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| Study on the chaotic dynamic properties of viscous fluid in four-screw extruders |
| Received:November 11, 2017 Revised:January 08, 2018 |
| View Full Text View/Add Comment Download reader |
| DOI：10.7511/jslx20171111001 |
| KeyWord:four-screw extruder numerical simulation Lagrangian coherent structures Poincaré section |
| Author | Institution |
| 朱向哲 |
辽宁石油化工大学 机械工程学院, 抚顺 |
| 佟莹 |
辽宁石油化工大学 机械工程学院, 抚顺 |
| 高鹤 |
辽宁石油化工大学 机械工程学院, 抚顺 |
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| Abstract: |
| Under the periodic disturbance of the screws,the fluid motion of viscous polymer melt in the screw extruder has the characteristics of chaos.Different from the traditional Euler method,in this paper,the Lagrangian method was used to investigate the fluid transport properties in the four-screw extruders.Based on the finite time invariant manifold theory,the finite time Lyapunov exponent (FTLE) and Lagrangian coherent structures (LCS) of the four-screw extruders were calculated considering the different initial time.The LCS as a boundary separated three regions with different mixing characteristics in the screw extruders,in which the local regions with poor or good mixing performances were also identified.The accuracy of LCS patterns was verified by comparing with Poincaré section.The results show that the center region of the co-rotating four-screw extruder is surrounded by a closed LCS under the periodic disturbance of the co-rotating four screws.Therefore,the center region is a dead region of fluid transportation.By changing the rotating direction of the four screws,the closed LCS surrounding the center region is eliminated.This results in the increase of material exchange and mixing efficiency in the counter-rotating four-screw extruder. |
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