Numerical simulation on mixing properties of wavy twin⁃screw elements

doi:10.19491/j.issn.1001-9278.2022.04.015

Abstract

Abstract:

A numerical simulation was conducted on the flow field and mixing properties of half intermeshing co?rotating/counter?rotating wavy twin?screw elements and intermeshing co?rotating/counter?rotating routine twin?screw elements using the Polyflow^? CFD software. The mixing performance of the two elements was investigated comparatively using the shear rate， mixing index， first characteristic value of inelastic stress tensor， residence time， time?averaged mixing efficiency， segregation scale， and other characteristic parameters. The simulation results indicated that the wavy twin?screw elements exhibited better mixing properties.

Key words: wavy twin?screw element, numerical simulation, mixing property

CLC Number:

TQ320.66⁺3

BAN Dongdong, WANG Danhua, LIU Kui, LI Yanan, LI Han, DAI Yahui. Numerical simulation on mixing properties of wavy twin⁃screw elements[J]. China Plastics, 2022, 36(4): 95-101.

Figures/Tables 14

Fig.1. Geometrical models of wavy twin?screw elements and their flow channel

Fig.2. Geometrical models of routine twin?screw elements and their flow channel

Fig.3. Wavy twin?screw elements and their flow channel grid partition

Fig.4. Routine twin?screw elements and their flow channel grid partition

Fig.5. Nephogram of shear rate

Fig.6. Distribution of maximum shear rate of the particle experiences in the flow channel

Fig.7. Nephogram of mixing index （at Z=25 mm cross?section）

Fig.8. Mixing index distribution at the outlet of the flow channel

Fig.9. Nephogram of first eigenvalue of inelastic stress tensor

Fig.10. First eigenvalue of inelastic stress tensor distribution at the outlet of the flow channel

Fig.11. Residence time distribution

Fig.12. Time?average mixing efficiency

Fig.13. Initial position tracer particle distribution

Fig.14. Segregation scale along the extrusion direction

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