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Uchibori, Akihiro; Watanabe, Akira*; Takata, Takashi; Ohshima, Hiroyuki
Nuclear Technology, 205(1-2), p.119 - 127, 2019/01
Times Cited Count：3 Percentile：31.36(Nuclear Science & Technology)To evaluate a sodium-water reaction phenomenon in a steam generator of sodium-cooled fast reactors, a computational fluid dynamics code SERAPHIM, in which a compressible multicomponent multiphase flow with sodium-water chemical reaction is computed, has been developed. The original SERAPHIM code is based on the difference method. In this study, unstructured mesh-based numerical method was developed to advance a numerical accuracy for the complex-shaped domain including multiple heat transfer tubes. Numerical analysis of an underexpanded jet experiment was performed as part of validation of the unstructured mesh-based numerical method. The calculated pressure profile and location of the Mach disk showed good agreement with the experimental data. Applicability of the numerical method for the actual situation was confirmed through the analysis of water vapor discharging into liquid sodium.
Uchibori, Akihiro; Watanabe, Akira*; Takata, Takashi; Ohshima, Hiroyuki
Journal of Nuclear Science and Technology, 54(10), p.1036 - 1045, 2017/10
Times Cited Count：5 Percentile：44.07(Nuclear Science & Technology)To evaluate a sodium-water reaction phenomenon in a steam generator of sodium-cooled fast reactors, a computational fluid dynamics code SERAPHIM, in which a compressible multicomponent multiphase flow with sodium-water chemical reaction is computed, has been developed. The original SERAPHIM code is based on the difference method. In this study, unstructured mesh-based numerical method was developed to advance a numerical accuracy for the complex-shaped domain including multiple heat transfer tubes. Numerical analysis of an underexpanded jet experiment was performed as part of validation of the unstructured mesh-based numerical method. The calculated pressure profile showed good agreement with the experimental data. Applicability of the numerical method for the actual situation was confirmed through the analysis of water vapor discharging into liquid sodium. The effect of use of the unstructured mesh was also investigated by the two analyses using structured and unstructured mesh.
Uchibori, Akihiro; Takata, Takashi; Ohshima, Hiroyuki; Watanabe, Akira*
Proceedings of 17th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-17) (USB Flash Drive), 12 Pages, 2017/09
To evaluate a sodium-water reaction phenomenon in a steam generator of sodium-cooled fast reactors, a computational fluid dynamics code SERAPHIM, in which a compressible multicomponent multiphase flow with sodium-water chemical reaction is computed, has been developed. The original SERAPHIM code is based on the difference method. In this study, unstructured mesh-based numerical method was developed to advance a numerical accuracy for the complex-shaped domain including multiple heat transfer tubes. Numerical analysis of an underexpanded jet experiment was performed as part of validation of the unstructured mesh-based numerical method. The calculated pressure profile and location of the Mach disk showed good agreement with the experimental data. Applicability of the numerical method for the actual situation was confirmed through the analysis of water vapor discharging into liquid sodium.
Ito, Kei; Kunugi, Tomoaki*; Ohno, Shuji; Kamide, Hideki; Ohshima, Hiroyuki
Journal of Computational Physics, 273, p.38 - 53, 2014/09
Times Cited Count：17 Percentile：70.94(Computer Science, Interdisciplinary Applications)Onishi, Ryoichi*; ; Takemiya, Hiroshi*; Guo, Z.*
Koku Uchu Gjutsu Kenkyujo Tokubetsu Shiryo, (41), p.47 - 52, 1999/02
no abstracts in English
; Onishi, Ryoichi*; *; Guo, Z.*
Parallel Computational Dynamics, p.267 - 274, 1999/00
no abstracts in English
; *
Physical Review E, 49(2), p.1251 - 1259, 1994/02
Times Cited Count：20 Percentile：66.67(Physics, Fluids & Plasmas)no abstracts in English
Murata, Hideo; *
Nihon Kikai Gakkai Rombunshu, B, 58(550), p.1912 - 1917, 1992/06
no abstracts in English
Iwasaki, Akihisa*; Sawa, Naoki*; Matsubara, Shinichiro*; Kitamura, Seiji; Okamura, Shigeki*
no journal, ,
A fast reactor core consists of several hundred core elements, which are hexagonal flexible beams embedded at the lower support plate in a hexagonal arrangement, separated by small gaps, and immersed in a fluid. Core elements have no support for vertical fixing in order to avoid the influence of thermal expansion and swelling. These days, in Japan, larger earthquake vibrations are postulated in seismic evaluations. So, it is necessary to consider vertical displacements (rising) and horizontal displacements of the core elements simultaneously because vertical seismic vibrations are larger than the acceleration of gravity. The 3D vibration behavior is affected by the fluid force of the ambient coolant and contact with the surrounding core elements. In this study, single-model vibration tests using a full-scale test model were conducted, and the basic characteristics of 3D vibration behavior of the core element were examined. In addition, structures restricting vertical displacements (dashpot structure) were devised, and their effectiveness was verified. As a result of the tests, the effects of the ambient condition (in air, in static water, and in flowing water), gap between the pads, vibration directions, vibration waves, and dashpot structures on the vibration behavior of the core element were examined. As regards the ambient condition, the vertical displacements were larger in flowing water that simulates the coolant flow than in air and in static water, because of upward fluid force in flowing water. As regards the gap between the pads, the larger the gaps was, the stronger the interferences due to horizontal displacements, and the smaller the vertical displacements were. The dashpot structure was verified to be suitable for reducing vertical displacements.
