阶梯式T型微通道内有序气泡群的形成和流动特性研究

doi:10.11949/0438-1157.20221014

摘要/Abstract

摘要：

微流控技术制备微气泡因其过程可控、操作范围宽等特性而备受关注。选择阶梯式T型微通道作为微气泡生成的设备，利用高速摄像机研究了高气相含量下气泡群的自组装行为和流动特性，探索了液相体积流量、液相黏度、气相输入压力和通道宽度等因素对气泡群的影响规律。结果表明，只有当通道内的气相含量大于液相含量时才能形成有序的气泡群(气泡群晶体)，且气泡群晶体在受限空间内能够沿着通道宽度或深度方向自组装成不同行数的结构。此外，系统研究了不同操作参数对气泡群晶体运动速度的影响规律。气泡群晶体运动速度随着液相体积流量变化的规律与气液两相的总体积流量变化规律一致。最后，提出了提升气液体系流动理想性的策略，并构建了预测气泡群晶体流动理想性的无量纲数学模型。

关键词: 微通道, 气液两相流, 气泡, 晶体, 流动特性

Abstract:

The preparation of microbubbles by microfluidic technology has attracted much attention due to its controllable process and wide operating range. In this work, a step T-junction microchannel was chosen as the device for the microbubble generation to study the bubble swarm self-assembly behavior and its flow characteristics. Effects of the liquid volumetric flow rate, liquid viscosity, gas injection pressure, and channel size on the bubble swarm were investigated. The results show that ordered bubble swarm (bubble swarm crystals) can be formed only when the gas phase content in the channel is greater than the liquid phase content, and the bubble swarm crystals can self-assemble into structures with different numbers of rows along the channel width or depth direction in the confined space. Besides, the effects of different operating parameters on the flow behavior of the bubble swarm crystal were explored. The variation rules of the flow velocity of the bubble swarm crystal with the liquid-phase volumetric flow rate are the same as the rules of the gas-liquid two-phase volumetric flow rate. Finally, the strategies to improve the flow ideality of the system are proposed, and a dimensionless model for the prediction of the flow ideality of the bubble swarm crystal is also developed.

Key words: microchannels, gas-liquid flow, bubble, crystal, hydrodynamics

中图分类号:

TQ 021.1

盛林, 昌宇, 邓建, 骆广生. 阶梯式T型微通道内有序气泡群的形成和流动特性研究[J]. 化工学报, 2023, 74(1): 416-427.

Lin SHENG, Yu CHANG, Jian DENG, Guangsheng LUO. Formation and flow characteristics of ordered bubble swarm in a step T-junction microchannel[J]. CIESC Journal, 2023, 74(1): 416-427.

图/表 14

表1 气液体系的物性参数（25℃）

Table 1 Physical properties of the gas-liquid system （25℃）

甘油质量分数/%	密度ρ/(kg·m^-3)	黏度μ/(mPa·s)	界面张力σ/(mN·m^-1)
80	1206	45.6	46.12
86	1223	89.8	47.88
90	1232	151.9	49.66
93	1237	240.5	50.89

图1 实验装置示意图

Fig.1 Schematic diagram of the experimental setup

图2 阶梯式T型微通道结构图（标尺为200 μm）

Fig.2 Structure of the step T-junction microchannel (the scale bar is 200 μm)

图3 不同操作参数的变化规律

Fig.3 Variation rules of different operating parameters

图4 气泡群流动状态图

Fig.4 Photograph of the bubble swarm flow state

图5 微流体晶体在微通道内的堆叠示意图

Fig.5 Schematic diagram of microfluidic crystals stacked in a microchannel

图6 气泡群在不同尺寸通道内的自组装行为

Fig.6 Self-assembly behavior of bubble swarm in channels with different widths

图7 气泡群晶体沿通道宽度方向排布行数分布

Fig.7 The number of rows of bubble swarm crystals arranged along the width of the channel

图8 气泡群晶体运动速度的变化规律

Fig.8 Variation rules of the velocity of the bubble swarm crystal

图9 气泡群晶体运动速度和气液两相的总体积流量随液相体积流量的变化规律

Fig.9 Variation of the velocity of bubble swarm crystal and total volumetric flow rate of gas-liquid two-phase with volumetric flow rate of liquid phase

图10 通道宽度和液相体积流量对流动理想性的影响规律

Fig.10 Influence of channel width and liquid volumetric flow rate on flow ideality of the system

图11 气相输入压力对流动理想性的影响规律

Fig.11 Influence of gas injection pressure on flow ideality of the system

图12 液相黏度对流动理想性的影响规律

Fig.12 Influence of liquid phase viscosity on flow ideality of the system

图13 无量纲气泡群晶体运动速度比较

Fig.13 Comparison of the dimensionless bubble velocity of the bubble swarm crystal

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