RELAP5 investigation on subchannel flow instability
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S. Wang
Abstract
Two-phase flow instability is a vitally important area of study for a large number of industrial systems. Density Wave Oscillation (DWO) is the most common type of flow instability caused by the change in flow rate or power in boiling systems. The code RELAP5 is used to simulate single channel, 2 × 2 subchannels, and 3 × 3 subchannels with typical BWR subchannel geometry. The onset of flow instability determinating criterion and the results of simulations are utilized to create a stable boundary. The stable boundary of a single channel is compared with those from results of other researchers. Some conclusions are made as follows. 3 × 3 subchannels are more stable than single channel and 2 × 2 subchannels. Open subchannels possess a larger stable region than close channels. The heating model is analyzed determining that asymmetrical heating has negative effect on stability as compared to symmetric heating. With the analysis of transit time, period and subcooling number, there is a positive linear relationship between the subcooling number and oscillation period.
Kurzfassung
Zweiphaseninstabilitäten ist in vielen technischen Systemen ein äußerst wichtiges Arbeitsthema. Dabei ist die wellenförmige Schwingung der Dichte der häufigste Typ der Strömungsinstabilität. Dieser wird entweder durch Änderungen der Strömungsrate oder der Leistung in siedenden Systemen hervorgerufen. Zur Untersuchung dieser Phänomene wurden typische Siedewasserunterkanalgeometrien (1 Kanal, 2 × 2 und 3 × 3-Unterkanalgeometrien) abgebildet und das Verhalten mit dem Programm RELAP5 berechnet. Daraus wurden für die verschiedenen Geometrien Kriterien zur Bestimmung des Beginns der Strömungsinstabilität abgleitetet. Diese wurden mit in der Literatur verfügbaren Daten verglichen. Die Ergebnisse zeigen, dass beim Vergleich der genannten Geometrien die 3 × 3-Unterkanalgeometrie die stabilsten Regionen zeigt und dass offene Unterkanäle stabilere Regionen erzeugen als geschlossene Kanäle. Asymmetrische Heizen der Kanäle erzeugt mehr Strömungsinstabilitäten als symmetrischen Heizen. Des Weiteren zeigt die Analyse von Übergangszeit, -periode und Unterkühlungszahl einen positiv linearen Zusammenhang zwischen der Unterkühlungszahl und der Oszillationsperiode.
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© 2016, Carl Hanser Verlag, München
Artikel in diesem Heft
- 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
Artikel in diesem Heft
- 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
