Abstract Disturbance waves in a downwards annular gas-liquid flow were investigated experimentally and numerically in this study. In the experiment, the brightness-based laser-induced fluorescence (BBLIF) technique was utilized to obtain high-resolution spatiotemporal measurements for the film thickness. In the simulations, the two-phase system was simulated by the volume of fluid (VOF) method together with newly developed turbulence damping models, without which the turbulence level around the film surface is considerably under-predicted. Qualitative and quantitative comparisons were carried out for the experimental and numerical data, during which a novel method was developed to extract complex wave structures in a direct manner. Comparisons showed that the model is able to reproduce the main stages of flow evolution, including development of high-frequency initial waves, their coalesce into stable large-scale disturbance waves, generation of slow and fast ripples, and disruption of fast ripples into droplets. The main properties of modeled waves are in decent agreement with the measured ones, apart from noticeably rarer generation of ripples. The presented methods offer a new and promising option to model various energy technology systems, where annular two-phase flow occurs.

中文翻译：

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环状气液流动扰动波形成与发展的实验与数值研究

摘要 本研究对向下环状气液流动中的扰动波进行了实验和数值研究。在实验中，基于亮度的激光诱导荧光（BBLIF）技术被用于获得薄膜厚度的高分辨率时空测量。在模拟中，两相系统通过流体体积 (VOF) 方法和新开发的湍流阻尼模型进行模拟，否则薄膜表面周围的湍流水平会被大大低估。对实验数据和数值数据进行了定性和定量比较，在此期间开发了一种以直接方式提取复杂波浪结构的新方法。比较表明该模型能够再现流动演变的主要阶段，包括高频初始波的发展，它们合并成稳定的大尺度扰动波，慢波和快波的产生，以及快波被破坏成液滴。建模波的主要特性与测量到的波的主要特性非常一致，除了显着更罕见的波纹生成。所提出的方法为模拟发生环形两相流的各种能源技术系统提供了一种新的、有前景的选择。