Abstract Free surfaces of large bubbles are involved in gas injection into liquid through a top-submerged lance. The Volume of Fluid (VOF) multiphase model is chosen to simulate these flows. However, the selection of an appropriate turbulence model remains a point of discussion. Therefore, three representative turbulence models, namely the Renormalization Group (RNG) k-e model, the Reynolds Stress model (RSM) and the Large Eddy Simulation (LES) model, respectively coupled with VOF simulations, are studied. The results are compared with Particle Imaging Velocimetry (PIV) experiments. Afterwards, the selected turbulence model is used to study the two-phase flow characteristics. It has been found that the three turbulence models are able to capture the main averaged features of the flow such as the flow structures and average velocity field. However, the RNG and RSM models are not capable of estimating the fluctuating flow parameters such as the Reynolds stresses. In contrast, the LES model gives very good agreement with experimental data. The subsequent study on flow characteristics also showed that the 3D VOF-LES model can describe the bubble behavior and surface fluctuation. Resorting to Fast Fourier Transform (FFT) method, it has been proven that the bubble frequency is around 20 Hz and the turbulence in the bubbly region is between the single phase -5/3 and two-phase -10/3 power law in the inertial sub-range. Finally, the effect of the contact angle between the formed bubbles and outer lance wall on the flow has been estimated. The results showed that contact angle has limited influence on the flow.

中文翻译：

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顶浸式喷枪容器中气泡流动的流体动力学研究

摘要 大气泡的自由表面通过顶部浸没的喷枪将气体注入液体中。选择流体体积 (VOF) 多相模型来模拟这些流动。然而，选择合适的湍流模型仍然是一个讨论的焦点。因此，研究了三种具有代表性的湍流模型，即重整化组（RNG）ke模型、雷诺应力模型（RSM）和大涡模拟（LES）模型，分别与VOF模拟相结合。将结果与粒子成像测速 (PIV) 实验进行比较。然后，选择的湍流模型用于研究两相流动特性。已经发现，三种湍流模型能够捕捉流动的主要平均特征，例如流动结构和平均速度场。然而，RNG 和 RSM 模型无法估计波动的流动参数，例如雷诺应力。相比之下，LES 模型与实验数据非常吻合。随后对流动特性的研究也表明，3D VOF-LES模型可以描述气泡行为和表面波动。借助快速傅里叶变换(FFT)方法，已经证明气泡频率在20Hz左右，气泡区域的湍流介于单相-5/3和两相-10/3幂律之间。惯性子范围。最后，估计了形成的气泡和外枪壁之间的接触角对流动的影响。结果表明接触角对流动的影响有限。