杨丽,张晖,王媛媛,程景萌,李姗姗.T型微通道中液—液两相流流动与混合过程分析[J].农业机械学报,2017,48(1):397-405.
YANG Li,ZHANG Hui,WANG Yuanyuan,CHENG Jingmeng,LI Shanshan.Hydrodynamics and Mixing Process Analysis of Liquid—Liquid Two-phase Flow in Microfluidic T-junction[J].Transactions of the Chinese Society for Agricultural Machinery,2017,48(1):397-405.
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T型微通道中液—液两相流流动与混合过程分析   [下载全文]
Hydrodynamics and Mixing Process Analysis of Liquid—Liquid Two-phase Flow in Microfluidic T-junction   [Download Pdf][in English]
投稿时间:2016-06-14  
DOI:10.6041/j.issn.1000-1298.2017.01.052
中文关键词:  微通道  两相流  混合  旋转扰动
基金项目:国家自然科学基金青年基金项目(51505123)和河北省高等学校自然科学青年基金项目(QN2016101)
作者单位
杨丽 河北工业大学 
张晖 河北工业大学 
王媛媛 河北工业大学 
程景萌 河北工业大学 
李姗姗 河北工业大学 
中文摘要:为了揭示T型微通道中液液两相流的混合特性,采用数值模拟与实验对液滴内流体的动态混合过程进行了分析。研究结果表明:在液滴生成时,旋转扰动作用决定了液滴内混合组分的初始分布,是影响混合性能的关键因素。旋转扰动作用使液滴内两相界面发生旋转,混合组分位于液滴的前后部位,从而在液滴内循环流的作用下加强混合。连续相流速是影响旋转扰动作用的主要因素,若连续相流速较小,液滴较长,旋转扰动作用不足以使液滴内的组分充分混合;若连续相流速较大,液滴较小,旋转扰动能够在整个液滴范围内起到作用,混合程度得到大幅提升。当连续相流速增大时,液滴尺寸减小,当Vo为0.04μL/min时,混合指数为0.82,是Vo为0.005μL/min时混合指数的2倍。
YANG Li  ZHANG Hui  WANG Yuanyuan  CHENG Jingmeng  LI Shanshan
Hebei University of Technology,Hebei University of Technology,Hebei University of Technology,Hebei University of Technology and Hebei University of Technology
Key Words:microchannels  two-phase flow  mixing  twirling effect
Abstract:In order to reveal the characteristics of droplet mixing in a microfludic T-junction, the dynamic mixing process in droplet was studied by numerical simulations and experiments. The microfluidic chip was manufactured by soft lithography based on polydimethylsiloxane (PDMS), and the experiment phenomena of droplet formation and mixing process were analyzed with microscope system. The research results showed that the mixing efficiency was significantly influenced by the twirling effect which controlled the initial distributions of mixture during the droplet formation stage. While the droplet was separated from the dispersed phase in the junction region, the combined effect of viscous shear exerted by the continuous phase and the re-orientation of flow induced a vortex in the dispersed phase. As the two-phase interface in the droplet was rotated by the twirling effect, the mixed solutions were distributed to the front and back parts of the droplets. Therefore, the internal recirculation flow can bring in convection mechanism thus improving mixing. The twirling effect was noticeably influenced by the velocity of continuous phase. When the velocity of the continuous phase was slow, the twirling effect cannot distribute effectively for long droplets because of the large amount of fluid contained in the droplets. In contrast, the twirling effect appeared to be very effective for short droplets as the amount of fluid was small. When the flow velocity of the continuous phase was 0.04μL/min, the mixing index was 0.82, which was two times higher than that of the mixing index when the flow velocity of the continuous phase was 0.005μL/min. This study provided the insight of droplet formation and mixing performance inside the droplet in droplet-based microfluidics and it should be helpful for microdevice design and optimization.

Transactions of the Chinese Society for Agriculture Machinery (CSAM), in charged of China Association for Science and Technology (CAST), sponsored by CSAM and Chinese Academy of Agricultural Mechanization Science(CAAMS), started publication in 1957. It is the earliest interdisciplinary journal in Chinese which combines agricultural and engineering. It always closely grasps the development direction of agriculture engineering disciplines and the published papers represent the highest academic level of agriculture engineering in China. Currently, nearly 8,000 papers have been already published. There are around 3,000 papers contributed to the journal each year, but only around 600 of them will be accepted. Transactions of CSAM focuses on a wide range of agricultural machinery, irrigation, electronics, robotics, agro-products engineering, biological energy, agricultural structures and environment and more. Subjects in Transactions of the CSAM have been embodied by many internationally well-known index systems, such as: EI Compendex, CA, CSA, etc.

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