The local phase distribution of adiabatic air-water two-phase flow in churn-turbulent to annular flows was experimentally investigated using the Two-Sensor Droplet-Capable Conductivity Probe (DCCP-2). The experiments were performed in a 2.54 cm inner diameter vertical round pipe at downward flows. Twelve flow conditions in churn-turbulent to annular flows were chosen for the current study. The inlet superficial gas velocity ranged from 5.68 m/s to 17.19 m/s, and the inlet superficial liquid velocity ranged from 1.21 m/s to 2.64 m/s. The DCCP-2 is able to distinguish droplets, liquid ligaments, bubbles, and continuous gas. The radial profiles of volume fraction, frequency, axial interfacial velocity, and chord length of droplets, ligaments and bubbles were measured. The experimental results showed that gas volume fraction had a center-peak distribution, and the maximum gas volume fraction in centerline could exceed 95%. The volume fraction of droplets was very low, only on the order of 0.1%. Droplet concentration also showed a center-peak distribution. Both ligament and bubble volume fraction showed a near-wall peak distribution. The ligament volume fraction in the near wall region could reach 80%, which indicated the existence of a film region near the wall and likely includes surface waves on the film. The volume fraction profile of gas, droplets, ligaments, and bubbles showed the tomography structure in churn-turbulent to annular flows. The effects of flow conditions on phase distribution were also studied. An interesting feature was that both the increase of gas flux and the increase of liquid flux tended to increase the bubble volume fraction. The statistical distribution of droplet size was found to be invariant of radial position. The droplet velocity at centerline was generally larger than the superficial gas velocity, which can be attributed to the gravitational effects at downward flows.

使用具有双传感器液滴能力的电导探头 (DCCP-2) 对从湍流到环形流的绝热空气-水两相流的局部相分布进行了实验研究。实验在向下流动的 2.54 厘米内径垂直圆管中进行。目前的研究选择了从湍流到环形流的 12 种流动条件。入口表观气体速度范围为5.68 m/s至17.19 m/s，入口表观液体速度范围为1.21 m/s至2.64 m/s。DCCP-2 能够区分液滴、液体韧带、气泡和连续气体。测量了液滴、韧带和气泡的体积分数、频率、轴向界面速度和弦长的径向分布。实验结果表明，气体体积分数呈中心峰分布，中心线最大气体体积分数可达95%以上。液滴的体积分数非常低，仅为 0.1% 的数量级。液滴浓度也显示出中心峰分布。韧带和气泡体积分数均显示近壁峰分布。近壁区域的韧带体积分数可达 80%，这表明靠近壁的薄膜区域的存在，可能包括薄膜上的表面波。气体、液滴、韧带和气泡的体积分数剖面显示了从湍流到环形流的层析成像结构。还研究了流动条件对相分布的影响。一个有趣的特征是气体通量的增加和液体通量的增加都倾向于增加气泡体积分数。发现液滴尺寸的统计分布是径向位置不变的。中心线处的液滴速度通常大于表观气体速度，这可归因于向下流动的重力效应。