螺旋输送机内的颗粒流动状态、出口质量流量、输送机功耗与磨损分布。【方法】使用计算流体动力学（computational fluid dynamics， CFD）与离散单元法（discrete element method， DEM）双向耦合数值模拟的方法，对螺旋输送机在不同转速下的质量流率进行分析对比，验证数值模型的正确性。【结果】 摩擦系数对颗粒的运动有较大影响，颗粒流的轴向速度峰值和质量流率峰值随着摩擦系数的增加先增大再减小；随着下料速度和摩擦系数的增大，输送机功率明显增大，且摩擦系数在高进料速度与低转速的情况下对功耗的影响相对于低进料速度和高转速更加明显；磨损较严重的区域集中在下料口处的螺旋轴与螺旋叶片的边缘处。【结论】 简单增大或减小摩擦系数并不能提高颗粒的轴向速度和质量流量，而是存在一个局部最优参数组合；适当地提高转速能够减小颗粒密实度与颗粒停留时间，从而减小输送机的功耗与几何体磨损。
关键词：超细碳酸钙；计算流体动力学；离散单元法；螺旋输送机；颗粒流动
As an important inorganic non-metallic powder material， ultrafine calcium carbonate is widely used in plastics， rubber， coatings， and paper making， etc. Due to its extremely small particle size and adhesive nature， there are difficulties in its
conveying process leading to lower conveying efficiency and increased equipment wear. Therefore， it requires improved design
and operation of conveying equipment. Screw conveyor， as an efficient and widely used solid material conveying equipment， is
characterized by its simple structure， low maintenance costs， and ability to convey materials in horizontal， inclined， or vertical directions. With the advancement of computer simulation technology， the discrete element method （DEM） technique has
become an important tool to study the particle flow and interactions in screw conveyor conveying process. Current research on
CFD-DEM coupling method for screw conveyors typically focuses on operational parameters for large particle materials. However， they overlook investigations into the role of geometric friction coefficients in the ultrafine powder conveying. In order to
improve the efficiency of screw conveyors and reduce power consumption and wear， the study was conducted to examine the particle flow state， outlet mass flow rate， conveyor power consumption， and wear distribution of ultrafine calcium carbonate in a
horizontal screw conveyor with variable diameter and pitch. This study provided theoretical and technical support for effective
transport of ultrafine powders， as well as new perspectives and methodological foundation for engineering applications and scien⁃
tific research in related fields.
Methods In this study, we adopt the CFD-DEM coupling method， using fluid dynamics software Fluent and discrete element software EDEM， to explore the gas-solid two-phase flow characteristics of ultrafine calcium carbonate powder in the process of horizontal variable-diameter variable-pitch spiral conveying with different operating parameters and geometric parameters, so as to provide theoretical and technical support for the effective conveying of ultrafine powders, and to provide new perspectives and methodological bases for the engineering applications and scientific researches in the related fields. It also provides a new perspective and methodological basis for engineering applications and scientific research in related fields. In the CFD-DEM gas-solid coupling，the gas phase is regarded as a continuous phase and satisfies the continuity equation and momentum conservation equation, and the turbulence model adopts the RNG k-ε model which is more in line with the complex turbulent flow inside the screw conveyor; the particles are regarded as a discrete phase, and their motion behaviors are described by the Newtonian kinetic equations［15-17］. The simulation model of horizontal variable diameter and pitch screw conveyor constructed in this paper，its simulation model and specific structure are shown in Figures 1 and 2. A tetrahedral unstructured mesh with high adaptability is chosen to be applied for meshing in this study, as shown in Figure 3. The parameter settings of the simulation experiment are detailed in Table 1.
Results Under identical conditions，an increase in the friction coefficient results in a corresponding increase in the initial particle velocity. As the particles advance, the space between them decreases, causing a more significant increase in the axial velocity and mass flow rate of particles with moderate friction coefficients. The conveyor power increases significantly with an increase in feeding speed and friction coefficient. The impact of the friction coefficient on power consumption is more pronounced at high feed speeds and low speeds than at low feed speeds and high speeds. The area of most severe wear is concentrated at the edge of the spiral shaft and spiral blade at the feed opening.
Conclusion Simply increasing or decreasing the friction coefficient will not improve particle axial velocity and mass flow， but there is a local optimum parameter combination. An appropriate increase in speed can reduce particle density and particle residence time， thereby reducing power consumption and geometric wear.
Keywords：ultrafine calcium carbonate； Computational fluid dynamics； Discrete element method； Screw conveyor； Particle flow
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