Bubble formation and dynamics in a quiescent high‐density liquid
Bubble formation and dynamics in a quiescent high‐density liquid
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DOI：
10.1002/aic.14896
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发表时间：
2015-11
期刊：
影响因子：
3.7
通讯作者：
I. Chakraborty;G. Biswas;Satyamurthy Polepalle;P. Ghoshdastidar
中科院分区：
文献类型：
--
作者：
I. Chakraborty;G. Biswas;Satyamurthy Polepalle;P. Ghoshdastidar
研究了高雷诺数静态高密度液态金属铅铋共晶（LBE）在恒流条件下的气泡形成过程。采用基于轴对称Navier-Stokes方程的水平集和流体体积耦合方法进行了数值模拟。该系统的液体密度与气体密度之比约为15261。描述了气泡形成机制从准静态到惯性主导，以及不同的气泡形成机制，如第1周期和第2周期的配对和聚并。在给定的Bond数Bo，雷诺数Re = 1时，计算了不同韦伯数下分离气泡的体积。研究发现，当韦伯数较高时，计算出的分离气泡体积接近3/5幂律。根据孔口气泡体积增长的时间演变，定量地确定了不同的气泡状态。结果表明，连续两个气泡在第2周期起泡状态下的体积增长量不相同，而在第1周期起泡状态下的体积增长量相同。研究了网格分辨率对从周期1向周期2过渡的影响。我们观察到，过渡对网格大小非常敏感。在韦伯-邦德数图上显示了第1周期和第2周期具有配对和聚并的过渡。随着键数We ~ Bo−1的减小，表明从第1周期到第2周期发生配对和聚并的韦伯数的临界值减小，这与标度论点一致。此外，还讨论了LBE和水系统中气泡形成和气泡聚并动力学的比较。研究发现，在高雷诺数气泡形成过程中，水中形成的气泡与LBE中形成的气泡在从第1周期到第2周期的转变过程中存在配对和聚并的差异。©2015美国化学工程师学会化学工程学报，61:3996-4012,2015
Gas bubble formation from a submerged orifice under constant-flow conditions in a quiescent high-density liquid metal, lead–bismuth eutectic (LBE), at high Reynolds numbers was investigated numerically. The numerical simulation was carried out using a coupled level-set and volume-of-fluid method governed by axisymmetric Navier–Stokes equations. The ratio of liquid density to gas density for the system of interest was about 15,261. The bubble formation regimes varied from quasi-static to inertia-dominated and the different bubbling regimes such as period-1 and period-2 with pairing and coalescence were described. The volume of the detached bubble was evaluated for various Weber numbers, We, at a given Bond number, Bo, with Reynolds number Re≫1. It was found that at high values of the Weber number, the computed detached bubble volumes approached a 3/5 power law. The different bubbling regimes were identified quantitatively from the time evolution of the growing bubble volume at the orifice. It was shown that the growing volume of two consecutive bubbles in the period-2 bubbling regime was not the same whereas it was the same for the period-1 bubbling regime. The influence of grid resolution on the transition from period-1 to period-2 with pairing and coalescence bubbling regimes was investigated. It was observed that the transition is extremely sensitive to the grid size. The transition of period-1 and period-2 with pairing and coalescence is shown on a Weber–Bond numbers map. The critical value of Weber number signalling the transition from period-1 to period-2 with pairing and coalescence decreases with Bond number as We∼Bo−1, which is shown to be consistent with the scaling arguments. Furthermore, comparisons of the dynamics of bubble formation and bubble coalescence in LBE and water systems are discussed. It was found that in a high Reynolds number bubble formation regime, a difference exists in the transition from period-1 to period-2 with pairing and coalescence between the bubbles formed in water and the bubbles formed in LBE. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3996–4012, 2015