Time-resolved two-dimensional X-ray densitometry of a two-phase flow downstream of a ventilated cavity

The two-dimensional characteristics of the vapor-liquid two-phase flow of liquid helium in a pipe are numerically investigated to realize the further development and high performance of new cryogenic engineering applications. First, the governing equations of the two-phase flow of liquid helium based on the unsteady thermal nonequilibrium multi-fluid model are presented and several flow characteristics are numerically calculated, taking into account the effect of superfluidity. Based on the numerical results, the two-dimensional structure of the two-phase flow of liquid helium is shown in detail, and it is also found that the phase transition of the normal fluid to the superfluid and the generation of superfluid counterflow against normal fluid flow are conspicuous in the large gas phase volume fraction region where the liquid to gas phase change actively occurs. Furthermore, it is clarified that the mechanism of the He I to He II phase transition caused by the temperature decrease is due to the deprivation of latent heat for vaporization from the liquid phase. According to these theoretical results, the fundamental characteristics of the cryogenic two-phase flow are predicted. The numerical results obtained should contribute to the realization of advanced cryogenic industrial applications.

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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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Experiment and Numerical Simulation of Bubble Behaviors in Argon Gas Injection Into Lead-Bismuth Pool

Volume 2: Thermal Hydraulics ◽

10.1115/icone14-89431 ◽

2006 ◽

Author(s):

Yumi Yamada ◽

Toyou Akashi ◽

Minoru Takahashi

Keyword(s):

Direct Contact ◽

Two Phase Flow ◽

Experimental Result ◽

Feed Water ◽

Force Model ◽

Phase Flow ◽

Two Dimensional ◽

Two Phase ◽

Argon Gas ◽

Bubble Rising

In a lead-bismuth alloy (45%Pb-55%Bi) cooled direct contact boiling water fast reactor (PBWFR), steam can be produced by direct contact of feed water with primary Pb-Bi coolant in the upper core plenum, and Pb-Bi coolant can be circulated by buoyancy forces of steam bubbles. As a basic study to investigate the two-phase flow characteristics in the chimneys of PBWFR, a two-dimensional two-phase flow was simulated by injecting argon gas into Pb-Bi pool in a rectangular vessel (400mm in length, 1500mm in height, 50mm in width), and bubble behaviors were investigated experimentally. Bubble sizes, bubble rising velocities and void fractions were measured using void probes. Argon gas was injected through five nozzles of 4mm in diameter into Pb-Bi at two locations. The experimental conditions are the pressure of atmospheric pressure, Pb-Bi temperatures of 443K, and the flow rate of injection Ar gas is 10, 20, and 30 NL/min. The measured bubble rising velocities were distributed in the range from 1 to 3 m/s. The average velocity was about 0.6 m/s. The measured bubble chord lengths were distributed from 1mm up to 30mm. The average chord length was about 7mm. An analysis was performed by two-dimensional and two-fluid model. The experimental results were compared with the analytical results to evaluate the validity of the analytical model. Although large diameter bubbles were observed in the experiment, the drag force model for spherical bubbles performed better for simulation of the experimental result because of high surface tension force of Pb-Bi.

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Two-Dimensional Numerical Simulation of Boiling Two-Phase Flow of Liquid Nitrogen.

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES ◽

10.2322/tjsass.43.114 ◽

2000 ◽

Vol 43 (141) ◽

pp. 114-121 ◽

Cited By ~ 5

Author(s):

Jun ISHIMOTO ◽

Mamoru OIKE ◽

Kenjiro KAMIJO

Keyword(s):

Numerical Simulation ◽

Liquid Nitrogen ◽

Two Phase Flow ◽

Phase Flow ◽

Two Dimensional ◽

Two Phase

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Application of Fast Synchrotron X-ray Imaging in Velocimetry of Cavitating Flows

10.5957/tos-2021-15 ◽

2021 ◽

Author(s):

Mingming Ge ◽

Guangjian Zhang ◽

Navid Nematikourabbasloo ◽

Kamel Fezzaa ◽

Olivier Coutier-Delgosha

Keyword(s):

Phase Contrast ◽

Two Phase Flow ◽

Motion Blur ◽

Hydrodynamic Cavitation ◽

Phase Flow ◽

Two Phase ◽

X Ray ◽

Sheet Cavitation ◽

Contraction Ratio ◽

Wide Range

Hydrodynamic cavitation is a complex two-phase flow phenomenon involving mass and heat transfer between liquid and vapor. It occurs in many widely-used hydraulic machines, such as pumps and marine propellers, and often leads to undesired effects like material erosion, noise, and vibration. To control these detrimental effects, the visualization of two-phase flow morphology inside the opaque cavity is a crucial point to improve the physical and numerical models of cavitation. The major challenge in experimental measurements of cavitating flow fields is the fact that multiple scattering and a direct reflection of visible light from phase boundaries make the flow optically opaque. In recent years, unlike traditional local measurements using various probes, the development of the third-generation synchrotron radiation sources promotes the application of Xray phase-contrast imaging, which enables clear visualization of boundaries between phases with different refractive indices. In this study, the partial cavity is formed in a convergent-divergent (Venturi) channel with a small contraction ratio where the relatively stable cavitation regime can be sustained in a wide range of cavitation numbers. The experiment performed at Advanced Photon Source (APS) of Argonne uses the short high-flux X-ray pulses emitted from synchrotron sources to capture fast dynamic events and minimize motion blur. The internal two-phase structures and bubble development dynamics inside the quasi-stable sheet cavitation can be identified. Aside from the detailed illustration of two-phase morphology, X-ray phase-contrast images were also used to perform velocimetry by tracking either seeded particles or phase interfaces inside the opaque regions. Through appropriate postprocessing to the recorded X-ray images of cavitation, the time resolved velocity and void fraction fields are obtained simultaneously. These unprecedented experimental data will be further explored in understanding fluid mechanics underneath the cavity, estimating slip velocity between fluid-vapor interactions, and reconstructing pressure fields for compressible flows.

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Study on Measurement Method of Moisture Content of Cold Cathode X-ray Two-Phase Flow

Springer Series in Geomechanics and Geoengineering - Proceedings of the International Field Exploration and Development Conference 2019 ◽

10.1007/978-981-15-2485-1_167 ◽

2020 ◽

pp. 1861-1872

Author(s):

Yun Wang ◽

Li-pin Li ◽

Huan Chen ◽

Jing-feng Yuan ◽

Mei-shuai Tong ◽

...

Keyword(s):

Moisture Content ◽

Measurement Method ◽

Two Phase Flow ◽

Phase Flow ◽

Cold Cathode ◽

Two Phase ◽

X Ray

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Measurement of Three-Dimensional Time-Averaged Void Fraction Distribution in Rod Bundle in Air-Water System by X-Ray CT Technique

Volume 4: Thermal Hydraulics ◽

10.1115/icone21-16814 ◽

2013 ◽

Cited By ~ 1

Author(s):

Kenichi Katono ◽

Jun Nukaga ◽

Takuji Nagayoshi ◽

Kenichi Yasuda

Keyword(s):

Fuel Assembly ◽

Void Fraction ◽

Two Phase Flow ◽

Three Dimensional ◽

Ct Images ◽

Phase Flow ◽

Two Phase ◽

X Ray ◽

Void Fraction Distribution ◽

Fraction Distribution

We have been developing a void fraction distribution measurement technique using the three-dimensional (3D) time-averaged X-ray CT (computed tomography) system to understand two-phase flow behavior inside a fuel assembly for BWR (boiling water reactor) thermal hydraulic conditions of 7.2 MPa and 288 °C. Unlike CT images of a normal standstill object, we can obtain 3D CT images that are reconstructed from time-averaged X-ray projection data of the intermittent two-phase flow. We measured the 3D void fraction distribution in a vertical square (5 × 5) rod array that simulated a BWR fuel assembly in the air-water test. From the 3D time-averaged CT images, we confirmed that the void fraction at the center part of the channel box was higher than that near the channel box wall, and the local void fraction at the central region of a subchannel was higher than that at the gap region of the subchannel. A comparison of the volume-averaged void fractions evaluated by the developed X-ray CT system with those evaluated by a differential pressure transducer in a void fraction range from 0.05 to 0.40 showed satisfactory agreement within a difference of 0.03.

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