Large-scale measurements of the physical characteristics of round vertical bubble plumes in liquids

Castello-Branco, Marco A. S. C.; Schwerdtfeger, Klaus

doi:10.1007/bf02663385

Cited by 55 publications

(6 citation statements)

References 18 publications

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“…These effects can also produce large structures driving the dispersed phase. The three-dimensionality of air-water bubbly flows was revealed in various experiments; Milgram (1983), Castello-Branco & Schwerdtfeger (1994), Kuwagi & Ozoe (1999) and Johansen et al (1988) discuss plume precession and swirling. The radial distributions of the void fraction and of the velocities were investigated by several authors, e.g.…”

Section: Turbulent Transport Mechanisms In Oscillating Bubble Plumes mentioning

confidence: 98%

Turbulent transport mechanisms in oscillating bubble plumes

et al. 2009

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The detailed investigation of an unstable meandering bubble plume created in a 2-m-diameter vessel with a water depth of 1.5 m is reported for void fractions up to 4% and bubble size of the order of 2.5 mm. Simultaneous particle image velocity (PIV) measurements of bubble and liquid velocities and video recordings of the projection of the plume on two vertical perpendicular planes were produced in order to characterize the state of the plume by the location of its centreline and its equivalent diameter. The data were conditionally ensemble averaged using only PIV sets corresponding to plume states in a range as narrow as possible, separating the small-scale fluctuations of the flow from the large-scale motions, namely plume meandering and instantaneous cross-sectional area fluctuations. Meandering produces an apparent spreading of the average plume velocity and void fraction profiles that were shown to remain self-similar in the instantaneous plume cross-section. Differences between the true local time-average relative velocities and the difference of the averaged phase velocities were measured; the complex variation of the relative velocity was explained by the effects of passing vortices and by the fact that the bubbles do not reach an equilibrium velocity as they migrate radially, producing momentum exchanges between high- and low-velocity regions. Local entrainment effects decrease with larger plume diameters, contradicting the classical dependence of entrainment on the time-averaged plume diameter. Small plume diameters tend to trigger ‘entrainment eddies’ that promote the inward-flow motion. The global turbulent kinetic energy was found to be dominated by the vertical stresses. Conditional averages according to the plume diameter showed that the large-scale motions did not affect the instantaneous turbulent kinetic energy distribution in the plume, suggesting that large scales and small scales are not correlated. With conditional averaging, meandering was a minor effect on the global kinetic energy and the Reynolds stresses. In contrast, plume diameter fluctuations produce a substantial effect on these quantities.

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Section: Turbulent Transport Mechanisms In Oscillating Bubble Plumes mentioning

confidence: 98%

Turbulent transport mechanisms in oscillating bubble plumes

et al. 2009

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“…Figure 6 shows the measured values of ū B for three different gas flow rate values. The cylinder diameter, D c , is 0.020 m. Three kinds of lines denote the predicted values based on the empirical equation derived by Castello-Branco et al 26) As the gas flow rate, Q g , increases, the mean bubble rising velocity, ū B , becomes large but is smaller than the calculated value for a bubbling jet in the absence of the cylinder.…”

Section: Gas Holdup a Amentioning

confidence: 95%

The Coanda Effect on Bubbling Jet behind a Horizontally Placed Circular Cylinder.

et al. 2002

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The motions of bubbles and liquid behind a circular cylinder placed horizontally in a vertical water-air bubbling jet were experimentally investigated. Bubbles approaching the cylinder were separated by the cylinder in the two ways along the side wall of the cylinder, and they gathered together again at a certain distance from the cylinder due to the Coanda effect. This situation was confirmed from the measurements of gas holdup and mean water velocity components. The mean bubble diameter behind the cylinder became small because disintegration of bubbles took place around the cylinder. The mean bubble rising velocity also became very low behind the cylinder. The horizontal spreading of the bubbling jet was significantly suppressed by the cylinder.

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“…where Fr is Froude number, v is gas velocity on the nozzle/plug exit [m/s], g is acceleration due to gravity [m/s 2 ], and d is diameter of nozzle/plug [m]. Schwerdtfeger et al [31][32][33] and Iguchi et al [22,23,25] used the modified Froude number (2), which considers the densities of liquid and gas phases:…”

Section: Ref D × H [Mm]mentioning

confidence: 99%

Influence of Gas Density and Plug Diameter on Plume Characteristics by Ladle Stirring

et al. 2021

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The paper presents new results concerning the influence of the gas density and porous plug diameter on the nature of liquid steel stirring with an inert gas in the ladle. The tests were carried out on a cold model of a 30t ladle using particle image velocimetry (PIV) with a high-speed camera to analyse the plume zone formed during the supply of argon and helium as a stirring gas. The similarity criteria for the investigation of stirring processes in cold model in the past were discussed and compared. The modified Morton number was used in this paper to relate the gas flow rate in the model with real objects. The presented results constitute complete documentation of the influence of the plug diameter and gas density on the size of formed gas bubbles and the velocity of gas bubbles rising in different zones of the plume, plume, and spout geometry, including the expansion angle, spout height, open eye area, and gas hold-up.

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Large-scale measurements of the physical characteristics of round vertical bubble plumes in liquids

Cited by 55 publications

References 18 publications

Turbulent transport mechanisms in oscillating bubble plumes

Turbulent transport mechanisms in oscillating bubble plumes

The Coanda Effect on Bubbling Jet behind a Horizontally Placed Circular Cylinder.

Influence of Gas Density and Plug Diameter on Plume Characteristics by Ladle Stirring

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