高回流循环被动式微混合器的特性研究

发布时间：2018-07-03 03:00

本文选题：微混合器 + 循环回流　；参考：《江苏大学》2017年硕士论文

【摘要】：作为微流控芯片的重要结构单元和微机电系统的前处理装置,微混合器伴随着微流控芯片和微机电系统的发展而兴起。根据有无增加额外动力源,微混合器可分为主动式和被动式两大类;相比较而言,被动式微混合器由于不需要添加额外动力源,因而具有结构简单、加工方便、易于集成、且不会影响有机流体的生化活性和理化性质等优点,使其在化学合成、生化分析、生物测量技术、药物控制释放等领域有着广阔的应用前景。为了克服微混合器混合过程中,中心面附近的流体混合效率比较高,而靠近壁面附近的流体混合效率比较低的缺点,本文设计出一种利用高速射流原理来实现高效回流的循环被动式微混合器,其具有结构简单,容易产生回流且回流率高,混合效率高等诸多优点。该微混合器主要利用高速射流对混合区流体的卷吸、掺混作用,使循环通道中产生回流,从而实现边界层附近混合效率较低流体的多次循环混合。本文通过ANSYS CFX数值模拟的方法,研究了不同结构参数和流体参数对微混合器混合性能的影响;同时,通过设计微流体混合实验,研究了微混合器的实际混合效果,并将实验结果和模拟结果进行了对比。数值模拟结果表明,射流强度越大,流体粘度越小,微混合器的回流率和混合效率就越高,而且缩小射流喷嘴宽度L,或适当降低微混合器高度H均可有效提高射流强度;而当射流强度达到一定程度时,射流迹线会在混合区产生偏转,从而导致两个循环通道中混合流体的回流量相差较大,这种不对称的循环回流使得混合区流体分子间的碰撞更为剧烈,混沌对流强度更强,此时通常能实现很高的混合效率;当Re15时,微混合器的最大回流率已超过22%,混合效率则超过95%。根据实验结果与数值模拟结果的对比,可以发现:微流体混合实验的实验结果与数值模拟结果保持了良好的一致性,从而证明了本文采用的数值模拟方法的准确性和可靠性;这也说明,本文所设计的微混合器具有很好的实际应用价值。
[Abstract]:As an important structure unit of microfluidic chip and pre-processing device of micro-electromechanical system, micro-mixer has been developed with the development of microfluidic chip and micro-electromechanical system. Based on the availability of additional power sources, micromixers can be divided into active and passive types; by comparison, passive micromixers have simple structures, easy processing and easy integration because they do not require additional power sources. It will not affect the biochemical activity and physicochemical properties of organic fluid, which makes it have a broad application prospect in the fields of chemical synthesis, biochemical analysis, biological measurement technology, drug release control and so on. In order to overcome the disadvantage of high mixing efficiency near the center surface and low mixing efficiency near the wall in the mixing process of the micro mixer, In this paper, a kind of circulating passive micro mixer with high efficiency is designed by using the principle of high speed jet. It has many advantages, such as simple structure, easy to produce reflux and high reflux rate, high mixing efficiency and so on. The micro mixer mainly uses the high speed jet to absorb and mix the fluid in the mixing zone, so that the reflux is produced in the circulation channel, so that the mixing efficiency near the boundary layer is low. In this paper, the influence of different structure parameters and fluid parameters on the mixing performance of the micro mixer is studied by means of ANSYS CFX numerical simulation, and the actual mixing effect of the micro mixer is studied by designing the micro fluid mixing experiment. The experimental results are compared with the simulation results. The numerical simulation results show that the greater the jet strength and the lower the fluid viscosity, the higher the reflux rate and mixing efficiency of the micro mixer, and reducing the jet nozzle width L or reducing the height H of the micro mixer can effectively increase the jet strength. However, when the jet intensity reaches a certain degree, the jet trace will deflect in the mixing zone, resulting in a large difference in the reflux of the mixed fluid in the two circulation channels. This asymmetric circumfluence makes the collision between molecules in the mixing region more intense and chaotic convection more intense, which usually achieves a high mixing efficiency; when Re15, The maximum reflux rate of the micro mixer is over 22 and the mixing efficiency is over 95. According to the comparison between the experimental results and the numerical simulation results, it can be found that the experimental results of the micro-fluid mixing experiment are in good agreement with the numerical simulation results, which proves the accuracy and reliability of the numerical simulation method used in this paper. It also shows that the micro mixer designed in this paper has good practical application value.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH-39;TN492

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