Performance of two fluid model based numeric tool with pressure and enthalpy as independent variables for simulation of two phase flow in axial and radial direction
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Abstract
Several numeric tools have been developed and reported in literature for simulation of two phase flow conditions. Most of the tools make use of the classical homogeneous equilibrium model of two phase flow which is reported to perform better under high pressure conditions with relatively small temperature gradients. System codes such as RELAP make use of two fluid model of two phase flow. Such system codes model the flow of two phases in one dimension in the axial direction. The provision of modeling flow in the direction perpendicular to the axial flow direction exists with the approximation of not considering the flux terms in the momentum equations in the perpendicular direction. This approach is reported to work well for situations with predominant single directional flows. To analyze certain situations with predominant flow in axial as well as radial directions a numeric tool (FLOW) has been developed. The approach employs the same momentum equation for axial as well as radial direction incorporating the flux terms in both directions. The pressure and the enthalpy of the fluid are used as independent variable in the formulation of the tool. The results are found to be in good agreement with 3D CFD simulations.
Kurzfassung
Eine Reihe numerischer Hilfsmittel zur Simulation von Zweiphasenströmungsbedingungen wurden entwickelt und in der Literatur beschrieben. Die meisten dieser Tools verwenden das klassische homogene Gleichgewichtsmodell der Zweiphasenströmung, das sich für Hochdruckbedingungen mit relativ kleinen Temperaturgradienten besser eignet. Systemprogramme, wie z. B. RELAP, verwenden das Zweiflüssigkeitenmodell der Zweiphasenströmung. Solche Systemprogramme modellieren die Strömung zweier Phasen in einer Dimension in axialer Richtung. Die Modellierung einer Strömung rechtwinklig zur axialen Strömungsrichtung wird mit Näherungen durchgeführt, die nicht alle Terme in rechtwinkliger Richtung berücksichtigen. Es wird berichtet, dass dieser Ansatz für Strömungen in überwiegend einer Richtung gute Ergebnisse liefern. Um gewisse Situationen mit überwiegender Strömung sowohl in axialer wie auch in radialer Richtung zu analysieren, wurde ein numerisches Tool (FLOW) entwickelt. Der Ansatz nutzt die gleiche Impulsgleichung für axiale wie auch für radiale Richtung und berücksichtigt die Strömungsterme in beiden Richtungen. Druck und Enthalpie der Flüssigkeit werden als unabhängige Variable bei der Formulierung des Tools verwendet. Die Ergebnisse stimmen gut überein mit 3D CFD Simulationen.
References
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© 2014, Carl Hanser Verlag, München
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- Contents/Inhalt
- Contents
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- Summaries
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- A model-based approach to operational event groups ranking
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