Microscopic Measurement of Particle Laden with aHigh Teperature Gas Flow by Using a Fluorescet Method

本研究的最终目的是更好地了解携带高温气流（气固悬浮流）的细颗粒的温度，从而估计悬浮流内部的传热，包括辐射换热。因此，在本研究项目中，提出了一种悬浮在气流中的粒子温度的微观测量方法。所提出的方法是基于“荧光法”，它利用了荧光强度和/或寿命的温度依赖性。也就是说，如果一个荧光粒子周期性地被闪烁的光激发，那么从该粒子发出的荧光也是周期性的，但荧光的相位发生了移位。激发灯和荧光灯的相位差与荧光的寿命有关，因此可以通过测量相移来确定荧光粒子的温度。在本方法中，荧光粒子通过激光多普勒测速仪（LDV）测量体积中产生的条纹被周期性地激发。利用该方法，通过测量散射光的频率和荧光灯的相移，可以同时确定单个粒子的速度和温度。建立了一个原型测量系统，并通过测量一个简单气滑悬浮流的温度场和速度场来验证该方法的正确性。此外，热在流化颗粒层内的扩散进行了实验研究；用CO_2气体激光器对颗粒层进行远程加热，并用红外热像仪测量了随时间变化的温度分布。结果清楚地表明，流化颗粒层的有效导热系数约为5 W/mK，小于文献报道的值。

The final goal of this study is to obtain better understandings of the temperature of fine particles laden with a high temperature gas fow ( a gas-solid suspension flow), so as to estimate the heat transfer within the suspension fow including radiative heat exchange. In this research project, therefore, a microscopic measurement method for the particle temperature suspended in a gas flow was proposed. The proposed method is based on the "fluorescent method", which utilizes the temperature dependency of intensity and/or lifetime of the fluorescent light. Namely if a fluorescent particle is periodically excited by a blinking light, fluorescent light from the particle is also periodic but the phase of fluorescent light is shifted. The phase difference between the exciting and fluorescent lights is related to the lifetime of fluorescence, and thus temperature of the fluorescent particle can be determined by measuring the phase shift. In the present method, fluorescent particles were periodically excited by making them passed through fringes generated in the measuring volume of a Laser-Doppler Velocimetry (LDV). By using this method, velocity and temperature of individual particles can be simultaneously determined by measuring the frequency of scattered light and the phase shift of fluorescent light, respectively. A prototype measurement system was constructed, and the propriety of the present method was confirmed by measuring the temperature and velocity fields in a simpe gas-slid suspension flow.In addition to this, diffusion of heat within a fluidized partcle layr was experimentaly examined ; the particle layr was reotely heated by using a CO_2 gas laser, and time-dependent temperature distributions were mesured by means of a IR thermograph. The results clearly showed that the effective thermal conductivity of thefluidized particle layr is a value of te order of 5 W/mK, which is smaller than the values reprted in literature.