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Journal Articles

Evaluation of gas entrainment flow rate by free surface vortex

Torikawa, Tomoaki*; Odaira, Naoya*; Ito, Daisuke*; Ito, Kei*; Saito, Yasushi*; Matsushita, Kentaro; Ezure, Toshiki; Tanaka, Masaaki

Konsoryu, 36(1), p.63 - 69, 2022/03

On free surface of a sodium cooled fast reactor, gas entrainment can be caused by free surface vortices, which may result in disturbance in core power. It is important to develop an evaluation model to predict accurately entrained gas flow rate. In this study, entrained gas flow rate a simple gas entrainment experiment is conducted with focusing on effect of pressure difference between upper and lower tanks. Pressure difference between upper and lower tanks are controlled by changing gas pressure in lower tank. As a result, it is confirmed that the entrained gas flow rate increases with increasing pressure difference between upper and lower tanks. By visualization of swirling annular flow in suction pipe, it is also observed that pressure drop in suction pipe increases with increase in entrained gas flow rate, which implies that entrained gas flow rate can be predicted by evaluation model based on pressure drop in swirling annular flow region.

Journal Articles

Gas entrainment phenomenon from free liquid surface in a sodium-cooled fast reactor; Measurements and evaluation on a gas core growth form the liquid surface

Uchida, Mao*; Alzahrani, H.*; Shiono, Mikihito*; Sakai, Takaaki*; Matsushita, Kentaro; Ezure, Toshiki; Tanaka, Masaaki

Proceedings of 19th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-19) (Internet), 16 Pages, 2022/03

Gas entrainment from cover gas is one of key issues for sodium-cooled fast reactors design to prevent unexpected effects to core reactivity. A vortex model based evaluation method has been developed to evaluate the surface vortex gas core growth at the free surface in the reactor vessel. In this study, water experiments were performed to clarify the prediction accuracy for the vortex gas core growth during the vortex drift motion using a circulating water tunnel with an open flow channel test section. Gas core growth were predicted by applying the evaluation method to the numerical analyses performed in the same geometry of the experiments, and compared with the experimental results. It was observed the gas core growth became large at downstream region where downward velocity became large in experiment. However, the gas core length which were predicted from numerical result showed a discrepancy with the experimental result on the peak position and an overestimation of peak value.

Journal Articles

Parametric analysis of bubble and dissolved gas behavior in primary coolant system of sodium-cooled fast reactors

Matsushita, Kentaro; Ito, Kei*; Ezure, Toshiki; Tanaka, Masaaki

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 9 Pages, 2019/05

A numerical simulation code named SYRENA has been developed in JAEA to analyze the behavior of entrained bubbles and dissolved gas in the primary coolant of sodium-cooled fast reactor (SFR). In the present study, a flow network model of SYRENA to a hypothetical pool type reactor was developed and the non-condensable gas behavior was investigated through the comparison with that in the loop type reactor. The effect of the dipped-plate (D/P) tentatively introduced into the pool-type reactor on the gas behavior was investigated through the parametric analyses about the sodium exchange flow rate through the D/P and the gas entrainment rate at the free surface. It was suggested that the increase in the exchange flow rate through the D/P doesn't always work to decrease the bubble volume in the primary coolant system.

Journal Articles

Visualization study on droplet-entrainment in a high-speed gas jet into a liquid pool

Sugimoto, Taro*; Saito, Shimpei*; Kaneko, Akiko*; Abe, Yutaka*; Uchibori, Akihiro; Ohshima, Hiroyuki

Proceedings of 26th International Conference on Nuclear Engineering (ICONE-26) (Internet), 7 Pages, 2018/07

A computational fluid dynamics code for a sodium-water reaction phenomenon in a steam generator of sodium-cooled fast reactors has been developed. In order to provide the data for validation of this code, the visualization experiment on liquid droplet entrainment in the high-pressure air jet submerged in the water pool was carried out. The experiment successfully elucidated the behavior, such as atomization of the relatively large diameter liquid droplet generated from the gas-liquid interface.

Journal Articles

Physics-basis simulation of bubble pinch-off

Ito, Kei; Koizumi, Yasuo; Ohshima, Hiroyuki; Kawamura, Takumi*

Mechanical Engineering Journal (Internet), 3(3), p.15-00671_1 - 15-00671_9, 2016/06

Journal Articles

Development of a mechanistic evaluation method for wastage environment under sodium-water reaction accident

Uchibori, Akihiro; Ohshima, Hiroyuki

Proceedings of 16th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-16) (USB Flash Drive), p.533 - 544, 2015/08

For assessment of the wastage environment under tube failure accident, a mechanistic computer code called SERAPHIM calculating compressible multicomponent multiphase flow with sodium-water chemical reaction has been developed. In this study, applicability of the SERAPHIM code including the numerical model for liquid droplet entrainment and transport was investigated through the analysis of the basic experiment and the experiment under actual condition of the steam generator. In the analysis of the basic experiment, the calculated pressure variation during liquid droplet entrainment was consistent with the experimental result. In the analysis of the actual condition, the calculated temperature distribution agreed with the measurement result well. The region with higher impingement velocity of the liquid droplet was close to the wastage region confirmed in the experiment. It was demonstrated that the SERAPHIM code could predict the wastage environment under the actual condition.

Journal Articles

Physics-basis simulation of bubble pinch-off

Ito, Kei; Koizumi, Yasuo*; Ohshima, Hiroyuki; Kawamura, Takumi*

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 6 Pages, 2015/05

The authors are developing a high-precision CFD code with an interface tracking method to simulate the gas entrainment (GE) phenomena in sodium-cooled fast reactors (SFRs), which might be caused by a highly-intensified free surface vortex. The GE in SFRs is characterized by an elongated interfacial dent along the vortex core and the bubble pinch-off at the tip of the dent. To simulate this complicated phenomenon, our simulation code has physics-basis algorithms which model accurately the interfacial dynamic behavior, the pressure jump condition at an interface and the surface tension. Several verification problems have been already solved and the accuracy of each individual algorithm is confirmed. In this paper, a basic experiment of the GE is simulated to validate the developed code. The simulation result of the entrained flow rate shows comparable value to the experimental data, that is, our simulation code is considered applicable to the evaluation of the GE in SFRs.

Journal Articles

Evaluation of gas entrainment flow rate using numerical simulation with interface-tracking method

Ito, Kei; Ohno, Shuji; Koizumi, Yasuo*; Kawamura, Takumi*

Proceedings of 10th International Topical Meeting on Nuclear Thermal Hydraulics, Operation and Safety (NUTHOS-10) (USB Flash Drive), 10 Pages, 2014/12

Journal Articles

Development of vortex model with realistic axial velocity distribution

Ito, Kei; Ezure, Toshiki; Ohshima, Hiroyuki

Nihon Kikai Gakkai Rombunshu (Internet), 80(818), p.FE0299_1 - FE0299_9, 2014/10

A vortex is considered as one of significant phenomena which may cause gas entrainment (GE) and/or vortex cavitation in sodium-cooled fast reactors. In this study, a new vortex model with realistic axial velocity distribution is proposed. As the verification, the new vortex model is applied to the evaluation of a simple vortex experiment, and shows good agreements with the experimental data in terms of the circumferential velocity distribution and the free surface shape. In addition, it is confirmed that the Burgers vortex model fails to calculate accurate velocity distribution with the assumption of uniform axial velocity. However, the calculation accuracy of the Burgers vortex model can be enhanced close to that of the new vortex model in consideration of the effective axial velocity which is calculated as the average value only in the vicinity of the vortex center.

Journal Articles

Effect of physical properties on gas entrainment rate from free surface by vortex, 2

Koizumi, Yasuo*; Ote, Naosuke*; Kamide, Hideki; Ohno, Shuji; Ito, Kei

Proceedings of 22nd International Conference on Nuclear Engineering (ICONE-22) (DVD-ROM), 7 Pages, 2014/07

Journal Articles

Axial variation of interfacial friction in a developing stratified-wavy two-phase flow

*; Kukita, Yutaka*; Tsuji, Yoshiyuki*

Eighth Int. Topical Meeting on Nuclear Reactor Thermal-Hydraulics (NURETH-8), 1, p.40 - 47, 1997/00

no abstracts in English

JAEA Reports

A Study of entrainment at a break and in the core during small break loss-of-coolant accidents in PWRs

Yonomoto, Taisuke

JAERI-Research 96-024, 154 Pages, 1996/05

JAERI-Research-96-024.pdf:5.87MB

no abstracts in English

JAEA Reports

Benchmark calculation of subchannel analysis codes

JAERI-Data/Code 96-004, 109 Pages, 1996/02

JAERI-Data-Code-96-004.pdf:2.3MB

no abstracts in English

Journal Articles

Flow regime transition to wavy dispersed flow for high-pressure steam/water two-phase flow in horizontal pipe

Nakamura, Hideo; Kukita, Yutaka; *

Journal of Nuclear Science and Technology, 32(7), p.641 - 652, 1995/07

 Times Cited Count:5 Percentile:50.76(Nuclear Science & Technology)

no abstracts in English

Journal Articles

An evaluation of Bernoulli effect on slugging in horizontal two-phase flow

Nakamura, Hideo; Kukita, Yutaka; *

Journal of Nuclear Science and Technology, 31(2), p.113 - 121, 1994/02

 Times Cited Count:1 Percentile:18.18(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Experimental study of aerosol reentrainment from flashing pool in ALPHA program

Kudo, Tamotsu; Yamano, N.; Moriyama, Kiyofumi; Maruyama, Yu; Sugimoto, Jun

3rd Int. Conf. on Containment Design and Operation,Conf. Proc., Vol. 1, 0, 10 Pages, 1994/00

no abstracts in English

JAEA Reports

Improvement of COBRA-TF code models for liquid entrainments in film-mist flow

Ezzidi, A.*; Okubo, Tsutomu; Murao, Yoshio

JAERI-M 93-133, 39 Pages, 1993/07

JAERI-M-93-133.pdf:0.99MB

no abstracts in English

JAEA Reports

Assessment of models in COBRA-TF code for liquid entrainments in film-mist flow

Okubo, Tsutomu; Ezzidi, A.*; Murao, Yoshio

JAERI-M 93-069, 115 Pages, 1993/03

JAERI-M-93-069.pdf:2.16MB

no abstracts in English

JAEA Reports

Plate-out distribution of iodine in a high temperature gas cooling in-pile loop facility

Matsumoto, Mikio; Endo, Yasuichi; ; Itabashi, Yukio; ; Yokouchi, Iichiro; Ando, Hiroei

JAERI-M 92-212, 62 Pages, 1993/01

JAERI-M-92-212.pdf:2.09MB

no abstracts in English

Journal Articles

On the rebound of aerosol particles flowing in a vertical pipe

Matsui, Hiroshi; Noguchi, Hiroshi

Earozoru Kenkyu, 8(1), p.58 - 65, 1993/00

no abstracts in English

30 (Records 1-20 displayed on this page)