啮合同向双螺杆挤出机中组合螺杆性能的数值研究(Ⅱ)混合特性分析

Numerical Simulation of Screw Assembly Performance for Intermeshing Co-rotating Twin-Screw Extruders (Ⅱ) Mixing Analysis

采用有限元软件POLYFLOW,对组合式啮合同向双螺杆挤出机ZSK60中不同构型的组合螺杆进行了混合分析。通过计算螺杆转过不同角度时的拟稳态流场,采用粒子示踪分析(PTA)方法,对组合螺杆中聚合物熔体的动态混合过程进行了可视化模拟;在此基础上通过对大量粒子运动轨迹的统计处理,分别采用停留时间分布、分布混合指数、分离尺度等累积混合指数表征了组合螺杆的轴向混合性能、分布混合性能以及分散混合性能。此外还研究了不同工艺条件下组合螺杆的混合特性。并将部分数值模拟结果与前人实验研究进行了对比。

Mixing analysis was performed for different screw assemblies in a modular intermeshing co-rotating twin-screw extruder ZSK60 using a finite element package POLYFLOW. Based on the quasi-steady flow fields calculated at different rotational angles of twin screws, dynamic mixing processes in the screw assemblies were simulated through particle tracking analysis (PTA). By statistical treatment of flow trajectories for a large number of mass points, mixing performances of the screw assemblies were characterized in terms of the residence time distribution, distributive mixing index, and segregation scale, respectively. Furthermore, mixing analysis was also carried out under different processing conditions for the screw assemblies. Some of the numerical results were compared with previous experimental results.