Slug flow is a flow pattern which occurs in conveyance systems containing a two phase-fluid flow. Large air bubbles entrapped along these systems interrupt the flow and conduct to undesirable pressures and their fluctuations. Most of the previous concerning studies on slug flow phenomenon were performed in micro-channels with small scales in which the expansion of the air bubbles was negligible. In contrast, we investigated the systems with large pressure drops which conduct to abrupt increases on the volume of air phase. In this research, the verification tests applying CFD techniques were performed in OpenFOAM software by interFoam solver. The performance of morning glory spillways is investigated under steady states. While during the occurrence of flood, by increasing the depth over the spillway crest, the discharge is augmented which conducts to entrap the air pockets with pressure and velocity fluctuations. These fluctuations influence on the life of structures and their performances. This study aimed on unsteady flow in a glory morning spillway and its consequences and proposing the measures for reducing the destructive effects of slug flow. The pressure and velocity fluctuation were considered as the indices for the performance of a hydraulic structure. Spatial and temporal variations of pressure and velocity along the spillway are evaluated. Also, the influences of spillway geometry on slug flow and the measures to attenuate its destructive effects are analyzed. The results showed that the better performances of morning glory spillway are coincided by the diameter of tunnel superior than the height of water above the crest.

中文翻译：

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厄尔布尔士牵牛花溢洪道段塞流现象调查及防治其破坏作用

团状流是一种流动模式，发生在包含两相流体流的输送系统中。沿这些系统截留的大气泡会中断流动并传导至不希望的压力及其波动。以往关于团状流现象的研究大多是在小尺度的微通道中进行的，其中气泡的膨胀可以忽略不计。相反，我们研究了具有大压降的系统，这些系统会导致空气相体积的突然增加。在这项研究中，应用 CFD 技术的验证测试由 interFoam 求解器在 OpenFOAM 软件中进行。在稳态下研究牵牛花溢洪道的性能。而在洪水发生期间，通过增加溢洪道顶部的深度，排放增加，其传导以捕获具有压力和速度波动的气穴。这些波动影响结构的寿命及其性能。本研究针对荣耀晨溢泄洪道的非定常流动及其后果，提出了减少段塞流破坏性影响的措施。压力和速度波动被认为是水工结构性能的指标。评估沿溢洪道的压力和速度的空间和时间变化。此外，还分析了溢洪道几何形状对团状流的影响以及减轻其破坏性影响的措施。结果表明，牵牛花溢洪道的较好性能与隧道直径优于顶部水位高度相吻合。