低雷诺数液—液两相流体的流动与混合

发布时间：2018-04-23 07:48

本文选题：微流控 + 微混合器　；参考：《哈尔滨工业大学》2015年硕士论文

【摘要】：微流控技术是一门在化工、生物工程、微机械和纳米材料等基础上发展起来的交叉学科,可广泛应用在层流微加工、纳米材料合成、萃取分离等方面。控制多相微流体的流动与混合是实现这些功能的前提和关键。本文通过数值模拟和实验系统的研究了微通道中雷诺数小于0.1时,互溶与不互溶液-液两相流体的流动状态。首先,本文通过数值模拟研究了微通道结构对互溶两相流体流动状态的影响。根据两相混合机制随流动状态的变化,设计出高效的微混合器。通过在微通道中引入不同尺寸、形状及对称性的混合单元,增强对流并引入局部涡流,在较短的时间和有限的空间条件下实现了极低雷诺数条件下混合强度的较大提高。流体经过两个互相串联的混合单元混合后,出口处的混合强度达到87%。其次,本文建立了不同驱动压力下油水两相界面演变的模型。通过数值模拟和理论分析,发现界面的形成、演变和运动都是入口驱动压力、通道内摩擦压降与液-液及液-固界面张力共同作用的结果;系统研究了不互溶液-液两相流型随流动条件的变化,根据模拟和实验结果绘制出两相流型相图。实验中,对实验装置进行改进,在出口处引入负压,并在微流控装置中集成加热器件。通过对驱动压力和界面张力的定量调控,在实际微通道内不互溶两相之间建立起平直、稳定的界面,并实现了对界面位置的控制。
[Abstract]:Microfluidic technology is an interdisciplinary subject developed on the basis of chemical engineering, bioengineering, micromechanics and nanomaterials. It can be widely used in laminar microprocessing, nano-material synthesis, extraction separation and so on. Controlling the flow and mixing of multiphase microfluids is the premise and key to realize these functions. In this paper, the flow state of intersoluble and non-solution-liquid two-phase fluids in microchannels with Reynolds number less than 0.1 has been studied by numerical simulation and experimental system. Firstly, the effect of microchannel structure on the flow state of intersoluble two-phase fluid is studied numerically. According to the change of two-phase mixing mechanism with the flow state, an efficient micro-mixer is designed. By introducing mixed elements of different sizes, shapes and symmetries into microchannels to enhance convection and introduce local eddy current, the mixing strength can be greatly improved under the condition of very low Reynolds number and short time and limited space. When the fluid is mixed through two mixing units in series, the mixing strength at the outlet reaches 87. Secondly, a model of oil-water interface evolution under different driving pressures is established. Through numerical simulation and theoretical analysis, it is found that the formation, evolution and movement of the interface are the result of the inlet driving pressure, the friction pressure drop in the channel and the liquid-liquid and liquid-solid interfacial tension. The variation of the flow pattern with the flow conditions is studied systematically. The phase diagram of the two-phase flow pattern is drawn according to the simulation and experimental results. In the experiment, the experimental device is improved, the negative pressure is introduced at the outlet, and the heater parts are integrated in the microfluidic device. Through the quantitative control of driving pressure and interfacial tension, a straight and stable interface was established between the insoluble two phases in the actual microchannel, and the position of the interface was controlled.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ021.1

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