Jean-marc Delhaye - Academia.edu (original) (raw)
Uploads
Papers by Jean-marc Delhaye
In this article some industrial processes involving gas-liquid flow, and some related problems ar... more In this article some industrial processes involving gas-liquid flow, and some related problems are reviewed, as well as several theoretical models for two-phase pipe flow. The development of such models requires a knowledge of the physical mechanisms involved. Frequently, these mechanisms are not well understood, as discussed in the part of this article which analyzes flooding in a vertical pipe. Two measuring techniques are described and some research topics are proposed.
Space-time or time-space averaged equations are developed because of their many applications in p... more Space-time or time-space averaged equations are developed because of their many applications in practical problems of two phase flow in channels. These composite-averaged equations can be obtained both ways and their equivalence is demonstrated. A relationship connecting the interfacial area to the speed of displacement of the interfaces is established. The local specific area is defined. The limiting form of the fundamental identity is derived. The resulting space-time or time-space equations are shown.
Nuclear Engineering and Design, 1993
ABSTRACT A careful measurement of the relevant two-phase flow parameters is the basis for the und... more ABSTRACT A careful measurement of the relevant two-phase flow parameters is the basis for the understanding of many thermohydraulic processes. Reliable two-phase instrumentation is therefore essential for the connection between analysis and experiment especially in the nuclear safety research where accident scenarios have to be simulated in experimental facilities and predicted by complex computer code systems. Ambitious development programs have been carried out in many institutions and countries to improve two-phase instrumentation. Advantages as well as limitations of some of these systems are discussed in this paper. In the last 10 to 15 years substantial progress has been made, although there are still goals for further developments. And it is still a fact that in many cases measured data taken from large experimental facilities cannot be compared directly to the parameters calculated by the codes. Careful comparison and interpretation of both calculated and measured results by experienced researchers will continue to be the key for thermohydraulic understanding of complex two-phase phenomena in the future.
Multiphase Science and Technology, 1997
![Research paper thumbnail of Summary on experimental methods for statistical transient analysis of two-phase gas-liquid flow. [BWR, PWR, and LMFBR]](https://attachments.academia-assets.com/91395078/thumbnails/1.jpg)
](Separation of Steam and Water Distributions According to Stefanovic et al 13 2. Separation of Ste... more Separation of Steam and Water Distributions According to Stefanovic et al 13 2. Separation of Steam and Water Distributions According to Barois. 14 3. Subcooled Boiling-temperature Histograms 15 4. Different Hypotheses Concerning the Separation of Liquid and Steam Histograms 16 5. Most Probable Liquid Temperature and Void Fraction above a Nucleus in Nucleate Boiling 17 6. Glass-rod Optical Probe 18
International Journal of Multiphase Flow, 1976
Much work has been expended in the study of two-phase, gas-liquid flows. While it has been recogn... more Much work has been expended in the study of two-phase, gas-liquid flows. While it has been recognized superficially that such flows are not homogeneous in general, little attention has been paid to the inherent discreteness of the two-phase systems. It has been a relatively recent development that fluctuating characteristics of two-phase flows have been studied in detail. As a result, new experimental devices and techniques have been developed for use in obtaining measurements of quantities previously ignored. This paper reviews and summarizes these methods in an effort to emphasize the importance of the fluctuating nature of these flows and as a guide to further research in this field.
Multiphase Science and Technology, 2013
Multiphase Science and Technology, 2003
This report outlines scientific issues whose resolution will help advance and define the field of... more This report outlines scientific issues whose resolution will help advance and define the field of multiphase flow. It presents the findings of four study groups and of a workshop sponsored by the Program on Engineering Physics of the Department of Energy. The reason why multiphase flows are much more difficult to analyze than single phase flows is that the phases assume a large number of complicated configurations. Therefore, it should not be surprising that the understanding of why the phases configure in a certain way is the principal scientific issue. Research is needed which identifies the microphysics controlling the organization of the phases, which develops physical models for the resultant multiscale interactions and which tests their validity in integrative experiments/theories that look at the behavior of a system. New experimental techniques and recently developed direct numerical simulations will play important roles in this endeavor. In gas-liquid flows a top priority is to develop an understanding of why the liquid phase in quasi-fully-developed pipe flow changes from one configuration to another. Mixing flows offer a more complicated situation in which several patterns can exist at the same time. They introduce new physical challenges. A second priority is to provide a quantitative description of the phase distribution for selected fully developed flows and for simple mixing flows (that could include heat transfer and phase change). Microphysical problems of interest are identified-including the coupling of molecular and macroscopic behavior that can be observed in many situations and the formation/destruction of interfaces in the coalescence/breakup of drops and bubbles. Solid-fluid flows offer a simpler system in that interfaces are not changing. However, a variety of patterns exist, that depend on the properties of the particles, their concentration and the Reynolds number characterizing the relative velocity. A top priority is the development of a physical understanding of inertial instabilities which give rise to structural features that have a large range of scales. Important microphysical problems are the understanding of particle/particle interactions, particle/boundary interactions that include the effect of wall roughness, and the influence of particles on fluid turbulence. These behaviors can differ depending on the characteristics of the particles, their size distribution and their concentration. For large concentrations, such as exist in granular flows, instabilities associated with particle-particle
Heat and Mass Transfer, 2006
La Houille Blanche, 1978
surface peut aussi s'exprimer sous la forme Différencions cette équation par rapport au temps. Sa... more surface peut aussi s'exprimer sous la forme Différencions cette équation par rapport au temps. Sachant que le vecteur normal unitaire n est lié à l'équation de la surface par la relation Nous commencerons par définir la vitesse de déplacement d'une surface en mouvement ainsi que la variable indicatrice de phase. Ensuite nous introduirons les opérateurs de moyenne spatiale instantanée et de moyenne temporelle locale (Delllaye & Achard, 1976). Enfin nous examinerons la commutativité de ces opérateurs et nous donnerons un théorème concernant les aires interfaciales.
Multiphase Science and Technology, 2011
Forced convective boiling is of great interest for several applications in the power and process ... more Forced convective boiling is of great interest for several applications in the power and process industry, particularly in nuclear plants. Depending on the type of pressurized water reactors, boiling may be encountered in the cooling channels during startup, nominal, incidental or accidental conditions with void fractions as large as 0.90. The objective of the present study is to characterize the two-phase flow patterns under such thermal hydraulic conditions. Using experimental data sets obtained on a Refrigerant 12 (R12) loop at CEA/Grenoble, we have shown that at high void fractions the flow behaves like a bubble emulsion; i.e., the liquid phase remains the continuous phase whatever the void fraction. On the basis of this conclusion, we propose a new model for the distribution parameter, C 0 , of the drift-flux model. This model is first qualified on subcooled, low void fraction R12 experimental data in a circular tube. The model is then shown to give results in good agreement with high void fraction saturated R12 data in a circular tube as well as with experimental data obtained for water saturated boiling at pressures greater than 10 MPa in narrow rectangular channels.
International Journal of Heat and Mass Transfer, 2021
Forced convective boiling is of great interest for several applications in the power and process ... more Forced convective boiling is of great interest for several applications in the power and process industry, particularly in nuclear plants. Under certain nominal, incidental or accidental conditions, a boiling crisis may occur resulting in the meltdown of the heating surface. It is then essential to predict as accurately as possible the thermal-hydraulic conditions leading to the occurrence of this boiling crisis. Such an objective cannot reasonably be achieved without a good description of the associated two-phase flow. The objective of the present study is twofold: (1) to identify the necessary key parameters for correctly describing boiling flows, and (2) to present in a didactic way an original stationary and local model involving these parameters. This new model is primarily based on four mixture balance equations, a submodel for the local vapor generation rate, and a turbulence submodel inspired by the pioneering work of [25]. The results obtained with this original boiling flo...
International Journal of Multiphase Flow
ABSTRACT
La Houille Blanche
Utilisation de sondes optiques miniatures en écoulement diphasique gaz-liquide Application à la m... more Utilisation de sondes optiques miniatures en écoulement diphasique gaz-liquide Application à la mesure du taux de présence local et de la vitesse locale de la phase gazeuse
International Journal of Multiphase Flow, 1996
In an airlift pumping process, air is injected into the pipe containing the fluid to be transferr... more In an airlift pumping process, air is injected into the pipe containing the fluid to be transferred. Small-diameter airlift pumps are in particular used for corrosive or radioactive liquids. Detailed experiments including differential pressure and void fraction measurements, are carried out on a 10 mm-diameter setup. Based on the results obtained, it is shown that existing models are not appropriate
Comptes Rendus de l'Académie des Sciences - Series IIB - Mechanics-Physics-Astronomy, 2000
Reçu le 14 septembre 1999, accepté après révision le 15 novembre 1999) Résumé. Le bilan d'aire in... more Reçu le 14 septembre 1999, accepté après révision le 15 novembre 1999) Résumé. Le bilan d'aire interfaciale dans un mélange diphasique prend des allures très différentes, suivant que la densité d'aire interfaciale est définie comme : i) la somme de toutes les aires des interfaces contenues dans un volume unité ou ii) la somme des aires des surfaces des particules dont le centre est situé dans ce volume unité. Nous montrons ici la parfaite compatibilité entre les deux équations de bilan, ainsi que les avantages respectifs de chacune des deux définitions. © 2000 Académie des sciences/Éditions scientifiques et médicales Elsevier SAS écoulements diphasiques / aire interfaciale / équation de bilan
International Journal of Multiphase Flow, 2003
This Report outlines scientific issues that involve microscopic phenomena in multiphase flows. A ... more This Report outlines scientific issues that involve microscopic phenomena in multiphase flows. A common theme is the need to understand the coupling between molecular scale phenomena and macroscopic phenomena. Phenomena to be discussed include boiling nucleation, contact line motion, flow regimes in microchannels, breakup and coalescence of fluid particles and jets, atomization and sprays, and the effects of surface-active molecules and drag-reducing polymers.
In this article some industrial processes involving gas-liquid flow, and some related problems ar... more In this article some industrial processes involving gas-liquid flow, and some related problems are reviewed, as well as several theoretical models for two-phase pipe flow. The development of such models requires a knowledge of the physical mechanisms involved. Frequently, these mechanisms are not well understood, as discussed in the part of this article which analyzes flooding in a vertical pipe. Two measuring techniques are described and some research topics are proposed.
Space-time or time-space averaged equations are developed because of their many applications in p... more Space-time or time-space averaged equations are developed because of their many applications in practical problems of two phase flow in channels. These composite-averaged equations can be obtained both ways and their equivalence is demonstrated. A relationship connecting the interfacial area to the speed of displacement of the interfaces is established. The local specific area is defined. The limiting form of the fundamental identity is derived. The resulting space-time or time-space equations are shown.
Nuclear Engineering and Design, 1993
ABSTRACT A careful measurement of the relevant two-phase flow parameters is the basis for the und... more ABSTRACT A careful measurement of the relevant two-phase flow parameters is the basis for the understanding of many thermohydraulic processes. Reliable two-phase instrumentation is therefore essential for the connection between analysis and experiment especially in the nuclear safety research where accident scenarios have to be simulated in experimental facilities and predicted by complex computer code systems. Ambitious development programs have been carried out in many institutions and countries to improve two-phase instrumentation. Advantages as well as limitations of some of these systems are discussed in this paper. In the last 10 to 15 years substantial progress has been made, although there are still goals for further developments. And it is still a fact that in many cases measured data taken from large experimental facilities cannot be compared directly to the parameters calculated by the codes. Careful comparison and interpretation of both calculated and measured results by experienced researchers will continue to be the key for thermohydraulic understanding of complex two-phase phenomena in the future.
Multiphase Science and Technology, 1997
Separation of Steam and Water Distributions According to Stefanovic et al 13 2. Separation of Ste... more Separation of Steam and Water Distributions According to Stefanovic et al 13 2. Separation of Steam and Water Distributions According to Barois. 14 3. Subcooled Boiling-temperature Histograms 15 4. Different Hypotheses Concerning the Separation of Liquid and Steam Histograms 16 5. Most Probable Liquid Temperature and Void Fraction above a Nucleus in Nucleate Boiling 17 6. Glass-rod Optical Probe 18
International Journal of Multiphase Flow, 1976
Much work has been expended in the study of two-phase, gas-liquid flows. While it has been recogn... more Much work has been expended in the study of two-phase, gas-liquid flows. While it has been recognized superficially that such flows are not homogeneous in general, little attention has been paid to the inherent discreteness of the two-phase systems. It has been a relatively recent development that fluctuating characteristics of two-phase flows have been studied in detail. As a result, new experimental devices and techniques have been developed for use in obtaining measurements of quantities previously ignored. This paper reviews and summarizes these methods in an effort to emphasize the importance of the fluctuating nature of these flows and as a guide to further research in this field.
Multiphase Science and Technology, 2013
Multiphase Science and Technology, 2003
This report outlines scientific issues whose resolution will help advance and define the field of... more This report outlines scientific issues whose resolution will help advance and define the field of multiphase flow. It presents the findings of four study groups and of a workshop sponsored by the Program on Engineering Physics of the Department of Energy. The reason why multiphase flows are much more difficult to analyze than single phase flows is that the phases assume a large number of complicated configurations. Therefore, it should not be surprising that the understanding of why the phases configure in a certain way is the principal scientific issue. Research is needed which identifies the microphysics controlling the organization of the phases, which develops physical models for the resultant multiscale interactions and which tests their validity in integrative experiments/theories that look at the behavior of a system. New experimental techniques and recently developed direct numerical simulations will play important roles in this endeavor. In gas-liquid flows a top priority is to develop an understanding of why the liquid phase in quasi-fully-developed pipe flow changes from one configuration to another. Mixing flows offer a more complicated situation in which several patterns can exist at the same time. They introduce new physical challenges. A second priority is to provide a quantitative description of the phase distribution for selected fully developed flows and for simple mixing flows (that could include heat transfer and phase change). Microphysical problems of interest are identified-including the coupling of molecular and macroscopic behavior that can be observed in many situations and the formation/destruction of interfaces in the coalescence/breakup of drops and bubbles. Solid-fluid flows offer a simpler system in that interfaces are not changing. However, a variety of patterns exist, that depend on the properties of the particles, their concentration and the Reynolds number characterizing the relative velocity. A top priority is the development of a physical understanding of inertial instabilities which give rise to structural features that have a large range of scales. Important microphysical problems are the understanding of particle/particle interactions, particle/boundary interactions that include the effect of wall roughness, and the influence of particles on fluid turbulence. These behaviors can differ depending on the characteristics of the particles, their size distribution and their concentration. For large concentrations, such as exist in granular flows, instabilities associated with particle-particle
Heat and Mass Transfer, 2006
La Houille Blanche, 1978
surface peut aussi s'exprimer sous la forme Différencions cette équation par rapport au temps. Sa... more surface peut aussi s'exprimer sous la forme Différencions cette équation par rapport au temps. Sachant que le vecteur normal unitaire n est lié à l'équation de la surface par la relation Nous commencerons par définir la vitesse de déplacement d'une surface en mouvement ainsi que la variable indicatrice de phase. Ensuite nous introduirons les opérateurs de moyenne spatiale instantanée et de moyenne temporelle locale (Delllaye & Achard, 1976). Enfin nous examinerons la commutativité de ces opérateurs et nous donnerons un théorème concernant les aires interfaciales.
Multiphase Science and Technology, 2011
Forced convective boiling is of great interest for several applications in the power and process ... more Forced convective boiling is of great interest for several applications in the power and process industry, particularly in nuclear plants. Depending on the type of pressurized water reactors, boiling may be encountered in the cooling channels during startup, nominal, incidental or accidental conditions with void fractions as large as 0.90. The objective of the present study is to characterize the two-phase flow patterns under such thermal hydraulic conditions. Using experimental data sets obtained on a Refrigerant 12 (R12) loop at CEA/Grenoble, we have shown that at high void fractions the flow behaves like a bubble emulsion; i.e., the liquid phase remains the continuous phase whatever the void fraction. On the basis of this conclusion, we propose a new model for the distribution parameter, C 0 , of the drift-flux model. This model is first qualified on subcooled, low void fraction R12 experimental data in a circular tube. The model is then shown to give results in good agreement with high void fraction saturated R12 data in a circular tube as well as with experimental data obtained for water saturated boiling at pressures greater than 10 MPa in narrow rectangular channels.
International Journal of Heat and Mass Transfer, 2021
Forced convective boiling is of great interest for several applications in the power and process ... more Forced convective boiling is of great interest for several applications in the power and process industry, particularly in nuclear plants. Under certain nominal, incidental or accidental conditions, a boiling crisis may occur resulting in the meltdown of the heating surface. It is then essential to predict as accurately as possible the thermal-hydraulic conditions leading to the occurrence of this boiling crisis. Such an objective cannot reasonably be achieved without a good description of the associated two-phase flow. The objective of the present study is twofold: (1) to identify the necessary key parameters for correctly describing boiling flows, and (2) to present in a didactic way an original stationary and local model involving these parameters. This new model is primarily based on four mixture balance equations, a submodel for the local vapor generation rate, and a turbulence submodel inspired by the pioneering work of [25]. The results obtained with this original boiling flo...
International Journal of Multiphase Flow
ABSTRACT
La Houille Blanche
Utilisation de sondes optiques miniatures en écoulement diphasique gaz-liquide Application à la m... more Utilisation de sondes optiques miniatures en écoulement diphasique gaz-liquide Application à la mesure du taux de présence local et de la vitesse locale de la phase gazeuse
International Journal of Multiphase Flow, 1996
In an airlift pumping process, air is injected into the pipe containing the fluid to be transferr... more In an airlift pumping process, air is injected into the pipe containing the fluid to be transferred. Small-diameter airlift pumps are in particular used for corrosive or radioactive liquids. Detailed experiments including differential pressure and void fraction measurements, are carried out on a 10 mm-diameter setup. Based on the results obtained, it is shown that existing models are not appropriate
Comptes Rendus de l'Académie des Sciences - Series IIB - Mechanics-Physics-Astronomy, 2000
Reçu le 14 septembre 1999, accepté après révision le 15 novembre 1999) Résumé. Le bilan d'aire in... more Reçu le 14 septembre 1999, accepté après révision le 15 novembre 1999) Résumé. Le bilan d'aire interfaciale dans un mélange diphasique prend des allures très différentes, suivant que la densité d'aire interfaciale est définie comme : i) la somme de toutes les aires des interfaces contenues dans un volume unité ou ii) la somme des aires des surfaces des particules dont le centre est situé dans ce volume unité. Nous montrons ici la parfaite compatibilité entre les deux équations de bilan, ainsi que les avantages respectifs de chacune des deux définitions. © 2000 Académie des sciences/Éditions scientifiques et médicales Elsevier SAS écoulements diphasiques / aire interfaciale / équation de bilan
International Journal of Multiphase Flow, 2003
This Report outlines scientific issues that involve microscopic phenomena in multiphase flows. A ... more This Report outlines scientific issues that involve microscopic phenomena in multiphase flows. A common theme is the need to understand the coupling between molecular scale phenomena and macroscopic phenomena. Phenomena to be discussed include boiling nucleation, contact line motion, flow regimes in microchannels, breakup and coalescence of fluid particles and jets, atomization and sprays, and the effects of surface-active molecules and drag-reducing polymers.