Turbulence structure of air-water bubbly flow—II. local properties

Serizawa, Akimi; Kataoka, Isao; Michiyoshi, Itaru

doi:10.1016/0301-9322(75)90012-9

Cited by 299 publications

(123 citation statements)

References 5 publications

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“…Serizawa et al [21], Michiyoshi and Serizawa [22], Revankar and Ishii [18], Liu and Bankoff [23] and Hibiki et al [24] reported that in contrast to the downward flow void fraction distribution, two-phase upward flow is expected to result in a peak void fraction close to the wall. Kashinsky and Randin [5] attributed this to the transverse lift force, as originally defined by Žun [20], acting on the bubble in an 01030-p. 5 upward flow (with an opposite sign to that for a downward flow), thus leading to wall peaked void fraction distribution profiles across the pipe section.…”

Section: Resultsmentioning

confidence: 99%

Two-phase distribution in the vertical flow line of a domestic wet central heating system

Fsadni

2013

EPJ Web of Conferences

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Abstract. The theoretical and experimental aspects of bubble distribution in bubbly two-phase flow are reviewed in the context of the micro bubbles present in a domestic gas fired wet central heating system. The latter systems are mostly operated through the circulation of heated standard tap water through a closed loop circuit which often results in water supersaturated with dissolved air. This leads to micro bubble nucleation at the primary heat exchanger wall, followed by detachment along the flow. Consequently, a bubbly two-phase flow characterises the flow line of such systems. The two-phase distribution across the vertical and horizontal pipes was measured through a consideration of the volumetric void fraction, quantified through photographic techniques. The bubble distribution in the vertical pipe in down flow conditions was measured to be quasi homogenous across the pipe section with a negligible reduction in t he void fraction at close proximity to the pipe wall. Such a reduction was more evident at lower bulk fluid velocities.

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Section: Resultsmentioning

confidence: 99%

Two-phase distribution in the vertical flow line of a domestic wet central heating system

Fsadni

2013

EPJ Web of Conferences

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“…気泡流には様々なスケールがあり、気泡が生成する乱れは多くの研究者の注目を集めている。その乱れは、流れ場と相互作用し、単相流とは異なる複雑な流動構造を示す [1][2][3][4][5][6]。特に気泡クラスターは、乱流の秩序渦構造よりも大きく、大規模な流動構造そのものを変化させる [7,8]。そのため気泡クラスター形成の有無について様々な報告が行われている [9][10][11]。気泡のクラスター形成は、まず理論的に予測された。ポテンシャル流れを仮定し、複数の気泡が上昇する際、気泡間相互作用によって水平面に気泡がクラスターを形成することが報告された [12,13]。一方で、実際の気泡流では、気泡同士の合体によって気泡径差が生まれ、通常気泡のクラスター構造は観察されない。さらに前述のポテンシャル流れを用いた理論でも、気泡径差を考慮するとクラスターは形成されない [14]。しかし、実験的研究において、界面活性剤や電解質を混入させることで気泡クラスターの形成が報告されている [15,16]。界面活性剤や電解質の混入は、気泡表面の境界条件を大きく変化させる。界面活性剤では気泡の抗力の増加や合体を防ぎ、電解質ではやクリーンな気泡を保ちながら気泡合体を防ぐ [17][18][19][20] /01 02 0/%/ü ! 1 ö 3 4 5 6 7 8 9 6 % !ú ÷ ù ' ü ü ö !…”

Section: 緒言unclassified

Influence of Surfactants on the Motion of a Pair of Bubbles in Quiescent Liquids

Kusuno¹,

Sanada²

2016

JAPANESE JOURNAL OF MULTIPHASE FLOW

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We experimentally investigated the motion of a pair of bubbles initially positioned inline configuration in ultrapure water or an aqueous surfactant solution. The bubble motion was observed by two high speed video cameras. The Reynolds number of bubbles were ranged from 50 to 200, and the bubbles hold a spherical shape in this range. In ultrapure water or small concentration of surfactant solution, initially the trailing bubble deviated from the vertical line on the leading bubble owing to the wake of the leading bubble. And then, the slight difference of the bubble radius changed the relative motion. When the trailing bubble slightly larger than the leading bubble, the trailing bubble approached to the leading bubble due to it's buoyancy difference. The bubbles attracted and collided only when the bubbles rising approximately side by side configuration. On the other hand, the trailing bubble was drafted to the wake region of leading bubble when the bubbles were rising in high concentration of surfactant solution. In this case, the bubbles always collided in line configuration. We consider that these phenomena are caused by the changes of lift force direction in the wake region owing to the surface contamination. In addition, bubble coalescence was inhibited in surfactant solution, even the relative motion was similar to the clean bubble case.

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“…In their pioneering work, Serizawa et al (1975) reported that the void fraction radial profile evolves from a wall-peak to a core-peak trend with an increased gas input (see Figure 5a). However, during these experiments the bubble size increased with gas input because a porous injector was used to generate the bubbles (Koide et al 1968).…”

Section: Void Fraction Radial Profilementioning

confidence: 99%

“…Depending on the flow conditions, the void fraction radial profile can present either a peak near the pipe wall or at the center line (Grossetête 1995, Liu 1993, Serizawa et al 1975, Wang et al 1987. In their pioneering work, Serizawa et al (1975) reported that the void fraction radial profile evolves from a wall-peak to a core-peak trend with an increased gas input (see Figure 5a).…”

Section: Void Fraction Radial Profilementioning

confidence: 99%

Fluid Mechanical Aspects of the Gas-Lift Technique

Guet

Ooms

2006

Annu. Rev. Fluid Mech.

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The gas-lift technique comprises the injection of gas bubbles in vertical oil wells to increase production. It is based on a reduction of the tubing gravitational pressure gradient. Several fluid-flow phenomena influencing such vertical gas-liquid flows are discussed. These effects include the radial distribution of void fraction and of gas and liquid velocity, flow regime changes, and system stability problems. Associated consequences for gas-lift performance and related optimization approaches are also discussed.

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Turbulence structure of air-water bubbly flow—II. local properties

Cited by 299 publications

References 5 publications

Two-phase distribution in the vertical flow line of a domestic wet central heating system

Two-phase distribution in the vertical flow line of a domestic wet central heating system

Influence of Surfactants on the Motion of a Pair of Bubbles in Quiescent Liquids

Fluid Mechanical Aspects of the Gas-Lift Technique

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