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JAEA Reports

Study on thermalhydraulics of thermal striping phenomena; Evaluation of transfer characteristics of temperature fluctuation based on conjugated numerical simulation in triple-parallel jet geometry

Kimura, Nobuyuki; Kamide, Hideki; Nagasawa, Kazuyoshi*; Emonot, P.*

JAEA-Research 2012-017, 97 Pages, 2012/07

JAEA-Research-2012-017.pdf:12.12MB

A quantitative evaluation on thermal striping is of importance for reactor safety. In this study, sodium and water experiments of parallel triple jets configuration were performed. For these experiments, numerical simulations were carried out to evaluate the transfer characteristics of temperature fluctuation from fluid to structure. The analysis code, called Trio-U, used in the study has been developed at the CEA in France. In the simulations, the calculated time-averaged temperature distributions in fluid and structure were close to the experimental results in sodium and water. The power spectrum densities of temperature fluctuation in fluid and structure were also in good agreements between the experiments and calculations. Furthermore the calculated decay characteristics of temperature fluctuation from fluid to structure were in good agreements with the experimental results.

Journal Articles

Large Eddy Simulation of highly-fluctuational temperature and velocity fields observed in a mixing-tee experiment

Coste, P.*; Quemere, P.*; Roubin, P.*; Emonot, P.*; Tanaka, Masaaki; Kamide, Hideki

Nuclear Technology, 164(1), p.76 - 88, 2008/10

 Times Cited Count:11 Percentile:36.2(Nuclear Science & Technology)

The WATLON experiment, a water facility about fluid mixing in a T-pipe, is calculated with a finite element volume method and a Large Eddy Simulation (LES) approach, with TRIO-U code. Its unstructured tetrahedron grids do not lead to the same noteworthy disagreements previously mentioned with Cartesian grids. Branch and main pipe inlet velocity fluctuations due to turbulence are simulated with the use of "periodic boxes". These more realistic inlet fluctuations allow physical instabilities to develop, improving the predictions. When an elbow is added upstream of the injection, the influence of the secondary flow on temperature averaged values and fluctuations is underlined.

Journal Articles

Study on thermal striping phenomena in triple-parallel jet; Transfer characteristics of temperature fluctuation in sodium and water based on conjugated numerical simulation

Kimura, Nobuyuki; Kamide, Hideki; Emonot, P.*; Nagasawa, Kazuyoshi*

Proceedings of 7th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, Operation and Safety (NUTHOS-7) (CD-ROM), 17 Pages, 2008/10

A quantitative evaluation on thermal striping, in which temperature fluctuation due to convective mixing between hot and cold fluids causes thermal fatigue in structural components, is of importance for reactor safety. It is necessary for the quantitative evaluation to investigate occurrence and propagate processes of temperature fluctuation, e.g., decay of temperature fluctuation near structures and transfer of temperature fluctuation from fluid to structures. In Japan Atomic Energy Agency, an innovative sodium cooled fast reactor has been designed. The transfer characteristics of temperature fluctuation from fluid to structure in sodium are quite different from that in water. In order to realize the sodium cooled fast reactor, the clarification of the transfer characteristics of temperature fluctuation is of importance for the rational design against the thermal striping phenomena. In this study, sodium and water experiments of parallel triple jets configuration were performed. For these experiments, numerical simulations were carried out to evaluate the transfer characteristics of temperature fluctuation from fluid to structure. The analysis code, called Trio_U, used in the study has been developed at the CEA in France. The large eddy simulation model is incorporated in the code. Furthermore, the code can calculate fluid and structural domains simultaneously. In the simulations, the calculated time-averaged temperature distributions in fluid and structure were close to the experimental results in sodium and water. The power spectrum densities of temperature fluctuation in fluid and structure were also in good agreements between the experiments and calculations. Furthermore the calculated decay characteristics of temperature fluctuation from fluid to structure were in good agreements with the experimental results.

Journal Articles

Study on thermal striping phenomena in triple-parallel jet; Investigation on non-stationary heat transfer characteristics based on numerical simulation

Kimura, Nobuyuki; Kamide, Hideki; Emonot, P.*; Nagasawa, Kazuyoshi*

Proceedings of 12th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-12) (CD-ROM), 14 Pages, 2007/09

A quantitative evaluation on thermal striping, in which temperature fluctuation due to convective mixing between hot and cold fluids causes thermal fatigue in structural components, is of importance for reactor safety. In this study, a water experiment of parallel triple jets configuration was performed in order to evaluate temperature fluctuation characteristics in fluid, transfer characteristics of temperature fluctuation from fluid to structure. The power spectrum densities of temperature fluctuation, furthermore, were in good agreements between the experiment and calculation. The calculated results showed that the heat transfer coefficient obtained from the experiment was appropriate and proper. The decay due to the heat transfer at the wall surface was dominant for the decay of temperature fluctuation at the neighborhood of the wall.

Journal Articles

Large eddy simulation of a mixing-T experiment

Coste, P.*; Quemere, P.*; Roubin, P.*; Emonot, P.*; Tanaka, Masaaki; Kamide, Hideki

Proceedings of 2006 International Congress on Advances in Nuclear Power Plants (ICAPP '06) (CD-ROM), p.1626 - 1635, 2006/06

The WATLON experiment, a water facility about fluid mixing in a T-pipe, is calculated with a finite element volume method and a Large Eddy Simulation (LES) approach, with TRIO-U code. Its unstructured tetrahedron grids do not lead to the same noteworthy disagreements previously mentioned with Cartesian grids. Branch and main pipe inlet velocity fluctuations due to turbulence are simulated with the use of "periodic boxes". These more realistic inlet fluctuations allow physical instabilities to develop, improving the predictions. When an elbow is added upstream of the injection, the influence of the secondary flow on temperature averaged values and fluctuations is underlined.

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