基于拉格朗日法偏心双螺杆挤出机混合机理分析

doi:10.19491/j.issn.1001-9278.2020.08.009

中国塑料 ›› 2020, Vol. 34 ›› Issue (8): 57-62.DOI: 10.19491/j.issn.1001-9278.2020.08.009

基于拉格朗日法偏心双螺杆挤出机混合机理分析

滕健¹, 王东阳², 朱向哲¹()

^1.辽宁石油化工大学机械工程学院，辽宁抚顺 113001
^2.抚顺市技师学院，辽宁抚顺 113123

收稿日期:2020-02-14 出版日期:2020-08-26 发布日期:2020-08-26
基金资助:
国家自然科学基金项目(51973085)

Analysis of Mixing Mechanism in Eccentric Twin⁃screws Extruders Based on Lagrangian Method

Jian TENG¹, Dongyang WANG², Xiangzhe ZHU¹()

^1.School of Mechanical Engineering, Liaoning Shihua University, Fushun 113001, China
^2.Fushun Technician Institute, Fushun 113123, China

Received:2020-02-14 Online:2020-08-26 Published:2020-08-26
Contact: Xiangzhe ZHU E-mail:xzzhu@126.com

摘要/Abstract

摘要：

利用有限时间李雅普诺夫指数(FTLE)和拉格朗日拟序结构(LCS)，并结合混合指数和瞬时混合效率等，对比分析了偏心距为0、2、4 mm的3种偏心双螺杆挤出机流场内的混合特性。结果表明，当偏心距为4 mm时，偏心双螺杆挤出机中流体粒子的遍历范围较大，拉格朗日拟序结构较为完整；流域中存在双曲不动点，流体粒子经历了相对较好的拉伸和压缩作用。通过瞬时混合效率参数分析表明，偏心距为4 mm的偏心双螺杆挤出机的混合效率优于其他2种模型。

关键词: 偏心双螺杆挤出机, 拉格朗日拟序结构, 有限时间李雅普诺夫指数, 混合指数, 瞬时混合效率

Abstract:

The mixing characteristics in the flow field of three eccentric twin?screw extruders with the eccentricities of 4 mm, 2 mm and 0 mm were comparatively investigated by use of a finite?time Lyapunov exponent (FTLE) and a Lagrangian coherent structure (LCS) combined with the mixing index and instantaneous mixing efficiency. The results indicated that when the eccentricity was 4mm, the fluid particles had a traversal range in the eccentric twin?screw extruder, and their Lagrangian coherent structure was relatively complete. There were some hyperbolic fixed points in the flow field, and the fluid particles underwent relatively good stretching and compressing actions. The analysis of instantaneous mixing efficiency parameters revealed that the mixing efficiency of the eccentric twin?screw extruder with an eccentricity of 4 mm was superior to the other two models.

Key words: twin screw extruder, lagrangian coherent structure, finite?time Lyapunov exponent, mixing index, instantaneous mixing efficiency

中图分类号:

TQ 320.5⁺2

滕健, 王东阳, 朱向哲. 基于拉格朗日法偏心双螺杆挤出机混合机理分析[J]. 中国塑料, 2020, 34(8): 57-62.

Jian TENG, Dongyang WANG, Xiangzhe ZHU. Analysis of Mixing Mechanism in Eccentric Twin⁃screws Extruders Based on Lagrangian Method[J]. China Plastics, 2020, 34(8): 57-62.

图/表 10

图1 偏心双螺杆几何模型和有限元模型

Fig.1 Eccentric twin?screws geometric and finite element models

图2 网格密度对速度的影响

Fig.2 Effect of mesh cells on velocity

图3 e=4 mm，t=0 s时不同积分时间向前FTLE

Fig.3 Forward time FTLE with different integration time while e=4 mm，t=0 s

图4 e=4 mm时不同初始时刻时间向前FTLE

Fig.4 Forward time FTLE with different initial time while e= 4 mm

图5 e=2 mm时不同初始时刻时间向前FTLE

Fig.5 Forward time FTLE with different initial time while e= 2 mm

图6 e=0 mm时间向前FTLE

Fig.6 Forward time FTLE while e=0 mm

图7 e=4 mm时不同初始时刻时间向后FTLE

Fig.7 Backward time FTLE with different initial time while e=4 mm

图8 不同偏心距模型的双曲LCS

Fig.8 Hyperbolic LCS from different eccentricity models

图9 不同偏心距模型的混合指数

Fig.9 Mixing index from different eccentricity models

图10 不同偏心距的瞬时混合效率

Fig.10 Instantaneous efficiency with different eccentricity

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基于拉格朗日法偏心双螺杆挤出机混合机理分析

Analysis of Mixing Mechanism in Eccentric Twin⁃screws Extruders Based on Lagrangian Method

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