U-RANS simulation of triple elbow flow with a 1/7 scale experimental loop simulating cold-leg piping of an advanced loop-type sodium-cooled fast reactor

Yamano, Hidemasa; Tanaka, Masaaki; Ebara, Shinji*; Hashizume, Hidetoshi*

Proceedings of 27th International Symposium on Transport Phenomena (ISTP-27) (USB Flash Drive), 8 Pages, 2016/09

In this study, Unsteady Reynolds Averaged Navier-Stokes equation (U-RANS) approach with the Reynolds Stress Model using commercial CFD code has been applied to the flow through triple short-elbows under a high Re (1.010). This numerical simulation has utilized a 1/7 scaled water experiment of the advanced SFR cold-leg piping in order to investigate the flow structure in a three-dimensionally connected triple elbows. As a result, applicability of the U-RANS numerical simulation method was confirmed by comparison between the numerical and experimental results under Re = 1.010 condition. The simulation has also shown that flow fields in the 1st elbow was different from that in the 2nd elbow and pressure fluctuation in the 2nd elbow was slightly larger than that in the 1st elbow because of the presence of their large vortex flow structure. This large vortex was generated due to a short distance between two elbows. On the other hand, the flow structure in the 3rd elbow was similar to that in the 1st elbow because the swirling flow formed in the 2nd elbow was alleviated in the 3rd elbow inlet which was located long way away from the 2nd elbow.

Characteristics of flow field and pressure fluctuation in complex turbulent flow in the third elbow of a triple elbow piping with small curvature radius in three-dimensional layout

Ebara, Shinji*; Takamura, Hiroyuki*; Hashizume, Hidetoshi*; Yamano, Hidemasa

Proceedings of 17th International Conference on Emerging Nuclear Energy Systems (ICENES 2015) (CD-ROM), 6 Pages, 2015/10

In this study, a flow visualization and pressure measurement were conducted by using an experimental setup including test sections of 1/7-scale models of the cold-leg piping of Japan sodium-cooled reactor with high Reynolds number region up to about one million. Regarding the flow field, flow separation appeared in the intrados of the third elbow. However, the separation region was smaller than that observed in the first elbow in the direction normal to the mean flow and was larger in the streamwise direction. This can be considered because of the swirling flow generated downstream of the second elbow which flowed into the third elbow with a little reduction. From the pressure fluctuation test, it was found that prominent frequencies of the pressure fluctuation appeared at about 0.4 in Strouhal number, which corresponds to a nondimensional frequency, in the region from 0 D to 0.4 D downstream of the elbow outlet, where D is the diameter of the piping. And weak peaks of about 0.7 in Strouhal number were observed in the region far 0.75 D downstream of the outlet.

U-RANS simulation of elbow flow with a 1/7 scale experimental loop simulating JSFR cold-leg piping

Yamano, Hidemasa; Kaneko, Tetsuya*; Aizawa, Kosuke; Tanaka, Masaaki; Ebara, Shinji*; Hashizume, Hidetoshi*

Proceedings of 9th Korea-Japan Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-9) (CD-ROM), 10 Pages, 2014/11

In this study, Unsteady Reynolds Averaged Navier-Stokes equations (U-RANS) approach with the Reynolds Stress Model using a commercial computational fluid dynamics code has been applied to the flow through single and double short-elbows under a high Reynolds number condition (1.010). This numerical simulation has utilized a 1/7 scaled water experiment simulating the JSFR cold-leg piping in order to investigate the flow pattern in a three-dimensionally connected double elbow. As a result, validity and applicability of the U-RANS numerical simulation method were confirmed by comparison between the numerical and experimental results. The simulation has also shown that unsteady flow fields including vortex structures in the 1st elbow were very different from that in the 2nd elbow. This is because horseshoe vortexes generated in the 1st elbow downstream enter sideways the 2nd elbow. In addition, the simulation has indicated that the influence of distance between two elbows in the double elbow flow addressed in this paper was small.

Rehearsal and actual measurement of Fugen spent fuel assemblies by integrated PNAR and SINRD under the JAEA-USDOE collaboration program

Hayashi, Kenta; Nakamura, Takahisa; Takagi, Hisatsugu; Horie, Kaoru; Nakayama, Tamotsu; Hashimoto, Kazuhiko; Hayashi, Shoichi; Nakamura, Shinji; Takenaka, Shigeki; Ishizuka, Nobuo; et al.

Proceedings of INMM 54th Annual Meeting (CD-ROM), 10 Pages, 2013/07

JAEA and USDOE (Los Alamos National Laboratory (LANL)) have been collaborating on spent fuel measurements with a PNAR/SINRD NDA instrument at Fugen, in the course of the NGSI Spent Fuel Nondestructive Assay Project. In this collaboration, LANL's role has been to design and fabricate the detector (integrated PNAR and SINRD system), while JAEA's role has been to undertake the installation of the detector at the appropriate position in the spent fuel pool and to prepare for the actual measurements. In this paper we report the rehearsal of the measurement using a mock-up detector and a dummy fuel assembly in December 2012 and the plan of actual measurements in June 2013 (at the time of submission of this paper).

Effects of separation vortices on pressure fluctuation of complex turbulent flow in a dual elbow with small curvature radius in a three-dimensional layout

Ebara, Shinji*; Konno, Hiroaki*; Hashizume, Hidetoshi*; Kaneko, Tetsuya; Yamano, Hidemasa

Proceedings of 8th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-8) (USB Flash Drive), 8 Pages, 2012/12

In this study, the characteristics of pressure fluctuation in a dual elbow piping simulating the cold-leg piping of the JSFR was elucidated by conducting a pressure measurement test using a scale model. As a result of the experiment, it was clarified that the pressure fluctuation characteristics of the dual elbow flow was very similar to that of the single elbow flow in and near the first elbow.

Prediction of unsteady flow field in a primary circuit hot-leg piping of a sodium-cooled fast reactor

Tanaka, Masaaki; Sago, Hiromi*; Iwamoto, Yukiharu*; Ebara, Shinji*; Ono, Ayako; Murakami, Takahiro*; Hayakawa, Satoshi*

Nihon Kikai Gakkai Rombunshu, B, 78(792), p.1392 - 1396, 2012/08

https://doi.org/10.1299/kikaib.78.1392

A study on flow induced vibration in the primary cooling system of Japan Sodium cooled Fast Reactor (JSFR) consisting of large diameter pipe and pipe elbow with short curvature radius ("short-elbow") has been conducted. Flow-induced vibration in the short-elbow is an important issue in design study of JSFR, because it may affect to structural integrity of the pipe. In this paper, unsteady flow characteristics in the JSFR short-elbow pipe related to the large-scale eddy motion were estimated based on knowledge from existing studies for curved pipes and scaled water experiments and numerical simulations for the JSFR hot-leg piping.

Pressure fluctuation characteristics of complex turbulent flow in a dual elbow with small curvature radius in a three-dimensional layout

Konno, Hiroaki*; Ebara, Shinji*; Hashizume, Hidetoshi*; Yamano, Hidemasa; Aizawa, Kosuke

Proceedings of 8th International Conference on Flow Dynamics (ICFD 2011) (USB Flash Drive), p.94 - 95, 2011/11

Pressure fluctuation characteristics of complex turbulent flow in a single elbow with small curvature radius for a sodium-cooled fast reactor

Ebara, Shinji*; Aoya, Yuta*; Sato, Tsukasa*; Hashizume, Hidetoshi*; Yuki, Kazuhisa*; Aizawa, Kosuke; Yamano, Hidemasa

Journal of Fluids Engineering, 132(11), p.111102_1 - 111102_7, 2010/11

https://doi.org/10.1115/1.4002813

A multi-elbow piping system is adopted for the Japan Sodium-cooled Fast Reactor (JSFR) cold-legs. Flow Induced Vibration (FIV) is considered to appear due to complex turbulent flow with very high Reynolds number in the piping. In this study, pressure measurement for a single elbow flow is conducted to elucidate pressure fluctuation characteristics originated from turbulent motion in the elbow, which lead potentially to the FIV. Two different scale models, 1/7 and 1/14-scale simulating the JSFR cold-leg piping, are tested experimentally to confirm whether a scale effect in pressure fluctuation characteristics exists. A distinguishing peak can be seen in each power spectrum density (PSD) profile of pressure fluctuation obtained in and downstream of the flow separation region for both scaled models. When nondimensionalized, the PSD profiles show good correspondence regardless of scale model and even of Reynolds number simulated in this study.

Flow structure investigation of triple elbow piping with swirling inlet conditions

Ebara, Shinji*; Mizutani, Jun*; Hashizume, Hidetoshi*; Yamano, Hidemasa

no journal, , 

In this study, the flow fields with the swirling flows as the inlet condition were analysed mainly in terms of fluctuating velocity fields. Experimental results just downstream of the first elbow revealed that the inlet swirling flow blocked the forming of Dean vortices and steady flow separation in the intrados of the elbow. This led dissipation of the prominent vortices structure in the flow fields, which is seen in those with a fully-developed turbulence as the inlet condition. However, intermittent flow separations appear and these cause the vortices structures with weak periodicity. From experimental results about the second and the third elbows, it was found that more than one periodic motion can be seen in the circumferential direction. This can be interpreted as the interaction between the swirling flow originated from the inlet condition and the intrinsic flow generated in the elbow piping.

Study on inhibition of pressure fluctuation induced by separation vortex shedding in primary cold-leg piping of sodium cooled fast reactor

Mizutani, Jun*; Takamura, Hiroyuki*; Ebara, Shinji*; Hashizume, Hidetoshi*; Yamano, Hidemasa

no journal, , 

In cold leg piping of primary cooling system of Japan Sodium-cooled Fast Reactor (JSFR), high Reynolds (Re) number and three dimensional arrangement of 3 elbow structure forms complex turbulent flow field, and pressure fluctuation induced by separation vortex release is postulated. inhibition of the separation is considered to lower the pressure fluctuation and changing inflow condition indicated possibility of inhibiting pressure fluctuation. In this study, 1/7 scale flow testing device simulating JSFR primary cold-leg piping was used to study conditions to reduce separation.