微流体三维速度场和温度场测试方法研究

发布时间：2018-03-08 15:52

本文选题：速度　切入点：温度　出处：《浙江大学》2015年硕士论文　论文类型：学位论文

【摘要】：在资源日渐短缺的今天,微型化得到了广泛运用,如微电子微机械系统和微全分析系统等,它们在很大程度上节约了资源和能源,提高了科研效率。近年来,越来越多的学者将目光投向流体流动的微型化上,以期达到优化工业设计、提高生产效率的目的。速度和温度是微流体两个重要的参量,其数值大小直接影响能耗以及反应的进行。而微流体尺度微小,需要发展出适用的测速和测温手段。本文研究微流体三维速度场和温度场的同时测量技术,提出联用显微全息PTV(MicroHPTV)、基于激光诱导荧光的测温术以及荧光颗粒离焦成像技术,设计并搭建了光学实验平台,开展了相关的研究：1. MicroHPTV测速技术原理及实验研究首先研究显微成像系统的景深大小及其影响因素。接着研究基于小波或者卷积的重建算法的若干聚焦判据曲线,结果表明小波域内采用亮度梯度局部方差判据法在重建z轴位置方面性能优越。再者以数值模拟的手段,考察显微全息三维定位和MicroHPTV技术的速度测量误差。然后将显微全息和该重建算法应用到大景深的离散颗粒场和倾斜的连续物的测量。最后,使用MicroHPTV技术测量微通道内流体的三维速度场,并与理论预测结果作对比分析。2.基于激光诱导磷光和荧光的测温技术的实验研究磷光和荧光的诱导成因类似,基于激光诱导磷光和荧光的测温技术均可以运用到微流体的测温中。首先研究并开发了工业型磷光材料ZnS:Eu的绝对磷光强度与温度的标定曲线。然后以罗丹明B和磺基罗丹明101制备成一定浓度比的混合水溶液,根据其荧光光谱与温度的变化曲线挑选出温度敏感与不敏感的荧光波段,搭建双色荧光测温实验平台,标定了荧光光强比与温度的测量曲线。根据标定曲线,即可由实验数据插值计算被测温度。3.三维速度场和温度场的同时测量研究首先针对显微成像系统景深较小的问题,开展了荧光颗粒离焦成像的特性研究,实验和模拟结果说明尽管荧光颗粒的绝对强度受离焦位置的影响,但是强度比却不受影响。接着提出利用显微全息进行颗粒的三维定位,运用颗粒匹配算法,推导出荧光图像上颗粒的三维位置,同时利用荧光的强度比与温度的单调相关性,得到三维温度场。最后联用MicroHPTV、双色荧光测温法和荧光颗粒离焦成像法,开展了微流体三维速度场和温度场同时测量的模拟研究,证实了测量技术的可行性,得到了微流体三维速度场和温度场的分布。
[Abstract]:In today's increasingly scarce resources, miniaturization has been widely used, such as microelectromechanical systems and micro-total analysis systems, which have largely saved resources and energy, and improved the efficiency of scientific research. More and more scholars are focusing on the miniaturization of fluid flow in order to optimize industrial design and improve production efficiency. Speed and temperature are two important parameters of microfluid. Its numerical value directly affects the energy consumption and the reaction, but the microfluid scale is small, so it is necessary to develop suitable velocity and temperature measurement methods. In this paper, the 3-D velocity field and temperature field of microfluid are studied simultaneously. Based on laser induced fluorescence thermometry and fluorescence particle defocusing imaging technology, an optical experimental platform is designed and built. The principle and experiment of MicroHPTV velocimetry technology are studied. Firstly, the depth of field and its influencing factors are studied. Then, some focus criterion curves of reconstruction algorithm based on wavelet or convolution are studied. The results show that the local variance criterion of brightness gradient in wavelet domain is superior in reconstruction of z axis position. The measurement error of microholographic 3-D positioning and MicroHPTV technique is investigated. Then the micro-holography and the reconstruction algorithm are applied to the measurement of discrete particle fields with large depth of field and tilted continuum. The three-dimensional velocity field of the fluid in microchannel was measured by MicroHPTV technique, and compared with the theoretical prediction results. 2. The experimental study on the laser-induced phosphorescence and fluorescence based on the temperature measurement technique is similar in origin of phosphorescence and fluorescence induction. The temperature measurement based on laser induced phosphorescence and fluorescence can be used to measure the temperature of microfluid. Firstly, the calibration curves of absolute phosphorescence intensity and temperature of industrial phosphor material ZnS:Eu are studied and developed. Then the calibration curves of absolute phosphorescence intensity and temperature of industrial phosphor material ZnS:Eu are studied and developed. The mixed aqueous solution with a certain concentration ratio was prepared by sulfonyl rhodamine 101. According to the variation curve of fluorescence spectrum and temperature, the temperature-sensitive and insensitive fluorescence bands are selected, and the experimental platform of two-color fluorescence temperature measurement is built, and the measuring curve of fluorescence intensity ratio and temperature is calibrated. The 3-D velocity field and temperature field are measured simultaneously. Firstly, aiming at the problem of small depth of field in microscopic imaging system, the characteristics of defocusing imaging of fluorescent particles are studied. The experimental and simulation results show that although the absolute intensity of fluorescent particles is affected by the defocus position, the intensity ratio is not affected. The three-dimensional position of the particles on the fluorescence image is deduced, and the three-dimensional temperature field is obtained by using the monotone correlation between the intensity ratio of fluorescence and temperature. Finally, the microHPTV, dual-color fluorescence thermometry and fluorescence particle defocusing imaging are combined. The three-dimensional velocity field and temperature field of microfluid are simulated and studied. The feasibility of the measurement technique is verified and the distribution of three-dimensional velocity field and temperature field of micro-fluid is obtained.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TK31

【相似文献】