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Tokuhiro, Akira; Kimura, Nobuyuki
Journal of Nuclear Science and Technology, -(-), 0 Pages, 2001/00
None
Kimura, Nobuyuki; ; ; ; Kamide, Hideki; Tokuhiro, Akira; Hishida, Koichi
JNC TN9400 2000-057, 60 Pages, 2000/05
JNC-TN9400-2000-057.pdf:2.11MB
ln experimental study for the thermohydraulics of fast reactor, a simple experiment with fine measurement has been desired for understanding of phenomena and for verification of computer code rather than mockup experiments of large scale. For such purposes quality of experimental data must be improved. ln the velocity measurement, instantaneous velocity profile will have great advances for the understanding of phenomena and for the verification of computer code. ln this report two methods of the velocity profile measurement are discussed; one is ultrasound Doppler velocimetry (UDV) and the other is particle image velocimetry (PIV). These methods were applied to water experiments. The UDV was applied to pipe flow, planer jet, and the inter-wrapper flow which is seen in the gap region between subassemblies of fast reactor core. Cross check with laser Doppler velocimetly showed proper measurement of the UDV. Problems including the application to sodium experiments are also discussed. The PIV was also applied to the inter-wrapper flow. For the application to complex flow geometry, noise reduction method was developed to improve the measurement accuracy.
Kimura, Nobuyuki; Tokuhiro, Akira; Kamide, Hideki
JNC TN9400 2000-027, 181 Pages, 2000/02
JNC-TN9400-2000-027.pdf:10.28MB
A quantitative evaluation on thermal striping, in which temperature fluctuation due to convective mixing among jets causes thermal fatigue in structural components, is of importance for reactor safety. ln this study, a water experiment was performed using vertical and parallel triple jets, those are cold jet on center and hot jets on both side. The experimental parameter was discharged velocity of the triple-jet and local temperature and velocity were measured by ultrasound Doppler velocimetry and movable thermocouples. The objective is a quantification of the mixing process in the multiple-jet. Under isovelocity condition, the jets oscillated periodically and mixing among thejets was promoted by periodic oscillation. The periodic oscillation was dependent on the Strouhal number based on the discharged velocity. Under non-isovelocity condition, on the other hand, the jets did not oscillate periodically and mixing among the jets progressed more gentle compared with the case under isovelocity condition. The tempwrature fluctuation could be decomposed into coherent and random components using the phase averaging process. The rate of the coherent component in the temperature fluctuation increased and the rate of random component in temperature fluctuation decreased in proportion as the discharged velocity was increased.
; Tokuhiro, Akira; Kimura, Nobuyuki;
Nuclear Engineering and Design, 202(1), p.77 - 95, 2000/00
Times Cited Count：40 Percentile：90.41(Nuclear Science & Technology)None
Kimura, Nobuyuki; Yasuda, Akihiro; ; Tokuhiro, Akira; ;
Proceedings of 8th International Conference on Nuclear Engineering (ICONE-8) (CD-ROM), 0 Pages, 2000/00
None
; Tokuhiro, Akira; ;
Proceedings of 8th International Conference on Nuclear Engineering (ICONE-8) (CD-ROM), 0 Pages, 2000/00
None
Tokuhiro, Akira; Kimura, Nobuyuki
JNC TN9400 2000-015, 26 Pages, 1999/09
JNC-TN9400-2000-015.pdf:1.43MB
The quantification of the rate-of-rise of the thermal stratification interface, a "thin" vertical zone where the temperature gradient is the steepest, is important in assessing the potential implications of thermally-induced stress problems in liquid-metal cooled reactors. Thermal stratification can likewise occur in confined volumes containing ordinary fluids (Pr
1), where there is an input of thermal convective energy. In the prominent case of liquid metal reactors, there have been many studies on quantifying the rate-of-rise of a defined stratification interface, in terms of one or more of the following dimensionless groups, mainly: Richardson (Ri), Reynolds (Re), Grashof (Gr), Rayleigh (Ra) and/or Froude (Fr) numbers. Stratification is also a transient process in the volume in question. In the present work the anthors presents a derivation based on order-of-magnitude analysis (OMA), including an sensible energy balance, that produces a new representation more consistent than p
Tokuhiro, Akira; Kimura, Nobuyuki;
JNC TN9400 2000-014, 86 Pages, 1999/06
JNC-TN9400-2000-014.pdf:11.72MB
Experiments were performed using the WAJECO facility to investigate the thermohydraulic mixing of multiple jets flowing out of a LMFBR core. Mixing is the root of the thermal striping problem. The multiple jets are typically at different velocities and temperatures and may induce thermal stresses upon components they impinge. In our study we modeled the mixing of three vertical jets, the central at a lower temperature than the two adjacent jets at equal temperatures. The jets are quasi-planar. The parameters were the average exit jet velocities (Uo,av) and the temperature difference between the "cold" and "hot" jets (
Thc=Thot-Tcold). Measurements of the liquid velocity, initially using laser Doppler velocimetry (LDV) and later ultrasound Doppler velocimetry (UDV), for both our reference single-jet and the triple-jet configuration, comprised Phase I of the experiments (up to 1994). Two reports (TN9410 96-181 and TN9410 96-296; in Japanese) reported on the hydraulic and heat tra
Tokuhiro, Akira
Journal of Nuclear Science and Technology, 36(6), p.540 - 548, 1999/06
None
Tokuhiro, Akira; Kimura, Nobuyuki
Nuclear Engineering and Design, 188(1), p.50 - 73, 1999/00
None
; Tokuhiro, Akira; Kimura, Nobuyuki;
Proceedings of 9th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-9), 0 Pages, 1999/00
None
Hirabayashi, Masaru; Kobayashi, Jun; Tokuhiro, Akira; Oki, Yoshihisa; ;
PNC TN9430 98-002, 29 Pages, 1998/01
no abstracts in English
Tokuhiro, Akira; ; ; Ohshima, Hiroyuki;
Nuclear Engineering and Design, 177, p.91 - 104, 1998/00
Times Cited Count：2 Percentile：23.04(Nuclear Science & Technology)None
Tokuhiro, Akira; Hishida, Koichi; *
Proc. of 1997 ASME Fluids Engineering Division Summer Meeting (FEDSM'97), 0 Pages, 1997/00
None
Tokuhiro, Akira; ; Kimura, Nobuyuki
Proceedings of 8th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics (NURETH-8), Vo.3, p.1712 - 1723, 1997/00
None
Kimura, Nobuyuki; Tokuhiro, Akira;
Vol.3,pp1724
1734, p.1724 - 1734, 1997/00
None
Tokuhiro, Akira; Kimura, Nobuyuki; ;
Proceedings of 5th ASME/JSME Joint Thermal Engineering Conference (CD-ROM), ,
None
; Tokuhiro, Akira; Kamide, Hideki; Kimura, Nobuyuki
Proceedings of 9th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NuReTH-9), ,
None
