Linear computed tomography of two-phase distribution in a rectangular channel

Tip clearance has a great effect on the flow and pressure fluctuation characteristics in a multiphase pump, especially at multiple operating points. The phase distribution and pressure fluctuation in tip clearance in a multiphase pump are revealed using the CFD (computational fluid dynamics) technology and high-speed photography methods. In this paper, the phase distribution, the gas-liquid two-phase velocity slip, and the pressure fluctuation intensity are comprehensively analyzed. Results show with the increase of the tip clearance, the multiphase pump pressurization performance is obviously deteriorated. In the meantime, the gas accumulation mainly occurs at the hub, the blade suction side (SS), and the tip clearance, and the maximum gas-liquid two-phase velocity difference is near the impeller streamwise of 0.4. In addition, the tip clearance improves the gas-liquid two-phase distribution in the pump, that is, the larger the tip clearance is, the more uniform the gas-liquid distribution becomes. Furthermore, the gas leads to the maximum pressure fluctuation intensity in the tip clearance which is closer to the tip leakage flow (TLF) outlet, and has a greater effect on the degree of flow separation in the tip clearance.

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Imaging and Resistivity Studies of Saturation Gradients in Two-Phase Flow in 3-D Porous Media

MRS Proceedings ◽

10.1557/proc-464-371 ◽

1996 ◽

Vol 464 ◽

Cited By ~ 1

Author(s):

E. H. Kawamoto ◽

Po-Zen Wong

Keyword(s):

Computed Tomography ◽

Porous Media ◽

Two Phase Flow ◽

Water Saturation ◽

Glass Beads ◽

Water Phase ◽

Phase Flow ◽

Two Phase ◽

Vertical Column ◽

X Ray

ABSTRACTWe have carried out x-ray radiography and computed tomography (CT) to study two-phase flow in 3-D porous media. Air-brine displacement was imaged for drainage and imbibition experiments in a vertical column of glass beads. By correlating water saturation Sw with resistance R, we find that there is a threshold saturation S* ≈ 0.2, above which R(SW) ∼ Sw−2, in agreement with the empirical Archie relation. This holds true for both drainage and imbibition with littlehysteresis, provided that Sw remains above S*. Should Sw drop below S* during drainage, R(Sw) rises above the Archie prediction, exhibiting strong hysteresis upon reimbibition. This behavior suggests a transition in the connectivity of the water phase near S*, possibly due to percolation effects.

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Flow regime identification and classification based on void fraction and differential pressure of vertical two-phase flow in rectangular channel

International Journal of Heat and Mass Transfer ◽

10.1016/j.ijheatmasstransfer.2018.12.015 ◽

2019 ◽

Vol 132 ◽

pp. 802-816 ◽

Cited By ~ 4

Author(s):

Vikrant Siddharudh Chalgeri ◽

Ji Hwan Jeong

Keyword(s):

Flow Regime ◽

Void Fraction ◽

Two Phase Flow ◽

Rectangular Channel ◽

Differential Pressure ◽

Phase Flow ◽

Two Phase ◽

Flow Regime Identification

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An Experimental Study on Liquid Film Dynamics and Interfacial Wave of Air-Water Two-Phase Flow in a Horizontal Channel

Volume 4: Thermal Hydraulics ◽

10.1115/icone21-15952 ◽

2013 ◽

Author(s):

Youjia Zhang ◽

Weimin Ma ◽

Shengjie Gong

Keyword(s):

Liquid Film ◽

Two Phase Flow ◽

Rectangular Channel ◽

Research Work ◽

Water Film ◽

Test Facility ◽

Phase Flow ◽

Interfacial Wave ◽

Film Rupture ◽

Two Phase

This study is concerned with liquid film dynamics and stability of annular flow, which plays an important role in understanding film rupture and dryout in boiling heat transfer. The research work starts from designing and making a test facility which enables the visualization and measurement of liquid film dynamics. A confocal optical sensor is applied to track the evolution of film thickness. A horizontal rectangular channel made of glass is used as the test section. Deionized water and air are supplied into that channel in such a way that an initial stratified flow forms, with the liquid film on the bottom wall. The present study is focused on characterization of liquid film profile and dynamics in term of interfacial wave and shear force induced film rupture under adiabatic condition. Based on the experimental data and analysis, it is found that given a constant water flowrate, the average thickness of water film decreases with increasing air flowrate, while the interfacial wave of the two-phase flow is intensified. As the air flowrate reaches a critical value, a localized rupture of the water film occurs.

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CFD simulation of air effect on flow field characteristics of hydro-viscous clutch with constant speed difference

Mechanics & Industry ◽

10.1051/meca/2018032 ◽

2018 ◽

Vol 19 (2) ◽

pp. 208

Author(s):

Xudong Zheng ◽

Fangwei Xie ◽

Diancheng Wu ◽

Xinjian Guo ◽

Bing Zhang ◽

...

Keyword(s):

Flow Field ◽

Cfd Simulation ◽

Power Transmission ◽

Volume Fraction ◽

Phase Distribution ◽

Constant Speed ◽

Distribution Law ◽

Two Phase ◽

Oil Film ◽

Speed Difference

The purpose of this paper is to study the air effects on transmission characteristics of hydro-viscous clutch and reveal the distribution law of the flow field of the oil film. The computational-fluid-dynamics (CFD) simulation model of oil film with radial oil grooves between friction pairs is taken as the study object. Considering the air effects, the pressure field, two-phase distribution, transmission torque and temperature field of the oil film are analyzed comparatively by using the CFD technology. The results show that the presence of air changes the pressure and temperature distributions of the oil film. With increase of the absolute rotational speed, the air volume fraction increases and the radius value of the air-liquid boundary decreases under condition of constant speed difference, which makes the coverage rate of the oil film on the surface of the friction disks reduce and the transmission torque of the oil film decrease. These simulation results are attributed to the study of hydro-viscous-drive and its applications. This paper also can provide a theoretical basis for the mechanism of power transmission through oil film in the presence of air effects.

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Effect of Metal Foam Insert Configurations on Flow Boiling Heat Transfer and Pressure Drop in a Rectangular Channel

Materials ◽

10.3390/ma14164617 ◽

2021 ◽

Vol 14 (16) ◽

pp. 4617

Author(s):

Sanghyun Nam ◽

Dae Yeon Kim ◽

Youngwoo Kim ◽

Kyung Chun Kim

Keyword(s):

Heat Transfer ◽

Pressure Drop ◽

Mass Flux ◽

Test Section ◽

Boiling Heat Transfer ◽

Metal Foam ◽

Flow Boiling ◽

Rectangular Channel ◽

Saturation Pressure ◽

Two Phase

Heat transfer under flow boiling is better in a rectangular channel filled with open-cell metal foam than in an empty channel, but the high pressure drop is a drawback of the empty channel method. In this study, various types of metal foam insert configurations were tested to reduce the pressure drop while maintaining high heat transfer. Specifically, we measured the boiling heat transfer and pressure drop of a two-phase vertical upward flow of R245fa inside a channel. To measure the pressure and temperature differences of the metal foam, differential pressure transducers and T-type thermocouples were used at both ends of the test section. While the saturation pressure was kept constant at 5.9 bar, the steam quality at the inlet of the test section was changed from 0.05 to 0.99. The channel height, moreover, was 3 mm, and the mass flux ranged from 133 to 300 kg/m2s. The two-phase flow characteristics were observed through a high-speed visualization experiment. Heat transfer tended to increase with the mean vapor quality, and, as expected, the fully filled metal foam channel offered the highest thermal performance. The streamwise insert pattern model had the lowest heat transfer at a low mass flux. However, at a higher mass flux, the three different insert models presented almost the same heat transfer coefficients. We found that the streamwise pattern model had a very low pressure drop compared to that of the spanwise pattern models. The goodness factors of the flow area and the core volume of the streamwise patterned model were higher than those of the full-filled metal foam channel.

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