Chaotic mixing in a single-screw extruder with a moving internal baffle

Authors

  • Baiping Xu,

    1. Technology Development Center for Polymer Processing Engineering of Guangdong Colleges and Universities, Guangdong Industry Technical College, Guangzhou 510641, China
    2. Key Laboratory of Advanced Materials and Technology for Packaging of Hunan Colleges and Universities, Hunan University of Technology, Zhuzhou Hunan 412008, China
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  • Yuejun Liu,

    1. Key Laboratory of Advanced Materials and Technology for Packaging of Hunan Colleges and Universities, Hunan University of Technology, Zhuzhou Hunan 412008, China
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  • Huiwen Yu,

    1. Technology Development Center for Polymer Processing Engineering of Guangdong Colleges and Universities, Guangdong Industry Technical College, Guangzhou 510641, China
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  • Lih-Sheng Turng

    Corresponding author
    1. Polymer Engineering Ctr. University of Wisconsin Madison, Madison, Wisconsin 53706-1539
    • Polymer Engineering Ctr. University of Wisconsin Madison, Madison, Wisconsin 53706-1539. E-mail: turng@engr.wisc.edu

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Abstract

A geometry in which the mixing of a single-screw extruder was enhanced by a reciprocating baffle is proposed in this article. The effect of the baffle's amplitude on the mixing kinematics of the screw channel was investigated. A model with the baffle lower than the screw channel and the corresponding mathematical model were developed. The periodic flow and mixing performance of Newtonian fluid in such an extruder were numerically simulated. The finite volume method was used, and the flow domain was meshed by staggered grids with the periodic boundary conditions of the barrier motion being imposed by the mesh supposition technique. Fluid particle tracking was performed by a fourth-order Runge–Kutta scheme. Distributive mixing was visualized by the evolution of passive tracers initially located at different positions. The growth of the interface stretch of tracers with time and the cumulative residence time distribution were also obtained. Poincaré sections were applied to reveal the geometrical scale of chaotic mixing patterns and the regions with embedded regular laminar flows. For comparison, the mixing performance in a conventional single extruder with fixed baffle was also investigated. POLYM. ENG. SCI., 54:198–207, 2014. © 2013 Society of Plastics Engineers

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