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Journal Articles

Study on mixing behavior in a tee piping and numerical analyses for evaluation of thermal striping

Kamide, Hideki; Igarashi, Minoru*; Kawashima, Shigeyo*; Kimura, Nobuyuki; Hayashi, Kenji

Nuclear Engineering and Design, 239(1), p.58 - 67, 2009/01

 Times Cited Count:124 Percentile:99.41(Nuclear Science & Technology)

Water experiments were carried out for thermal hydraulic aspects of thermal striping in a mixing tee, which has main to branch diameter ratio of 3. Detailed temperature and velocity fields were measured by a movable thermocouple tree and particle image velocimetry. Flow patterns in the tee were classified into three groups, which had own temperature fluctuation profiles. The power spectrum density (PSD) of temperature fluctuation showed an unique profile, which is normalized by St number, when the flow velocity ratio and flow pattern was identical. Numerical simulation based on finite difference method showed alternative vortex development behind the jet from the branch pipe in a case of wall jet. Mixing behavior in the tee was discussed based on the measured data and the simulation.

JAEA Reports

Study on Mixing Phenomena in T-Pipe Junction; Temperature Measurement Test in Pipe by Liquid Crystal Sheet

Tanaka, Masaaki; Kawashima, Shigeyo*; Igarashi, Minoru; Hayashi, Kenji; Tobita, Akira; Kamide, Hideki

JNC TN9400 2003-117, 65 Pages, 2004/03

JNC-TN9400-2003-117.pdf:3.49MB

Temperature fluctuation due to mixing of hot and cold fluids gives thermal fatigue to the structure (thermal striping phenomena).Investigation of this phenomenon is significant for the safety of a fast breeder reactor, which uses liquid metal as a coolant. In Japan Nuclear Cycle Development Institute, experiments and numerical analyses have been carried out to understand this phenomenon and also to construct the evaluation rule, which can be applied to the design. A water experiment of fluid mixing in T-pipe with long cycle fluctuation (WATLON),which notices thermal striping phenomena in the T-pipe junction, is performed to investigate the key factor of mixing phenomena by reason of long cycle fluctuation observed in a plant. By the former visualization test, it was showed that the flow pattern of branch pipe jet could be classified into (A) impinging jet, (B) deflecting jet (C) re-attachment jet and (D) wall jet according to the inflow condition. It was confirmed that the each jet pattern could be predicted by the momentum ratio of the each piping fluid. In this study, a thermo-chromic liquid crystal sheet was put on the inner wall in the main pipe, and temperature field on the wall surface was visualized. We established a new method to convert the color image data to temperature data. And measurement uncertainty of this method was evaluated + and - about 2.0 [deg-C], using by the typical picture in the temperature calibration test. From the temperature fluctuation visualization test by liquid crystal sheet, the cold spot was formed in just downstream region from the outlet of the branch pipe in the cases of the wall jet and impinging jet. Since this cold spot moved in time, high value of temperature fluctuation intensity was shown around the cold spot. And the validity of this method was shown from the comparison of the thermocouple data installed in a wall surface with the temperature conversion result.

JAEA Reports

Study on Mixing Phenomena in T-pipe Junction; Clarification of fluid mixing phenomena and temperature fluctuation transfer from fluid to structure

Igarashi, Minoru; Tanaka, Masaaki; Kimura, Nobuyuki; Nakane, Shigeru*; Kawashima, Shigeyo*; Hayashi, Kenji; Tobita, Akira; Kamide, Hideki

JNC TN9400 2003-092, 100 Pages, 2003/11

JNC-TN9400-2003-092.pdf:5.1MB

A water experiment for thermal hydraulics in a mixing tee was performed to investigate thermal striping phenomena. Measurement of flow velocity using particle image velocimetry and temperature measurement were carried out. Normalized power spectrum density of temperature fluctuation had same profile, when the momentum ratio of the main and branch pips is the same. From the velocity measurement test, when the momentum ratio is the same, flow pattern at mixing region shows the alomost same tendency. Temperature transfer characteristics from fluid to structure can be estimated by a constant heat transfer coefficient in time.

JAEA Reports

Study on mixing phenomena in T-pipe junction; Experimental analysis using DNS and investigation of mixing process

Igarashi, Minoru; Kawashima, Shigeyo*; Nakane, Shigeru*; Tanaka, Masaaki; Kimura, Nobuyuki; Kamide, Hideki

JNC TN9400 2003-005, 80 Pages, 2003/02

JNC-TN9400-2003-005.pdf:3.68MB

In the place where hot and cold fluids are mixed, a time and spatial temperature fluctuation occurs. When this temperature fluctuation amplitude is large, it causes high cycle thermal fatigue in surrounding structure (thermal striping phenomena). Mixing area of high and low temperature fluid exists not only in an atomic power plant but also in a general plant, then, it is significant to investigate this phenomena and also to establish an evaluation rule. In Japan Nuclear Cycle Development Institute, several experiments and the improvement of the analysis methods have been carried out to understand thermal striping phenomena and also to construct an evaluation rule, which can be applied to design. Water Experiment on Fluid Mixing in T-pipe with Long Cycle Fluctuation (WATLON), aiming at examining thermal striping phenomena in a mixing tee, is performed to investigate key factors of mixing phenomena. In this study, in order to investigate the fluid mixing phenomena, temperature and flow velocity distribution were measured by movable thermocouple tree and particle image velocimetory (PIV). And the analysis using a in-house direct numerical simulation (DNS) code, DINUS-3 was performed to understand applicability of the analytical method in mixing tee. The temperature and velocity fields obtained from the DINUS-3 were in good agreement with the experimental results. And the prominent frequency of temperature fluctuation was also in good agreement. The DINUS-3 calculation simulated vortex structure in the wake region behind the branch pipe jet. The results of analysis showed that a Karman vortex generated in the wake region behind the branch pipe jet influenced the temperature fluctuation behavior in the mixing tee. And the analytical results revealed that the vortex generated in the wake region behind the branch pipe jet showed the 3-dimensional behavior.

JAEA Reports

Study for subassembly porous blockage in fast breeder reactors; Pre-subchannel analysis of 37-pin bundle sodium test

Iitsuka, Toru; Oki, Yoshihisa; Kawashima, Shigeyo*; Nishimura, Motohiko; Isozaki, Tadashi; Kamide, Hideki

PNC TN9410 98-022, 58 Pages, 1998/03

PNC-TN9410-98-022.pdf:1.72MB

Assessment of the maximum temperature and the position of the hot spot is the most important issues on the reactor safety when the local subchannel porous blockage is occurred. From these background, authors are going to perform a sodium experiment with 37-pin bundle test rig simulating the porous blockage, to understand the phenomena and acquire data for thermal-hydraulic analysis code validation. Before the execution of sodium test, one basic experiment and some using subchannel analysis code ASFRE-III had been done. The basic experiment was a water test to examine the pressure loss characteristics of the porous blockage. The pressure loss correlation derived from the water test was applied to the subsequent subchannel analysis of the 37-pin bundle sodium test rig. The analysis such predicted that the difference between the maximum temperature and the inlet temperature would be in propotion to the power to flow rate ratio, within the condition of the power=100$$sim$$400 W/cm and the flow rate =200$$sim$$480 $$ell$$/min. And it was also shown that the maximum subchannel temperature would not over the operational limit temperature 650 $$^{circ}$$C, if the power to flow rate ratio were kept lower than 0.75(W/cm)/$$ell$$/min). The map was made to predict the maximum temperature from the experimental conditions.

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