CFD analysis on mixing effects of spacer grids with different dimples and sizes for advanced fuel assemblies
-
B. W. Yang
Abstract
The thermal hydraulic characteristics of a mixing vane grid are largely dependent on the structure of key components, such as strip, spring, dimple, weld nugget, as well as the mixing vane configuration. In this paper, several types of spacer grids with different dimple shapes are modeled under subcooled boiling conditions. Prior to the application of CFD on the dimple shape analysis, the mixing effects of spacer grids were studied. After the dimple shape analysis, the side channel effect is discussed by comparing the simulation results of a 3 × 3 and a 5 × 5 spacer grid. The two phase flow CFD models in this study are validated through simple geometry showing that the calculated void fraction is in good agreement with the experimental data. The dimple comparison result shows that varying dimple structures can result in different temperatures, lateral velocities and void fraction distributions downstream of the spacer grids. Comparison of two sizes of spacer grids demonstrate that the side channel generates different flow distribution pattern in the center channel.
Kurzfassung
Die thermohydraulischen Kenngrößen eines Mischfahnengitters hängen stark von der Geometrie der Hauptkomponenten (wie Streifen, Feder, Noppen, Schweißlinsen) und von der Anordnung ab. In diesem Beitrag werden für verschiedene Noppenausführungen Rechnungen bei unterkühlten Siedebedingungen vorgestellt. Basierend auf einer Untersuchung von Mischungsverhalten bei Abstandshaltern wurden CFD-Rechnungen zum Einfluss der Geometrie der Noppen durchgeführt. Anschließend wurde der Seitenkanaleinfluss für 3 × 3- und 5 × 5-Abstandshaltergitter untersucht. Validiert wurden die Rechnungen an experimentellen Daten an einfachen Geometrien. Dabei zeigte sich eine gute Übereinstimmung bei den berechneten Dampfgehalten. Insgesamt beeinflussen unterschiedliche Noppengeometrien sowohl die Temperaturen als auch die Geschwindigkeiten und Dampfgehaltsverteilungen im Bereich nach der Durchströmung des Abstandshaltergitters. Des Weiteren wurde gezeigt, dass Seitenkanäle unterschiedliche Strömungsformen im Zentralkanal erzeugen.
References
1 Liu, C. C.; Ferng, Y. M.: Numerically simulating the thermal–hydraulic characteristics within the fuel rod bundle using CFD methodology. Nuclear Engineering and Design240 (2010) 3078–308610.1016/j.nucengdes.2010.05.021Search in Google Scholar
2 Connera, M. E.; Bagliettob, E.; Elmahdia, A. M.: CFD methodology and validation for single-phase flow in PWR fuel assemblies. Nuclear Engineering and Design240 (2010) 2088–209510.1016/j.nucengdes.2009.11.031Search in Google Scholar
3 Navarro, M. A.; Santos, A. A. C.: Evaluation of a numeric procedure for flow simulation of a 5 × 5 PWR rod bundle with a mixing vane spacer. Progress in Nuclear Energy53 (2011) 1190–119610.1016/j.pnucene.2011.08.002Search in Google Scholar
4 Karoutas, Z.; Gu, C.; Sholin, B.: 3-D flow analyses for design of nuclear fuel spacer. In: Proceedings of the 7th International Meeting on Nuclear Reactor Thermal-hydraulics NURETH-7, New York, USA, pp. 3153–3174 (1995)Search in Google Scholar
5 Anglart, H.; Nylund, O.: CFD application to prediction of void distribution in two-phase bubbly flows in rod bundles. Nuclear Engineering and Design163 (1996) 81–9810.1016/0029-5493(95)01160-9Search in Google Scholar
6 Kurul, N.; Podowski, M. Z.: Multidimensional effects in forced convection subcooled boiling. Proceedings of the Ninth International Heat Transfer Conference. 1990, 2: 19–2410.1615/IHTC9.40Search in Google Scholar
7 ANSYS-Inc.2010. ANSYS CFX 13.0: Solver Theory GuideSearch in Google Scholar
8 Ishii, M.; Zuber, N.: Drag coefficient and relative velocity in bubbly, droplet or particulate flows. AIChE Journal25 (1979) 843–85510.1002/aic.690250513Search in Google Scholar
9 Krepper, E.; Končar,B.; Egorov, Y.: CFD modelling of subcooled boiling–concept, validation and application to fuel assembly design. Nuclear Engineering and Design237 (2007) 716–73110.1016/j.nucengdes.2006.10.023Search in Google Scholar
10 Tomiyama, A.: Struggle with computational bubble dynamics. Multiphase Science and Technology10 (1998) 369–40510.1615/MultScienTechn.v10.i4.40Search in Google Scholar
11 Antal, S. P.; Lahey, R. T.; Flaherty, J. E.: Analysis of phase distribution in fully developed laminar bubbly two-phase flow. International Journal of Multiphase Flow17 (1991) 635–65210.1016/0301-9322(91)90029-3Search in Google Scholar
12 Burns, A. D.; Frank.T.; Hamill, I. et al.: The Favre averaged drag model for turbulent dispersion in Eulerian multi-phase flows. 5th international conference on multiphase flow, ICMF. 2004, 4Search in Google Scholar
13 Kurul, N.; Podowski, M. Z.: On the modeling of multidimensional effects in boiling channels. ANS Proceeding of the 27th National Heat Transfer Conference. 1991Search in Google Scholar
14 Lemmert, M.; Chawla, J. M.: Influence of flow velocity on surface boiling heat transfer coefficient. Heat Transfer in Boiling237 (1977) 247Search in Google Scholar
15 Tolubinsky, V. I.; Kostanchuk, D. M.: Vapour bubbles growth rate and heat transfer intensity at subcooled water boiling. Proceedings of the 4th international heat transfer conference. 1970, 510.1615/IHTC4.250Search in Google Scholar
16 Cole, R.: A photographic study of pool boiling in the region of CHF. AIChEJ, 6 (1960) 533–542. 10.1002/aic.690060405Search in Google Scholar
17 Bartolomei, G. G.; Brantov, V. G.; Molochnikov, Y. S. et al.: An experimental investigation of true volumetric vapor content with subcooled boiling in tubes. Thermal Engineering29 (1982) 132–135Search in Google Scholar
18 Qi, S.: Experimental research on local characteristics of a vertical upward steam-water flow. Chengdu: Nuclear Power Institute of China, 2000Search in Google Scholar
© 2016, Carl Hanser Verlag, München
Articles in the same Issue
- Contents/Inhalt
- Contents
- Summaries/Kurzfassungen
- Summaries
- Editorial
- Challenges in reactor core thermal-hydraulics: subchannel analysis, CFD modeling and rod bundle CHF
- Technical Contributions/Fachbeiträge
- Subchannel analysis and correlation of the Rod Bundle Heat Transfer (RBHT) steam cooling experimental data
- CFD analysis on mixing effects of spacer grids with different dimples and sizes for advanced fuel assemblies
- An experimental investigation on dynamics and heat transfer associated with a single droplet impacting on a hot surface above the Leidenfrost point temperature
- Study on effects of mixing vane grids on coolant temperature distribution by subchannel analysis
- Reflood experiments in rod bundles with flow blockages due to clad ballooning
- The effect of spacer grid critical component on pressure drop under both single and two phase flow conditions
- Numerical method improvement for a subchannel code
- Numerical investigation on the characteristics of two-phase flow in fuel assemblies with spacer grid
- Effects of axial power shapes on CHF locations in a single tube and in rod bundle assemblies
- CFD evaluation on the thermohydraulic characteristics of tube support plates in steam generator
- Analysis of heat transfer under high heat flux nucleate boiling conditions
- Review of the correlation developments and a new concept based on mixing mechanism for heat transfer enhancement of spacer grids
- A comparison of the CFD simulation results in 5 × 5 sub-channels with mixing grids using different turbulence models
- Simulation of isothermal multi-phase fuel-coolant interaction using MPS method with GPU acceleration
- RELAP5 investigation on subchannel flow instability
Articles in the same Issue
- Contents/Inhalt
- Contents
- Summaries/Kurzfassungen
- Summaries
- Editorial
- Challenges in reactor core thermal-hydraulics: subchannel analysis, CFD modeling and rod bundle CHF
- Technical Contributions/Fachbeiträge
- Subchannel analysis and correlation of the Rod Bundle Heat Transfer (RBHT) steam cooling experimental data
- CFD analysis on mixing effects of spacer grids with different dimples and sizes for advanced fuel assemblies
- An experimental investigation on dynamics and heat transfer associated with a single droplet impacting on a hot surface above the Leidenfrost point temperature
- Study on effects of mixing vane grids on coolant temperature distribution by subchannel analysis
- Reflood experiments in rod bundles with flow blockages due to clad ballooning
- The effect of spacer grid critical component on pressure drop under both single and two phase flow conditions
- Numerical method improvement for a subchannel code
- Numerical investigation on the characteristics of two-phase flow in fuel assemblies with spacer grid
- Effects of axial power shapes on CHF locations in a single tube and in rod bundle assemblies
- CFD evaluation on the thermohydraulic characteristics of tube support plates in steam generator
- Analysis of heat transfer under high heat flux nucleate boiling conditions
- Review of the correlation developments and a new concept based on mixing mechanism for heat transfer enhancement of spacer grids
- A comparison of the CFD simulation results in 5 × 5 sub-channels with mixing grids using different turbulence models
- Simulation of isothermal multi-phase fuel-coolant interaction using MPS method with GPU acceleration
- RELAP5 investigation on subchannel flow instability
