Simulation of a jet flow rectified by a grating-type structure using immersed boundary methods

Hirose, Yoshiyasu; Abe, Satoshi; Ishigaki, Masahiro*; Shibamoto, Yasuteru; Hibiki, Takashi*

Progress in Nuclear Energy, 169, p.105085_1 - 105085_13, 2024/04

https://doi.org/10.1016/j.pnucene.2024.105085

Opposing mixed convection heat transfer for turbulent single-phase flows

Motegi, Kosuke; Shibamoto, Yasuteru; Hibiki, Takashi*; Tsukamoto, Naofumi*; Kaneko, Junichi*

International Journal of Energy Research, 2024, p.6029412_1 - 6029412_22, 2024/01

https://doi.org/10.1155/2024/6029412

Convection, wherein forced and natural convections are prominent, is known as mixed convection. Specifically, when a forced convection flow is downward, this flow is called opposing flow. Several heat transfer correlations have been reported related to single-phase opposing flow; however, these correlations are based on experiments conducted in various channel geometries, working fluids, and thermal flow parameter ranges. Because the definition of nondimensional parameters and their validated range confirmed by experiments differ for each correlation reported in previous studies, establishing a guideline for deciding which correlation should be selected based on its range of applicability and extrapolation performance is important. This study reviewed the existing heat transfer correlations for turbulent opposing-flow mixed convection and the single-phase heat transfer correlations implemented in the thermal-hydraulic system codes. Furthermore, we evaluated the predictive performance of each correlation by comparing them with the experimental data obtained under various experimental conditions. The Jackson and Fewster, Churchill, and Swanson and Catton correlations (Int. J Heat Mass Transf., 1987) can accurately predict all the experimental data. The effect of the difference in the thermal boundary conditions, i.e., uniform heat flux and uniform wall temperature, on the turbulent mixed-convection heat transfer coefficient is not substantial. We confirmed that heat transfer correlations using the hydraulic-equivalent diameter as a characteristic length can be used for predictions regardless of channel-geometry differences. Furthermore, correlations described based on nondimensional dominant parameters can be used for predictions regardless of the differences in working fluids.

Numerical simulation of bubble hydrodynamics for pool scrubbing

Okagaki, Yuria; Shibamoto, Yasuteru; Wada, Yuki; Abe, Satoshi; Hibiki, Takashi*

Journal of Nuclear Science and Technology, 60(8), p.955 - 968, 2023/08

https://doi.org/10.1080/00223131.2022.2161656

Experimental study on local interfacial parameters in upward air-water bubbly flow in a vertical 66 rod bundle

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

International Journal of Heat and Mass Transfer, 144, p.118696_1 - 118696_19, 2019/12

https://doi.org/10.1016/j.ijheatmasstransfer.2019.118696

Some characteristics of gas-liquid two-phase flow in vertical large-diameter channels

Shen, X.*; Schlegel, J. P.*; Hibiki, Takashi*; Nakamura, Hideo

Nuclear Engineering and Design, 333, p.87 - 98, 2018/07

https://doi.org/10.1016/j.nucengdes.2018.04.001

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.

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

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.

An Improved fast neutron radiography quantitative measurement method

Matsubayashi, Masahito; Hibiki, Takashi*; Mishima, Kaichiro*; Yoshii, Koji*; Okamoto, Koji*

Nuclear Instruments and Methods in Physics Research A, 533(3), p.481 - 490, 2004/11

https://doi.org/10.1016/j.nima.2004.06.142

The validity of a fast neutron radiography quantification method, the -scaling method, which was originally proposed for thermal neutron radiography was examined with Monte Carlo calculations and experiments conducted at the YAYOI fast neutron source reactor. Water and copper were selected as comparative samples for a thermal neutron radiography case and a dense object, respectively. Although different characteristics on effective macroscopic cross-sections were implied by the simulation, the -scaled experimental results with the fission neutron spectrum cross-sections were well fitted to the measurements for both the water and copper samples. This indicates that the -scaling method could be successfully adopted for quantitative measurements in fast neutron radiography.

Study on point of net vapor generation by neutron radiography in subcooled boiling flow along narrow rectangular channels with short heated length

Kureta, Masatoshi; Hibiki, Takashi*; Mishima, Kaichiro*; Akimoto, Hajime

International Journal of Heat and Mass Transfer, 46(7), p.1171 - 1181, 2003/03

https://doi.org/10.1016/S0017-9310(02)00398-8

no abstracts in English

Measurement of boiling flow by high-frame-rate neutron radiography, 2; Point of net vapor generation of flow-boiling in rectangular channels with short heated length

Kureta, Masatoshi; Hibiki, Takashi*; Mishima, Kaichiro*; Akimoto, Hajime

Nihon Kikai Gakkai Rombunshu, B, 67(661), p.2295 - 2303, 2001/09

https://doi.org/10.1299/kikaib.67.2295

no abstracts in English