Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf
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A Generalized Multi-Field Two-Fluid Approach for Treatment of Multi-Scale Interfacial Structures in High Void-Fraction Regimes
Montoya, G.; Baglietto, E.; Lucas, D.; Krepper, E.
High void fraction multiphase-flow regimes are commonly encountered in the nuclear industry where safety analysis of nuclear power plants requires reliable predictions on steam-water flows in case of different accident scenarios. Within the boiling phenomena in pipes, a transition throughout different flow patterns from bubbly to churn to annular flow is expected to occur. Those flow regimes, characterized by very high void fractions, are represented by different scales in terms of their gas structures.
A concept has been recently developed for the treatment of multiphase flows where different scales in terms of interfacial structures can be found. This approach, known as Generalized TwO Phase flow or GENTOP, considers the definition of a fully-resolved continuous gas phase where the continuous gas summarizes all gas structures which are large enough to be resolved within the computed mesh. The concept works as part of an extension of the bubble population balance approach known as the inhomogeneous MUSIG, which allows the consideration of different bubble size groups, each with its own velocity field. Within the polydispersed gas, bubble coalescence and breakup allow the transfer between different size structures, while the modeling of mass transfer between the polydispersed and continuous gas, allows considering transitions between different gas morphologies depending of the flow situations.
Keywords: CFD; GENTOP; MUSIG; multi-scale; multiphase-flow
MIT Energy Night, 18.10.2013, Cambridge, United States of America