共轴流水包油型微液滴形成过程的实验与数值模拟研究

发布时间：2018-01-26 10:25

本文关键词： 微流控共轴流水包油液滴形成液滴粒径　出处：《高校化学工程学报》2017年02期 　论文类型：期刊论文

【摘要】：在不同操作条件下对水包油系统中微液滴的形成过程及粒径大小进行了系统实验观察和测试,同时利用VOF/CSF模型对液滴形成过程进行了数值模拟,模拟结果与实验非常吻合;在此基础上,考虑两相流速、黏度、界面张力及壁面效应等因素,对液滴形成过程进行了进一步的模拟研究。结果表明,与传统油包水系统相比,水包油系统液滴的形成也有滴流(dripping)和射流(jetting)两种流型,但水包油系统能在更高的两相流速下保持滴流操作,而射流主要出现在离散相速度极高的条件下且很不稳定;滴流条件下生成的液滴具有很高的单分散性,且可改变流速提高产生频率,而射流条件下产生的液滴单分散性差,且易于出现卫星液滴;滴流条件下影响液滴粒径的显著因素是连续相流速、黏度、界面张力和壁面效应,其中前三者的影响可用毛细管数表征;研究对各影响因素的作用机理进行了阐释,并综合实验与模拟结果,给出了不同操作条件和装置尺寸下液滴生成粒径的预测关联式。
[Abstract]:The formation process and particle size of microdroplets in oil-in-water system were observed and measured under different operating conditions. The VOF/CSF model was used to simulate the formation process of droplets. The simulation results are in good agreement with the experiments. On this basis, considering the factors of two-phase flow rate, viscosity, interfacial tension and wall effect, the formation process of liquid droplets is further simulated. The results show that compared with the traditional oil-in-water system. The formation of droplets in oil in water also has two flow patterns: dripping) and jet jetting.However, the water in oil system can keep dripping operation at higher two-phase flow rate. The jet appears mainly under the condition of extremely high velocity of discrete phase and is very unstable. The droplets produced under the dripping condition have high monodispersity and can change the velocity of flow to increase the frequency of the droplets, while the droplets produced under the jet conditions have poor monodispersity and are prone to the appearance of satellite droplets. The significant factors affecting droplet size under drip condition are continuous phase flow rate, viscosity, interfacial tension and wall effect, among which the first three effects can be characterized by capillary number. In this paper, the mechanism of influencing factors is explained, and the prediction correlation of droplet size under different operating conditions and device sizes is given by synthesizing the experimental and simulation results.
【作者单位】：四川大学化学工程学院;
【分类号】：TQ021.1
【正文快照】： 利用微通道制备微液滴由于生成液滴粒径大小可控、单分散性好、可操作性强,被广泛应用于微化工、胶体工程、新材料制备等领域[1~4]。常见的微通道主要有T型通道、流动聚焦、共轴流三种[5~7]。共轴流通道作为唯一一种从三维流动尺度制备液滴的方式,液滴受力均匀,产生稳定,在制

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