连续相速度脉动对微通道内聚合物液滴生成和形貌的影响规律

doi:10.11949/0438-1157.20250087

摘要/Abstract

摘要：

采用三维直接数值模拟方法，研究了连续相速度脉动对微通道内聚合物液滴生成与形貌的影响规律。基于黏弹塑性Saramito模型和流体体积法，结合局部自适应网格细化技术，分析了液滴的生成过程与形态特征。结果表明，适当的速度脉动可以促进液滴生成，分散相的最大拉伸长度随脉动频率的增加呈现先减小后增大的趋势，脉动振幅的增加会缩短分散相的拉伸长度。脉动作用下，液滴形貌发生显著变化。当液滴速度占主导地位时，液滴头部和侧面会出现明显的轴向拉伸应力。而当连续相速度占主导地位时，液滴侧面拉伸应力显著减小，液滴长度被压缩。此外，连续相速度脉动下，液滴平均长度可以调控在102~193 μm。液滴平均长度和宽度由脉动频率主导，振幅的影响较小。

关键词: 脉动流, 聚合物液滴, 微通道, 非牛顿流体, 黏弹塑性, 数值模拟

Abstract:

The influence of continuous-phase velocity pulsation on the generation and morphology of polymer droplets in microchannels is studied using three-dimensional direct numerical simulation. Based on the elastoviscoplastic Saramito model and the fluid volume method, combined with the local adaptive mesh refinement technology, the droplet generation process and morphological characteristics were analyzed. The results show that elastoviscoplastic velocity pulsation promotes droplet generation, and the maximum stretching length of the dispersed phase first decreases and then increases as the pulsation frequency rises. The pulsation amplitude shortens the stretching length of the dispersed phase. Under the influence of pulsation, the droplet morphology undergoes significant changes. When droplet velocity dominates, significant axial tensile stresses appear at the head and sides of the droplet. When the continuous-phase velocity dominates, the tensile stress on the sides of the droplet decreases significantly, and the droplet length is compressed. Furthermore, under velocity pulsations of the continuous phase, the average droplet length is adjustable between 102 μm and 193 μm. The average length and width of the droplets are controlled by pulsation frequency, with little influence from the pulsation amplitude.

Key words: pulsatile flow, polymer droplet, microchannel, non-Newtonian fluid, elastoviscoplasticity, numerical simulation

中图分类号:

TQ 021.1

段炼, 周星睿, 袁文君, 陈飞. 连续相速度脉动对微通道内聚合物液滴生成和形貌的影响规律[J]. 化工学报, 2025, 76(9): 4578-4585.

Lian DUAN, Xingrui ZHOU, Wenjun YUAN, Fei CHEN. Effects of continuous phase velocity pulsations on the formation and morphology of polymer droplets in microchannels[J]. CIESC Journal, 2025, 76(9): 4578-4585.

图/表 10

图1 流动聚焦型微通道模型示意图

Fig.1 Schematic diagram of flow-focused microchannel model

图2 网格无关性验证

Fig.2 Grid independence validation

图3 模拟结果与实验结果的对比

Fig.3 Comparison of simulation results with experimental results

图4 恒定和脉动速度下流型的变化对比

Fig.4 Comparison of flow pattern transition at constant and pulsating velocity

图5 脉动频率对分散相拉伸长度的影响

Fig.5 Effect of pulsation frequency on the extension length of the dispersed phase

图6 脉动振幅对分散相拉伸长度的影响

Fig.6 Effect of pulsation amplitude on the extension length of the dispersed phase

图7 聚合物液滴内部速度和连续相速度随时间的变化

Fig.7 Variation of the polymer droplet internal velocity and continuous phase velocity with time

图8 聚合物液滴形貌和应力张量分量的变化

Fig.8 Variation of polymer droplet morphology and stress tensor components

图9 一个脉动周期内连续相流速，聚合物液滴长度、宽度以及变形程度随时间的变化

Fig.9 Variation of continuous phase velocity, polymer droplet length, and width, and deformation index with time during a pulsation period

图10 不同脉动频率和振幅下聚合物液滴的性质

Fig.10 Polymer droplet properties at different pulsation frequencies and amplitudes

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