Academic literature on the topic 'Fragmentation des liquides'
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Journal articles on the topic "Fragmentation des liquides":
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Milman, Boris L., and Zeev B. Alfassi. "Detection and Identification of Cations and Anions of Ionic Liquids by Means of Electrospray Ionization Mass Spectrometry and Tandem Mass Spectrometry." European Journal of Mass Spectrometry 11, no. 1 (February 2005): 35–42. http://dx.doi.org/10.1255/ejms.663.
Abstract:
Electrospray ionization (ESI) and collision-induced dissociation (CID) spectra of nine ionic liquids have been measured. The main fragmentations of most of these ionic liquid cations were due to the loss of a butene molecule. In contrast to tetraalkylammonium ions, CID spectra of aromatic cations may represent insufficient information for unambiguous identification due to their only partial fragmentation. CID spectra of ionic liquid anions, however, allowed their reliable recognition, since isomers/isobars of such inorganic species are rare. Detection limits of cations and anions in a mixture of different ionic liquids seemed to depend on their surface activity as determined by the hydrophobicity of these species.
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Blink, James A., and William G. Hoover. "Fragmentation of suddenly heated liquids." Physical Review A 32, no. 2 (August 1, 1985): 1027–35. http://dx.doi.org/10.1103/physreva.32.1027.
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Mazid, Romiza R., R. Vijayaraghavan, Douglas R. MacFarlane, Christina Cortez-Jugo, and Wenlong Cheng. "Inhibited fragmentation of mAbs in buffered ionic liquids." Chemical Communications 51, no. 38 (2015): 8089–92. http://dx.doi.org/10.1039/c5cc01877c.
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Planchette, C., E. Lorenceau, and G. Brenn. "The onset of fragmentation in binary liquid drop collisions." Journal of Fluid Mechanics 702 (May 1, 2012): 5–25. http://dx.doi.org/10.1017/jfm.2012.94.
Abstract:
AbstractBinary collisions of drops of immiscible liquids are investigated experimentally at well-defined conditions of impact. In the experiments we vary all relevant properties of an aqueous and an oil phase, the impact parameter, the drop size and the relative velocity. The drops observed after the collisions exhibit three main phenomena: full encapsulation, head-on fragmentation, and off-centre fragmentation. The regimes characterized by these phenomena replace the ones observed in binary collisions of drops of the same liquid: coalescence, reflexive separation, and stretching separation. Our aim is a universal description of the two fragmentation thresholds of such collisions. Based on the capillary instability and an energy balance, we establish for head-on collisions a scaling law for the evolution of the threshold impact velocity with the properties of the liquids and the droplet size. The fragmentation threshold for off-centre collisions is compared to established models from the literature, which appear unsatisfactory. Introducing an effective impact parameter, which accounts empirically for the deformation and rotation of the drops upon impact, we describe this fragmentation threshold in a universal way. For both fragmentation thresholds, the agreement between experimental data and their theoretical representation is very good. Our work yields new insight into binary collisions of drops and proposes a perspective to develop a more general description with implications for binary collisions of drops of a single liquid as well.
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Milne, A., A. Longbottom, D. L. Frost, J. Loiseau, S. Goroshin, and O. Petel. "Explosive fragmentation of liquids in spherical geometry." Shock Waves 27, no. 3 (July 8, 2016): 383–93. http://dx.doi.org/10.1007/s00193-016-0671-y.
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Planchette, C., H. Hinterbichler, M. Liu, D. Bothe, and G. Brenn. "Colliding drops as coalescing and fragmenting liquid springs." Journal of Fluid Mechanics 814 (February 3, 2017): 277–300. http://dx.doi.org/10.1017/jfm.2016.852.
Abstract:
A universal modelling approach of drop fragmentation after head-on drop collisions is presented. In this approach, the colliding drops are seen as liquid springs that coalesce, compress and relax, leading the merged drop to break up if it reaches a critical aspect ratio. Combining energetic balance of the compression and relaxation phases with a Rayleigh-like criterion, we deduce the fragmentation threshold velocity for the collision of two and three drops of the same liquid and of two drops of immiscible liquids. Predictions and experimental results obtained for these three kinds of collisions using various liquids and drop sizes are found to be in good agreement over a wide domain whose boundaries are discussed.
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Schaumberg, Christian Alexander, Markus Wollgarten, and Klaus Rademann. "Fragmentation mechanism of the generation of colloidal copper(i) iodide nanoparticles by pulsed laser irradiation in liquids." Physical Chemistry Chemical Physics 17, no. 27 (2015): 17934–38. http://dx.doi.org/10.1039/c5cp01153a.
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Conrad, Justin A., Shinae Kim, and Mark S. Gordon. "Ionic liquids from a fragmented perspective." Physical Chemistry Chemical Physics 21, no. 31 (2019): 16878–88. http://dx.doi.org/10.1039/c9cp02836f.
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Landeau, M., R. Deguen, and P. Olson. "Experiments on the fragmentation of a buoyant liquid volume in another liquid." Journal of Fluid Mechanics 749 (May 16, 2014): 478–518. http://dx.doi.org/10.1017/jfm.2014.202.
Abstract:
AbstractWe present experiments on the instability and fragmentation of volumes of heavier liquids released into lighter immiscible liquids. We focus on the regime defined by small Ohnesorge numbers, density ratios of the order of one, and variable Weber numbers. The observed stages in the fragmentation process include deformation of the released fluid by either Rayleigh–Taylor instability (RTI) or vortex ring roll-up and destabilization, formation of filamentary structures, capillary instability, and drop formation. At low and intermediate Weber numbers, a wide variety of fragmentation regimes is identified. Those regimes depend on early deformations, which mainly result from a competition between the growth of RTI and the roll-up of a vortex ring. At high Weber numbers, turbulent vortex ring formation is observed. We have adapted the standard theory of turbulent entrainment to buoyant vortex rings with initial momentum. We find consistency between this theory and our experiments, indicating that the concept of turbulent entrainment is valid for non-dispersed immiscible fluids at large Weber and Reynolds numbers.
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Aiyyzhy, K. O., E. V. Barmina, V. V. Voronov, G. A. Shafeev, G. G. Novikov, and O. V. Uvarov. "Laser ablation and fragmentation of Boron in liquids." Optics & Laser Technology 155 (November 2022): 108393. http://dx.doi.org/10.1016/j.optlastec.2022.108393.
Dissertations / Theses on the topic "Fragmentation des liquides":
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Néel, Baptiste. "Déstabilisation, rupture et fragmentation spontanées et stimulées de films liquides." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0578/document.
Abstract:
Placée sous le signe de la fragmentation liquide, cette thèse met l'emphase sur une série d'étapes pouvant, d'un film suspendu, mener à une assemblée de gouttes : déstabilisation, rupture puis fragmentation. Elle prend appui sur des expériences originales, analysées à l'aide de modèles à la portée générale. En guise de prologue, capillarité, cisaillement et viscosité sont discutées à travers l'étude de la déstabilisation Marangoni d'un filament d'huile visqueuse déposé à la surface de l'eau. La mise en mouvement du filament, pilotée par une différence de tensions de surface, produit une cascade critique auto-similaire, accélérée jusqu'à la dilution complète de l'huile, miscible à l'eau. Sur un film, l'effet Marangoni créé par un déficit localisé de tension de surface, dont le support (la température ou un soluté) diffuse, engendre sa déstabilisation, étudiée au deuxième chapitre. L'analyse linéaire exhibe une échelle de temps inertielle basée sur le cisaillement surfacique, sur laquelle s'établit un écoulement interstitiel, caractérisé expérimentalement. Le scénario introduit un nombre de Péclet, critère pour la rupture spontanée des films épais. Les conséquences sur la stabilité finale du film sont explorées au troisième chapitre, avec la revue des possibles régularisations. La dynamique de rupture est interprétée en termes de choc. Enfin, suivant la rupture d'un film en divers points, la collision de cylindres liquides est isolée en tant que mécanisme individuel de fragmentation. L'analyse détaillée de l'impact révèle la transition entre deux régimes, vers des gouttes de plus en plus finesThis thesis deals primarily with liquid films fragmentation. It consists, thanks to quantitative and original experiments, in the transformation of a free suspended film into a collection of droplets: destabilization, rupture, and fragmentation.In a prologue, notions of capillarity, momentum transfer and viscosity are introduced by the Marangoni-driven destabilization of a thin thread of viscous oil on water. The difference of surface tension feeds an accelerated, critical, self-similar cascade which ends up with the complete dilution of oil into water. When applied to a free film, the Marangoni effect driven by a localized deficit of surface tension, whose carrier (temperature or a solute) is diffusing into the liquid, destabilizes it (chapter two). The linear instability analysis points out the crucial role of an inertial timescale based on the surface shear stress. Experiments validate the prediction of an interstitial flow, which digs out the film in the case of a surface tension deficit. These observations offer new insights into a long-standing problem, namely the spontaneous nucleation of holes on planar liquid films.The third chapter investigates the consequences of the linear instability, as far as the film final stability is concerned, reviewing possible regularizations. The rupture dynamics is described within the framework of shocks. In the final chapter, the collision of liquid cylinders is identified as an individual mechanism for liquid fragmentation. The impact dynamics is analyzed, leading to two principal fragmentation regimes. The onset to the splashing one, which produces fine and fast droplets, is described
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Vu, Trung-Thanh. "Processus d'atomisation des nappes liquides turbulentes : analyse expérimentale et développements numériques." Thesis, Normandie, 2017. http://www.theses.fr/2017NORMR053/document.
Abstract:
Le processus d’atomisation est important pour la performance des moteurs à combustion interne. Grâce à un injecteur, le carburant liquide est admis dans la chambre de combustion et se divise en gouttelettes. Plus petites les gouttes, plus rapide leurs évaporation et meilleur le mélange air-carburant. Une meilleure combustion pourrait être obtenue, avec faibles émissions polluantes. La qualité de l’atomisation est influencée principalement par la géométrie de l’injecteur et les conditions opératoires qui forment la structure de l’écoulement interne, la turbulence, le profil de vitesse à la sortie de l’injecteur, la cavitation, etc. Tous ces aspects sont déterminants pour la rupture de l’écoulement externe. Un autre paramètre clé pour optimiser le processus d’atomisation est les propriétés physiques des carburants. On pense, parmi autres, à la tension de surface dynamique contrôlée par la diffusion des surfactants sur l’interface liquide-gaz ou à la viscosité extensionnelle qui rend un liquide plus résistant à l’étirement, influençant donc la rupture. Les effets de la géométrie de l’injecteur, les conditions opératoires et les propriétés physiques des liquides sur l’atomisation sont inter-dépendents. Les analyses expérimentales nous aident à comprendre les mécanismes impliquant et leurs interactions. D’une part, elles sont utiles pour les simulations numériques qui devraient être réalisées suivant la configuration considérée. D’autre part, les critères quantitatifs pourraient être établis afin de valider les résultats numériques. En suivant cette méthodologie de recherche, nous souhaiterons étudier l’atomisation d’une nappe liquide turbulente produite par un injecteur triple-disque. Les mesures expérimentales fournissent les images de la nappe, utilisées comme l’entrée d’une approche multi-échelle. Nous étudions, grâce à la dernière, les comportements de la nappe, des ligaments qui apparaissent à ses bords et des gouttelettes. De plus, deux méthodes de frontières immergées sont développées pour résoudre en même temps l’écoulement interne et le processus d’atomisation. Nous réalisons deux applications, la première pour un jet liquide éjecté par un injecteur cylindrique et la deuxième pour une nappe plane produite par un injecteur triple-disqueLiquid fuel atomization is crucial for the performance of internal combustion engines. Through an injector, the liquid is delivered into the combustion chamber and breaks down into droplets. The finer the drops, the quicker their evaporation and the more proper their mixing with air. A proficient combustion could hence be expected, with low pollutant emissions. Atomization quality is primarily affected by the injector design and the operating conditions which shape the internal flow structure, the turbulence level, the velocity profile at the nozzle outlet, the cavitation and so forth. All these features are determinants of the breakup of the external liquid flow. Another key parameter to optimize the atomization process is the fuel physical properties. One can think of, among others, the dynamic surface tension controlled by the diffusion of the surfactants on the liquid-gas interface or the extensional viscosity which makes a liquid to become more resistant to the stretching, thereby affecting the breakup. Effects of the injector design, the operating conditions and the liquid properties on the atomization are inter-dependent. Analyses of experimental data help us to understand the involved mechanisms and their interactions. On the one hand, this is useful for the numerical developments which should be carried out depending upon the configuration. On the other hand, quantitative criterion could be established to validate the simulation results. Following the above research methodology, we aim to study the disintegration of planar turbulent liquid sheets produced by a triple-disk injector. Experimental measurements provide the sheet images, used as input for a multi-scale analysis. We investigate, thanks to the latter, the behaviours of the liquid sheet, the ligaments appearing on its edges and the resulting droplets. Moreover, two immersed boundary methods are developed, aiming to simultaneously solve the nozzle flow and the breakup process. We carry out two applications, the first one on a liquid jet ejected by a cylindrical nozzle and the other a planar sheet issuing from a triple-disk injector
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Zainoun, Najib. "Contrôle de la fragmentation des jets liquides issus d'un disque tournant." Paris, CNAM, 2005. http://www.theses.fr/2005CNAM0520.
Abstract:
Sur un nouveau générateur d'aérosols contrôlés, basé sur la fragmentation des jets issus d'un disue en rotation, que nous avons mis au point et automatisé, deux modèles ont été développés afin de déterminer la trajectoire des jets et les conditions exactes de leurs fragmentations. Le premier modèle détermine avec une bonne précision la trajectoire des jets grâce à l'introduction d'une loi empirique prédisant la force de traînée aérodynnamique. Le deuxiéme modèle, approchant le jet par une succession de tronçons cylindriques, permet de montrer que la perturbation qui se propage et s'amplifie le long du jet est une onde purement progressive avançant à une vitesse qui égale la somme de la vitesse de l'écoulement et la célérité des ondes dans un liquide au repos. Il est alors possible de prédire les distances de fragmentation d'un jet donne lieu à un aérosol monodisperse sans satellite et la taille des gouttes en fonction des propriétés physiques du liquide à disperser. L'étude a également montré que, dans le cas des disques lisse, les jets tournent plus lentement que le disque. Lorsque les disques présentant des dents régulièrement réparties à la périphérie, on observe, selon la taille relative des dents et des jets sur les dents. Cette perturbation constitue une source de vibration, qui contrôle la fragmentation de façon analogue à la mise en vibration du disque par une cellule piézoélectrique. Les mesures cinématiques et granulométriques ont été réalisées à l'aide de photographies de l'écoulement et granulomètre numérique spécifique présenté dans le documentOn a new generator of controlled aerosols, based on the fragmentation of the jets resulting from a disc in rotation, which we developed and automated, two models were developed and automated, two models were developed in order to determine the trajectory of the jets and the exact conditions of their break-up. The first model determines the trajectory of the jets with good precision thanks to the introduction of an ampirical law predicting the aerodynamic force of trail. The second model, approaching the jet by a succession of cylindrical sections, makes it possible to show that the disturbance which spreads and develops along the jet is a purely progressive wave advancing with a speed equal to the sum of the velocity of the flow and the celirity of capillary waves in a rest liquind. Thus, it is possible to predict the distances of natural and forced break-up, the most-unstable frequency, the zone in which the break-up of a jet induce an aerosol monodispersed without satellite and the size of the drops according to the physical properties of the liquid to be dispersed. The study also showed that, in the case of the smooth dics, the jets turn slower than the disc. When the dics present regularly distributed teeth at its periphery, we observe, according to the relative size of teeth and jets, or a periodic disturbance of the jets created by the jets crossing over the teeth. This disturbance constitutes a source of vibration, which controls the break-up in a similar way when starting the vibration of the disc by using a piezoelectric cell. The kinematics and granulometrics measurements were realised by using the photographs of the flow and a specific numerical granulometer presented in the document
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Hadj, Achour Miloud. "Fragmentation de métal liquide dans l'eau." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0215/document.
Abstract:
Le phénomène de dispersion/fragmentation du corium reste un des éléments les plus complexes et incertains de la modélisation d’un accident nucléaire. Afin de valider les modèles de sous-maille actuellement implémentés dans le logiciel MC3D (développé à l’IRSN), une expérimentation sans explosion de vapeur a été imaginée. Il s’agit d’un jet de métal liquide à bas point de fusion (métal de Field) interagissant avec de l’eau stagnante dans une cuve de large dimension. Cette thèse comporte deux volets ; le premier porte sur l’étude de la fragmentation dite secondaire d’une goutte isolée de métal de Field, à bas nombre de Weber. Dans ce but un dispositif expérimental GaLaD (générateur de goutte à la demande) a été conçu par nos soins. Cette partie a permis de faire une revue de littérature sur la fragmentation liquide-liquide, avec une comparaison quantitative de la fragmentation secondaire des gouttes uniques dans le cas liquide-liquide et dans le cas gaz-liquide. Le second volet concerne l’étude d’un jet de métal de Field, le dispositif GaLaD a pu être modifié de façon à pouvoir générer de petits jets de métal liquide dans l’eau. Les résultats obtenus ont permis une meilleure compréhension des phénomènes physiques mis en jeu avec un modèle d’entrainement diphasique pour modéliser le jet. Dans le cadre de cette thèse, un dispositif expérimental supplémentaire désigné par JaLaD est développé. Dans la suite, ce dispositif sera dédié à l’étude des jets dans l’eau et doit nous permettre de réinterpréter les données d’expériences classiques via de nouvelles mesures innovantesThe phenomenon of dispersion/fragmentation of corium remains one of the most complex and uncertain elements of nuclear accident modeling. In order to validate the sub-mesh models implemented in the MC3D software (developed by IRSN), an experiment without vapor explosion has been conceived. It consists of a low-melting liquid metal jet (Field metal) interacting with a stagnant water in a large tank. This thesis is divided into two parts ; the first one is related to the study of the so-called secondary fragmentation of an isolated drop of Field’s metal, for low Weber number. To this end, we designed an experimental device, GaLaD (drop-on-demand droplet generator). In this part, a literature review on liquid-liquid fragmentation is conducted with a quantitative comparison of the secondary fragmentation for a single drop in the liquid-liquid and the gas-liquid cases. The second part concerns the study of a jet of Field’s metal. For this purpose, GaLaD was modified, so as to be able to generate small jet of liquid metal in water. The obtained results allowed a better understanding of the physical phenomena involved in two-phase turbulent jet fragmentation. In the framework of this thesis, an additional experimental device designated by JaLaD is developed. Subsequently, this device will be dedicated to the study of metal jet in water and must allow us to reinterpret the data of classical experiments via new innovative measurement techniques
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Castrillon, Escobar Sebastian. "Instabilité et dispersion de jets de corium liquides : analyse des processus physiques et modélisation dans le logiciel MC3D." Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0102/document.
Abstract:
Lors d’un accident grave dans un réacteur nucléaire (REP ou REB en particulier), le combustible fondu (corium) peut se déverser dans le réfrigérant (eau). L’interaction entre les deux fluides est appelée Interaction Combustible-Réfrigérant. Sous certaines conditions, cette interaction peut conduire à une «explosion de vapeur» qui peut menacer le confinement du réacteur nucléaire. L’ICR est une interaction de caractère multiphasique complexe où divers phénomènes physiques interviennent de manières couplées. Elle débute par une phase de mélange entre les fluides (prémélange), se traduisant par la fragmentation du corium et sa dispersion dans le réfrigérant. Ce processus de fragmentation impacte les échanges thermiques (ébullition et mise en mouvement du fluide environnant (réfrigérant)) et les processus chimiques (oxydation du corium et génération d’hydrogène). Cette thèse apporte de nouveaux éléments concernant la compréhension physique et la modélisation du phénomène de fragmentation du corium, dont l’objectif principal est d’améliorer la modélisation dans le logiciel de thermohydraulique multiphasique MC3D, développé par l’IRSN. L’étude proposée se base sur l’hypothèse de la modélisation de la fragmentation comme un phénomène multi-échelle avec un découplage entre taux de fragmentation du jet et dimension des gouttes résultantes. Elle suppose un processus de fragmentation qui est le résultat d’une déstabilisation primaire (passage jet -> grosses gouttes) pilotée par les grandes échelles de l’écoulement et d’un processus de déstabilisation secondaire menant à une fragmentation finale dépendante des paramètres plus «locaux» de l’écoulement. Nous avons conjugué notre modélisation avec une méthode de type MUSIG récemment introduite dans le logiciel MC3D. Les gouttes de corium y sont représentées, via un découpage en classes, par plusieurs champs de masse et d’énergie avec des diamètres distincts. Malgré les avancées dans la modélisation de la fragmentation, la compréhension des mécanismes et la caractérisation de la fragmentation des gouttes liquides est encore très imparfaite, particulièrement dans le cas liquide/liquide. Le travail de thèse s’est alors orienté vers l’analyse de ce processus en utilisant le logiciel de simulation GERRIS. L’étude conduit à proposer une nouvelle carte de régimes de fragmentation en configuration liquide/liquide, une compréhension plus approfondie de la dynamique de fragmentation et une analyse sur l’interaction vortex-goutte pilotant la transition entre les régimesIn the case of a severe accident in a nuclear power plant, the molten core may flow into water and interact with it. The consequences of this fuel-coolant interaction (FCI) for the follow-up of the accident may be numerous so the phenomenon needs to be described accurately, one of them called “steam explosion” can lead to the failure of the nuclear reactor containment. FCI is a complex multiphase interaction involving several physical phenomena. The premixing phase of the interaction consists in the fragmentation and dispersion of corium in the coolant pool. This phase is driven by the fragmentation process which modifies heat transfers (coolant boiling dynamics) and chemical reactions (corium oxidation and hydrogen generation). This thesis brings new elements about the corium jet and droplet breakup with the main goal of improve fragmentation models on the MC3D multiphase code, developed by the IRSN. Our study is based on a multi-scale fragmentation process where the jet fragmentation rate and final droplet dimensions are not coupled themselves. We suppose a fragmentation process resulting from a primary instability (mass transfer within jet and big droplets) depending on the large flow scales and a secondary instability depending on the small flow scales (leading to final droplet breakup). This model has been implemented in MC3D in combination with the MUSIG method recently added to MC3D. In this method, droplets are represented using several classes, each of them with their own droplet diameter, mass and energy fields. Despite new improvements on modeling corium fragmentation, there is still a lack on the comprehension and characterization on the liquid droplet fragmentation, particularly on liquid/liquid configurations. In this thesis, we study in detail droplet breakup using the computational fluid dynamics software GERRIS. As a result, we find a new droplet breakup classification in liquid/liquid configurations, we improve the droplet breakup dynamics comprehension and we analyze the droplet-vortex interaction to determine breakup regime transition
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CHICHEPORTICHE, JEAN-MARC. "Etude de la fragmentation commandee des jets liquides issus d'un disque en rotation et realisation d'un generateur de gouttelettes monodispersees." Paris 6, 1993. http://www.theses.fr/1993PA066057.
Abstract:
Nous avons concu un generateur de gouttelettes supermicroniques fonde sur la methode du disque tournant grace auquel il est possible de disperser, a dimension de gouttelettes equivalente, une quantite de liquide par unite de temps incontestablement superieure a celle obtenue avec la technique classique de l'orifice vibrant. Pour parvenir a ce resultat, il est necessaire d'une part que le film liquide se desintegre au bord du disque sous la forme de petits jets liquides ou ligaments et, d'autre part, de creer une onde capillaire centree sur le disque se propageant du centre vers son bord. La perturbation alors transmise aux ligaments permet de controler la fragmentation de ceux-ci. Le systeme d'ondes naturellement present sur le ligament, qui conduit a la formation des gouttelettes, s'accorde alors avec la perturbation creee artificiellement. Selon les valeurs de la frequence et de l'amplitude de vibration excitant la surface du film liquide, il est possible de generer un nuage de gouttelettes presentant une population mono, bi ou tri-modale. Le ligament, qui est aussi une ligne d'emission, est approche par un modele d'ecoulement unidimensionnel dans le repere tournant lie au disque. La tension superficielle et les forces aerodynamiques sont ici prises en compte. Une comparaison avec la fragmentation des jets cylindriques montre des differences qui s'interpretent parfaitement lorsque l'on tient compte de l'evolution spatio-temporel du rayon des ligaments. En outre une etude de la cinematique des gouttelettes generees a partir des ligaments ainsi que la mesure de la granulometrie nous ont permis de mettre en evidence un coefficient inferieur a 1: quotient de la celerite des ondes capillaires presentes sur le ligament, sur la vitesse debitante
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Lhuissier, Henri. "Nappes, trous, ligaments et gouttes." Phd thesis, Université de Provence - Aix-Marseille I, 2011. http://tel.archives-ouvertes.fr/tel-00600229.
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Ce manuscrit aborde le problème de l'atomisation des films liquides à travers diverses expériences portant sur leur formation, déstabilisation et fragmentation. Une première partie identifie et décrit deux mécanismes de désintégration à l'œuvre lors de la rétractation d'un film de savon. Lorsque le film se détache sur une frontière, le bord de Plateau est entrainé et son accélération explique la déstabilisation. Lorsque le perçage a lieu au centre, le battement du film résultant de l'interaction avec l'atmosphère au repos conduit à sa fragmentation. Une second étude explique le plissement singulier de certaines cloches liquides par un ressaut hydraulique à interfaces libres assurant la transition d'un écoulement super-critique vis-à-vis des ondes capillaires à un écoulement sub-critique. La courbure marquée associée à cette transition impose au liquide une accélération centripète susceptible de déstabiliser la cloche en aval. La formation des embruns par l'intermédiaire de l'éclatement des bulles de surface est abordée dans une troisième partie. La géométrie des bulles, le mécanisme de drainage de leurs films et les événements de perçage sont étudiés afin de rendre compte de l'épaisseur de la bulle au début de l'éclatement. La dynamique ultérieure de fragmentation est détaillée conduisant à une caractérisation du spray produit. Une dernière partie étudie l'atomisation effervescente sur une expérience modèle : une nappe liquide plane ensemencée en fines bulles d'air favorisant la nucléation de trous. Sur la base de mesures des taux de nucléation et croissance des trous, un modèle statistique du réseau de ligaments liquides formés par la réunion des bourrelets ceinturant les trous permet un description du spray issu de la fragmentation du réseau.
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Kewalramani, Gagan Vikram. "Experimental and theoretical analysis of a turbulent two-phase jet." Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0012.
Abstract:
L'objectif de la présente thèse est d'étudier les jets diphasiques liquide-liquide. Les caractéristiques d'un jet diphasique (distinct d'un jet monophasique) sont la fragmentation du fluide injecté et l'échange d'énergie entre les fluides. La mesure expérimentale de la dynamique des vitesses dans un jet diphasique est habituellement un défi du fait de leur opacité. Pour accéder optiquement à la dynamique d'un jet diphasique, un fluide transparent à indice de réfraction égal à celui de l'eau (appelé fluide Cargille) mais avec une densité environ deux fois plus élevée que l'eau est injecté dans le réservoir d'eau. En ajoutant un colorant fluorescent au fluide transparent et un ensemencement par des particules, la dynamique du fluide est accessible optiquement lorsqu'il est éclairé par un laser. Une procédure pour obtenir des informations sur la dynamique des gouttes et sa relation avec la vitesse du fluide porteur à l'aide d'images acquises à grande vitesse est détaillée dans cette thèse. Pour étudier les jets diphasiques, deux montages expérimentaux (i) JaLaD et (ii) JeDi sont développés. Les travaux de cette thèse peuvent être classés en plusieurs parties qui sont expliquées comme suit. Partie-I : Analyse PTV : l'algorithme de Particle Tracking Velocimetry (PTV) Track est utilisé sur les expériences JaLad. Avec le logiciel de PTV Track, les trajectoires lagrangiennes du liquide fragmenté sont analysées. Une procédure de détection de la fragmentation primaire, des fragmentations secondaires et des collisions a été développé. La méthodologie de la détection de la fragmentation et des collisions est également vérifiée avec des images générées synthétiquement. Partie II : Analyse du jet monophasique : Avant d'aborder la mesure d'un jet diphasique, les jets monophasiques sont étudiés sur les expériences JeDi. Les contraintes turbulentes de Reynolds sont développées pour obtenir une expression mathématique de la dissipation de l'énergie cinétique turbulente et sa dissipation. Partie III : Mesure et analyse simultanées PTV-PIV : dans les expériences JeDi, une mesure simultanée des deux fluides est effectuée. Les méthodes de flux optique et de vélocimétrie par image de particules (PIV) sont utilisés pour mesurer les caractéristiques de la phase dispersée (Cargille) et du fluide porteur (eau) respectivement. Pour cette partie de la thèse, un laser de 527 nm et deux caméras sont utilisées. La caméra 1 avec un filtre passe-haut (λ > 530 nm) et caméra 2 avec un filtre passe-bas (λ < 530 nm) sont synchronisées avec le laser. Les deux systèmes enregistrer des images au même instant dans le temps et visualisent le même plan. Avec cet arrangement, la caméra 1 enregistre uniquement le signal LIF dans le Cargille et la caméra 2 enregistre uniquement le signal PIV dans l'eau. Les images enregistrées sont traitées pour obtenir la vitesse moyenne des deux phases. Un modèle intégral simple pour l'entraînement et l'atomisation basée sur des quantités moyennes eulériennes pondérées par la densité est enfin développée et validé par des résultats expérimentauxThe objective of the present thesis is to study two-phase liquid-liquid jets. Someof the features of a two-phase jet (distinct from single phase jet) are fragmentation ofthe injected fluid and energy exchange between fluids. Experimental measurementof the velocity dynamics in a two-phase jet is challenging because it's opacity. Tooptically access the dynamics of a two-phase jet, a transparent fluid with refractiveindex equal to water (referred as Cargille fluid) but with density twice as water isinjected into water tank. By adding a fluorescent dye to the transparent fluid andseeding particles to water, the dynamics of both the fluid are accessible opticallywhen illuminated by laser. A procedure to obtain information of the dynamics ofthe drops and its relation with velocity of the carrier fluid using high speed imagesis detailed in this thesis. To study two phase jets, two experimental setup (i) JaLaDand (ii) JeDi are developed. The work in this thesis can be categorized into severalparts that are explained as follows.Part-I: PTV analysis: Particle Tracking Velocimetry (PTV) algorithm Track isused on JaLad experiments. With PTV software Track, the Lagrangian trajectoriesof the fragmented liquid are analyzed. A procedure to detect primary fragmentation,secondary fragmentation and collision is developed. The methodology of fragmentationand collision detection is also verified with synthetically generated images.Part II: Single phase jet analysis: Before stating the measurement of a twophasejet, single-phase jets are studied on JeDi experiments. Relations to describeReynolds turbulent stress are developed to obtain a mathematical expression forturbulent kinetic energy dissipation and its dissipation.Part III: Simultaneous PTV-PIV measurement and analysis: In JeDi experiments,simultaneous measurement of both the fluids is perfomed. Optical flow and ParticleImage Velocimetry (PIV) are used for measuring dispersed phase (Cargille) andcarrier fluid (water) velocity respectively. For this part of the thesis, two lasers andtwo cameras are used. Camera 1 with a high pass filter (λ > 530 nm) and Camera 2with a low pass filter (λ < 530 nm) are synchronized with two lasers. Both systemsrecord images at the same instant in time and view the same plane. With the followingarrangement, Camera 1 only records the LIF signal in Cargille and Camera2 only records the PIV signal in water. The recorded images are processed to obtainthe average velocity of both phases. A simple integral model for entrainment andatomization based on Eulerian mass weighted average quantities is finally developedand validated against experimental results
9
Meignen, Renaud. "Modélisation de la fragmentation d'un jet liquide à très haute température dans un liquide froid volatil." Grenoble INPG, 1995. http://www.theses.fr/1995INPG0181.
Abstract:
Dans l'industrie nucleaire, la sequence accidentelle la plus grave prevoit dans une de ses phases, la coulee du cur en fusion (temperature de l'ordre de 3000 k) en jets d'un diametre d'une dizaine de centimetres, dans l'eau presente en fond de cuve. Les conditions de destabilisation puis de fragmentation du jet sont l'objet de cette etude. Tres peu d'experiences relatives a ce probleme ont ete realisees, du fait des conditions extremes, et de l'eventualite d'explosion de vapeur. A l'issue d'une etude bibliographique approfondie, trois points importants sont a modeliser: la structure du film vapeur s'etablissant entre le jet chaud et le refrigerant, l'instabilite de petite echelle, responsable de l'atomisation du jet, et une instabilite de grande echelle mettant en jeu l'ecoulement jet-vapeur-refrigerant complet. Le modele de film vapeur turbulent s'appuie sur une proposition de loi de couche limite turbulente sur plaque fortement chauffee et prend en compte les forces de volumes et la tres forte vaporisation due au rayonnement. Le modele d'instabilite en ondes courtes est adapte d'un modele miles et brooke benjamin ou l'on a ajoute la contribution due au fort gradient de viscosite et de densite dans la couche limite gazeuse. Le taux de fragmentation calcule est tout a fait comparable aux resultats experimentaux. Le modele d'instabilite de grande echelle a trois phases est entierement personnel. Une version simple avec deux phases permet de retrouver, pour la premiere fois, des resultats experimentaux en jets liquide/gaz et liquide/liquide. La version triphasique permet de confirmer la possibilite d'instabilites de grande echelle
10
Miller, Catherine Elizabeth. "Characterization of ion Cluster fragmentation in ionic liquid ion sources." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122372.
Abstract:
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Thesis: Ph. D., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2019
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 273-281).
Ion electrospray propulsion is a cutting-edge micropropulsion technology that could revolutionize the capabilities of microsatellites. Ion electrospray thrusters could also be used on large spacecraft for precision attitude control applications such as gravity wave detection and exoplanet imaging. Novel room temperature molten salts, called ionic liquids, are used as propellant, which are composed purely of positive and negative molecular ions. When exposed to strong electric fields, ions and metastable clusters of ions are evaporated from the bulk liquid surface. The free ions and ion clusters can be accelerated to high velocities, producing thrust at high specific impulse. The performance of ion electrospray thrusters is affected by the composition of the ion beam and the amount of ion clusters that break apart during the acceleration phase. To improve thruster performance, a better understanding of the fundamental physics of ion evaporation and cluster break-up is needed.
The break-up of ion clusters, also called fragmentation, is not a well understood phenomenon. It has been observed in past experiments, but the rates of break-up have not been measured. The focus of this work is to experimentally investigate fragmentation more deeply than ever before. To accomplish this, a specialized instrumentation suite has been designed, built, and tested to measure fragmentation characteristics in unprecedented detail. A full-beam, spherical geometry retarding potential analyzer is used to measure the rates of fragmentation of ion clusters both outside the thruster and within the acceleration region for the first time. A narrow-beam, high time-resolution time of flight mass spectrometer is used to measure the beam composition. Single emitters based on resorcinol formaldehyde carbon xerogels were used as ion sources. Four ionic liquids spanning a wide range of liquid properties were characterized: EMI-FAP, EMI-Im, EMI-BF4, and BMI-I.
Analytical models were also developed to enhance the interpretation of the experimental results. The experimental measurements show that the amount of fragmentation increases with distance from the thruster and follows a constant rate equation. The mean lifetimes of ion clusters outside of the thruster range from 1-6 [mu]s, indicating that these clusters are quite unstable. It is observed that the fragmentation throughout most of the acceleration region is linear with respect to electric potential, which can be understood using analytical models. Rapid fragmentation likely occurs immediately after evaporation due to the strong electric fields near the emission site, which has significant implications for thruster performance. It is also observed that clusters of complex molecular ions which consist of many atoms tend to be the most stable. The initial temperature of ion clusters, which range from 520 K - 790 K, were estimated using analytical methods.
The effect of liquid temperature on the rates of fragmentation was also investigated. In conclusion, the work in this thesis provides a greatly enhanced understanding of ion cluster fragmentation, particularly how it is affected by ionic liquid properties, liquid temperature, and electric fields.
This research was supported by a NASA Space Technology Research Fellowship
by Catherine Elizabeth Miller.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Aeronautics and Astronautics
Book chapters on the topic "Fragmentation des liquides":
1
Hirata, So, Kandis Gilliard, Xiao He, Murat Keçeli, Jinjin Li, Michael A. Salim, Olaseni Sode, and Kiyoshi Yagi. "Ab initioIce, Dry Ice, and Liquid Water." In Fragmentation, 245–96. Chichester, UK: John Wiley & Sons, Ltd, 2017. http://dx.doi.org/10.1002/9781119129271.ch9.
2
Shkrob, Ilya A., Timothy W. Marin, and James F. Wishart. "Radiation Induced Reactions and Fragmentation in Room Temperature Ionic Liquids." In Applications of EPR in Radiation Research, 453–85. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-09216-4_12.
3
Santha Kumar, Arunjunai R. S., and Nikhil K. Singha. "Reversible Addition-Fragmentation Chain Transfer (RAFT) Polymerization in Ionic Liquids: A Sustainable Process." In Materials Horizons: From Nature to Nanomaterials, 183–93. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-1251-3_8.
4
Van de Walle, J., and P. Joyes. "Role of fragmentation processes in the liquid metal ion source production of aggregates." In Small Particles and Inorganic Clusters, 221–24. Berlin, Heidelberg: Springer Berlin Heidelberg, 1989. http://dx.doi.org/10.1007/978-3-642-74913-1_50.
5
Grady, Dennis. "Dynamic fragmentation of solids and liquids." In Physics of Shock and Impact, Volume 1. IOP Publishing, 2017. http://dx.doi.org/10.1088/978-0-7503-1254-7ch2.
6
Robert Owen Bussey III, Dr. "Advantages of Ion Mobility Coupled with HPLC/UPLC." In Analytical Liquid Chromatography - New Perspectives [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.102380.
Abstract:
Ion mobility is a new separation technique that can be coupled with high performance liquid chromatography (HPLC) or ultra-performance liquid chromatography (UPLC). Variances in cross-sectional ionic areas of different molecules create differential speeds through a gas allowing for millisecond separations. Combining ion mobility with both liquid chromatography and mass spectrometry with fragmentation, separations can be achieved on the second (HPLC), millisecond (ion mobility), and microsecond (mass spectrometry) timescales. This orthogonal separation greatly cleans up mass spectral data of co-eluting peaks from the liquid chromatography and adds to the descriptive data of each ion. With descriptive data such as retention time, cross-sectional area, m/z ratio, and mass spectral fragmentation, many options become available for analytical analysis. Options ranging from descriptive data collation into instrument libraries to sensitivity enhancement for trace analysis will be explored in this chapter along with the description of different forms of ion mobility.
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Z. Mamadalieva, Nilufar, and Hidayat Hussain. "LC-HR-MS Based Approach to Identify Triterpenes in Astragalus Species." In New Findings from Natural Substances, 116–32. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/9789815051421122010008.
Abstract:
Astragalus genus has been recorded as yielding a wide range of flavonoids, triterpenes, triterpene saponins, and polysaccharides. Cycloartane- and oleanane-type triterpenes are widely distributed in this genus with intriguing biological effects. Combining liquid chromatography (LC) with high-resolution mass spectrometry (HR.MS) has provided a valuable tool in the analysis of these triterpenes in plants. In this chapter, we summarized the main triterpenes studied by liquid chromatography high.resolution mass spectrometry (LC-HR-MS) associated with mass analysers, molecular weight information and mass fragmentation, presenting an interesting overview of increasing interest for cycloartane- and oleanane-type triterpenes.Astragalus genus has been recorded as yielding a wide range of flavonoids, triterpenes, triterpene saponins, and polysaccharides. Cycloartane- and oleanane-type triterpenes are widely distributed in this genus with intriguing biological effects. Combining liquid chromatography (LC) with high-resolution mass spectrometry (HR.MS) has provided a valuable tool in the analysis of these triterpenes in plants. In this chapter, we summarized the main triterpenes studied by liquid chromatography high.resolution mass spectrometry (LC-HR-MS) associated with mass analysers, molecular weight information and mass fragmentation, presenting an interesting overview of increasing interest for cycloartane- and oleanane-type triterpenes.
8
Calbrix, Corentin, Alexei Stoukov, Axelle Cadière, Benoit Roig, and Dominique Legendre. "Numerical simulation of the aerial drops of the Canadair CL-415 and the Dash-8 airtankers." In Advances in Forest Fire Research 2022, 1719–24. Imprensa da Universidade de Coimbra, 2022. http://dx.doi.org/10.14195/978-989-26-2298-9_265.
Abstract:
Fighting wildland fires is a major issue for the protection of populations and environment with a need of more efficient means to fight fires. Airtankers are able to drop volumes of liquid (water or fire retardant) varying from less than 1m3 to several tens of m3, directly on fire or with the objective to form barriers of retardant to stop or reduce the fire propagation. However, the dynamics of a liquid dropped from an airplane has received few attentions in the scientific community, and related studies have mostly focused on Newtonian liquid jets injection in cross flow from millimetric injectors for combustion applications. For firefighting purpose, the liquid can be a retardant (a non Newtonian fluid) and the characteristic size of the delivery systems is of the order of a meter. The objective of this work is to demonstrate that Computational Fluid Dynamics (CFD) can be used to provide a deep understanding of the liquid fragmentation and dispersion when dropped from an aircraft. A numerical investigation is proposed for the analysis of airtanker performance and applied here to the biggest airtankers used in Europe: the Canadair CL-415 and the Dash-8. A numerical approach based on the Volume of Fluid method (VoF) is used to provide an accurate description of the tank discharge as well as to study the liquid ejection, fragmentation and atomization in air. The 3D unsteady resolution of the Navier-Stokes equations for both the liquid and the air allows us to provide a description of the main characteristics of the resulting liquid cloud, characterized by the vertical penetration of the liquid, its lateral expansion and the process of atomization.
9
"Nuclear fragmentation and the liquid–gas phase transition." In Nuclear Dynamics in the Nucleonic Regime, 232–78. CRC Press, 2000. http://dx.doi.org/10.1201/9781420033793-10.
10
"Nuclear fragmentation and the liquid–gas phase transition." In Nuclear Dynamics in the Nucleonic Regime. Taylor & Francis, 2000. http://dx.doi.org/10.1201/9781420033793.ch8.
Conference papers on the topic "Fragmentation des liquides":
1
Keshavarz, Bavand, and Gareth McKinley. "Video: Rotary fragmentation of viscoelastic liquids." In 68th Annual Meeting of the APS Division of Fluid Dynamics. American Physical Society, 2015. http://dx.doi.org/10.1103/aps.dfd.2015.gfm.v0090.
2
García, C. Pérez, A. Gardmartín, and H. L. Mancini. "FRAGMENTATION OF DROPS IN MISCIBLE LIQUIDS." In Proceedings of the Workshop. WORLD SCIENTIFIC, 1995. http://dx.doi.org/10.1142/9789814447089_0005.
3
Rimbert, Nicolas, M. Hadj-Achour, and M. Gradeck. "Liquid-Liquid Secondary Fragmentation with Solidification." In ILASS2017 - 28th European Conference on Liquid Atomization and Spray Systems. Valencia: Universitat Politècnica València, 2017. http://dx.doi.org/10.4995/ilass2017.2017.5034.
Abstract:
In the event of a hypothetical core disruptive accident in nuclear power plants, the molten core may flow out thereactor vessel and interact with the cold water. The evolution of the accident is strongly affected by the fragmentation of the jet of molten metallic fuel due to its interaction with the water (i.e. this situation is known as fuel coolant interaction, FCI). In order to evaluate and predict the various consequences of a FCI, many researches are conducted with either corium or high melting temperature molten metal, where premixing stage evolves with an important production of steam. This steam production that is unavoidable because the high temperature of corium leads to difficulties for using optical diagnostics. Hence, in our case, we use a eutectic alloy (Field’s metal) with a low melting point (62°C) in order to be able to visualize correctly the droplet fragmentation processes.The present work focuses on the fragmentation of a single Field’s metal liquid droplet with mass equals to 0.27g (±0.01g). The liquid droplet interacts with a water pool whose temperature range between 20°C to 60°C. According to its Weber number, it fragments in different ways. For each experiment, a single droplet has been visualized using a high-speed camera (at 8000 fps). All measurements (drop size, velocity, impact parameter and geometrical properties of the drops after the penetration) into the pool are evaluated using an open source image processing. Solidified fragments can then be sieved and the size PDF determined. Focus of the present work is put on the evolution of the Sauter Mean Diameter with increasing Weber number and varying bath pool temperature. It is shown that using a simple crust model during solidification and defining an effective Weber number which include the crust elasticity all the curves collapse on the same master curve for all the water bathtemperature considered.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.5034
4
Planchette, Carole, Hannes Hinterbichler, and Günter Brenn. "Drop Stream – Immiscible Jet Collisions: Regimes and Fragmentation Mechanisms." In ILASS2017 - 28th European Conference on Liquid Atomization and Spray Systems. Valencia: Universitat Politècnica València, 2017. http://dx.doi.org/10.4995/ilass2017.2017.4707.
Abstract:
We investigate the collision of a continuous liquid jet with a regular stream of immiscible droplets. The immiscible liquids, namely silicon oil for the continuous jet and an aqueous glycerol solution for the drop stream, are selected to enable the total wetting of the drops by the jet liquid. Four different regimes are experimentally identified: drops in jet, encapsulation without satellites, encapsulation with satellites from the jet liquid and mixed fragmentation. The drops in jet regime, potentially of great interest for new applications, corresponds to a regular stream of drops embedded in a continuous jet and is described and reported for the first time. Using well known aspects of drop collision and jet stability, we propose to model the transition between the drops in jet regime and the others. Two dimensionless parameters are derived from this analysis which are thus used to produce a simple regime map where the drops in jet regime can be well distinguished from the other outcomes.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4707
5
Thievenaz, Virgile, and Alban Sauret. "Video: Fragmentation of viscous compound liquid ligaments." In 74th Annual Meeting of the APS Division of Fluid Dynamics. American Physical Society, 2021. http://dx.doi.org/10.1103/aps.dfd.2021.gfm.v0069.
6
Kuroda, Taihei, Yutaka Abe, Akiko Kaneko, Iwasawa Yuzuru, Hideki Nariai, Hiroshi Sakaba, Kazuya Koyama, and Eiji Matsuo. "Estimation of Fragmentation on Jet Breakup in Coolant." In 2012 20th International Conference on Nuclear Engineering and the ASME 2012 Power Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/icone20-power2012-54399.
Abstract:
Fast Breeder Reactor (FBR) is designed with safety in mind. However, there is billion to one possibility that a hypothetical Core Disruptive Accident (CDA) occurs. When CDA occurs, the Post Accident Heat Removal (PAHR) must be achieved. In the PAHR, the molten material is required to be fragmented and solidified in sodium coolant. In order to estimate whether the molten material jet is completely solidified in sodium coolant or not, it is significant to estimate jet breakup length. Although, the jet breakup length is influenced with fragmentation behavior, the correlation between them is not clear yet. Therefore, it is strongly required to clarify the mechanism of the fragmentation behavior on the jet surface. The objective of the present study is to estimate fragmentation on jet breakup in coolant experimentally. Tap water and Fluorinert™ (FC-3283) are used as simulated coolant and molten material, respectively. Flourinert is transparent and colorless liquid and its density is higher than water, therefore we can observe internal flow structure of Fluorinert. Fluorinert injected into water, and the jet breakup behavior and the fragmentation behavior of the jet are observed by using high speed video camera. In order to estimate fragmentation on liquid jet, we identified the position of the interface with back lighting technique and also, we conducted velocity measurement with Particle Image Velocimetry (PIV) technique simultaneously. It is observed that interfacial waves of the jet are generated. Waves are pulled with surrounding liquid and grown up. Finally, a fragment is separated as a droplet from front edge of the wave. Also, the vorticity is evaluated from the velocity data in order to investigate influence of the flow field in detail. From the result of calculating vorticity, the high value was estimated when jet was fragmented. It is suggested that fragmentation behavior correlates with the surrounding flow field. And the energy ratio contributing to fragmentation is calculated from velocity field. The energy ratio is important to investigate the amount of the fragmentation on liquid jet. Fragmentation on jet breakup in coolant is estimated.
7
Asma, Cem, Davide Masutti, and Olivier Chazot. "Experimental Investigation of Liquid Fragmentation In Hypersonic Crossflow." In 27th AIAA Applied Aerodynamics Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2009. http://dx.doi.org/10.2514/6.2009-3506.
8
Zhang, Zhi-gang, and Ken-ichiro Sugiyama. "Fragmentation of a Single Molten Stainless Steel and Aluminum Droplet Penetrating a Sodium Pool." In 18th International Conference on Nuclear Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/icone18-29523.
Abstract:
In order to clarify the fragmentation of molten core structural material (stainless steel) and molten metallic fuel and claddings on liquid phase formed by metallurgical reactions (liquefaction temperature = 650°C) during core disruptive accidents (CDAs), the present study focuses on the fragmentation of single molten stainless steel (316SS) and aluminum droplet penetrating a sodium pool. The temperatures of 3–5g molten aluminum droplets were 1002 to 1399°C, and the sodium pool was about 300°C. The instantaneous contact interface temperatures (Ti) between the molten aluminum droplets and liquid sodium were calculated to be from 741°C below the boiling point of sodium (Tc,bp) to 1019°C above Tc,bp. The temperatures of 5g molten 316SS droplets were 1510 to 1706°C, and the temperatures of sodium pool vary about 300–400°C. The Ti values between the molten 316SS droplets and liquid sodium were calculated to be from 916 to 1082°C. Fragmentation of the single molten aluminum droplet was clearly observed even at Ti ≪ Tc,bp. When Ti is approximately equal to or higher than the boiling point, the intensive fragmentation of droplet was clearly observed independent of Wea condition. Fragmentation of the single molten 316SS droplet was clearly observed even at Ti below its melting point. The Dm values of aluminum and 316SS droplets with relatively high Wea tend to be lower than those of droplets with relatively low Wea under the relatively low Ti condition. These results indicate the fragmentation of the molten core structural material and eutectic alloy fuels in liquid phase formed by the metallurgical reactions could possibly occur under the low Ti condition below and above the sodium boiling point, which is promising to assure the termination of accidents in CDAs and useful to the core design with enhanced safety in FBRs.
9
Iwasawa, Yuzuru, Yutaka Abe, Akiko Kaneko, Taihei Kuroda, Eiji Matsuo, Hideki Nariai, Kazuya Koyama, Hiroshi Sakaba, and Kazuhiro Itoh. "Jet Breakup Behavior With Surface Solidification." In 2012 20th International Conference on Nuclear Engineering and the ASME 2012 Power Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/icone20-power2012-54412.
Abstract:
When a hypothetical Core Disruptive Accident (CDA) occurs in Fast Breeder Reactor (FBR), it is strongly required that the molten core material can be solidified and cooled down by the sodium coolant in a reactor vessel. In order to estimate whether the molten material jet is completely solidified by sodium coolant, it is necessary to understand the interaction between the molten core material and the coolant. The objectives of the present study are to clarify the correlation of the jet breakup and fragmentation behavior and the dominant factors of both behaviors considering surface solidification. In order to investigate the influence of surface solidification on jet breakup and fragmentation behavior, experiments under surface solidification and liquid-liquid contact condition are conducted. Although the molten material jet is fragmented with each condition, jet breakup and fragmentation behaviors on each condition are different. In addition, when the surface solidification occurs, there is possibility that the material strength of solidified crust on the surface affects jet breakup and fragmentation behaviors. Then, numerical calculation based on hydrodynamics and material mechanics is conducted to evaluate the influence of the material strength on jet breakup and fragmentation behaviors. In comparison with the numerical estimation and mass median diameters obtained from experimental results, the effect of solidification on jet breakup and fragmentation behavior of molten material jet is discussed.
10
Markus, Havell, Jun Zhao, Tania Contente-Cuomo, Elizabeth Raupach, Ahuva Odenheimer-Bergman, Sydney Connor, Bradon McDonald, et al. "Abstract PR14: Sub-nucleosomal fragmentation in urine cell-free DNA." In Abstracts: AACR Special Conference on Advances in Liquid Biopsies; January 13-16, 2020; Miami, FL. American Association for Cancer Research, 2020. http://dx.doi.org/10.1158/1557-3265.liqbiop20-pr14.
Reports on the topic "Fragmentation des liquides":
1
Blink, J. A. Fragmentation of suddenly heated liquids. Office of Scientific and Technical Information (OSTI), March 1985. http://dx.doi.org/10.2172/5770870.
2
Laney, Culbert B. Relationships between Liquid Atomization and Solid Fragmentation. Fort Belvoir, VA: Defense Technical Information Center, March 2016. http://dx.doi.org/10.21236/ad1004358.
3
Hassanein, A., and I. Konkashbaev. Modeling and simulation of fragmentation of suddenly heated liquid metal jets. Office of Scientific and Technical Information (OSTI), June 2001. http://dx.doi.org/10.2172/783632.
4
Heinen, Jennifer M. (O'Donnell). Early career: Templating of liquid crystal microstructures by reversible addition-fragmentation chain transfer polymerization. Office of Scientific and Technical Information (OSTI), December 2014. http://dx.doi.org/10.2172/1166808.
5
Snyder, Victor A., Dani Or, Amos Hadas, and S. Assouline. Characterization of Post-Tillage Soil Fragmentation and Rejoining Affecting Soil Pore Space Evolution and Transport Properties. United States Department of Agriculture, April 2002. http://dx.doi.org/10.32747/2002.7580670.bard.
Abstract:
Tillage modifies soil structure, altering conditions for plant growth and transport processes through the soil. However, the resulting loose structure is unstable and susceptible to collapse due to aggregate fragmentation during wetting and drying cycles, and coalescense of moist aggregates by internal capillary forces and external compactive stresses. Presently, limited understanding of these complex processes often leads to consideration of the soil plow layer as a static porous medium. With the purpose of filling some of this knowledge gap, the objectives of this Project were to: 1) Identify and quantify the major factors causing breakdown of primary soil fragments produced by tillage into smaller secondary fragments; 2) Identify and quantify the. physical processes involved in the coalescence of primary and secondary fragments and surfaces of weakness; 3) Measure temporal changes in pore-size distributions and hydraulic properties of reconstructed aggregate beds as a function of specified initial conditions and wetting/drying events; and 4) Construct a process-based model of post-tillage changes in soil structural and hydraulic properties of the plow layer and validate it against field experiments. A dynamic theory of capillary-driven plastic deformation of adjoining aggregates was developed, where instantaneous rate of change in geometry of aggregates and inter-aggregate pores was related to current geometry of the solid-gas-liquid system and measured soil rheological functions. The theory and supporting data showed that consolidation of aggregate beds is largely an event-driven process, restricted to a fairly narrow range of soil water contents where capillary suction is great enough to generate coalescence but where soil mechanical strength is still low enough to allow plastic deforn1ation of aggregates. The theory was also used to explain effects of transient external loading on compaction of aggregate beds. A stochastic forInalism was developed for modeling soil pore space evolution, based on the Fokker Planck equation (FPE). Analytical solutions for the FPE were developed, with parameters which can be measured empirically or related to the mechanistic aggregate deformation model. Pre-existing results from field experiments were used to illustrate how the FPE formalism can be applied to field data. Fragmentation of soil clods after tillage was observed to be an event-driven (as opposed to continuous) process that occurred only during wetting, and only as clods approached the saturation point. The major mechanism of fragmentation of large aggregates seemed to be differential soil swelling behind the wetting front. Aggregate "explosion" due to air entrapment seemed limited to small aggregates wetted simultaneously over their entire surface. Breakdown of large aggregates from 11 clay soils during successive wetting and drying cycles produced fragment size distributions which differed primarily by a scale factor l (essentially equivalent to the Van Bavel mean weight diameter), so that evolution of fragment size distributions could be modeled in terms of changes in l. For a given number of wetting and drying cycles, l decreased systematically with increasing plasticity index. When air-dry soil clods were slightly weakened by a single wetting event, and then allowed to "age" for six weeks at constant high water content, drop-shatter resistance in aged relative to non-aged clods was found to increase in proportion to plasticity index. This seemed consistent with the rheological model, which predicts faster plastic coalescence around small voids and sharp cracks (with resulting soil strengthening) in soils with low resistance to plastic yield and flow. A new theory of crack growth in "idealized" elastoplastic materials was formulated, with potential application to soil fracture phenomena. The theory was preliminarily (and successfully) tested using carbon steel, a ductile material which closely approximates ideal elastoplastic behavior, and for which the necessary fracture data existed in the literature.
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Or, Dani, Shmulik Friedman, and Jeanette Norton. Physical processes affecting microbial habitats and activity in unsaturated agricultural soils. United States Department of Agriculture, October 2002. http://dx.doi.org/10.32747/2002.7587239.bard.
Abstract:
experimental methods for quantifying effects of water content and other dynamic environmental factors on bacterial growth in partially-saturated soils. Towards this end we reviewed critically the relevant scientific literature and performed theoretical and experimental studies of bacterial growth and activity in modeled, idealized and real unsaturated soils. The natural wetting-drying cycles common to agricultural soils affect water content and liquid organization resulting in fragmentation of aquatic habitats and limit hydraulic connections. Consequently, substrate diffusion pathways to soil microbial communities become limiting and reduce nutrient fluxes, microbial growth, and mobility. Key elements that govern the extent and manifestation of such ubiquitous interactions include characteristics of diffusion pathways and pore space, the timing, duration, and extent of environmental perturbations, the nature of microbiological adjustments (short-term and longterm), and spatial distribution and properties of EPS clusters (microcolonies). Of these key elements we have chosen to focus on a manageable subset namely on modeling microbial growth and coexistence on simple rough surfaces, and experiments on bacterial growth in variably saturated sand samples and columns. Our extensive review paper providing a definitive “snap-shot” of present scientific understanding of microbial behavior in unsaturated soils revealed a lack of modeling tools that are essential for enhanced predictability of microbial processes in soils. We therefore embarked on two pronged approach of development of simple microbial growth models based on diffusion-reaction principles to incorporate key controls for microbial activity in soils such as diffusion coefficients and temporal variations in soil water content (and related substrate diffusion rates), and development of new methodologies in support of experiments on microbial growth in simple and observable porous media under controlled water status conditions. Experimental efforts led to a series of microbial growth experiments in granular media under variable saturation and ambient conditions, and introduction of atomic force microscopy (AFM) and confocal scanning laser microscopy (CSLM) to study cell size, morphology and multi-cell arrangement at a high resolution from growth experiments in various porous media. The modeling efforts elucidated important links between unsaturated conditions and microbial coexistence which is believed to support the unparallel diversity found in soils. We examined the role of spatial and temporal variation in hydration conditions (such as exist in agricultural soils) on local growth rates and on interactions between two competing microbial species. Interestingly, the complexity of soil spaces and aquatic niches are necessary for supporting a rich microbial diversity and the wide array of microbial functions in unsaturated soils. This project supported collaboration between soil physicists and soil microbiologist that is absolutely essential for making progress in both disciplines. It provided a few basic tools (models, parameterization) for guiding future experiments and for gathering key information necessary for prediction of biological processes in agricultural soils. The project sparked a series of ongoing studies (at DTU and EPFL and in the ARO) into effects of soil hydration dynamics on microbial survival strategy under short term and prolonged desiccation (important for general scientific and agricultural applications).