A note on two-phase separated flow models

Rousseau, J. C.; Ferch, R. L.

doi:10.1016/0301-9322(79)90034-x

Cited by 24 publications

(13 citation statements)

References 3 publications

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“…[Ransom and Scofield, 1976], [Stuhmiller, 1977], [Rousseau and Ferch, 1979], [Banerjee and Chan, 1980], [Hancox et.al., 1980], as well as others. All of these 33 researchers were trying to gain closure of this equation system (the classical 6-equations system) through algebraic means -and were meeting some limited success.…”

Section: Seven Equation Two-pressure Two-velocity Hyperbolic Well-mentioning

confidence: 99%

Progress in the Development of Compressible, Multiphase Flow Modeling Capability for Nuclear Reactor Flow Applications

Berry¹,

Saurel²,

Petitpas³

et al. 2008

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8 MotivationIn nuclear reactor safety and optimization there are key issues that rely on in-depth understanding of basic two-phase flow phenomena with heat and mass transfer. Within the context of multiphase flows, two bubble-dynamic phenomena -boiling (heterogeneous) and flashing or cavitation (homogeneous boiling), with bubble collapse, are technologically very important to nuclear reactor systems. The main difference between boiling and flashing is that bubble growth (and collapse) in boiling is inhibited by limitations on the heat transfer at the interface, whereas bubble growth (and collapse) in flashing is limited primarily by inertial effects in the surrounding liquid. The flashing process tends to be far more explosive (and implosive), and is more violent and damaging (at least in the near term) than the bubble dynamics of boiling. However, other problematic phenomena, such as crud deposition, appear to be intimately connecting with the boiling process. In reality, these two processes share many details.Flashing occurs in flowing liquid systems when the pressure falls sufficiently low in some region of the flow, reaching a metastable state where the temperature is higher than the saturated one at the reduced pressure of this expanded state. Then the superheated liquid releases its metastable energy (stored as internal energy) very quickly, even explosively, producing either pure vapor (bubble) or liquid-vapor mixture at high velocity, [2]. Expansion effects in nuclear reactor systems are often due to geometrical effects, as for example in nozzles where flashing appears at locations where the pressure is relatively low and the liquid superheated. In the case of twophase blowdown (from the superheated liquid state), bubble collapse is usually not important, but the flashing of superheated liquid strongly influences critical flow rates. In other cases, besides the performance limitations which this cavitation may cause in flow systems, subsequent bubble collapse may be responsible for damage to nearby solid surfaces.Many nuclear reactor applications rely on convective nucleate boiling to efficiently remove high heat fluxes from heated surfaces. Nucleate boiling is a very effective heat transfer mechanism, however it is well known that there exists a critical value of the heat flux at which nucleate boiling transitions to film boiling (departure from nucleate boiling (DNB) and boiling crisis), a very poor heat transfer mechanism. In most practical applications it is imperative to maintain the operating heat flux below such critical value, which is called the Critical Heat Flux (CHF). In this case, the presence of a nearby solid surface is necessary for the rapid supply of the latent heat inherent in the phase change. The presence of these surfaces is known to modify the flow patterns and other characteristics of these multiphase flows, and therefore must be interactively coupled with analyses of these phenomena. And again, as mentioned above, DNB is believed to play an integral role in performance degradatio...

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Section: Seven Equation Two-pressure Two-velocity Hyperbolic Well-mentioning

confidence: 99%

Progress in the Development of Compressible, Multiphase Flow Modeling Capability for Nuclear Reactor Flow Applications

Berry¹,

Saurel²,

Petitpas³

et al. 2008

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show abstract

“…Cette hypothèse d'isobaricité est fortement remise en cause dans de nombreux modèles (tout en conservant l'interaction par la pression). Son importance sur le couplage des phases au niveau propagation est en effet très fort [6], couplage qui n'est pas réaliste dans certains types d'écoulement notamment dans les écoulements stratifiés [7].…”

Section: Hypothèse Sur Les Pressionsunclassified

Modélisation des écoulements diphasiques dans les codes avancés décrivant l'accident de dépressurisation dans les réacteurs à eau sous pression

Reocreux

1979

La Houille Blanche

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“…He pointed out that the interfacial pressure based on the unequal phase velocities contributed to achieving real eigenvalues in the equation system. Rouseau and Ferch [7] introduced a static pressure difference between the phases and derived a condition for the hyperbolic governing equations. They found that the strati¢ed-£ow problem becomes well posed when an interfacial inertia layer is made to respond to a pressure difference between the phases; see also Ransom and Sco¢eld [8].…”

Section: Introductionmentioning

confidence: 99%