Three-Dimensional Temperature Measurement by Liquid Crystal Thermometry and Its Application to the Study of Turbulent Thermal Convection

Abstract

A new calibration technique of liquid crystal thermometry has been introduced to the quantitative measurement of temperature in a thermal fluid and applied to the study of turbulent thermal convection. The present calibration technique improves the accuracy of temperature measurement in comparison with the classical calibration technique with hue. Three-dimensional temperature measurement of turbulent thermal convection over a horizontal smooth surface is carried out at a flux Rayleigh number of 3×10⁹ by scanning a light sheet normal to the image plane and capturing a number of sequential visualized images. The spatial temperature distributions of thermal plumes over a horizontal surface are demonstrated by the reconstruction of isothermal contour surfaces and various cross-sectional views of the plumes. These results indicate the presence of a polygonal cell structure close to the surface and the generation of plumes at the intersections of high-temperature lines.