The interfacial structure of annular flow in upward inclined pipes is examined experimentally by a non-intrusive multilayer conductance liquid film sensor (LFS). In horizontal and inclined pipes, cross-sectional distribution of gas and liquid phases is asymmetric even on average. Thus, the ratio between the characteristic film thickness and the mean dominant wave parameters may vary significantly as a function of the azimuthal and inclination angles. Interface structure in upward annular flow is characterized by two kinds of waves, ripples and disturbance waves. An interface dominated by consecutive large amplitude disturbance waves may also contain numerous ripples. To differentiate between ripples and disturbance waves, a criterion based on statistical wave properties is required. Identification of individual waves is carried out using a zero-crossing procedure with a new reference value. This approach allows to identify both small and large amplitude waves at the interface, calculating the wave heights based on their individual crest and trough. The wave height probability density function (pdf) for a wave system consisting of ripples and disturbance waves is bimodal, with the first peak representing ripples and the second disturbance waves. The local minima between the two peaks in the pdf defines the boundary between ripples and disturbance waves for each flow condition and azimuthal angle. The clear differentiation of the two kinds of waves allows to focus on detailed description of the statistical properties of ripples that are presented as a function of the pipe inclinations angles (ranging from near horizontal to vertical) and for all azimuthal location across the pipe circumference.

通过非侵入式多层电导液膜传感器（LFS）实验性地检查了向上倾斜的管道中环形流动的界面结构）。在水平管和倾斜管中，气相和液相的横截面分布平均而言甚至是不对称的。因此，特征膜厚度和平均主波参数之间的比率可以根据方位角和倾斜角而显着变化。向上环形流动的界面结构以波动和扰动波两种形式为特征。由连续的大振幅干扰波控制的界面也可能包含许多纹波。为了区分波纹和干扰波，需要基于统计波特性的标准。单个波的识别使用带有新参考值的零交叉过程执行。这种方法可以识别界面处的小振幅波和大振幅波，根据波峰和波谷计算波高。波高概率密度函数（pdf）对于由波动和扰动波组成的波系统是双峰的，第一个峰值代表波动，第二个波峰代表波动。pdf中两个峰值之间的局部最小值定义了每种流动条件和方位角的波动和干扰波之间的边界。两种波的明显区别使我们可以专注于波纹统计特性的详细描述，波纹的统计特性是根据管道倾斜角度（从近水平到垂直范围）以及整个管道圆周上所有方位角位置的函数而呈现的。