Abstract Co-current two-phase simulations of gas-liquid flow with mixture velocities from 1.2 to 4.2 m/s were run in a partially eccentric annulus and compared with entirely eccentric and concentric experimental data collected at the Institute for Energy Technology in Norway. The gas-phase was sulphur hexafluoride (SF6) for all cases, while the liquid-phase was Exxsol D60 for the horizontal cases and a mixture of Exxsol D60 and Marcol 82 for the inclined case. The outer diameter of the annulus was 0.1 m for all cases, while the inner diameter was 0.05 m in the horizontal configuration and 0.04 m for the inclined configuration. The purpose of this paper is to explore the effect of the holdup fraction, mixture velocity, and interior pipe’s position on the pressure gradient and flow regime, in effect a study of the pressure gradient and holdup fraction transients. The comparisons between simulations and experiments indicate that moving the pipe from an entirely eccentric to the partially eccentric configuration has a drastic impact on the pressure gradient. In all 4 cases where the inner pipe was changed from a completely eccentric geometry in the experiments to a less eccentric configuration in the simulations, we notice an increase of 48–303% of the mean pressure gradient. Comparatively, the 4 cases where the pipe was moved from a concentric experimental configuration to a more eccentric configuration in the simulations result in less drastic pressure gradient changes. Two cases were within 22% of the experimental results for mean, maximum, and minimum pressure gradient, while the last two cases exceeded the minimum and mean pressure gradients by 25–250%, respectively. The flow regime is rarely significantly affected by a change in eccentricity; 2 out of the 8 horizontal cases indicate either a transition from wavy flow to slug flow or significantly larger waves. The most prominent and frequent discrepancies identified were altered slug and wave frequencies. The last case, a 4o inclined, partially eccentric simulation was compared to an entirely eccentric experiment and results in a 0.2 Hz increase in wave frequency, up from the experimental 0.56 Hz and a 49% increase in the mean pressure gradient.

中文翻译：

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偏心环空 0−4o 倾角的两相流模拟

摘要 混合速度为 1.2 至 4.2 m/s 的气液并流两相模拟在部分偏心的环空中运行，并与挪威能源技术研究所收集的完全偏心和同心的实验数据进行比较。对于所有情况，气相是六氟化硫 (SF6)，而对于水平情况，液相是 Exxsol D60，对于倾斜情况，液相是 Exxsol D60 和 Marcol 82 的混合物。在所有情况下，环的外径为 0.1 m，而水平配置的内径为 0.05 m，倾斜配置的内径为 0.04 m。本文的目的是探讨滞留率、混合速度和内部管道位置对压力梯度和流态的影响，实际上是对压力梯度和滞留率瞬变的研究。模拟和实验之间的比较表明，将管道从完全偏心配置移动到部分偏心配置会对压力梯度产生巨大影响。在所有 4 种情况下，内管从实验中的完全偏心几何形状更改为模拟中偏心较小的配置，我们注意到平均压力梯度增加了 48-303%。相比之下，模拟中管道从同心实验配置移动到更偏心配置的 4 种情况导致压力梯度变化较小。两个案例在平均、最大和最小压力梯度的实验结果的 22% 以内，而后两种情况分别超过最小和平均压力梯度 25-250%。流态很少受到偏心率变化的显着影响；8 个水平案例中的 2 个表明从波浪流过渡到段塞流或显着更大的波浪。确定的最突出和最常见的差异是改变的段塞波频率。最后一种情况，将 4o 倾斜、部分偏心的模拟与完全偏心的实验进行比较，结果波频率增加了 0.2 Hz，高于实验的 0.56 Hz，平均压力梯度增加了 49%。8 个水平案例中的 2 个表明从波浪流过渡到段塞流或显着更大的波浪。确定的最突出和最常见的差异是改变的段塞波频率。最后一种情况，将 4o 倾斜、部分偏心的模拟与完全偏心的实验进行比较，结果波频率增加了 0.2 Hz，高于实验的 0.56 Hz，平均压力梯度增加了 49%。8 个水平案例中的 2 个表明从波浪流过渡到段塞流或显着更大的波浪。确定的最突出和最常见的差异是改变的段塞波频率。最后一种情况，将 4o 倾斜、部分偏心的模拟与完全偏心的实验进行比较，结果波频率增加了 0.2 Hz，高于实验的 0.56 Hz，平均压力梯度增加了 49%。