Letteratura scientifica selezionata sul tema "Lits fluidisé"
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Articoli di riviste sul tema "Lits fluidisé"
1
Miháltz, P., Zs Csikor, P. Chatellier e B. Siklódi. "Optimisation de la concentration de biomasse dans un réacteur à lit fluidisé". Revue des sciences de l'eau 14, n. 2 (12 aprile 2005): 131–45. http://dx.doi.org/10.7202/705413ar.
Testo completoAbstract (sommario):
Une étude expérimentale de la dénitrification a été réalisée sur des bioréacteurs à lits fluidisés alimentés avec un effluent dont la teneur en nitrates peut atteindre 900 mg N-NO3- /l. Des mesures ont montré, qu'à ces concentrations, il n'y a pas d'inhibition des substrats (NO3- et éthanol). Le flux de nitrates éliminé par le réacteur a atteint 10 kg N-NO3- /m3j avec pratiquement 100 % d'élimination des nitrates. Ce flux semble toutefois dépendre de la quantité de biomasse dénitrifiante sur le support de sable. Pour le contrôle optimal du procédé, il est indispensable de pouvoir - déterminer facilement la concentration massique (G) de la biomasse - éviter les valeurs extrêmes conduisant à une expansion trop importante du lit et à des limitations diffusionnelles. Une étude préalable des auteurs a servi comme base pour établir la corrélation entre le gradient de pression dans le lit, exprimé en fonction de l'écart de masse volumique (Cp), et les valeurs de G. Une corrélation a été déterminée et les constantes validées pour une gamme de G allant jusqu'à 100 mg MVS/g support. La concentration volumique de biomasse (X) a été ensuite établie à l'aide de paramètres caractérisant le comportement hydrodynamique du lit fluidisé. Dans le cas du système étudié, la valeur maximale de X est de 19 - 20 g MVS/l. Ceci correspond à des valeurs de G de 80-100 mg MVS/g support. Les corrélations obtenues peuvent servir pour le dimensionnement ainsi que pour l'optimisation de l'épaississeur du biofilm dans la conduite du réacteur.
2
Dufour, I., A. Maali, Y. Amarouchene, C. Ayela, B. Caillard, A. Darwiche, M. Guirardel et al. "The Microcantilever: A Versatile Tool for Measuring the Rheological Properties of Complex Fluids". Journal of Sensors 2012 (2012): 1–9. http://dx.doi.org/10.1155/2012/719898.
Testo completoAbstract (sommario):
Silicon microcantilevers can be used to measure the rheological properties of complex fluids. In this paper, two different methods will be presented. In the first method, the microcantilever is used to measure the hydrodynamic force exerted by a confined fluid on a sphere that is attached to the microcantilever. In the second method, the measurement of the microcantilever's dynamic spectrum is used to extract the hydrodynamic force exerted by the surrounding fluid on the microcantilever. The originality of the proposed methods lies in the fact that not only may the viscosity of the fluid be measured, but also the fluid's viscoelasticity, that is, both viscous and elastic properties, which are key parameters in the case of complex fluids. In both methods, the use of analytical equations permits the fluid's complex shear modulus to be extracted and expressed as a function of shear stress and/or frequency.
3
Ruvalcaba, J. Ramiro Rodriguez, Brigitte Caussat, Merhdji Hemati e Jean-Pierre Couderc. "Étude hydrodynamique des lits fluidisés sous vide et sous haute température". Canadian Journal of Chemical Engineering 77, n. 1 (febbraio 1999): 35–44. http://dx.doi.org/10.1002/cjce.5450770107.
Testo completo
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Chehbouni, A., J. Chaouki, C. Guy e D. Klvana. "Description et modélisation des structures globale et locale des lits fluidisés en régime turbulent". Chemical Engineering Journal and the Biochemical Engineering Journal 61, n. 2 (febbraio 1996): 73–82. http://dx.doi.org/10.1016/0923-0467(95)03029-8.
Testo completo
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King, Danielle, Hakan Başağaoğlu, Hoa Nguyen, Frank Healy, Melissa Whitman e Sauro Succi. "Effects of Advective-Diffusive Transport of Multiple Chemoattractants on Motility of Engineered Chemosensory Particles in Fluidic Environments". Entropy 21, n. 5 (4 maggio 2019): 465. http://dx.doi.org/10.3390/e21050465.
Testo completoAbstract (sommario):
Motility behavior of an engineered chemosensory particle (ECP) in fluidic environments is driven by its responses to chemical stimuli. One of the challenges to understanding such behaviors lies in tracking changes in chemical signal gradients of chemoattractants and ECP-fluid dynamics as the fluid is continuously disturbed by ECP motion. To address this challenge, we introduce a new multiscale numerical model to simulate chemotactic swimming of an ECP in confined fluidic environments by accounting for motility-induced disturbances in spatiotemporal chemoattractant distributions. The model accommodates advective-diffusive transport of unmixed chemoattractants, ECP-fluid hydrodynamics at the ECP-fluid interface, and spatiotemporal disturbances in the chemoattractant concentrations due to particle motion. Demonstrative simulations are presented with an ECP, mimicking Escherichia coli (E. coli) chemotaxis, released into initially quiescent fluids with different source configurations of the chemoattractants N-methyl-L-aspartate and L-serine. Simulations demonstrate that initial distributions and temporal evolution of chemoattractants and their release modes (instantaneous vs. continuous, point source vs. distributed) dictate time histories of chemotactic motility of an ECP. Chemotactic motility is shown to be largely determined by spatiotemporal variation in chemoattractant concentration gradients due to transient disturbances imposed by ECP-fluid hydrodynamics, an observation not captured in previous numerical studies that relied on static chemoattractant concentration fields.
6
Sabiri, Nour-Eddine, e Jacques Comiti. "Ecoulement de fluides newtoniens et non newtoniens à travers des lits fixes stratifiés". Canadian Journal of Chemical Engineering 75, n. 6 (dicembre 1997): 1030–37. http://dx.doi.org/10.1002/cjce.5450750605.
Testo completo
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Duravac. "Vacuum publications Duravac Vacuum Fluids 1986 Price List". Vacuum 36, n. 10 (ottobre 1986): 748. http://dx.doi.org/10.1016/0042-207x(86)90543-9.
Testo completo
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Major, Laura. "“There Were Some Things That Did Not Change”: Postcolonial Reckonings with Gender in The No. 1 Ladies’ Detective Agency Series". College Literature 51, n. 1 (gennaio 2024): 84–105. http://dx.doi.org/10.1353/lit.2024.a917865.
Testo completoAbstract (sommario):
Abstract: Though seemingly romanticized, Alexander McCall Smith’s popular No. 1 Ladies’ Detective Agency series reckons with the gendered realities of postcolonial Botswana by creating a paradox that resists a simple reading of gender and feminism in the locale it inhabits. The series’ heroine, though traditional, defies gender roles, practicing a situated and culturally specific version of women’s empowerment. Indeed, when discussing gender in postcolonial Africa, we should not apply Western notions of feminism. Homi Bhabha’s notion of hybridity, which recognizes locality, fluidity, and mutual influence in the construction of postcolonial identity, is a useful lens through which to understand the series’ paradoxes.
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Wang, Jie, Ming Jun Xu, Lin Li Shi, Qi Shi, Yong Chao Wang e Yi Xiang Duan. "A Computer-Controlled In Situ Analysis Instrument Based on Laser Induced Breakdown Spectroscopy". Applied Mechanics and Materials 556-562 (maggio 2014): 561–66. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.561.
Testo completoAbstract (sommario):
A portable LIBS device capable of analyzing material component especially for drilling fluids in the drilling site was designed and assembled. A position adjustable apparatus was developed, which permits the applications in outdoor environments. The alkali metal elements such as potassium (K), calcium (Ca), sodium (Na), magnesium (Mg), aluminum (Al), have been detected in the drilling fluids using the newly developed portable LIBS device. The results show that the device well performs qualitative analysis, and also has potential predominance for the quantitative analysis in-situ.
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Esen, Oğul, Miroslav Grmela, Hasan Gümral e Michal Pavelka. "Lifts of Symmetric Tensors: Fluids, Plasma, and Grad Hierarchy". Entropy 21, n. 9 (18 settembre 2019): 907. http://dx.doi.org/10.3390/e21090907.
Testo completoAbstract (sommario):
Geometrical and algebraic aspects of the Hamiltonian realizations of the Euler’s fluid and the Vlasov’s plasma are investigated. A purely geometric pathway (involving complete lifts and vertical representatives) is proposed, which establishes a link from particle motion to evolution of the field variables. This pathway is free from Poisson brackets and Hamiltonian functionals. Momentum realizations (sections on T * T * Q ) of (both compressible and incompressible) Euler’s fluid and Vlasov’s plasma are derived. Poisson mappings relating the momentum realizations with the usual field equations are constructed as duals of injective Lie algebra homomorphisms. The geometric pathway is then used to construct the evolution equations for 10-moments kinetic theory. This way the entire Grad hierarchy (including entropic fields) can be constructed in a purely geometric way. This geometric way is an alternative to the usual Hamiltonian approach to mechanics based on Poisson brackets.
Tesi sul tema "Lits fluidisé"
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Nacef, Saci. "Hydrodynamique des lits fluidisés gaz-liquide-solide". Vandoeuvre-les-Nancy, INPL, 1991. http://www.theses.fr/1991INPL056N.
Testo completoAbstract (sommario):
@L'objectif de ce travail est l'étude de l'hydrodynamique des réacteurs à lit fluidisé gaz-liquide-solide à co-courant ascendant de gaz et de liquide et à phase liquide continue, en s'intéressant particulièrement aux effets d'échelle, de distributeur et de la présence d'inhibiteurs de coalescence. Une banque de données sur les paramètres hydrodynamiques a été établie ; elle contient actuellement près de 7000 données dues aux travaux de 38 équipes, dont notre groupe. L'étude expérimentale porte sur le minimum de fluidisation, les régimes d'écoulement et les retentions des phases ; elle a été effectuée dans une colonne d'assez grande taille (diamètre 0,15 m, hauteur 5 m). Nous avons effectué des mesures avec quatre configurations d'un distributeur à plaque perforée et un distributeur à mélangeur statique. Les liquides utilisés sont l'eau et des solutions aqueuses diluées de différents alcools ou de sel. Les diamètres de particules sont compris entre 1 et 4 mm. Le type de distributeur et l'inhibiteur de coalescence ont des effets très importants sur les régimes d'écoulement et la vitesse minimale de fluidisation triphasique : en particulier, nous décrivons un régime d'écoulement nouveau, le pistonnage. Nous proposons une corrélation originale pour estimer la vitesse minimale de fluidisation pour l'eau. En ce qui concerne les rétentions de phases, les effets du distributeur et d l'inhibiteur de coalescence sont également très influents, surtout sur la rétention gazeuse et la porosité du lit. Nous proposons une technique de caractérisation du distributeur basée sur le concept de vitesse de glissement. Les corrélations empiriques et les modèles de prédiction fondés sur les modèles de trainées de bulles, d'une manière générale, sont peu satisfaisantes. Nous proposons quelques directions de recherches pour tenter de remédier à cet état
2
Sabiri, Nour-Eddine. "Etude de l'écoulement des fluides newtoniens et non newtoniens à travers les milieux poreux : lits fixes et lits fluidisés". Nantes, 1995. http://www.theses.fr/1995NANT2052.
Testo completoAbstract (sommario):
Dans ce memoire nous proposons un modele permettant d'evaluer les chutes de pression lors de l'ecoulement de fluides non newtoniens purement visqueux a travers les milieux poreux. Il est base sur une representation capillaire du milieu prenant en compte sa structure au travers de deux parametres: la tortuosite et la surface specifique dynamique. Le comportement rheologique des fluides, sur l'ensemble de l'intervalle de variation du gradient de vitesse determine a l'aide du modele, est represente par une serie de lois puissance. Ce modele est valide experimentalement pour des lits fixes de spheres et de particules non spheriques de formes diverses dans un large domaine de nombre de reynolds allant du regime de darcy au regime inertiel. Ce modele a egalement ete teste sur des milieux poreux stratifies. Des lits fixes tasses de plaquettes ont ete etudies selon deux configurations opposees particule-ecoulement. Dans les deux configurations nous avons mesure experimentalement les chutes de pression et determine les parametres structuraux du milieu, puis nous avons analyse les differences concernant leur comportement hydrodynamique. Le modele propose donne des resultats satisfaisants dans les deux configurations. Nous avons ensuite effectue une etude concernant les milieux poreux reticules de tres forte porosite et etudie sa limite de validite dans ce cas. Dans une deuxieme partie nous proposons d'etendre ce modele aux lits fluidises en prenant en compte la variation de la tortuosite en fonction de la porosite durant l'expansion pour chaque type de lit. Le modele a ete teste avec des fluides newtoniens et non newtonien purement visqueux sur des lits de spheres et de plaquettes. Il permet une bonne evaluation de la vitesse minimale de fluidisation et une bonne representation de l'expansion dans un domaine de porosite qui a ete precise dans chacun des cas
3
Aguillon, Martinez Javier. "Étude du comportement hydrodynamique des lits fluidisés circulants avec injection d'air secondaire". Compiègne, 1995. http://www.theses.fr/1995COMPD826.
Testo completoAbstract (sommario):
L'hydrodynamique du procédé de combustion de charbon dans un lit fluidisé circulant est étudiée. Cette étude vise, en particulier, l'effet de l'injection d'air secondaire sur le comportement de la suspension. Nous avons utilisé une installation pilote en similitude avec la centrale thermique de Carling (Lorraine, France). L'étude a mis en évidence l'existence de deux régimes hydrodynamiques séparés par une concentration critique de solide. La comparaison des diagrammes de régime, avec et sans air secondaire, a montré que cette concentration est unique dans les deux cas. La structure de l'écoulement diphasique a été étudiée au moyen d'une sonde de prélèvement non-isocinétique et d'une sonde à fibres optiques placées à trois niveaux de la colonne. La combinaison des techniques de prélèvement de solide et de mesure des vitesses de particules a permis de développer une méthode pour estimer la concentration locale de solide. L'étude des profils de flux massiques de solide a montré que la distribution des iso-flux dépend sensiblement de la vitesse superficielle du gaz. De plus, nous avons constaté que ces iso-flux sont indépendants de l'injection d'air secondaire. Par ailleurs, nous avons constaté que la configuration d'arrivée d'air secondaire dans la colonne, est très importante. Pour réduire l'influence de cette injection sur la structure de l'écoulement, il faut éviter la formation de jets au niveau de l'injection d'air secondaire. L'ensemble des informations obtenues dans cette étude, nous a permis de proposer des modèles de profils de flux massique et de concentration de solide sous forme de corrélations adaptées à une extrapolation industrielle.
4
Motte, Jérôme. "Étude du comportement hydrodynamique de mélanges multi-solides dans un lit fluidisé circulant". Compiègne, 1996. http://www.theses.fr/1996COMPD947.
Testo completoAbstract (sommario):
Cette recherche s'était donnée comme objectif de caractériser l'hydrodynamique, en lit fluidisé circulant (LFC), de mélanges d'espèces particulaires se différentiant par la masse volumique et/ou la taille. L'installation expérimentale utilisée, d'échelle semi-industrielle se compose d'une colonne de transport de 8 m de haut, connectée à un système de recyclage des solides comprenant une vanne non-mécanique de réinjection (jambe en L). Une telle configuration permettait de contrôler indépendamment vitesse de gaz et débit de solide dans des gammes respectives de 3,3 à 6,6 m/s et de 0 à 200 kg/m2/s. Trois solides différents ont été utilisés : un sable (198 um ; 2650 kg/m3), un minerai de fer (83 m ; 5200 kg/m3) et un support de catalyseur de craquage catalytique (70 m ; 1200 kg/m3). L'étude s'est focalisée sur la zone dite établie de la colonne pour laquelle on a pu démontrer, qu'en plus d'une concentration uniforme de la suspension, la structure d'écoulement y était axialement invariante. Cette région apparut comme fragile puisque sensible a l'introduction d'une sonde de prélèvement servant à la détermination des flux locaux de solide. La réversibilité du phénomène a néanmoins montre que la structure d'écoulement perturbée tendait à se ré-établir. L'existence systématique de trois régimes hydrodynamiques a été confirmée pour tous les solides transportés : à taux de charge croissant, le premier est le Régime des Profils semblables (RPS), auquel succède ensuite le Régime de Transition (RT) puis le Régime Dense (RD). L'analyse des comportements en mélanges a mise en évidence une ségrégation radiale partielle des phases particulaires, se manifestant de façon inégale suivant les différences de masse volumique ou de taille, tout en étant étroitement liée aux caractéristiques propres de chacun des régimes. En retour, ces derniers ont été notablement affectes par le ratio de circulation des espèces. Cet effet s'est alors traduit par un abaissement significatif des conditions de transition de régime avec l'augmentation de la fraction de fines/légères particules.
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Saberi, Babak. "Développement des techniques de mesure dans les écoulements polyphasiques et les lits fluidisés". Compiègne, 1996. http://www.theses.fr/1996COMPD944.
Testo completoAbstract (sommario):
Le présent travail a été effectué dans l'objectif de mettre au point des techniques de mesure pour la détermination des grandeurs hydrodynamiques principales dans les systèmes de lit fluidisés et lits fluidisés circulants. Ces grandeurs sont la vitesse de particules, la vitesse et la taille des bulles, le flux massique de solide, et la concentration de particules. L'étude sur la mesure de la vitesse de particules a été orientée vers l'adaptation d'une technique de sonde à fibres optiques, à la mesure de la vitesse dans les lits fluidisés circulants. Le travail a montré que le facteur de temps de mesure joue un rôle primordial dans l'obtention des vitesses moyennes fiables, dans la zone de forte perturbation, proche de la paroi du lit. La faisabilité de la mesure séparée des composantes de vitesse descendantes et ascendantes dans cette zone a aussi été démontrée. Un système de mesure à fibres optiques a été conçu et mis au point pour la mesure de la vitesse et de la taille des bulles. La performance de la sonde a été vérifiée par des mesures visuelles dans un lit bidimensionnel. L'effet de la fluctuation des signaux dus à la présence de solide et des paramètres d'acquisition ont été étudiés. La sonde a aussi été utilisée dans un lit fluidisé tridimensionnel et une qualité de mesure satisfaisante a été acquise. Une technique de prélèvement, à vitesse d'aspiration contrôlée, a été développée pour la mesure du flux massique de solide dans les lits fluidisés circulants. En utilisant une sonde appropriée, cette méthode donne le flux net avec une précision satisfaisante. Un nouveau système de mesure de la concentration de solide, à fibres optiques, a été expérimenté. Deux types d'étalonnage : ex-situ et in-situ ont été mis au point. L'étalonnage ex-situ a permis d'obtenir une courbe d'étalonnage couvrant une large plage de concentration. L'application de la technique in-situ élimine les effets perturbateurs et fournit une courbe d'étalonnage plus précise dans la plage des concentrations rencontrées dans le LFC. Certaines des techniques développées dans le présent travail ont été utilisées pour la mesure des propriétés des écoulements gaz-solide dans des installations industrielles.
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Saberi, Shadi. "Modélisation des systèmes à écoulement gaz-solide : application aux cas des réacteurs à lit fluidisé circulant". Compiègne, 1996. http://www.theses.fr/1996COMPD945.
Testo completoAbstract (sommario):
Ce travail a été consacré au développement d'un modèle théorique dans le but de décrire le comportement des écoulements gaz-solide concentrés dans les lits fluidisés circulants (LFC), en mettant l'accent sur le comportement des clusters ou des ensembles de particules. Cette modélisation a été effectuée en utilisant l'approche eulérienne pour les deux phases gazeuse et solide. Un modèle de fermeture pour la phase solide a été proposé en définissant une énergie cinétique liée aux fluctuations macroscopiques. L'équation de transport de cette énergie, comprend une viscosité apparente pour la phase solide, différente de la viscosité produite due aux collisions. En vue de déterminer cette viscosité, un modèle empirique, basé sur le concept de longueur de mélange de la phase solide a été utilisée. La longueur de mélange a été estimée par la mesure des cofluctuations de vitesses axiales et des profils de vitesses moyennes axiales dans la zone établie d'une maquette LFC. Le modèle a été évalué en effectuant quelques exemples d'applications numériques sur des géométries bidimensionnelles, correspondants à différentes zones et échelles d'écoulement dans les systèmes LFC. Il a permis de décrire quelques aspects caractéristiques du comportement de la phase solide. Un degré significatif de ségrégation entre les phases a été observé, avec des concentrations plus importantes au niveau des parois. Le modèle doit être complété par des fermetures pour les corrélations entre les vitesses de gaz et de solide, l'anisotropie des fluctuations de vitesse, et les variations de la longueur de mélange de la phase solide.
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Helland, Eivind. "Etude des écoulements fluide-solide dans les lits fluidisés : simulation numérique et analyse des hétérogénéités". Aix-Marseille 1, 2000. http://www.theses.fr/2000AIX11053.
Testo completoAbstract (sommario):
L'objectif de cette thèse est de contribuer à une meilleure compréhension des écoulements fluide-particules dans un réacteur à lit fluidisé. Pour cela, nous avons choisi de développer un code de calcul basé sur l'approche Eulérienne-Lagrangienne dans une configuration bidimensionnelle. Cette méthodologie simplifiée permet d'accéder aux grandeurs dynamiques des phases et suivre les trajectoires de chaque particule. Nous avons étudié deux cas distincts. Un premier, relatif à un écoulement diphasique fluide-solide pour une concentration de solide faible (<10%), porte sur l'analyse des hétérogénéités et des structures de clusters. Le second cas correspond à un état de lit fluidisé dense pour mieux comprendre la naissance des bulles et le comportement des hétérogénéités dans les lits fluidisésThe goal of this work is to contribute to a better understanding of gas-particle flows. We have developed a code based on the Eulerian-Lagrangian approach in a two-dimensional configuration. This method allows us to follow the trajectory of each particle in the riser in order to study the discrete behavior of the solid phase. We have investigated the gas-solid flow both in diluted and dense fluidized beds. In the first case, we studied the clustering behavior of the particles caused by hydrodynamics and modified by collision characteristics. In the second, we investigated a dense bed in order to get a better understanding of the bubble formation, which is linked to porosity perturbations within the bed
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Quan, Haiqin. "Etude théorique et expérimentale des micro-lits fluidisés : hydrodynamique et modélisation numérique". Thesis, Ecole centrale de Lille, 2017. http://www.theses.fr/2017ECLI0027/document.
Testo completoAbstract (sommario):
Le travail de thèse porte sur l’étude et la mise au point de nouvelles technologies et de procédés miniaturisés en lit fluidisé. Ce procédé représente une véritable rupture technologique devant les procédés à lits fluidisé traditionnels et offre de nombreux avantages : surface d’échange élevée, bon mélange gaz-solide dans le réacteur, utilisation de faible quantité de produit, coût faible... La présente étude regroupe trois études : conception des micro-lits fluidisés, diagnostic et analyse de l’hydrodynamique des couches fluidisées et modélisation numérique.Dans ce travail quatre MFBs (Micro Fluidized Bed) de 20-4 mm ont été étudiés et comparés à deux réacteurs relativement grands de 100-50 mm. Le rapport du diamètre du réacteur à la hauteur statique des particules (Hs/Dt) a été fixé entre 1-4. La vibration mécanique a été appliquée dans le réacteur de 4 mm. Une nouvelle méthode de diagnostic des régimes de fluidisation a été développée. Elle est basée sur les analyses des fluctuations de pression et le traitement du signal. La modélisation numérique suivant la méthode Eulérien-Eulérien (2D) a été développée. Les résultats obtenus permettent d’identifier six régimes d'écoulement: lit fixe, bouillonnant, bouillonnant/pistonnage, pistonnage, pistonnage/turbulent et bouillonnant/turbulent. On note une fluidisation partielle autour de Hs/Dt=1-2, tandis que le régime de pistonnage s’installe rapidement après le minimum de fluidisation à Hs/Dt=3-4. Dans le réacteur de 4 mm, la fluidisation des particules du groupe B de Geldart montre une meilleure qualité. Les résultats numériques (modélisation) montrent une très bonne concordance avec les données expérimentalesMicro-fluidized bed (MFB) exhibits great advantages such as a large specific contact surface, a fast dissipation of heat (ideal for exothermic reactions) and better mass and heat transfers, but suffers from difficulties in precise control and shows strong frictional wall effect. Present study was conducted experimentally and numerically to understand fundamental hydrodynamics in MFBs. Experimental work was carried out in four MFBs of 20-4 mm compared to two relatively large beds of 100-50 mm using three types of particles (B347: 347 μm, 2475 kg/m3; B105: 105 μm, 8102 kg/m3; A63: 63.8μm, 2437 kg/m3). The ratio of static bed height (Hs) to bed diameter (Dt) was set between 1-4. Mechanical vibration was applied to the 4 mm bed. A new method for flow regimes diagnosis was developed based on pressure fluctuation analyses, which mainly include calculating the standard deviation, autocorrelation function, probability density function, power spectral density function and time-frequency analysis. Numerical simulations were performed under Eulerian-Eulerian framework in 2D. Six flow regimes were identified: fixed bed, bubbling, bubbling/slugging, slugging, slugging/turbulent and bubbling/turbulent. Partial fluidization is encountered at Hs/Dt=1-2 while slugging prevails quickly after minimum fluidization at Hs/Dt=3-4. In the 4 mm bed, fluidization of B347 particles show better fluidization quality, while an increase in Umf is observed for B105 and A63 particles. Mechanical vibration reduces partial fluidization, thus resulting in larger ΔP and smaller Umf. A larger Umb and a delayed Uc were obtained as well. Results by simulations agree reasonably well with experimental data
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Özel, Ali. "Simulation aux grandes échelles des lits fluidisés circulants gaz-particule". Thesis, Toulouse, INPT, 2011. http://www.theses.fr/2011INPT0090/document.
Testo completoAbstract (sommario):
Les simulations numériques des équations d’Euler deux-fluides réalisé sur des maillages grossiers éliminent les structures fins d’écoulement gaz-solide dans les lits fluidisés. Pour précisément estimer l’hydrodynamique globale de lit, il faut proposer une modélisation qui prend en compte les effets de structure non-résolue. Dans ce but, les maillages sont raffinés pour obtenir le résultat de simulation pleinement résolue ce que les grandeurs statistiques ne modifient plus avec un autre raffinement pour le lit fluidisé périodique dilué gaz-particules sur une géométrie 3D cartésienne et ce résultat est utilisé pour tests "a priori". Les résultats de tests "a priori" montrent que l’équation filtrée de la quantité de mouvement est effectuée mais il faut prendre en compte le flux de la fraction volumique de solide de sous-maille en raison de l’interaction locale de la vitesse du gaz et la fraction volumique de solide pour la force traniée. Nous proposons les modèles fonctionnels et structurels pour le flux de la fraction volumique de solide de sous-maille. En plus, les modèles fermetures du tenseur de sous-maille de la phase dispersée sont similaires aux modèles classiquement utilisés en écoulement turbulent monophasique. Tous les modèles sont validés par test "a priori" et "a posteriori"Eulerian two fluid approach is generally used to simulate gas-solid flows in industrial circulating fluidized beds. Because of limitation of computational resources, simulations of large vessels are usually performed by using too coarse grid. Coarse grid simulations can not resolve fine flow scales which can play an important role in the dynamic behaviour of the beds. In particular, cancelling out the particle segregation effect of small scales leads to an inadequate modelling of the mean interfacial momentum transfer between phases and particulate shear stresses by secondary effect. Then, an appropriate modelling ac counting for influences of unresolved structures has to be proposed for coarse-grid simu-lations. For this purpose, computational grids are refined to get mesh-independent result where statistical quantities do not change with further mesh refinement for a 3-D peri-odic circulating fluidized bed. The 3-D periodic circulating fluidized is a simple academic configuration where gas-solid flow conducted with A-type particles is periodically driven along the opposite direction of the gravity. The particulate momentum and agitation equations are filtered by the volume averaging and the importance of additional terms due to the averaging procedure are investigated by budget analyses using the mesh independent result. Results show that the filtered momentum equation of phases can be computed on coarse grid simulations but sub-grid drift velocity due to the sub-grid correlation between the local fluid veloc- ity and the local particle volume fraction and particulate sub-grid shear stresses must be taken into account. In this study, we propose functional and structural models for sub- grid drift velocity, written in terms of the difference between the gas velocity-solid volume fraction correlation and the multiplication of the filtered gas velocity with the filtered solid volume fraction. Particulate sub-grid shear stresses are closed by models proposed for single turbulent flows. Models’ predictabilities are investigated by a priori tests and they are validated by coarse-grid simulations of 3-D periodic circulating, dense fluidized beds and experimental data of industrial scale circulating fluidized bed in manner of a posteriori tests
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Sellami, Jawhar. "Conception, mise en œuvre, développement et modélisation de réacteurs de précipitation utilisant des lits fluidisés". Thesis, Vandoeuvre-les-Nancy, INPL, 2008. http://www.theses.fr/2008INPL088N/document.
Testo completoAbstract (sommario):
L’objectif de ce travail est de concevoir, développer, mettre en œuvre et optimiser une technologie continue permettant une bonne maîtrise des réactions de précipitation, processus chimique rapide donnant naissance à une phase solide. Ce précipiteur est un réacteur multifonctionnel à lit fluidisé qui n’a pas connu le même essor que les cristallisoirs à lit fluidisé. Deux approches expérimentales ont été adoptées : (1) l’étude des phénomènes de mélange des réactifs et (2) l’étude de l’influence des conditions opératoires sur la précipitation d’un produit modèle. Le produit modèle choisi pour cette étude est la calcite, le polymorphe le plus stable du carbonate de calcium qui possède trois polymorphes : la vaterite, l’aragonite et la calcite. Cette dernière est obtenue via la réaction de précipitation entre les solutions de chlorure de calcium et de carbonate de sodium à une température de 20° C et en présence d’un agent complexant (citrate de sodium) pour orienter la forme cristalline recherchée. Une étude cinétique a été menée pour la détermination des cinétiques de nucléation et de croissance cristalline de la calcite en milieu citrate. Le réacteur à lit fluidisé, de volume de 10 L, constitué de deux zones : cylindrique de fluidisation et de classification des particules et cylindro-conique de décantation, a été conçu au Laboratoire des Sciences du Génie Chimique. L’étude du mélange global, réalisée à l’aide de la réaction de décoloration acide-base et l’étude hydrodynamique, réalisée à l’aide de suspensions de microbilles, ont permis de développer et d’optimiser ce réacteur multifonctionnel. La faisabilité de la précipitation de la calcite en lit fluidisé a été ensuite vérifiée. Les expériences effectuées en présence d’une charge solide conséquente ont permis de diminuer la sursaturation et de favoriser la croissance cristalline. Le précipité obtenu présente une distribution de taille relativement étroite et la forme des particules obtenues est sensiblement sphérique. Enfin, des essais de modélisation du réacteur à lit fluidisé ont été entrepris pour réaliser des simulations à l’aide du code de calcul commercial FLUENTThe objective of this work is to conceive, develop, implement and to optimize a continuous technology allowing a good control of the precipitation reactions, fast chemical process, giving birth to a solid phase. This precipitor is a multipurpose engine with fluidized bed which did not make the same great strides like fluidized bed crystallizers. Two experimental approaches were adopted : (1) the study of the mixing phenomena of the reagents and (2) the study of the influence of the operating conditions on the precipitation of a model product. The model product selected for this study is the calcite, the polymorphic most stable phase of calcium carbonate which has three polymorphs: vaterite, aragonite and calcite. The latter is obtained by the precipitation reaction between the calcium chloride and sodium carbonate solutions at a temperature of 20° C and a complexing agent (sodium citrate) to have the required crystalline form. A kinetic study was undertaken for the determination of the nucleation and crystalline growth kinetics of calcite in citrate medium. The fluidized bed reactor, having a volume of 10 L, consisted of two zones: cylindrical for fluidization and classification of the particles and cylindro-conical for decantation, was conceived at the Chemical Engineering Science Laboratory (LSGC). The study of mixing phenomena, performed using the decoloration acid-base reaction and the hydrodynamic study, carried out using suspensions of glass microballs, made it possible to develop and optimize this multipurpose reactor. The feasibility of the precipitation of calcite in a fluidized bed was then checked. The experiments carried out in the presence of an important solid content made it possible to decrease supersaturation and to support the crystalline growth. The precipitate obtained presents a relatively narrow size distribution and the particle shape is appreciably spherical. Lastly, the modelling tests of the fluidized bed reactor were undertaken to carry out simulations using the FLUENT commercial computer code
Libri sul tema "Lits fluidisé"
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J, Anthony E., a cura di. Fluidized bed combustion. New York: M. Dekker, 2004.
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Deruelle, Nathalie, e Jean-Philippe Uzan. Fields and matter. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198786399.003.0026.
Testo completoAbstract (sommario):
This chapter discusses the laws of relativistic dynamics for continuous media, namely, the ‘fields’ that mediate interactions in relativistic theories, and also fluids. The concept of field introduced by Faraday and formalized by Maxwell lies at the heart of contemporary physics. The intuitive idea behind this concept is, on the one hand, that massive bodies, owing to their internal constitution, impregnate space with what are called ‘fields’, potential entities which are only revealed by the presence of other bodies possessing the same type of charge. On the other hand, there is the idea that the interactions between these bodies, which determine their motion, are effected through the intermediary of these fields. This physical concept of a field is represented mathematically by one or several functions of points p in Minkowski spacetime.
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Combustion and gasification in fluidized beds. Boca Raton, FL: Taylor & Francis, 2005.
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New Edition Diverticular Diet Cookbook, Meal Plan and Food List: The Detailed Guide to Living with Diverticular Disease. Containing Food to Eat and Avoid with Recipes Ranging from Clear Fluids to Foods with Low Residue and High Fiber Content. Independently Published, 2022.
Cerca il testo completoCapitoli di libri sul tema "Lits fluidisé"
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Butcher, Tim A. "Magnetic Action at a Distance: Fields, Gradients and Currents in Fluids". In Topics in Applied Physics, 11–21. Cham: Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-58376-6_2.
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AbstractA brief introduction to the main concepts that underpin the interaction of magnetic fields with fluids is given. The effect of the main magnetic force densities, the Kelvin force in a magnetic field gradient and the Lorentz force in magnetohydrodynamics is discussed. The focus lies on incompressible fluids that are enclosed by solid walls such as are prevalent in microfluidic systems. These are only influenced by rotational body forces.
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Casey, James, e Marcel J. Crochet. "List of Publications of Paul M. Naghdi". In Theoretical, Experimental, and Numerical Contributions to the Mechanics of Fluids and Solids, 33–47. Basel: Birkhäuser Basel, 1995. http://dx.doi.org/10.1007/978-3-0348-9229-2_3.
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Abidi, Sophia. "3 Between communities and identities". In Living at Night in Times of Pandemic, 47–62. Bielefeld, Germany: transcript Verlag, 2024. http://dx.doi.org/10.14361/9783839467268-004.
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In this article, Sophia Abidi maps out an exhaustive list of cultural areas of Berlin and the different clubbing scenes and nightlife subcultures it generates. Through insightful ethnographic fieldwork of her PhD thesis project and qualitative interviews with young people participating in the scene collected through her research, she reflects on the place of leisure-focused lifestyles within the composition of sub-communities. This project also refers to analysing the hedonistic behaviours within Berlin's prominent techno and queer scene and its correlation with social and cultural identities. By studying different parties and venues, this paper analyses the diversity available in fashion, types of drugs, the genre of music or social interactions. It examines the impact of a subculture and its characteristics on a multifaceted nightlife. This paper aims to relate the importance of Berlin's nightlife as a strategic cultural hub, allowing space for young people to be actors in the techno and queer scene to explore their individual and collective identities. It brings a better understanding of the fluidity and diversity of the leisure-life-related events and places in Berlin and helps evaluate the limits these scenes generate.
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"List of Figures". In Fluidity, a cura di Marcel Finke e Kassandra Nakas, 295–300. Dietrich Reimer Verlag, 2022. http://dx.doi.org/10.5771/9783496030614-295.
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"Duality, Fluidity, and Equilibrium". In Taken from the Lips: Gender and Eros in Mesoamerican Religions, 13—Ins4. BRILL, 2006. http://dx.doi.org/10.1163/9789047408680_006.
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Schulkin, Jay. "The Concept of Sport". In Sport. Columbia University Press, 2016. http://dx.doi.org/10.7312/columbia/9780231176767.003.0001.
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"List of Figures and Illustrations". In Global Fluids, viii. Berghahn Books, 2018. http://dx.doi.org/10.2307/j.ctvw04bzv.3.
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"List of Symbols". In Life in Moving Fluids, 403–6. Princeton University Press, 2020. http://dx.doi.org/10.2307/j.ctvzsmfc6.23.
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"List of algorithms". In Molecular Simulation of Fluids, 567–69. Elsevier, 2024. http://dx.doi.org/10.1016/b978-0-323-85398-9.00005-8.
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Witten, T., e P. Pincus. "Polymer molecules". In Structured Fluids, 41–82. Oxford University PressOxford, 2004. http://dx.doi.org/10.1093/oso/9780198526889.003.0003.
Testo completoAbstract (sommario):
Abstract In this chapter we have our first in-depth encounter with a specific fluid structure: the flexible chain molecules known as polymers. The basis for much of their distinctive behaviour lies in their flexibility and randomness. This chapter focus on the properties of individual molecules that embody this flexibility and randomness. The next chapter focuses on the further properties that emerge when large numbers of polymers interact in a liquid. There we will also treat the basic motions of a polymer solution: diffusion and flow. The Preface notes a number of other texts covering these polymer phenomena.
Atti di convegni sul tema "Lits fluidisé"
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Nogues, M., M. Valles, M. Bourouis, D. Boer e A. Coronas. "Absorption-Compression Heat Pump for Space Heating and Cooling Using Organic Fluids". In ASME 2000 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/imece2000-1290.
Testo completoAbstract (sommario):
Abstract The combination of compression and absorption technologies can provide heat pumps with high efficiency and a wide operating range. The aim of this research project lies in the development and testing of a gas-fired double effect absorption-compression heat pump working with organic pairs for space heating and cooling. For these applications, the use of suitable organic working pairs makes possible heat pump operation at higher temperature lifts than that of conventional water-lithium bromide systems. In our research, the combination Methanol and Tetraethylenglycoldimethylether (TEGDME) has been selected as working pair. The heat pump is targeted to operate in both cooling and heating modes. Therefore, the basic structure of the heat pump is an absorption-compression double effect cycle for cooling mode, that can be switched to a single effect cycle, in order to achieve the required higher temperature lift for the heating operation. The nominal working conditions for cooling are 5°C at the evaporator and 35 to 45°C at me absorber-condenser. These conditions can be achieved with a double effect absorption-compression cycle. Different solution circuit flow configurations as serial, parallel and reverse flow have been considered. The heating operation of the heat pump aims at a temperature of the useful delivered heat between 45 and 60°C for an evaporator temperature of 0°C. In order to achieve the required temperature lift with an attractive performance (COP in the heating mode higher than unity), the unit should operate as a single effect absorption-compression heat pump. The performance analysis was based on a thermodynamic model considering the equilibrium properties of the working pair and energy and mass balances in the different components. Results in both operating modes have been evaluated in terms of the solution flow rate, the coefficient of performance COP and the primary energy ratio PER. Very interesting performances are found even for high temperature lifts. The serial flow configuration has been selected due to its good performance and technological aspects. This work forms part of the project CLIMABGAS. A prototype of this heat pump is under construction for a cooling power of 20 kW and a heating power of 24.5 kW.
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Shiari, Behrouz, Mahdi M. Sadeghi, Ali Darvishian e Khalil Najafi. "A Discrete Model for an Electrostatically Driven Micro-Hydraulic Actuator". In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-39019.
Testo completoAbstract (sommario):
High-force, large-deflection actuators are critical for devices such as valves and pumps used in micro-fluidic systems. The major technical impediment in improving the performance of the micro-actuators lies in the lack of understanding the physical phenomena and their interactions of electric, mechanical, and fluidic fields for performing their intended functions. Because of the complexity of the actuator, the fully coupled numerical analysis such as finite element analysis is extremely expensive. Here, we introduce a discrete model of an Electrostatic Micro-Hydraulic (EMH) actuator. The model considers all dynamic forces which are involved in a time operation of the hydraulic actuator cell and covers three major physics: electrostatic, mechanical and fluidic. The physics have been coupled together to investigate the dynamic of the device. The discrete dynamic model developed in this work may be used for simple yet accurate predictions of dynamic performance of such actuators, and is preferable to more complicated and very expensive coupled numerical models. The analysis relies on physics-based equations and can be modified to accommodate different chamber geometries, different material properties and different working fluids. Results from the analytical model compare favorably with experimental measurements.
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Liu, Jing, e Yang Yang. "Cryogenic and Fluidic Ways Lead to Low Cost Micro/Nano Devices". In ASME 2009 7th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2009. http://dx.doi.org/10.1115/icnmm2009-82143.
Testo completoAbstract (sommario):
Building systems as compactly as possible has been a major theme in modern science and engineering practices. However, such enthusiastic endeavor often encounters big troubles due to high cost and complexity of the process it involves. Part of the reasons comes from the methodology itself, the fabrication, designing and characterization procedure etc. Among various disciplines to making micro/nano object, those enabled from the thermal and hydrodynamic science plays a rather important role. In this article, we will illustrate a cryogenic way for realizing a group of different micro/nano devices which can be implemented as mechanical, hydraulic, electrical, or optical functional units. The basic principle of the method lies in the formation of ice crystals in small area, from which micro/nano aqueous objects or signals transmitting across them can be blocked, manipulated and analyzed. In this way, a series of micro/nano devices such as freeze tweezer, ice valve, freeze-thaw pump, electrical or optical signal switch and micro thermal analyzer etc. can be developed via a rather simple and low cost way. As examples, some latest advancement made in the authors’ lab will be reviewed. Their innovative applications in a wide variety of micro/nano engineering fields will be discussed. Further, to illustrate the low cost way to directly manufacture micro/nano objects, we will explain a bubble fabrication method whose basic principle lies in the chemical reaction occurring at the fluidic interfaces between two or more soap adjacent bubbles. A unique virtue of the bubble is that it can have a rather huge diameter however an extremely small membrane thickness, whose smallest size can even reach nano scale. Therefore, the administrated chemical reaction in the common interface of the contacting bubbles would lead to products with extremely small size. Particularly, all these results were achieved via a rather straightforward way. The bubble builds up a bridge between the macroscopic manipulation/observation and the fabrication in small world. Several typical micro structures as fabricated in the lab will be illustrated. As a flexible, easily controllable, and low cost method, the bubble fabrication can possibly be developed as a routine strategy for making micro/nano structures in the near future.
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Mahat, Meg, Tae Y. Choi, Nasrasadani Seifolah e Arup Neogi. "Dual Pump Femtosecond Laser Induced Plasma". In ASME 2008 Heat Transfer Summer Conference collocated with the Fluids Engineering, Energy Sustainability, and 3rd Energy Nanotechnology Conferences. ASMEDC, 2008. http://dx.doi.org/10.1115/ht2008-56096.
Testo completoAbstract (sommario):
Laser-induced breakdown spectroscopy (LIBS) can provide a noncontact way of inspecting a specimen including distinct signature of atomic composition of the sample. Ultra-short pulse laser enables characterization of any materials by utilizing the multiphoton process, which is a dominant carrier generation mechanism for dielectric materials. Additionally, femtosecond LIBS yields low background and better defined atomic lines than the nanosecond LIBS. We have performed a time-resolved emission intensity measurement for an iron oxide (Fe3O4, magnetite). The emission intensity has the peak value at 100 ps time delay, signifying that the succeeding pump beam is interacting with the plasma generated in the vicinity of the sample by the preceding beam. The dual pulses significantly enhance the atomic emission as compared to single pulse excitation and enables ultrafast time-resolved spectroscopy.
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Wang, Jiaqi, Hirofumi Miki, Kean C. Aw e Rajnish N. Sharma. "A New Diffuser/Nozzle Structure With Extended Sidewalls for Maximising the Valveless Micropump Performance". In ASME 2014 12th International Conference on Nanochannels, Microchannels, and Minichannels collocated with the ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/icnmm2014-21325.
Testo completoAbstract (sommario):
A micropump is a crucial component in a microfluidic device, as it could generate accurate tiny amounts of fluid and hence reduces the reagents cost and shortens the analysis time. A conventional pump requires valves, which are difficult to be assembled when reduced to micro scale. Hence valveless pump would be the obvious solution. To achieve the flow directing capability, gradually expanding/contracting diffuser/nozzle elements are used as the “fixed valves” in valveless micropumps. The fluid flowing along the nozzle direction receives a larger pressure loss than that along the diffuser direction. Therefore, with periodic oscillation of the flow, there would be a net flux along the diffuser direction. Based on previous researches, the performance of a valveless micropump primarily relies on the flow-directing capability of the diffuser/nozzle element, which is also known as diffuser efficiency, η. A higher η means a higher flow-directing ability and thus, a larger flux of a valveless micropump. There are many researchers attempting to maximise η. In this work, a new diffuser/nozzle structure with extended sidewalls at the large end, named as “lips”, is proposed, investigated and simulated. Introducing more frictional pressure loss in the nozzle direction, the “lips” could increase the η by a maximum of 31%, which correlates to an improvement of 23% for the net flux of the entire micropump. Later, more simulations with different lip lengths, thicknesses and extended angles of the “lips” were also investigated and compared. The results show that η increases with the “lips” length at the beginning and reaches a peak at some length. Further, the thickness of the “lips” has nearly no influence on the performance improvement. Finally it was found that the highest η occurs when the “lips” are almost perpendicular to the outlet plane.
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Yedidiah, S. "An Updated Study of Recirculation at the Inlet of a Rotodynamic Impeller". In ASME 2005 Fluids Engineering Division Summer Meeting. ASMEDC, 2005. http://dx.doi.org/10.1115/fedsm2005-77048.
Testo completoAbstract (sommario):
This paper presents an updated report of certain causes and effects of recirculation at the inlet of a rotodynamic impeller. It demonstrates how certain geometrical features of the inlet parts of the blades are affecting the pattern of the inlet-recirculation, and how this pattern is affected by the flow-rate. It demonstrates the effects of recirculation on the steepness of the QH-curve at reduced flow-rates, and the occasionally observed hysteresis within a certain range of partial flow-rates. Also, it discusses the manner in which recirculation is producing very intense instabilities at reduced NPSH, in axial-flow impellers and inducers. The conclusions arrived at are supported by results of test, reported in different papers. In addition of the above, it lists some of the uses of our present knowledge of the causes and effects of inlet-recirculation, which have been successfully applied in practice.
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Ababneh, Amer Khalil, e Charles Garris. "Direct Interaction of Fluid-to-Fluid in an Unsteady Ejector With a Zero-Degree Conning Radial Diffuser". In ASME 2009 Fluids Engineering Division Summer Meeting. ASMEDC, 2009. http://dx.doi.org/10.1115/fedsm2009-78544.
Testo completoAbstract (sommario):
Unsteady ejectors have been investigated as advanced technologies to classical ejectors for the purpose of energizing secondary fluids whereby the attractiveness of these devices lies in their mechanical simplicity. The primary fluid is accelerated to Mach 2 utilizing eight rectangular supersonic nozzles. The geometry of the diffuser where the primary and secondary fluids interact and hence exchanging energy is considered to be an important factor in affecting the performance. Specifically, proper design of the diffuser contributes significantly for producing quality flow; e.g., reducing the likelihood of developing shocks, and hence less of entropy generation, which is an indication for degrading the potential for energy exchange. The diffuser is chosen to be upright, or zero-degree conning, thus allowing the two fluids to smoothly come into contact. Because of their prime potential application being in thrust augmentation and refrigeration the working fluid was chosen to be water vapor, which is more suitable with the later application. A CFD package; i.e., FLUENT, was employed for the investigation.
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Milanovic, Ivana, e Sunil Kumar. "Just-In-Time and Iterative Learning in Thermo-Fluids". In ASME 2024 Fluids Engineering Division Summer Meeting collocated with the ASME 2024 Heat Transfer Summer Conference and the ASME 2024 18th International Conference on Energy Sustainability. American Society of Mechanical Engineers, 2024. http://dx.doi.org/10.1115/fedsm2024-122894.
Testo completoAbstract (sommario):
Abstract We examine the use of simulations as a tool for both just-in-time learning and iterative and integrative learning processes. Specifically, we investigate the utility of the simulation assignments and their lineup in fluid mechanic course on the improvement of student comprehension, retention of material, and critical thinking. Simulation assignments were added to the list of student deliverables in the undergraduate lecture-based thermo-fluids courses almost a decade ago. They have been designed as weekly projects with an inquiry-based component, thus moving students from structured to unstructured tasks. This approach brought the digital engineering process into the curriculum, increased the average study time, provided students with opportunities to explore modern topics with modern tools, and enabled industry certification in simulation technology. Appropriately designed and delivered simulation assignments accomplish the following goals simultaneously. They (1) enable students to acquire both knowledge and skills at the moment of need untethered from the classroom; (2) deliver relatable and visually exciting materials that keep learners engaged; (3) improve understanding of theory while going beyond the relatively simple pencil & paper problems, and (4) revisit difficult concepts multiple times over the semester and examine them from a different perspective. Our results are illustrated with qualitative and quantitative evidence. Qualitative data provide samples of student work while quantitative assessments include grades, surveys, and course evaluations.
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Böhle, M. "Numerical Investigation of the Flow in Hydrostatic Journal Bearings With Porous Material". In ASME 2018 5th Joint US-European Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/fedsm2018-83437.
Testo completoAbstract (sommario):
The numerical prediction of load capacity, stiffness, power loss etc. of hydrostatic journal bearings must be performed for technical applications. CFD offers one possibility but is time consuming. In the present contribution a fast working numerical method is introduced based on the numerical solution of the Reynolds equation for hydrodynamic lubrication (REHL). It is applied in order to examine the flow inside three-dimensional journal bearings. The emphasis lies on the treatment of journal bearings with porous material. By the application of porous material the lubricant can be fed uniformly around the shaft and therefore improves the reliability of the journal bearing. The contribution gives a short outline of the possibilities and limitations of the application of the REHL. A detailed description of a finite difference method is given by which the REHL is solved. It is described in detail how the load capacity, stiffness, volume flow rate etc. of classical hydrodynamic journal bearings and journal bearings with porous material can be treated by the REHL whereby the emphasis lies on the treatment of journal bearings with porous material. Darcy’s law is implemented in the numerical method in order to take into account the pressure loss of the porous material which is the flow restrictor of the journal bearing. Many results are shown and discussed. Pressure distributions, load capacity, volume flow rates through the porous material, direction of force for a hydrodynamic and porous bearing etc. are shown and discussed in dependence of the eccentricity of the shaft.
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Young, Monica J., Mark N. Glauser, Hiroshi Higuchi e Jeffrey Taylor. "Towards Sensing and Control of Separation in Subsonic Flows". In ASME/JSME 2003 4th Joint Fluids Summer Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/fedsm2003-45586.
Testo completoAbstract (sommario):
The purpose of this study is to validate the use of Proper Orthogonal Decomposition POD and Modified Linear Stochastic Estimation mLSE based low-dimensional methods to model an external flow over a NACA 4412 airfoil. By using a combination of Particle Image Velocimetry PIV and multiple airfoil surface pressure measurements, the full velocity field (mean plus fluctuating) is estimated through implementation of a modified complementary technique. We will identify a low-dimensional mean flow just from the wall pressure, specifically observing when the profiles are at the incipient condition. This gives a reasonable estimate of the low-dimensional velocity field. The importance of this work lies in that the flow is estimated from the wall pressure only, providing a practical means for estimating the flow state. This is particularly important for flow control applications.