Abstract Temporal and spatial-resolved data on the interfacial structure in upward vertical and inclined two-phase annular flows were accumulated using a novel non-intrusive multilayer conductance sensor. The sensor provides simultaneous measurement of the film thickness across the entire pipe circumference, enabling a three dimensional reconstruction of the wavy interface. Measurements were performed for two liquid (water) flow rates and a single high gas (air) flow rate. Three types of interfacial waves were identified, including ripples, disturbance and rogue waves. Rogue waves can be described as an infrequent solitary disturbance wave propagating over a ripple-dominant interface. Detailed statistical properties of the interfacial shape, such as the mean film thickness, wave height distribution, wave frequency spectra, wave propagation velocities and more, were obtained as a function the pipe inclination and azimuthal angle. The statistical analysis of the wavy interface presented in this study sheds light on a complex flow pattern of annular flow in inclined pipes, which has remained relatively unstudied experimentally. For inclined pipes, gravity imposes an asymmetric film distribution resulting in the thickest film at the bottom of the pipe. At this location, waves attain larger amplitudes while maintaining slower propagation velocities as compared to smaller amplitude waves at the top of the pipe. Generally, the wave frequency throughout the pipe circumference increases with inclination angle. For a larger liquid flow rate, the interface was found to be primarily dominant by disturbance waves. For a lower liquid velocity, the interfacial structure was found to be highly dependent on both the azimuthal and the inclination angles. An interface wave type map is presented as a function of those angles.

中文翻译：

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斜管内向上气液环流界面结构

摘要 使用新型非侵入式多层电导传感器积累了向上垂直和倾斜两相环形流界面结构的时间和空间分辨数据。该传感器可同时测量整个管道圆周上的薄膜厚度，从而能够对波浪形界面进行三维重建。对两种液体（水）流速和一种高气体（空气）流速进行了测量。确定了三种类型的界面波，包括波纹、扰动和流氓波。流氓波可以描述为在纹波主导界面上传播的罕见孤立干扰波。界面形状的详细统计特性，如平均膜厚、波高分布、波频谱、波传播速度等，是作为管道倾角和方位角的函数获得的。本研究中提出的波状界面的统计分析揭示了倾斜管道中环形流的复杂流动模式，这在实验中仍然相对未经研究。对于倾斜的管道，重力会施加不对称的薄膜分布，导致管道底部的薄膜最厚。在这个位置，与管道顶部的较小振幅波相比，波在保持较慢的传播速度的同时获得较大的振幅。通常，整个管道圆周上的波频率随着倾斜角的增加而增加。对于较大的液体流速，发现界面主要由扰动波主导。对于较低的液体速度，发现界面结构高度依赖于方位角和倾角。界面波型图显示为这些角度的函数。