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

研究了用液晶显示和PIV技术同时测量三组分的温度和速度场技术。该方法进一步扩展到三维扫描光片测量技术，用于对流换热的研究。(1)人工彩色图像对温度和速度测量不确定度的评定研究了人工彩色图像的生成方法，通过液晶可视化模拟彩色图像的颜色变化。这幅彩色图像被用来估计光片平面内的温度和速度的两个分量。通过使用观测的立体构型，该方法也被扩展到速度的三个分量。结果表明，添加一定量的示踪粒子可以提高速度测量的精度，但添加过多的粒子…会提高速度测量的精度由于可测温度面积的减小，S更不适合用于温度测量。在温度测量中，HIS三种颜色参数的温度校准比其他方法具有更高的精度。立体观测发现，存在一个最佳的离轴观测角度，以提高同时测量的精度。(2)立体观测系统在热对流研究中的应用在一个三维体积的试验截面上进行了热对流现象中的温度和速度的同时测量。实验是针对湍流Rayleigh-Bernard对流中从下加热、上边界冷却的流体层进行的。结果表明，热羽流和冷羽流分别产生于加热边界和冷却边界，并在流体层中部相互作用。研究发现，这些羽流的产生在空间上是随机的，在结构上是三维的。但是，羽流的垂直速度与温度起伏有很好的相关性，并且随距离壁面的距离而变化。三维测量还发现，受热面附近的羽流结构为轮辐式结构。较少

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