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JAEA Reports

Flow separation at inlet causing transition and intermittency in circular pipe flow

Ogawa, Masuro*

JAEA-Technology 2019-010, 22 Pages, 2019/07

JAEA-Technology-2019-010.pdf:1.5MB

Transition phenomena from laminar to turbulent flow are roughly classified into three categories. Circular pipe flow of the third category is linearly stable against any small disturbance, despite that flow actually transitions and transitional flow exhibits intermittency. These are among major challenges that are yet to be resolved in fluid dynamics. Thus, author proposes hypothesis as follows; "Flow in a circular pipe transitions from laminar flow because of vortices released from separation bubble forming in vicinity of inlet of pipe, and transitional flow becomes intermittent because vortex-shedding is intermittent." Present hypothesis can easily explain why linear stability theory has not been able to predict transition in circular pipe flow, why circular pipe flow actually transitions, why transitional flow actually exhibits intermittency even due to small disturbance, and why numerical analysis has not been able to predict intermittency of transitional flow in circular pipe.

Journal Articles

Influence of inlet velocity condition on unsteady flow characteristics in piping with a short elbow under a high-Reynolds-number condition

Ono, Ayako; Tanaka, Masaaki; Kobayashi, Jun; Kamide, Hideki

Mechanical Engineering Journal (Internet), 4(1), p.16-00217_1 - 16-00217_15, 2017/02

In the design of the Advanced Sodium-cooled Fast Reactor in Japan, the Reynolds number in the primary hot leg (H/L) piping reaches 4.2$$times$$10$$^{7}$$. Furthermore, a short elbow is used in the H/L piping to achieve a compact plant layout. In the H/L piping, flow-induced vibration is a concern due to the excitation force caused by pressure fluctuation in the short elbow. In this report, the influence of inlet velocity condition on the unsteady velocity characteristics in the short elbow was studied by controlling the flow patterns at the elbow inlet. Measured velocity distributions indicated that the inlet velocity profiles affected a circumferential secondary flow, which then affected an area of flow separation at the elbow. It was also found that the velocity fluctuation at low frequency components observed upstream of the elbow could remain in downstream of the elbow though its intensity was attenuated.

Journal Articles

The Effect of profile of inlet velocity on the pressure fluctuation on the inside wall of short-elbow

Ono, Ayako; Tanaka, Masaaki; Kobayashi, Jun; Kamide, Hideki

Proceedings of 9th Korea-Japan Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-9) (CD-ROM), 7 Pages, 2014/11

Journal Articles

Research on PARC process for future reprocessing

Asakura, Toshihide; Hotoku, Shinobu; Ban, Yasutoshi; Matsumura, Masakazu*; Kim, S.-Y.; Mineo, Hideaki; Morita, Yasuji

Proceedings of International Conference ATALANTE 2004 Advances for Future Nuclear Fuel Cycles, 5 Pages, 2004/06

In JAERI, PARC process based on PUREX technique has been studied to as the basis of future reprocessing. The key of concept is to obtain the products, U and Pu, within only a single extraction cycle by separating Np and Tc from U and Pu before U/Pu partition. Two flow-sheet tests on the process were performed with 44 GWd/t PWR spent-fuel solutions. It was demonstrated that remaining Np in raffinate from co-extraction could be decreased to 13 % compared to the dissolver solution with increased solvent flow rate and with increased nitric acid concentration of FP scrubbing solution. It was demonstrated that Np separation (selective reduction by n-butyraldehyde) efficiency could be improved from 36 % to 78 % by flow-sheet modification; increasing reductant concentration and scrubbing solution flow rate. The feasibility of the Tc separation technique by high acid scrubbing was demonstrated.

Journal Articles

A Steady-state simulation model of gas separation system by hollow-filament type membrane module

Iwai, Yasunori; Yamanishi, Toshihiko; Nishi, Masataka

Journal of Nuclear Science and Technology, 36(1), p.95 - 104, 1999/01

 Times Cited Count:11 Percentile:65.07(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Numerical evaluation of interfacial area concentration using the immiscible lattice gas

Watanabe, Tadashi; Ebihara, Kenishi

Nucl. Eng. Des., 188(1), p.111 - 121, 1999/00

 Times Cited Count:6 Percentile:46.57(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Three-dimensional numerical analysis of mixed convective heat transfer in a horizontal square channel with heated and cooled side walls

*; Kunugi, Tomoaki; *

Nihon Kikai Gakkai Rombunshu, B, 61(586), p.2228 - 2234, 1995/06

no abstracts in English

Journal Articles

Numerical analysis of mixed convective heat transfer in a square channel uniform wall temperature

Kunugi, Tomoaki; *; *

Nihon Kikai Gakkai Rombunshu, B, 60(572), p.1393 - 1400, 1994/04

no abstracts in English

Journal Articles

Effects of three dimensional flow separation due to non-uniform heating on laminar mixed convection in a square channel

Kunugi, Tomoaki; *; *

Proc. of 10th Int. Heat Transfer Conf., 0, p.501 - 506, 1994/00

no abstracts in English

Journal Articles

Liquid and gas entrainment to a small break hole from a stratified two-phase region

Yonomoto, Taisuke; *

Int. J. Multiph. Flow, 17(6), p.745 - 765, 1991/00

 Times Cited Count:48 Percentile:88.09(Mechanics)

no abstracts in English

Journal Articles

On a potential flow theory for a bluff body in a parallel channel, Pt.2; Circular cylinder

Nihon Kikai Gakkai Rombunshu, B, 52(473), p.436 - 440, 1986/00

no abstracts in English

Journal Articles

On a potential flow theory for a bluff body in a parallel channel, Pt1; Normal flat plate

Nihon Kikai Gakkai Rombunshu, B, 52(473), p.431 - 435, 1986/00

no abstracts in English

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