Surface vortex formation and free surface deformation in an unbaffled vessel stirred by on-axis and eccentric impellers

Yamamoto, Takuya; Fang, Yu; Komarov, Sergey V.

doi:10.1016/j.cej.2019.02.130

Cited by 30 publications

(16 citation statements)

References 41 publications

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“…However, the velocity below the impeller is still very small no matter how fast the IRS is. These phenomena were also observed by T. Yamamoto et al [7][8][9][10] in the flow characteristic of aluminum melt by mechanically stirring. miniscule, making it particularly difficult to achieve global mixing of species in the reactor.…”

Section: Fluid Flow Pattern and Qualifying Inactive Zonesupporting

confidence: 71%

“…For example, Visuri et al [1] have given a recent review in modeling hot metal desulfurization and summarized the previous contributions and work on fluid flow phenomena, mixing patterns, and particle/bubble dispersions in KR processes. Yamamoto et al [7,8] investigated the flow characteristic of aluminum melt by mechanically stirring and found that the impeller depths, rotation speeds, and impeller twisting angles impact the mixing time. Kato et al [9] evaluated the flow pattern and mass transfer in an aluminum melting furnace using a numerical simulation.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Impeller Rotational Speed and Immersion Depth on Flow Pattern, Mixing and Interface Characteristics for Kanbara Reactors Using VOF-SMM Simulations

Shen³

et al. 2021

Metals

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The Kanbara Reactor (KR) is a primary desulfurization technology in the hot metal pretreatment refining process that is widely employed in the modern steelmaking industry. The operating parameters of KR impeller immersion depth (IID) and rotation speed (IRS) have a crucial impact on the process performance and the desulfurization effect. Still, their influences have not been fully understood. This study systematically investigated the effects of IID and IRS on the flow pattern, mixing behavior, vortex core depth, and free surface characteristics for KR processes based on a 3D Volume of Fluid (VOF) model coupled with the sliding mesh method (SMM). The model was validated via scale-down water model experiments and then applied to the KR process, and simulations found that IID and IRS have different impacts on the flow pattern. Specifically, the discharge flow location moves downward with IID increasing, but the discharge strength and mean velocity hardly changes. Comparatively, the rise of IRS significantly increases the mean velocity, but few changes occur to the discharge flow position. Increasing IRS improves bath hydrodynamics, strengthens recirculation, and efficiently shortens mixing time, but IID has a neglectable effect on these features. The minimum mixing time is 55 s at a maximum IRS of 260 rpm. Moreover, the vortex core depth and free surface velocity visibly increase with the increase of IRS. Comparatively, IID has a limited effect on the flow and mixing behavior but directly impacts the distribution of recirculation regions at the axial direction and the velocity gradient on the free surface at the radial direction. Furthermore, the correlation equations of these critical parameters as a function of the operating parameters were obtained. The results from this study may provide references for operating optimizations and industrial practices of KRs.

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Section: Fluid Flow Pattern and Qualifying Inactive Zonesupporting

confidence: 71%

Section: Introductionmentioning

confidence: 99%

Effects of Impeller Rotational Speed and Immersion Depth on Flow Pattern, Mixing and Interface Characteristics for Kanbara Reactors Using VOF-SMM Simulations

Shen³

et al. 2021

Metals

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“…The simulation technique was the same as that used in our previous study. Hence, the details, including the model validation, can be found in our earlier papers [ 20 , 21 ]. Briefly, an open source software, OpenFOAM (Version 2.3x, Software for CFD; OpenCFD Ltd.: Bracknell, UK), was applied for the calculations.…”

Section: Methodsmentioning

confidence: 99%

“…Certain features of surface vortex formation and free surface turbulence have been investigated in our previous studies. In particular, Yamamoto et al [ 20 ] showed that on-axis impeller stirring leads to formation of not only a large vortex around the impeller axis, but also trailing vortices, which significantly affect the turbulent motion of the free surface of the liquid. The goal of the present study is to investigate the incorporation and dispersion of particles into a water bath from a free surface vortex, and thus to clarify the key variables and mechanisms influencing the efficiency of the vortex treatment.…”

Section: Introductionmentioning

confidence: 99%

Incorporation of Powder Particles into an Impeller-Stirred Liquid Bath through Vortex Formation

2021

Self Cite

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The present study addresses the incorporation of fine particles into liquids via the creation of a large-scale swirling vortex on the liquid free surface using a rotary impeller positioned along the axis of a cylindrical vessel. Four types of particles are used in the experiments to investigate the incorporation efficiency of the particles into a water bath under different impeller rotation speeds. Additionally, the vortex characteristics are investigated numerically. The results reveal that two factors, namely the particle wettability and turbulent oscillations at the bottom part of vortex surface, play dominant roles in determining the particle incorporation behavior. Hydrophobic particles are incapable of being incorporated into the water bath under any of the conditions examined in the present study. Partly wettable particles are entrained into the water bath, with the efficiency increasing with the impeller rotation speed and particle size. This is because an increase in the impeller rotation speed causes vortex deformation, whereby its bottom part approaches the impeller blades where the turbulent surface oscillations reach maximum amplitudes. Another possible mechanism of particle incorporation is the effect of capillary increases of liquid into the spaces between particles, which accumulate on the bottom surface of the vortex.

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“…Li 16 used the user designed functions method to preadd Coriolis force to a model to explore the mechanism behind free surface vortices. Yamamoto et al 17 and Domfeh, et al 18 studied the characteristics of free surface vortices using OpenFOAM, an open-source software.…”

Section: Introductionmentioning

confidence: 99%

Numerical and Experimental Studies of an Oil Slick Recovery Method That Uses a Free Surface Vortex

Yang

Liu

et al. 2020

ACS Omega

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To study the flow characteristics of water and oil in a free surface vortex with an oil slick on the water surface, the flow phenomenon was simulated using FLUENT software and compared with the experimental phenomenon. The volume of the fluid model was used to obtain the oil–gas–water three-phase eddy current field, yielding the flow structure and evolution process of the free surface vortex. The results reveal that the oil and water distribution follows a specific rule, from the beginning of the vortex at the free surface, through continuous downward extension and finally reaching stability. A few other parameters were also calculated, including the vertical distribution of the vortex core radius, the maximum tangential velocity and the radial velocity at the vortex core radius, and the variation of the velocity components of each phase in the flow field with position and time. The research reveals the oil transportation characteristics of free surface vortices and provides a method for recovering an oil slick using its surface vortex characteristics.

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Surface vortex formation and free surface deformation in an unbaffled vessel stirred by on-axis and eccentric impellers

Cited by 30 publications

References 41 publications

Effects of Impeller Rotational Speed and Immersion Depth on Flow Pattern, Mixing and Interface Characteristics for Kanbara Reactors Using VOF-SMM Simulations

Effects of Impeller Rotational Speed and Immersion Depth on Flow Pattern, Mixing and Interface Characteristics for Kanbara Reactors Using VOF-SMM Simulations

Incorporation of Powder Particles into an Impeller-Stirred Liquid Bath through Vortex Formation

Numerical and Experimental Studies of an Oil Slick Recovery Method That Uses a Free Surface Vortex

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