Turbulence structure of air-water bubbly flow—I. measuring techniques

Serizawa, Akimi; Kataoka, Isao; Michiyoshi, Itaru

doi:10.1016/0301-9322(75)90011-7

Cited by 275 publications

(94 citation statements)

References 4 publications

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“…The technique employed in this paper to investigate the time dependent local properties of bubbly, inclined oil-inwater flows involves the use of arrays of miniature, multi-sensor needle conductance probes. Arrays of two different types of probe are used: (i) dual-sensor conductance probes [1], [2] [3] which, over a short time interval, can measure the local volume fraction of both the oil and the water and the local axial velocity of the oil droplets and (ii) four-sensor probes which can also measure the local volume fraction of both the oil and the water but which can also measure the local velocity vector of the oil droplets. Previous research [4] has shown that local needle conductance probes disturb the flow only minimally.…”

Section: Introductionmentioning

confidence: 99%

Large probe arrays for measuring mean and time dependent local oil volume fraction and local oil velocity component distributions in inclined oil-in-water flows

Lucas

Zhao

2013

Flow Measurement and Instrumentation

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Arrays of dual-sensor and four-sensor needle conductance probes have been used to measure the mean and time dependent local properties of upward inclined, bubbly oil-in-water flows (also known as dispersed oil-in-water flows) in a 153mm diameter pipe. The flow properties that were measured were (i) the local in-situ oil volume fraction α ; (ii) the local oil velocity o u in the axial direction of the pipe (the Z direction); and (iii) the local oil velocity Y u in the direction from the lower side of the inclined pipe to its upper side (the Y direction). Oil velocities in the X direction (orthogonal to the Y and Z directions) were found to be negligible. For all of the flow conditions investigated it was found that the mean value of α varied from a maximum value at the upper side of the inclined pipe to a minimum value at the lower side, and that the rate of decrease of this mean value of α with distance in the Y − direction became greater as the pipe inclination angle θ from the vertical was increased. It was also found that the mean value of o u was greatest at the upper side of the inclined pipe and decreased towards the lower side of the inclined pipe, the rate of decrease with distance in the Y − direction again becoming greater as θ was increased. it was found that the standard deviation in the cross-pipe oil velocity component Y u was approximately equal to the standard deviation in the axial velocity component o u . These large temporal variations in the local flow properties have been attributed to the presence of large scale Kelvin-Helmholtz waves which intermittently appear in the flow. It is believed that the techniques outlined in this paper for measuring the standard deviation of local flow properties as a function of the sampling period T will be of considerable value in validating mathematical models of time dependent oilwater flows. It should be noted that the principal focus of this paper is on the measurement techniques that were used and the methods of data analysis rather than the presentation of exhaustive experimental results at numerous different flow conditions.

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Section: Introductionmentioning

confidence: 99%

Large probe arrays for measuring mean and time dependent local oil volume fraction and local oil velocity component distributions in inclined oil-in-water flows

Lucas

Zhao

2013

Flow Measurement and Instrumentation

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“…Various approaches including optical, ultrasonic, multiple probe, and chemical methods, have been used in the past for interfacial surface area measurement (Akita and Yoshida, 1974;Al Taweel et. al, 1984;Banerjee and Lahey, 1981;Serizawa et al, 1975;Greaves and Kobbacy, 1984;Dankwerts and Sharma, 1966). The chemical method is among the most popular, and is based on the determination of the absorption rate of a gaseous substance by the liquid followed by a chemical reaction with a fast, irreversible, first or second order reaction, the average interfacial area concentration can be measured according to the surface renewal theory of Danckwerts (1955).…”

Section: Introductionmentioning

confidence: 99%

Bubble Size Control to Improve Oxygen-Based Bleaching: Characterization of Flow Regimes in Pulp-Water-Gas Three-Phase Flows

Karrila¹

2006

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SUMMARYThis document reports on the results of a research program aimed at the elucidation of various hydrodynamic aspects of low consistency paper pulp-water-gas three-phase flows, conducted jointly by the G.W. Woodruff School of Mechanical Engineering, Georgia Tech, and the Institute of Paper Science and Technology.Hydrodynamic flow characteristics of solid-liquid-gas slurry made by intimately mixing fibrous paper pulp with water and air were first investigated in a short, vertical circular column.The pulp consistency (weight fraction of pulp in the pulp-water mixture) was varied in the low consistency range of 0.0 ~ 1.5%. The test section was 1.8 m long, with 5.08 cm inner diameter.Mixing of the slurry prior to entering the test section was done using a patented mixer with controlled cavitation that generated finely dispersed micro-bubbles. Flow structures, gas holdup (void fraction), and the geometric and population characteristics of gas bubbles in the gas-pulpliquid three-phase flow were experimentally investigated, using visual observation, Gamma-ray densitometry, and flash X-ray photography. Superficial velocities of the gas and liquid/pulp mixture covered the ranges 0~26 cm/s and 21~51 cm/s, respectively.Five distinct flow regimes could be visually identified. These included dispersed bubbly, characterized by isolated micro-bubbles entrapped in fiber networks; layered bubbly, characterized by bubbles rising in a low consistency annular zone near the channel wall; plug; churn-turbulent; and slug. The dispersed and layered bubbly regimes could be maintained only at very low gas superficial velocities or gas holdups. Flow regime maps were constructed using phasic superficial velocities as coordinates, and the regime transition lines were found to be sensitive to consistency.The cross section-average gas holdup data showed that both the dispersed and the layered bubbly regimes could best be represented by the homogeneous mixture model. The drift flux model could best be applied to the reminder of the data when the plug and churn-turbulent flow regimes were treated together, and the slug flow was treated separately. The drift flux parameters depended on the pulp consistency.The feasibility of using artificial neural networks (ANNs) for the identification of the flow regimes in the aforementioned three phase gas/liquid/pulp fiber systems, using the statistical characteristics of pressure fluctuations measured by a single pressure sensor, was then examined.The aforementioned experimental test facility was used for this purpose. Experiments were carried out in the transparent, vertical circular column. The pulp consistency (weight fraction of 2 pulp in the pulp-water mixture) was varied in the low consistency range of 0.0 ~ 1.5%, and flow structures and other hydrodynamic characteristics were experimentally investigated. Local pressure fluctuations at a station 1.2 m above the test section inlet were also recorded using a highsensitivity pressure transducer that was installed in a manner not to cause flow distu...

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“…The length of the experimental pipe is not given in papers [9,10], so the pipe length was set to 10 m in our calculations, as in calculations of Troshko and Hassan [7]. The length of the pipe is 2.15 m in Serizawa experiments [11]. The calculations conducted show that flow settles rather quickly: at ∼2 m from inlet of the test section.…”

Section: Validation Series Amentioning

confidence: 99%

“…In Figs. 3-5 W1 denotes the Wang, et al, experiment #1 [9], L8 denotes the Liu experiment #8 [10], and S2 denotes the Serizawa, et al, experiment #2 [11]; parameters of mixture at inlet (superficial velocity of liquid J l and gas J g , and volume fraction of gas α) are presented in Table 1. As in calculations of Troshko and Hassan [7], the bubble diameter used in our calculations was taken D b =2.8 mm for simulations of both the Liu experiment and the Wang, et al, experiment.…”

Section: Validation Series Amentioning

confidence: 99%

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Validation of CFD-BWR, a new two-phase computational fluid dynamics model for boiling water reactor analysis

Ustinenko¹,

Samigulin²,

Иоилев³

et al. 2008

Nuclear Engineering and Design

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Turbulence structure of air-water bubbly flow—I. measuring techniques

Cited by 275 publications

References 4 publications

Large probe arrays for measuring mean and time dependent local oil volume fraction and local oil velocity component distributions in inclined oil-in-water flows

Large probe arrays for measuring mean and time dependent local oil volume fraction and local oil velocity component distributions in inclined oil-in-water flows

Bubble Size Control to Improve Oxygen-Based Bleaching: Characterization of Flow Regimes in Pulp-Water-Gas Three-Phase Flows

Validation of CFD-BWR, a new two-phase computational fluid dynamics model for boiling water reactor analysis

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