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Journal Articles

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 (1.0$$times$$10$$^{6}$$). 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 = 1.0$$times$$10$$^{6}$$ 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.

Journal Articles

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

International Journal of Hydrogen Energy, 41(17), p.7139 - 7145, 2016/05

 Times Cited Count:4 Percentile:14.83(Chemistry, Physical)

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.

Journal Articles

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.

Journal Articles

Development of electromagnetic non-destructive testing method for the inspection of heat exchanger tubes of Japan Sodium-cooled Fast Reactor, 2; Detection of flaws on the inner surface using electromagnetic waves

Sasaki, Kota*; Yusa, Noritaka*; Wakai, Takashi; Hashizume, Hidetoshi*

Electromagnetic Nondestructive Evaluation (XVIII), p.244 - 251, 2015/06

 Times Cited Count:0 Percentile:0.05

Journal Articles

Influence of piping layout upon the characteristics of flow separation and pressure fluctuation in the primary cold-leg of sodium cooled fast reactor

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

Proceedings of 10th International Topical Meeting on Nuclear Thermal Hydraulics, Operation and Safety (NUTHOS-10) (USB Flash Drive), 12 Pages, 2014/12

In this study, the influence of the inflow condition upon the flow separation and pressure fluctuation characteristic was evaluated by using a 1/7-scale mockup of the cold-leg piping of Japan Sodium-cooled Fast Reactor. The inflow condition to the 3rd elbow was changed from previous studies by varying the distance between the 2nd and 3rd elbows from 6.4D to 9.4D, where D is the pipe diameter. The visualization experiment showed that the flow separation appeared in the intrados of the 3rd elbow as was the case with 6.4D and separated regions became larger than that in the case of 6.4D. This is because a swirling flow observed at the inlet of the 3rd elbow became weaker than that of the case of 6.4D. The frequency analysis of pressure fluctuations showed that gentle but apparent peaks in the power spectral density (PSD) distributions of pressure fluctuations were observed at about 0.4 of the Strouhal number around the separated regions, and this peak value was half of that in the case of 6.4D. In addition, prominent peaks in the PSD distributions were observed at about 0.6 of the Strouhal number in the downstream of the reattachment point in the intrados. The peak value was approximately 3 times larger than that in the case of 6.4D. The results revealed the weakened swirling flow made the separated region larger in the downstream and the pressure fluctuation magnitude stronger.

Journal Articles

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 (1.0$$times$$10$$^{6}$$). 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.

Journal Articles

Numerical study of the MHD flow characteristics in a three-surface-multi-layered channel with different inlet conditions

Aoyagi, Mitsuhiro; Ito, Satoshi*; Hashizume, Hidetoshi*

Fusion Engineering and Design, 89(7-8), p.1227 - 1231, 2014/10

 Times Cited Count:1 Percentile:10.7(Nuclear Science & Technology)

A 3D MHD flow simulation was conducted to clarify the effects of the inlet flow condition on the result of the validation experiment carried out previously and on the design window of the first wall using a three-surface-multi-layered channel. MHD pressure drop was influenced by the inlet condition largely. The numerical model with turbulent velocity profile showed qualitatively good agreement with the experimental result. The first wall temperature distribution obtained by the 3D simulation corresponded well the one by the 2D simulation assuming fully developed flow. This meant complicated three-dimensional inlet flow condition generated in the L-shape elbow would not affects the existing design window.

JAEA Reports

Basic study on flow separation phenomenon in cooling system piping in fast reactors; Clarification of complex flow structure in a multi-elbow in a high Reynolds number regime (Joint research report in JFY2008 and JFY2009)

Ebara, Shinji*; Yuki, Kazuhisa*; Hashizume, Hidetoshi*; Aizawa, Kosuke; Yamano, Hidemasa

JAEA-Research 2013-011, 72 Pages, 2013/10

JAEA-Research-2013-011.pdf:11.34MB

In Tohoku University, different scale model experiments were carried out in order to clarify unsteady flow fields and pressure fluctuation characteristics in the cold leg piping by means of visualization experiment and pressure measurement, respectively, and to investigate the scale effect. In JFY2008, the visualization experiment by PIV measurement for the 1/15 scale piping was carried out using a double elbow geometry. Besides, shakedown tests of the 1/7 scale model were conducted for the case of a single elbow. In JFY2009, visualization experiments for the 1/7 scale models with the single and a three-dimensionally connected double elbow geometries were carried out. From these obtained data, effects of the multiple elbows on the flow field were assessed. In addition, the pressure measurements for single elbow flows by using 1/15 and 1/7 scale models were performed. In JAEA, numerical analyses for the 1/7 scale double elbow experiments were performed using the commercial thermal-hydraulics code STAR-CD. The analyses showed that the calculated velocity distributions were in good agreement with the visualization experimental results. It was confirmed, from these analyses, that the URANS analysis method validated for the single elbow flow has applicability to the double elbow flow.

Journal Articles

Enhancement of microwave nondestructive testing method for the inspection of pipes by optimizing the microwave probe profile

Sasaki, Kota*; Yusa, Noritaka*; Wakai, Takashi; Hashizume, Hidetoshi*

Hozengaku, 12(1), p.81 - 86, 2013/04

This study reports the development of a new microwave probe for the nondestructive testing of a pipe. Three-dimensional finite element simulations are carried out to optimize the profile of a microwave probe, whose results show that a probe with elliptic profile enables smaller reflection at the probes as well as much better single-mode propagation inside the pipe than conventional ones. Experimental validations are carried out using a straight brass pipe with an inner diameter of 39 mm and a total length of 2 m. The results of the experiments clearly demonstrate that the new microwave probe provides clearer signals due to simulated rectangular wall thinning.

Journal Articles

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.

Journal Articles

Development on microwave nondestructive testing of a wall thinning inside a pipe by optimizing microwave probe and analyzing wall thinning profile

Sasaki, Kota*; Liu, L.*; Yusa, Noritaka*; Wakai, Takashi; Hashizume, Hidetoshi*

Proceedings of 1st International Conference on Maintenance Science and Technology for Nuclear Power Plants (ICMST-Tokyo 2012) (CD-ROM), 2 Pages, 2012/11

Journal Articles

Flow visualization and frequency characteristics of velocity fluctuations of complex turbulent flow in a short elbow piping under high Reynolds number condition

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

Journal of Fluids Engineering, 134(10), p.101201_1 - 101201_8, 2012/10

 Times Cited Count:24 Percentile:75.55(Engineering, Mechanical)

By means of 2D PIV (2-dimensional Particle Image Velocimetry), flow visualization experiments are carried out for a single short elbow piping which is a 1/7-scale model of the cold-leg piping of Japan Sodium-cooled Fast Reactor in order to investigate the minute flow field related especially to flow separation appearing in the intrados side of the elbow and frequency characteristics of the flow velocity fluctuation for various Reynolds number flow. A periodic motion with St of 0.5 appeared near the separation region if the Reynolds number changes.

Journal Articles

Flow structure of high Reynolds number flow in a dual-elbow piping simulating cold-legs of JSFR

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

Proceedings of 15th International Symposium on Flow Visualization (ISFV-15) (CD-ROM), 10 Pages, 2012/06

Flow visualization experiment with 2D-PIV in a dual elbow system simulating the cold-leg piping of the JSFR was performed varying Reynolds number from 0.3$$times$$10$$^{6}$$ to 1.0$$times$$10$$^{6}$$. The tested piping has two short elbows which are three-dimensionally connected with a straight pipe. In the dual elbow system, separation vortices are shed from the separated region like a single elbow one. These vortices flow by the inrados of the second elbow and its lower stream. The post-critical regime of the dual elbow flow appears when Reynolds number is larger than about 0.5$$times$$10$$^{6}$$, as with the single elbow system.

Journal Articles

Matched refractive-index PIV visualization of complex flow structure in a three-dimentionally connected dual elbow

Yuki, Kazuhisa*; Hasegawa, Shunsuke*; Sato, Tsukasa*; Hashizume, Hidetoshi*; Aizawa, Kosuke; Yamano, Hidemasa

Nuclear Engineering and Design, 241(11), p.4544 - 4550, 2011/11

 Times Cited Count:23 Percentile:88.07(Nuclear Science & Technology)

Journal Articles

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

Journal Articles

PIV measurements of a complex turbulent flow in a short elbow piping under a high Reynolds number condition

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

Proceedings of 9th International Symposium on Particle Image Velocimetry (PIV '11) (USB Flash Drive), 6 Pages, 2011/07

Journal Articles

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

 Times Cited Count:8 Percentile:45.74(Engineering, Mechanical)

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.

Journal Articles

Pressure measurement test of single elbow simulating Na cooled fast reactor cold-leg piping

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

Proceedings of 18th International Conference on Nuclear Engineering (ICONE-18) (CD-ROM), 9 Pages, 2010/05

In this study, pressure measurement test is conducted to find out the FIV characteristic features related to the elbow turbulent flow, using 1/7 scale experimental loop simulating the JSFR cold leg piping. As the first step of multielbow piping, pressure measurement for single elbow was performed. The same measurement procedure was taken as a 1/15 scale experiment to assess the influence originated from the different scale flow at the same Reynolds number.

Journal Articles

Unsteady hydraulic characteristics in large-diameter pipings with elbow for JSFR, 3; Flow structure in a 3-dimentionally connected dual elbow simulating cold-leg piping in JSFR

Yuki, Kazuhisa*; Hasegawa, Shunsuke*; Sato, Tsukasa*; Hashizume, Hidetoshi*; Aizawa, Kosuke; Yamano, Hidemasa

Proceedings of 13th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-13) (CD-ROM), 11 Pages, 2009/09

In this study, the flow structures in a 3-dimentionally connected dual elbow, which simulates a part of the cold leg, are visualized by PIV measurement, and it is discussed on the detailed flow transition from the 1st elbow to the 2nd elbow and the generation of unsteady flow such as a separation that influences flow-induced vibration. Experimental apparatus has a 1/15 scale test section of actual design whose inner diameter and curvature radius ratio are 56mm and 1.0, respectively. For visualization without any image distortion, matched refractive-index PIV measurement is carried out using NaI solution as the working fluid. The Reynolds number is 50,000, and the inlet flow condition to the test section is a fully developed turbulent flow. It is confirmed that it generates a separation along the inner wall of the 1st elbow and one large swirling flow in the 2nd elbow. Furthermore, unsteady flow formed in and/or behind the separation region is transported downstream and flows into the center area of the 2nd elbow.

JAEA Reports

Basic study on flow separation phenomenon in cooling system piping in fast reactors; Clarification of complex flow structure in a multi-elbow in a high Reynolds number regime (Joint research report in FY2007)

Yuki, Kazuhisa*; Hashizume, Hidetoshi*; Nakanishi, Shigeyuki*; Aizawa, Kosuke; Yamano, Hidemasa

JAEA-Research 2009-017, 55 Pages, 2009/08

JAEA-Research-2009-017.pdf:16.5MB

At Tohoku University, 1/15 scale and 1/7 scale flow tests are being performed in order to clarify an unsteady flow structure in the cold leg piping and to investigate the scale effect. In FY2007, the 1/15 scale test was carried out using a double elbow geometry. It was confirmed that there existed a separation along the inner wall of the 1st elbow and a large swirling flow in the 2nd elbow. Furthermore, the unsteady flow formed in and/or behind the separation region was transported downstream and flows into the center area of the 2nd elbow. At JAEA, a numerical analytical evaluation method is being developed to evaluate the feasibility of the reactor design. In FY2007, numerical analyses for the 1/15 scale test were performed using the commercial thermal-hydraulics code FLUENT. The analyses showed that the trend of calculated velocity distributions was in good agreement with the visualization test results.

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