曲管内における流動を伴う凍結に関する基礎的研究

第1報　凍結状態の非定常性

抄録

The purpose of the present study is to examine experimentally the transient freezing process in the curved channel containing flows and the interface heat transfer. The 180° curved test section was constructed of rectangular channel with concave and convex walls which were cooled through thin copper plates, and the insulated upper and lower parts were made of transparent acrylic plate. Inlet Reynolds number was from 200 to 3040 corresponding to Dean number from 64 to 973 and wall temperature -5∼-15°C. It was observed how the freeze layer, which developed in the straight section, be haved along the curved channel. The position of the first expansion along the flow direction X_L is experimentally arranged as the function of Rei. Acceleration of the water by freezing and the characteristics of curved channel at the water-ice interface produce a greater heat transfer through the thin freeze layer than would exist without solidification. The average Nusselt number Num around the wall at each time is expressed by the function of dimensionless time τ* (product of Fourier number and Stefan number) and inlet Reynolds number.