Abstract The gas–liquid two-phase countercurrent flow in horizontal pipes is closely related to the safe operation of marine diesel engines with underwater exhausts, and nuclear power plants with pressurized water reactors. A visualization experiment on the effect of the diameter size on the counter current flow limitation (CCFL) characteristics of horizontal pipes was performed in the diameter range of 20–130 mm using air and water as the two phases. The results indicate that with a certain gas flow rate, the flow rate of the backflow liquid significantly increases with increasing diameter. Wallis models and those using the Froude–Ohnesorge numbers can correlate the effect of the change in diameter size when the diameters are greater than 100 mm, whereas they lose normalization capability with diameters less than 100 mm. From an analysis of the physical mechanism of formation of this diameter effect, a novel correlation model based on a new dimensionless group for each phase, consisting of the dimensionless inertia and dimensionless viscous force, was proposed for predicting the CCFL characteristics of small diameter pipes. Meanwhile, another correlation based on the Wallis model was also advanced for predicting the CCFL characteristics of large diameter pipes.

中文翻译：

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直径对水平圆管气液CCFL特性影响的实验研究

摘要 水平管内气液两相逆流与水下尾气船用柴油机和压水堆核电站的安全运行密切相关。以空气和水为两相，在20-130 mm直径范围内进行了直径尺寸对水平管逆流限制（CCFL）特性影响的可视化实验。结果表明，在一定的气体流量下，回流液体的流量随着直径的增加而显着增加。Wallis 模型和那些使用 Froude-Ohnesorge 数的模型可以关联直径大于 100 毫米时直径大小变化的影响，而当直径小于 100 毫米时，它们失去归一化能力。通过分析这种直径效应形成的物理机制，提出了一种基于每相新的无量纲组的新型相关模型，该模型由无量纲惯性和无量纲粘性力组成，用于预测小直径管道的 CCFL 特性。同时，还提出了另一种基于 Wallis 模型的相关性，用于预测大直径管道的 CCFL 特性。