Optical Investigation of Transport Phenomena During Solidification Process
This work demonstrates the feasibility of applying optical methods, which depend on the spatial variations in the refractive index of the liquid, to characterize the transport phenomena during solidification of pure water and aqueous ammonium chloride solution in a rectangular cavity. In the first case, holographic interferometry is applied to visualize the convective flow and temperature field during a water freezing process. Experimental results indicate that the supercooling and density inversion significantly influence the water freezing process. In the second case, the solidification processes of aqueous ammonium solution are observed using the shadowgraph method. The solidification process in eutectic composition resembles that of pure substances. In a hypoeutectic solution, double-diffusive layer and remelting occur in the lower part of the flow that is stable. On the other hand, in a hypereutectic solution, double-diffusive layer and remelting occur in the upper part of the flow. The layer is ruined seriously and the flow is unstable. In the third case, a twowavelength holographic interferometry technique is applied to further investigate ]the temperature and concentration fields of a double-diffusive layered system. Merits and limitations of the interferometric method are discussed as well.
KeywordsTest Section Solidification Process Mushy Zone Cold Wall Rectangular Cavity
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