SIMULATANEOUS MEASUREMENT OF TEMPERATURE AND VELOCITY IN THRR-DIMENSIONAL SPACE BY LIQUID CRYSTALS AND APPLICATION TO STUDY OF TURBULENCE STRUCTURE OF THERMAL CONVECTION

本文采用液晶显示技术和PIV技术，研究了三组分流体温度场和速度场的同时测量技术。将该方法进一步推广到光片扫描三维测量技术，用于热对流的研究。这里得到的结果总结如下。(1)人工彩色图像测量温度和速度的不确定度评定研究了一种利用液晶显示模拟颜色变化的人工彩色图像生成方法。该彩色图像用于评估光片平面中的温度和速度的两个分量。该方法也通过使用观测的立体配置而扩展到速度的三个分量。结果表明，加入一定量的示踪粒子可以提高流速测量的精度，但加入太多的示踪粒子会导致流速测量精度下降， ...更多信息 s的温度测量，因为减少了可测量的温度区域。在温度测量中，采用三色参数HIS进行温度标定，其精度优于其他三种方法。从立体观测中发现，存在一个最佳离轴观测角，以提高同时测量的精度。(2)立体声系统在热对流研究中的应用在三维试验段中对热对流现象进行了温度和速度的同时测量。实验是针对在湍流Rayleigh-Bernard对流中从下边界加热、在上边界冷却的流体层进行的。结果表明，热羽流是由加热边界产生的，冷羽流是由冷却边界产生的，它们在流体层中部相互作用。结果表明，这些羽流的产生在空间上是随机的，在结构上是三维的。然而，羽流的垂直速度和温度波动是很好的相关性和变化的距离壁。三维测量还发现，在加热表面附近的羽流结构呈轮辐状。少

The research was carried out for investigating the simultaneous measurement technique of temperature and velocity field of three components with a liquid crystal visualization and PIV technique. This method was further extended to three-dimensional measuring technique by scanning a light sheet, which was used for the study of thermal convection. The results obtained here are summarized as follows.(1) Evaluation of uncertainty in temperature and velocity by artificial color imageA method for generating artificial color image was studied to simulate the color change by liquid crystal visualization. This color image was used for evaluating the temperature and two-components of velocity in a light sheet plane. This method was extended to three-components of velocity as well by using a stereoscopic configuration of the observation. The results indicate that the accuracy of velocity measurement was improved by adding a certain amount of tracer particles, but the addition of too many particle … More s is not suitable for the temperature measurement because of the reduction of measurable temperature area. Temperature calibration by three color parameters HIS produces a better accuracy than the others in temperature measurement. It is found from the stereo observation that there is an optimum off-axis observation angle for improving the accuracy of simultaneous measurement.(2) Application of stereo system to thermal convection studySimultaneous measurement of temperature and velocity in a thermal convection phenomenon was carried out in a three-dimensional volume of test section. The experiments are made for a fluid layer heated from below and cooled at the top boundary in a turbulent Rayleigh-Bernard convection. The results indicate that the hot plumes are generated from the heated boundary and cold plumes are created from the cooled boundary, and they interact with each other in the middle of the fluid layer. It is found that these generation of the plumes are random in space and three-dimensional in structure. However, the vertical velocity of the plumes and the temperature fluctuations are well correlated and varied with the distance from the wall. It is also found from the three-dimensional measurement that the structure of the plumes near the heated surface has a form of spoke structure. Less