Two-phase Flow Characteristics under Taylor-Spiral Flow Condition

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In this investigation, experimental studies with rotational annular channel, which consisted of rotational inner cylinder and stationary outer cylinder, were conducted by using three kinds of working fluids, i.e.air-water, liquid nitrogen and silicon oil.The experimental apparatuses for the investigations of air-water and liquid nitrogen were similar configuration, and flow and heat transfer characteristics were measured. On the basis on the experimental results of the air-water two-phase flow, pressure drop, flow regime transition, void fraction and bubble characteristics were discussed, and fundamental flow characteristics have been confirmed. In the case of the stationary condition, Misihima-Ishii's flow regime map, which is obtained for the round pipe, could be adapted, and flow regime transition conditions moved to the lower volumetric flow velocity condition with the increasing of the rotational speed. In the investigation, this flow regime transition was explained by the discussion of the bubble characteristics, which was obtained by using the flow image processing, and also drift-flux model had been adapted.In the case of the experiment of the liquid nitrogen, outer cylinder was heated by electric heater, and heat transfer characteristics and dryout characteristics had been confirmed.Former investigations were conducted under forced convection, but the investigation of the silicon oil was conducted under pool condition. In this case inner cylinder is not column but conical, and this conical inner cylinder was cooled. In the experiment, the flow characteristics and temperature distribution was visualized by using the thermo-sensitive liquid crystal and PIV, and flow transition was explained as the phenomena of the mixed convection, i.e. the interaction between the natural convection by the cooling of the inner cylinder and the forced convection caused by the rotation of the inner cylinder.