JOPSS - Search Results

Search Results: Records 1-19 displayed on this page of 19

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Journal Articles

Flow regime and void fraction predictions in vertical rod bundle flow channels

Han, X.*; Shen, X.*; Yamamoto, Toshihiro*; Nakajima, Ken*; Sun, Haomin; Hibiki, Takashi*

International Journal of Heat and Mass Transfer, 178, p.121637_1 - 121637_24, 2021/10

https://doi.org/10.1016/j.ijheatmasstransfer.2021.121637

Times Cited Count：7 Percentile：57.51(Thermodynamics)

Journal Articles

Axial flow characteristics of bubbly flow in a vertical large-diameter square duct

Shen, X.*; Sun, Haomin; Deng, B.*; Hibiki, Takashi*; Nakamura, Hideo

Proceedings of 17th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-17) (USB Flash Drive), 14 Pages, 2017/09

An experimental study on the upward bubbly air-water flows in a vertical large-diameter square duct have been performed by using four-sensor probes. The four-sensor probe were applied in the local measurements at 3 axial positions along the flow direction to obtain interfacial area concentration, 3-D bubble velocity vector and bubble diameter. The obtained void fraction, interfacial area concentration, 3-D bubble velocity vector and bubble diameter provided valuable insight into the flow structure and will serve as a valuable database to develop the mechanistic models for interfacial area transport equation sources and sinks.

Journal Articles

Gas-liquid bubbly flow structure in a vertical large-diameter square duct

Shen, X.*; Sun, Haomin; Deng, B.*; Hibiki, Takashi*; Nakamura, Hideo

Progress in Nuclear Energy, 89, p.140 - 158, 2016/05

https://doi.org/10.1016/j.pnucene.2016.02.014

Times Cited Count：23 Percentile：89.61(Nuclear Science & Technology)

An experimental study was performed on the local structure of upward air-water two-phase flow in a vertical large diameter square duct by using a four-sensor probe. The four-sensor probe method classifying spherical and non-spherical bubbles was applied as a key measurement way to obtain local parameters such as 3-D bubble velocity vector, bubble diameter and interfacial area concentration. Both the local void fraction and interfacial area concentration indicated radial core-peak and wall-peak distributions at low and high liquid flow rates respectively. The 2 components of the bubble velocity vector in the cross-section revealed that there exists a rotating secondary flow in the octant symmetric triangular area and the magnitude of the rotating secondary flow increases with the liquid flow rate. Some of constitutive correlations of drift-flux model and interfacial area concentration are reviewed to study their predictabilities against the present data.

Journal Articles

Phase equilibria and thermal expansion of CaTiO $_{3}$ doped with neptunium

Sato, Tsuyoshi*; Yamashita, Toshiyuki; Matsui, Tsuneo*

Journal of Nuclear Materials, 344(1-3), p.67 - 72, 2005/09

https://doi.org/10.1016/j.jnucmat.2005.04.018

Times Cited Count：3 Percentile：24.17(Materials Science, Multidisciplinary)

Phase relationships between NpO $_{2}$ and CaTiO $_{3}$ or Ca(Ti, Al)O $_{3}$ were investigated by X-ray diffraction (XRD) analysis, using specimens prepared at 1773 K in Ar-8%H $_{2}$ . Single phase solid solutions were formed 0-7.5 mol%Np and 1-10 mol%Np for CaTiO $_{3}$ and Ca(Ti, Al)O $_{3}$ , respectively. By substituting Al for Ti in CaTiO $_{3}$ , Np solubility in Ca(Ti, Al)O $_{3}$ increased. Solubility of Np was compared with those of U and Pu, and was discussed with oxidation states and ionic radii of dopants. Thermal expansions of (Ca,Np)TiO $_{3}$ were measured from room temperature to 1273 K in Ar-8%H $_{2}$ using high-temperature XRD technique. These specimens showed nearly the same value of volumetric thermal expansion coefficients, suggesting that the incorporation of tetravalent Np into CaTiO $_{3}$ had practically no effect on stabilization of the crystal lattice. This finding was in a marked contrast to that of Pu doped CaTiO $_{3}$ , where pronounced stabilization in the crystal was observed by incorporating Pu into CaTiO $_{3}$ .

JAEA Reports

Numerical analysis of interfacial growth and deformation in horizontal stratified two-phase flow by lattice Boltzmann method

Ebihara, Kenichi

JAERI-Research 2005-004, 121 Pages, 2005/03

JAERI-Research-2005-004.pdf:19.79MB

This report is the JAERI's report version of the doctor thesis by the author. In this report, first, the validity and usefulness of the application of the two-phase fluid model of the lattice-gas method and the lattice Boltzmann method(LBM) are examined. On the basis of the examination, next, the horizontal stratified two-phase flow that is the fundamental and important flow is simulated by the HCZ model which is one of the two-phase fluid model of the LBM. It is seen that the interfacial growth of the HCZ model satisfies the Kelvin-Helmholtz instability theory and reproduces the theoretical two-phase flow regime map of Taitel and Dukler(T-D map). It is found that more superficial flow velocity of the rare phase is necessary in the channel with the narrow width. The HCZ model can also simulate the droplet generation accompanying more complex interfacial phenomena and reproduce the experimental correlation of Ishii and Grolmes in the range of the distribution of the experimental data.

Journal Articles

Study on interfacial growth and deformation of horizontal stratified two-phase flow by lattice Boltzmann method

Ebihara, Kenichi

Tsukuba Daigaku Daigakuin Shisutemu Joho Kogaku Kenkyuka Hakase Gakui Rombun, 134 Pages, 2004/09

In this thesis, first the liquid-gas models of the lattice method are examined by applying them to two-phase flow simulations. Next the liquid-gas model(the HCZ model) of the lattice Boltzmann method is applied to the three-dimensional simulation of the horizontal stratified two-phase flow. The following results are obtained. (1)The two- and three- dimensional interface simulated by the HCZ model satisfies the Kelvin-Helmholtz instability theory. (2)In the simulation of the interfacial growth in the rectangular channel, it is found that the relation between the interfacial growth and the flow state is in agreement with the flow regime map proposed theoretically by Taitel and Dukler. (3)It is also found that the three dimensionality becomes remarkable and the interfacial growth needs more flow rate of the rare phase than that of the theoretical flow regime map when the channel width is narrower. (4)In the droplet creation simulation, it is found that the relation between the droplet creation and the flow state simulates the experimental correlation proposed by Ishii and Grolmes.

Journal Articles

The Lattice Boltzmann simulation of the droplet creation in the horizontal stratified two-phase flow

Ebihara, Kenichi; Watanabe, Tadashi

Nagare, 23(4), p.253 - 261, 2004/08

http://ci.nii.ac.jp/naid/110003890172

The lattice Boltzmann method for one-component two-phase fluid is applied to the simulation of the droplet creation in the horizontal stratified two-phase flow. It is observed in several flow states that the droplet tears from the interface wave. The dimensionless numbers that characterize the flow state are also measured during the simulations. After checking the influence of the lattice length and width to the simulation result, the relation between the droplet creation and the measured dimensionless numbers is compared with the inception criteria of the droplet creation that was proposed on the basis of experimental data by Ishii and Grolmes. It was found that the simulation results are included in the devitation of experimental data from the correlation of Ishii-Grolmes.

Journal Articles

Phase relations of AgI under high pressure and high temperature

Otaka, Osamu*; Takebe, Hitoshi*; Yoshiasa, Akira*; Fukui, Hiroshi*; Katayama, Yoshinori

Solid State Communications, 123(5), p.213 - 216, 2002/08

https://doi.org/10.1016/S0038-1098(02)00290-9

Times Cited Count：18 Percentile：64.18(Physics, Condensed Matter)

Using a multi-anvil high-pressure device and synchrotron radiation, X-ray observations of AgI high pressure and high temperature up to 6.0 GPa and 1000 K have been performed to investigate the phase relations between -AgI, rocksalt-type, disordered rocksalt-type, and liquid phases. The three phases of -AgI, disordered rocksalt-type, and liquid meet in a triple point in the vicinity of 823 K and 1.3 GPa. The melting curve of the disordered rocksalt phase is linear with a positive slope. The transition between rocksalt and the disordered rocksalt phases is a broad and diffuse disordering type within the same structure. The formation of the disordered rocksalt phase has been hence estimated with the variation of a relative intensity ratio of (111) and (200) diffraction from the rocksalt phase. With increasing pressure the rocksalt phase becomes stabel at high temperature. At 6.0 GPa the rocksalt phase directly melts without the transition to the disordered rocksalt phase.