Two-phase Flow Characteristics under Taylor-Spiral Flow Condition

本文采用空气-水、液氮和硅油三种工质，对由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。研究空气-水和液氮的实验装置结构相似，并测量了流动和传热特性。在空气-水两相流动实验结果的基础上，讨论了压降、流型转变、空隙率和气泡特性，确定了基本流动特性。在静止条件下，可以对圆管的Misihima-Ishii流型图进行调整，随着转速的增加，流型过渡条件向低体积流速条件移动。在研究中，通过对气泡特征的讨论来解释这种流型转变，并采用了漂移通量模型。在液氮实验中，采用电加热器对外筒进行加热，确定了传热特性和干燥特性。以往的研究都是在强制对流条件下进行的，而硅油的研究都是在水池条件下进行的。在这种情况下，内筒不是柱状的，而是锥形的，这个锥形的内筒被冷却了。在实验中，利用热敏液晶和PIV可视化了流动特性和温度分布，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与内筒旋转引起的强制对流相互作用。

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.