Vapor core turbulence in annular two-phase flow

Trabold, Thomas A.; Kumar, Ranganathan

doi:10.1007/s003480050024

Cited by 5 publications

(4 citation statements)

References 6 publications

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“…Trabold and Kumar [161,235] found the vapour turbulence was enhanced by the droplets over the range of drop size and concentration. However, improvement of the experimental technique and reduction in the measurement uncertainties were highly recommended as the uncertainty could be up to 25%.…”

Section: Droplet Behaviourmentioning

confidence: 99%

Two-Phase Annular Flow in Vertical Pipes: A Critical Review of Current Research Techniques and Progress

Xue¹,

Stewart

Kelly

et al. 2022

Water

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Two-phase annular flow in vertical pipes is one of the most common and important flow regimes in fluid mechanics, particularly in the field of building drainage systems where discharges to the vertical pipe are random and the flow is unsteady. With the development of experimental techniques and analytical methods, the understanding of the fundamental mechanism of the annular two-phase flow has been significantly advanced, such as liquid film development, evolution of the disturbance wave, and droplet entrainment mechanism. Despite the hundreds of papers published so far, the mechanism of annular flow remains incompletely understood. Therefore, this paper summarizes the research on two-phase annular flow in vertical pipes mainly in the last two decades. The review is mainly divided into two parts, i.e., the investigation methodologies and the advancement of knowledge. Different experimental techniques and numerical simulations are compared to highlight their advantages and challenges. Advanced underpinning physics of the mechanism is summarized in several groups including the wavy liquid film, droplet behaviour, entrainment and void fraction. Challenges and recommendations are summarized based on the literature cited in this review.

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Section: Droplet Behaviourmentioning

confidence: 99%

Two-Phase Annular Flow in Vertical Pipes: A Critical Review of Current Research Techniques and Progress

Xue¹,

Stewart

Kelly

et al. 2022

Water

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“…Second, the film sensor has a quartz coating which prevents the formation of bubbles on its surface due to heating [6]. Third, the film sensor is recomended to make measurements in two-phase flows in a number of papers [7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Fourth, the substrate heating losses of the film sensor in water can be neglected [11].…”

mentioning

confidence: 99%

“…King's law [21] is used in our work as a law connecting the flow rate with the energy spent on heating the film. Using [7][8][9][10][11][12][13][14][15][16][17][18][19][20]22], King's law for a supersonic microbubble-fluid flow is written as…”

mentioning

confidence: 99%

Shock wave in a bubble flow with high gas content

Данилов

Сон

2011

EPL

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“…Our earlier paper [8] provided an introduction to the measurement methods and database in adiabatic annular flow, and presented void fraction and droplet velocity distributions at 2.4 MPa in a narrow duct. These data from the hot-film anemometer were further analyzed to obtain the turbulence intensity [9], which was shown to increase with increasing droplet diameter. We also presented new measurements in adiabatic flow [lo] to illustrate the effect of pressure on flows with low surface tension and low liquid-to-vapor density ratio.…”

mentioning

confidence: 99%

Effect of Pressure With Wall Heating in Annular Two-Phase Flow

Kumar

Trabold

2003

Journal of Fluids Engineering

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The local distributions of void fraction, interfacial frequency and velocity have been measured in annular flow of R-134a through a wall-heated, high aspect ratio duct. High aspect ratio ducts provide superior optical access to tubes or irregular geometries. This work expands upon earlier experiments conducted with adiabatic flows in the same test section. Use of thin, transparent heater films on quartz windows provided sufficient electrical power capacity to produce the full range of two-phase conditions of interest. With wall vapor generation, the system pressure was varied from 0.9 to 2.4 MPa, thus allowing the investigation of flows with liquid-to-vapor density ratios covering the range of about 7 to 27, far less than studied in air-water and similar systems. There is evidence that for a given cross-sectional average void fraction, the local phase distributions can be different depending on whether the vapor phase is generated at the wall, or upstream of the test section inlet. In wall-heated flows, local void fraction profiles measured across both the wide and narrow test section dimensions illustrate the profound effect that pressure has on the local flow structure; notably, increasing pressure appears to thin the wallbounded liquid films and redistribute liquid toward the edges of the test section. This general trend is also manifested in the distributions of mean droplet diameter and interfacial area density, which are inferred from local measurements of void fraction, droplet frequency and velocity. At high pressure, the interfacial area density is increased due to the significant enhancement in droplet concentration.

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Vapor core turbulence in annular two-phase flow

Cited by 5 publications

References 6 publications

Two-Phase Annular Flow in Vertical Pipes: A Critical Review of Current Research Techniques and Progress

Two-Phase Annular Flow in Vertical Pipes: A Critical Review of Current Research Techniques and Progress

Shock wave in a bubble flow with high gas content

Effect of Pressure With Wall Heating in Annular Two-Phase Flow

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