非牛顿流体微流场测量Micro-PIV系统研究

摘要

A Micro-PIV system for non-Newtonian fluid field measurement was introduced.The system mainly included three parts:micro flow field excitation,micro flow observation and data processing part.For the diversity of the micro flow excitation for the non-Newtonian fluid,there were many differences for the micro flow field excitation part from the normal Micro-PIV system.A microscope hot and cool stage,a waveform generator and a magnetic field generator were included in this part,and with these self-made instruments,the non-Newtonian micro flow were excited.The observation and record part mainly included the fluorescence microscope,the CCD and so on,which is used to observe and record the movement of the fluorescent tracer particles.The data processing part was used for image processing to the video file of the tracer particles from the observation part.This system was used to measure the micro flow field under the action of the electric field and the temperature field for the test.In the experiment,the non-Newtonian fluid liquid crystalline 5CB was used.Under the electric field,the micro flow was induced.The experiment was focusing on the measurement of the velocity profile of the side liquid crystalline cell.The obtained results agree to the simulation results very well qualitatively,and with this system,the results can be achieved faster and more accurate than the traditional experiment method.In addition,the liquid crystalline defects caused by the temperature field were studied with this system,and the temperature changing trend at which the liquid crystalline defect was formed was achieved.Under the condition of continuous heating and cooling processing,the defect forming temperature increases from 31.25 ℃ to 34.4 ℃.%介绍了一种专用于非牛顿流体微流动测量Micro-PIV系统,主要包括微流场激发、微流动观察记录与数据处理三大部分.针对非牛顿流体流动激发形式多样性的特点,微流场激发部分包括显微镜冷热台、波形发生器和磁场发生仪,可以产生激发非牛顿流体为流场所需的电、磁及温度场.观察记录部分主要包括荧光显微镜、CCD等,用于观察并记录荧光示踪粒子的运动,获取荧光示踪粒子运动的视频文件.数据处理部分用于将视频文件进行图像处理以得到所需流场数据.应用该系统对非牛顿流体5CB液晶在电场作用下所激发的微流动进行了测量,重点测量了液晶盒侧面的速度剖面图,所得到的试验结果与计算结果非常吻合,且比传统测量方法更加快速、准确.此外,对温度场变化产生的液晶缺陷进行了试验研究,得到了连续加热冷却状态下的液晶缺陷形成温度变化趋势,即形成缺陷的温度逐渐升高,从开始的31.25 ℃ 逐渐升高至34.4 ℃后保持平稳.