Local flow measurements of vertical upward bubbly flow in an annulus

Hibiki, Takashi; Situ, Rong; Mi, Ye; Ishii, Mamoru

doi:10.1016/s0017-9310(02)00421-0

Cited by 46 publications

(36 citation statements)

References 22 publications

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“…Thus, the flow conditions covered most of a bubbly flow region, including the bubbly-to-slug flow transition region and the finely dispersed bubbly flow region. As Table 5.1 Dimensions of flow loop used in the experiment (Hibiki et al, 1998b). shown in Fig.5.1, the observed void distribution agreed with the phase distribution pattern transition boundaries by Serizawa and Kataoka (1988).…”

Section: Random Collision Xhrbulent Imdactsupporting

confidence: 85%

“…In order to evaluate the contributions of bubble coalescence, breakup, and expansion to the interfacial area transport, typical changes of interfacial area concentration due to each mechanism along axial position are shown in Figs.5.3 and 5.4. The changes of the system pressure, the void fiaction and the Sauter (Hibiki et al, 1998b;Hibiki and Ishii,-1999) One-Group IAC Transport Equation, 43 Data sets (Hibiki et al, 1998b;Hibiki and Ishii, 1999) Void Transport Equation, 7 Data sets (Hibiki et al, 1998b) -----.---------_-------------------------mean diameter along the flow direction are also shown in Fig.5.5. For the case of low liquid velocity and low void fiaction such as <jf>=0.491 d s and <j,0>--0.0275 m/s (<m~=a.5>=4.90 %), the change of the intefiacial area concentration predicted by the derived one-group models (Eq~(4.4) and (4.24)) suggests that bubble coalescence due to random collision between bubbles and bubble breakup due to random collision between bubbles and turbulent eddies are not marked (See Fig.5.3).…”

Section: Contributions Of Bubblementioning

confidence: 99%

“…The two-group model will be developed with the necessary inter-group coupling terms due to turbulent impact and wake entrainment as well as sink and source terms due to wake entrainment and turbulent impact in the group 11 (see Table 4.1). In the present analysis, some other mechanisms, such as coalescence due to rand6m collision between cap bubbles and breakage due to flow instability, are excluded because only limited data sets taken in a round pipe with the inner diameter of 50.8 mm are available to validate the two-group model (Hibiki et al, 1998b). In such a relatively small pipe, cap and slug bubbles would rise around the center of the pipe resulting in a minor role of random collision between cap The mechanisms indicated by bold letters are considered in the present work.…”

Section: Classification Of Interfacial Area Transport Mechanismsmentioning

confidence: 99%

See 2 more Smart Citations

Interfacial area and interfacial transfer in two-phase systems. DOE final report

Ishii¹,

Hibiki²,

Revankar³

et al. 2002

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Section: Random Collision Xhrbulent Imdactsupporting

confidence: 85%

Section: Contributions Of Bubblementioning

confidence: 99%

Section: Classification Of Interfacial Area Transport Mechanismsmentioning

confidence: 99%

See 1 more Smart Citation

Interfacial area and interfacial transfer in two-phase systems. DOE final report

Ishii¹,

Hibiki²,

Revankar³

et al. 2002

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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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“…They commented that in the 1980s and 1990s, extensive experiments were performed to identify important parameters to determine the lateral bubble migration characteristics. The experiments showed that relatively small and large bubbles tend to Grace 1976 Lain 1999 Tomiyama 1998 migrate toward a channel wall and center, respectively (Žun, 1998;Liu, 1993;Hibiki and Ishii, 1999;Hibiki et al, 2001Hibiki et al, , 2003. A numerical simulation of single bubbles (Tomiyama et al, 1993(Tomiyama et al, , 1995b suggested that the bubble migration toward the pipe center was related closely to a slanted wake behind a deformed bubble.…”

Section: Lift Forcementioning

confidence: 99%

Coupled Lagrange-Euler Model for Simulation of Bubbly Flow in Vertical Pipes Considering Turbulent 3d Random Walks Models and Bubbles Interaction Effects

Essa¹

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A novel Two-way coupled Euler-Lagrange mode, including bubble-bubble collision, coalescence, with variable bubble radius, and bubbles breakup was applied to simulate air-water bubbly flow in vertical pipes. This approach uses the Continuous Random Walks CRW models for creating the velocity fluctuations according to the given state of turbulent kinetic energy and Dissipation rate at the location of the bubbles which is solved by the turbulence model. This dissertation i) describes the development of the Euler-Lagrange Approach under study, ii) presents a study for the two-way coupling effect on both the continuous and dispersed phases properties, iii) studies the effect of both the lift force coefficient and bubble induced turbulence BIT relations on the gas void fraction distributions, iv) studies the effect of the bubbles coalescence and breakup on bubble sizes and gas void fraction distributions. And presents the results of the simulations performed under each of these considerations.The two-way coupling process takes the effect of the dispersed phase on the continuous one through inserting source terms in the conservation equations of momentum and Turbulence. Also it modifies the volume of the computational cells in the Euler solver available for the continuous phase according to the void fraction of each cell. During the two-way coupling process, some studies needed to be performed like the adjustment of the lift force coefficient and the relation due to the change of the liquid velocity profiles as a result of the two-way coupling.The bubble-bubble collision was applied in the two-way coupling process. It was found that considering the collision appears on the void fraction distribution only in the high velocity and high gas holdup cases with very small effect. The bubble-bubble coalescence was applied as a complementary part of the collision process using the film drainage model of Chesters (1991). This model compares the film drainage time with the contact time to calculate the coalescence efficiency. The coalescence model was tested first before applying the breakup, so the bubbles size increased only and this affected on the void fraction distribution badly. Then the breakup model of Martínez-Bazán (1999a, b) was applied to perform the equilibrium in the bubble sizes. These two processes of the coalescence and breakup found to consume long computational time, the reason that did not give us a chance for testing many cases with considering both coalescence and breakup.The main investigation point through the development of this work was the BIT kinetic energy term and its effect on the used CRW model. This was considered in nearly every phase of the model development to study the effect of the BIT under the different considerations of the bubbles interaction mechanisms. It could be concluded a final vi expression for the BIT relation that is used successfully with the CRW models under consideration.vii ResumenUna nueva aproximación euleriana-lagarangiana, en su forma de acople en dos vías, para ...

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Local flow measurements of vertical upward bubbly flow in an annulus

Cited by 46 publications

References 22 publications

Interfacial area and interfacial transfer in two-phase systems. DOE final report

Interfacial area and interfacial transfer in two-phase systems. DOE final report

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

Coupled Lagrange-Euler Model for Simulation of Bubbly Flow in Vertical Pipes Considering Turbulent 3d Random Walks Models and Bubbles Interaction Effects

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