Laser Speckle Photography And The Study Of Heat Transfer Applications

In this paper, the law of the space speckle motion induced by a light beams passing through a phase object is proposed for the first time and investigated systematically. It laies a foundation for the measurement of the parameters of phase objects by laser speckle photography. This technique has been successfully applied to the experimental investigation of heat transfer, which consists of the following three parts. (1) The heat transfer of natural convection for a heated vertical plate with large wall-to-ambient temperature differences and for a channel formed by two heated parallel plates are studied. A method of measuring heat transfer rate per unit plate height with edge effect is presented. (2) Axial symmetrical temperature fields and concentration fields in flow fluids have been measured. (3) The mathematical and physical models and the experimental methods for the measurement of three dimensional temperaturefields in fluids are described. Finally, two experimental techniques -thereflective laser speckle photography and the image shift are presented to improve the measurement sensitivity. They extend applicable scope of laser speckle potography in study of heat transfer.