Abstract In this paper, we have performed an experimental study of the effect of changing the surface tension of the water in vertical annular concurrent two-phase flow (air + liquid) by adding small amounts of 1-butanol to the liquid phase. Adding small amounts of this chemical compound diminishes the surface tension of the water, while the dynamic viscosity remains practically unchanged. A set of experiments have been performed in the interval of surface tension values that ranges from 72 10-3N/m to 45 10-3 N/m, and with different values of the superficial velocities of the gas and liquid flows. In this broad range of surface tensions and boundary condition values the average amplitude and frequency of the disturbance waves have been measured for each boundary condition and surface tension value. In addition, we also measured the mean amplitude of the ripple waves, the mean value of the unperturbed base thickness, and the average film thickness. Also, we have obtained a set of correlations expressing all these magnitudes in non-dimensional form in terms of the Reynolds number of the gas, the Reynolds number of the liquid and the Kapitza number. Finally, we have performed a brief discussion and comparison with the results of other authors.

中文翻译：

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液体和气体表观速度和表面张力变化对环形并发向上垂直流界面波和膜厚影响的实验研究

摘要 在本文中，我们通过向液相中加入少量 1-丁醇，对垂直环形并行两相流（空气 + 液体）中改变水表面张力的影响进行了实验研究。添加少量这种化合物会降低水的表面张力，而动态粘度几乎保持不变。在表面张力值范围为 72 10-3 N/m 到 45 10-3 N/m 的区间内进行了一组实验，并且具有不同的气体和液体流的表观速度值。在这个广泛的表面张力和边界条件值范围内，已经测量了每个边界条件和表面张力值的扰动波的平均振幅和频率。此外，我们还测量了波纹波的平均幅度、未受干扰的基底厚度的平均值和平均薄膜厚度。此外，我们还获得了一组以无量纲形式表示所有这些量级的相关性，即气体的雷诺数、液体的雷诺数和卡皮察数。最后，我们进行了简短的讨论，并与其他作者的结果进行了比较。