Euler-Euler simulation and X-ray measurement of bubble chain in a shallow container filled with liquid metals. (31st December 2018)

• Record Type: Journal Article
• Authors: Liu, Liu; Keplinger, Olga; Ma, Tian; Ziegenhein, Thomas; Shevchenko, Natalia; Eckert, Sven; Yan, Hongjie; Lucas, Dirk
• Is Part Of: Chemical engineering science. Volume 192(2018)
• Page Start: 288
• Page End: 305
• Publication Date: 2018-12-31
• Subjects: Liquid metal two-phase flow -- Bubble chain -- X-ray radiography -- Bubble induced turbulence model -- CFD -- Euler-Euler two-fluid model; Chemical engineering -- Periodicals; Génie chimique -- Périodiques; Chemical engineering; Periodicals; Electronic journals; 660
• DOI: 10.1016/j.ces.2018.07.034
• Languages: English
• ISSNs: 0009-2509

Abstract

Highlights: Bubble chain in liquid metals was studied by X-ray radiography. Oscillating frequencies of bubble chains were identified by FFT method. Significance of the BIT model and turbulent viscosity approach for simulating bubble chains was demonstrated. Resolved and unresolved liquid velocity fluctuations were studied. Abstract: An Euler-Euler two-fluid approach was used to simulate the behavior of gas bubbles rising in a stagnant liquid metal. A single point injection with four gas flow rates resulted in the formation of bubble chains undergoing either slight or distinct oscillations of the bubble trajectories. A set of interfacial closures with a shear stress transport (SST) k - ω turbulence models was applied for simulating the transient behavior of the bubble chain. X-ray radiography measurements were conducted to establish an experimental data base for validating the numerical results. The experiments provide a visualization of the bubble chain in a flat container and allow determining the bubble size and integral void fraction. Two bubble induced turbulence (BIT) models (Rzehak and Krepper, 2013a, Sato et al., 1981) and a modified turbulent viscosity approach (Johansen et al., 2004) were applied within this study. For all gas flow rates, the Rzehak and Sato BIT model alone predicted a steady bubble chain in contrast to the oscillating bubble plume observed in the experiments. Without a BIT model the oscillating bubble chain can be predicted but the oscillation frequency is underestimated especially for high gas flow rates. In addition, calculations without a BIT model predicted over-dispersion of the averaged gas fraction through the whole fluid container for the high gas flow rates. The best results in terms of a satisfying agreement with the experimental data were achieved by adopting a modified turbulent viscosity approach proposed by Johansen together with the Rzehak and Krepper BIT model. These findings demonstrate the significance of the turbulence model.