Application of SPH-DEM coupling simulation method in meshing twin-screw extruder

doi:10.16085/j.issn.1000-6613.2024-0930

Abstract

Abstract:

In order to investigate the flow of solid-liquid two-phase material, the force on the particle, and the mixing process of two-phase material in the meshing twin-screw extruder, smooth particle hydrodynamics (SPH) coupled with discrete element method (DEM) was used in this paper for simulation. Because of its meshless nature, SPH method could effectively overcome the difficulty of meshing on the special structure of meshing twin-screw by finite element method. Based on the established fluid cell model, fluid viscosity model, solid particle model and particle contact model, the flowing and mixing process of solid-liquid two-phase material inside the screw section and kneader block section of the meshing twin-screw was simulated, and the force behavior and interaction of solid-liquid two-phase material in the conveying section and mixing section of the extruder were analyzed, respectively. The simulation results showed that the flow mode of the mixture of fluid-coated solid particles in the extruder was to move slowly along the axial direction while rotating with the screw in the circumferential direction, and the mixture reached the exit after 12s of feeding. The force of mixture in the kneader block section was significantly larger than that in the screw section, and the maximum normal force, tangential force and fluid force on the particle all occurred in the region of the first kneader disk. The filling degree and mixing effect of solid-liquid two-phase material in the kneader block section were higher than that in the screw section, and the Lacey mixing index of mixed material was up to 0.9.

Key words: SPH-DEM coupling method, meshing twin-screw, solid-liquid mixing, force on the particle, multiphase flow, computer simulation

摘要：

为探究啮合型双螺杆挤出机内固液两相物料的流动方式、颗粒受力及两相混合过程，本文采用光滑粒子流体动力学（SPH）与离散单元法（DEM）耦合的方法进行了仿真模拟。由于其无网格特性，SPH方法能够有效克服有限元方法在针对啮合型双螺杆这一特殊结构上划分网格困难的问题。基于所建立的流体单元模型、流体黏度模型和固体颗粒模型、颗粒接触模型等，对啮合型双螺杆的螺纹段和捏合块段内固液两相物料的流动混合过程进行了模拟，分析了固液两相物料分别在挤出机输送段和混合段的受力行为以及流动过程中的相互作用。模拟结果表明：流体包裹固体颗粒的混合物料在挤出机中的流动方式为随螺杆作周向转动的同时沿轴向方向缓慢推进，在加料12s后混合物料到达出口；混合物料在捏合块段的受力明显大于螺纹段，颗粒受到的法向力、切向力和流体力最大值均出现在第一个捏合盘区域；固液两相物料在捏合块段的填充程度和混合效果均高于螺纹段，混合后物料的Lacey混合指数高达0.9。

关键词: SPH-DEM耦合方法, 啮合型双螺杆, 固液混合, 颗粒受力, 多相流, 计算机模拟

CLC Number:

TQ027.3⁺6

YANG Wenming, XIE Linsheng, WANG Yu, MA Yulu, LI Guo. Application of SPH-DEM coupling simulation method in meshing twin-screw extruder[J]. Chemical Industry and Engineering Progress, 2025, 44(7): 3748-3756.

杨文明, 谢林生, 王玉, 马玉录, 李果. SPH-DEM耦合模拟方法在啮合型双螺杆挤出机中的应用[J]. 化工进展, 2025, 44(7): 3748-3756.

Figures/Tables 11

References 36

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参数	数值
中心距C/mm	30
螺杆直径D/mm	34
螺纹段长度/mm	32
捏合块段长度/mm	32
捏合块元件轴向间隙/mm	1
螺杆-螺杆间隙δ₁/mm	1
螺杆-机筒间隙δ₂/mm	1

参数	数值
中心距C/mm	30
螺杆直径D/mm	34
螺纹段长度/mm	32
捏合块段长度/mm	32
捏合块元件轴向间隙/mm	1
螺杆-螺杆间隙δ₁/mm	1
螺杆-机筒间隙δ₂/mm	1

参数	数值
入口颗粒流率/kg·h^-1	10
入口流体流率/kg·h^-1	10
流体及颗粒密度/kg·m^-3	2500
固体颗粒直径/mm	0.5
SPH粒子尺寸/mm	0.2
螺杆转速/r·min^-1	60
流体黏度/Pa·s	15

参数	数值
入口颗粒流率/kg·h^-1	10
入口流体流率/kg·h^-1	10
流体及颗粒密度/kg·m^-3	2500
固体颗粒直径/mm	0.5
SPH粒子尺寸/mm	0.2
螺杆转速/r·min^-1	60
流体黏度/Pa·s	15