Two-phase Flow Characteristics under Taylor-Spiral Flow Condition

本文以空气-水、液氮和硅油三种工质为工质，对旋转内筒和静止外筒组成的旋转环形通道进行了实验研究，其中空气-水和液氮的实验装置结构相似，并对流动和换热特性进行了测量。根据气液两相流的实验结果，对气液两相流的压降、流型转变、含气率和气泡特性进行了讨论，确定了气液两相流的基本流动特性。在静止条件下，Misihima-Ishii的流态图，这是获得的圆管，可以适应，和流态过渡条件移动到较低的体积流速的条件下，随着转速的增加。本文采用流动图像处理技术获得了气泡的流动特征，并采用漂移通量模型对气泡的流动特性进行了分析，对这种流型转变进行了解释;在液氮实验中，采用电加热器对外筒进行加热，确定了外筒的传热特性和干涸特性;前人的研究是在强制对流条件下进行的，但对硅油的研究是在水池条件下进行的。在这种情况下，内筒不是圆柱形而是圆锥形，并且该圆锥形内筒被冷却。利用温敏液晶和PIV技术对管内流动特性和温度分布进行了可视化，并将流动转变解释为混合对流现象，即内筒冷却引起的自然对流和内筒旋转引起的强迫对流的相互作用。

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.