非牛顿流体在微尺度管道内流动的实验研究

发布时间：2018-10-18 19:11

【摘要】：非牛顿流体是一类不遵守牛顿粘性定律的流体的统称。在自然界中与人造物中都广泛的存在,血液和聚丙烯酰胺(PAM)水溶液就是分别属于自然界和人造物中的非牛顿流体,它们虽同属一个类别,但其实际的微观结构可谓天差地别。本文中通过微流动实验的方式,探究了这两种流体在微管道流动过程中的流动特性,总结出了这两种非牛顿流体在流动中表现出来的一部分规律。论文的主要内容和结果如下:1.搭建微管道芯片流动实验平台,设计了一种对实验装置要求不高的压力测量方法。自行搭建的实验平台可以满足包括流动实验、控制、观测、记录以及压力测量在内的实验需求。2.在单根毛细微管道中,进行了以压力驱动的PAM水溶液流动实验。实验结果表明,在管径足够小的毛细管中PAM水溶液需要一定的临界压力才能开始流动,并且其临界压力与PAM的平均分子量有着直接的关系。同时考察了实验其他参数对于PAM水溶液流动特性的影响。给出了一个特定条件下PAM水溶液临界压力与质量分数之间的数值关系,讨论了临界压力出现的原因。3.通过对肿瘤组织血管网络形态的分析,提取了其主要特征,结合肿瘤组织血管真实尺寸设计制作了微管道芯片。在置信度分析之后,使用红细胞悬液代替全血做为流动介质在微管道芯片中进行了流动实验,通过对以图像序列为形式的实验结果的分析,得到了红细胞悬液中的红细胞速度以及悬液流动特性与红细胞比容(Hct)、入口流速、管道尺寸结构之间的关系,并对其中的规律做了一定的总结。4.通过对视网膜血管网的分形结构的分析,模拟其几种比较典型的特征结构,结合血管的真实尺寸,本文设计制作了两系列共四种微管道芯片,同样通过进行了流动实验并通过数据处理分析了在这两个系列微管道中红细胞悬液的流动特性,还证实了在实验用微管道中Fahreaus效应的存在,并利用实验结果进行了交叉验证。
[Abstract]:A non-Newtonian fluid is a general term for a class of fluids that do not abide by Newton's laws of viscosity. Blood and polyacrylamide (PAM) aqueous solution are non-Newtonian fluids in nature and artifical creation respectively. Although they belong to the same category, their actual microstructure is very different. In this paper, the flow characteristics of these two kinds of fluids in the flow process of microtubes are investigated by means of microflow experiments, and some laws of the two non-Newtonian fluids are summarized. The main contents and results are as follows: 1. A pressure measurement method with low requirement for the experimental device was designed. The self-built experimental platform can meet the experimental requirements including flow experiment, control, observation, record and pressure measurement. 2. A pressure driven flow experiment of PAM aqueous solution was carried out in a single hairy fine tube. The experimental results show that a certain critical pressure is required for the flow of PAM aqueous solution in a capillary tube with a small diameter, and the critical pressure is directly related to the average molecular weight of PAM. The effects of other experimental parameters on the flow characteristics of PAM aqueous solution were also investigated. The numerical relationship between the critical pressure and the mass fraction of PAM aqueous solution under a specific condition is given, and the reasons for the occurrence of the critical pressure are discussed. By analyzing the shape of vascular network of tumor tissue, the main features were extracted, and the microchannel chip was designed and fabricated in combination with the real size of tumor tissue vessel. After the confidence degree analysis, the red blood cell suspension was used instead of the whole blood as the flow medium to carry out the flow experiment in the microtube chip, and the results of the experiment in the form of image sequence were analyzed. The relationship between erythrocyte velocity and flow characteristics of erythrocyte suspensions and the inlet velocity of erythrocyte specific volume (Hct),) and the size and structure of the tube are obtained, and the rules are summarized. 4. By analyzing the fractal structure of retinal vascular network and simulating several typical characteristic structures of retinal vascular network, two series of four kinds of micropipe-chips were designed and fabricated in this paper, combined with the real size of blood vessels. The flow characteristics of red blood cell suspensions in these two microchannels were also analyzed by flow experiments and data processing. The existence of Fahreaus effect in microtubes was also confirmed, and the experimental results were used to cross-verify the flow characteristics of red blood cell suspensions.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O373

【参考文献】