Download or read book MODELISATION TRIDIMENSIONNELLE DE LA CAVITATION PARTIELLE DANS LES TURBOMACHINES written by FRANCOIS-XAVIER.. CATELAN and published by . This book was released on 1996 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: DANS LA CONCEPTION DES TURBOMACHINES, LA CAVITATION REPRESENTE GENERALEMENT LE PHENOMENE PHYSIQUE QUI LIMITE LE PLUS LES PERFORMANCES. LE COMPORTEMENT CAVITANT DE L'APPAREIL DOIT DONC ETRE CONNU A L'AVANCE ET NECESSITE DONC LE PLUS SOUVENT DES ESSAIS SUR UN PROTOTYPE. LES MODELES NUMERIQUES DE PREVISION DE LA CAVITATION REPRESENTENT UNE APPROCHE COMPLEMENTAIRE QUI PERMET D'AGIR AU NIVEAU DE L'AVANT-PROJET ET DU PROJET. L'OUTIL NUMERIQUE DEVELOPPE DANS LE CADRE DE CETTE THESE CONSIDERE LA CAVITE COMME UNE PERTURBATION DE L'ECOULEMENT NON CAVITANT. DANS CETTE APPROCHE, LA RESOLUTION EST EFFECTUEE EN COUPLANT UN CALCUL 3D NON CAVITANT A UN CALCUL 3D DE CAVITE. LE COUPLAGE S'EFFECTUE PAR LA GEOMETRIE DE LA POCHE DE VAPEUR QUI DIMINUE D'AUTANT LE DOMAINE DE CALCUL. UNE ATTENTION PARTICULIERE EST PORTEE AU PROBLEME POSE PAR LE DETACHEMENT DES CAVITES EN UTILISANT NOTAMMENT LES RESULTATS D'UNE CAMPAGNE DE MESURES SUR DEUX PROFILS PLACES DANS UNE VEINE FIXE. UNE FORMULATION PARTICULIERE DE LA CONDITION DE CAVITE AU NIVEAU DU DETACHEMENT A ETE MISE AU POINT, AINSI QU'UN CRITERE DE POSITIONNEMENT DU POINT DE DETACHEMENT. LA SENSIBILITE DES RESULTATS A LA DISCRETISATION DU BORD D'ATTAQUE DES PROFILS A EGALEMENT ETE ETUDIEE. CE CODE A PERMIS LE CALCUL DE REGIMES CAVITANTS POUR DEUX MACHINES AXIALES PRESENTANT UN ECOULEMENT FORTEMENT TRIDIMENSIONNEL. L'INTERET DE LA MODELISATION TRIDIMENSIONNELLE PRESENTEE DANS CETTE ETUDE EST MIS EN LUMIERE PAR L'AMELIORATION DU PARAMETRE DE CAVITATION OBTENU APRES LE COUPLAGE. D'AUTRE PART, LES FORMES DE POCHE CALCULEES SONT EN ACCORD AVEC LES VISUALISATIONS FAITES LORS D'ESSAIS SUR CES GEOMETRIES

Download or read book Pr diction par mod lisation num rique tridimensionnelle des effets de la cavitation poche dans les turbomachines hydrauliques written by Roland Hirschi and published by . This book was released on 1998 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Cavitation Instabilities and Rotordynamic Effects in Turbopumps and Hydroturbines written by Luca d'Agostino and published by Springer. This book was released on 2017-03-17 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book provides a detailed approach to the physics, fluid dynamics, modeling, experimentation and numerical simulation of cavitation phenomena, with special emphasis on cavitation-induced instabilities and their implications on the design and operation of high performance turbopumps and hydraulic turbines. The first part covers the fundamentals (nucleation, dynamics, thermodynamic effects, erosion) and forms of cavitation (attached cavitation, cloud cavitation, supercavitation, vortex cavitation) relevant to hydraulic turbomachinery, illustrates modern experimental techniques for the characterization, visualization and analysis of cavitating flows, and introduces the main aspects of the hydrodynamic design and performance of axial inducers, centrifugal turbopumps and hydo-turbines. The second part focuses on the theoretical modeling, experimental analysis, and practical control of cavitation-induced fluid-dynamic and rotordynamic instabilities of hydraulic turbomachinery, with special emphasis on cavitating turbopumps (cavitation surge, rotating cavitation, higher order cavitation surge, rotordynamic whirl forces). Finally, the third part of the book illustrates the alternative approaches for the simulation of cavitating flows, with emphasis on both modeling and numerical aspects. Examples of applications to the simulation of unsteady cavitation in internal flows through hydraulic machinery are illustrated in detail.

Download or read book Mod lisation de la cavitation partielle dans les pompes written by Jean-Luc Schultz and published by . This book was released on 1988 with total page 281 pages. Available in PDF, EPUB and Kindle. Book excerpt: PROBLEMES D'HYDRODYNAMIQUE. MODELISATION QUASI-TRIDIMENSIONNELLE PAR ELEMENTS FINIS DE LA CAVITATION PARTIELLE

Download or read book MODELISATION DE LA CAVITATION PARTIELLE EN CONFIGURATIONS BIDIMENSIONNELLE ET TRIDIMENSIONNELLE written by JEAN-MARC.. PEALLAT and published by . This book was released on 1994 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: LE PRESENT TRAVAIL S'INSCRIT DANS LE CADRE DE L'ETUDE DE LA CAVITATION PARTIELLE SUR LES PALES D'UNE HELICE MARINE. EN EFFET, LA RECHERCHE DE PERFORMANCES DE PLUS EN PLUS POUSSEES ET LE SOUCI D'EVITER LES EFFETS NEFASTES DE LA CAVITATION (BRUIT, EROSION) CONDUISENT LES CONSTRUCTEURS A CONCEVOIR LES HELICES TOUT EN TENANT COMPTE DE LEUR FONCTIONNEMENT EN REGIME CAVITANT. AINSI, L'INTERET D'OUTILS INFORMATIQUES MODELISANT CELUI-CI RESIDE DANS L'OPTIMISATION DES FORMES GEOMETRIQUES DES PALES. COMPTE TENU DES METHODES EXISTANTES EN ECOULEMENT BIDIMENSIONNEL ET DE L'IMPOSSIBILITE DE LES ETENDRE AUX CAS DE CALCULS TRIDIMENSIONNELS, UNE METHODE ORIGINALE DE PRISE EN COMPTE DE LA CAVITE PAR SUIVI D'INTERFACE A ETE DEVELOPPEE. LE NOMBRE DE CAVITATION EST IMPOSE, LA GEOMETRIE DE LA POCHE SE FORME AU COURS DES ITERATIONS, GRACE AU DEBIT DE VITESSE NORMALE OBTENU SUR LA POCHE ET SON SILLAGE. CETTE METHODE A ETE DEVELOPPEE DANS UN PREMIER TEMPS DANS LE CADRE DES ECOULEMENTS BIDIMENSIONNELS AFIN DE MIEUX ETABLIR SON MECANISME. LE CODE DE CALCUL MIS AU POINT A ETE VALIDE AU REGARD DE MESURES EXPERIMENTALES, ET IL CONSTITUE UN MOYEN DE CALCUL FIABLE ET PEU COUTEUX. DE PLUS, IL PEUT SERVIR DE BASE A DES EXTENSIONS DE CALCUL TELLES QUE LES ECOULEMENTS CONFINES OU LA SUPERCAVITATION. LA DEUXIEME ETAPE DE NOTRE DEMARCHE A ETE D'ETENDRE LA METHODE AUX AILES SOUS-MARINES. LE MANQUE DE MESURES CONCERNANT LA CAVITATION PARTIELLE SUR DES HYDROFOILS N'A PAS PERMIS UNE VALIDATION COMPLETE DU CODE TRIDIMENSIONNEL. CEPENDANT LES RESULTATS OBTENUS SONT COHERENTS ET CORRESPONDENT D'UNE MANIERE QUALITATIVE AUX OBSERVATIONS EXPERIMENTALES

Download or read book Mod lisation des coulements cavitants written by Olivier Coutier-Delgosha and published by . This book was released on 2001 with total page 435 pages. Available in PDF, EPUB and Kindle. Book excerpt: L'étage d'aspiration des turbopompes de moteurs spéciaux cryotechniques, appelé inducteur, opère en régime cavitant, ce qui induit deux types de problèmes. D'une part, la vapeur modifie la charge des aubages et peut donc dégrader la performance de l'inducteur. D'autre part, la cavitation est à l'origine d'instabilités qui engendrent des efforts fluctuants et parfois dissymétriques sur les autres composants. En collaboration avec le CNES et Snecma Moteurs, l'analyse de ces mécanismes d'instabilité a donné lieu à un travail de recherche au LEGI, auquel cette thèse contribue sur le plan numérique. Le modèle physique de cavitation utilisé est basé sur la prise en compte d'un seul fluide, dont la densité varie entre celle de la vapeur et du liquide.La vitesse est la même pour les deux phases, et le taux de vide local est gouverné par une loi d'état barotrope qui relie directement les variations de pression et de densité. Deux approches parallèles ont été suivies sur la base de ce modèle. La première est 2D : elle a été développée au sein de l'équipe et améliorée lors de la présente étude en ce qui concerne la modélisation physique de la turbulence et la résolution numérique. Elle permet d'étudier des configurations simplifiées fixes et 2D représentatives d'un inducteur, en approfondissant l'analyse des propriétés du mélange liquide/vapeur et les aspects instationnaires. Une étude détaillée de l'auto-oscillation des poches de cavitation sur des profils Venturi a ainsi été menée. La seconde approche est l'extension 3D du modèle physique sur la base numérique du code commercial FINE/TURBO tm développé par NUMECA International. Les comportements cavitants quasi-statiques de plusieurs roues centrifuges ont été modélisés de manière satisfaisante : les courbes de chute de performance et les structures diphasiques dans les machines sont en bon accord avec les résultats expérimentaux. Des premiers calculs prometteurs sur des géométries d'inducteurs ont également été obtenus.

Download or read book Cavitation Induced Instabilities Associated with Turbomachines written by David Miner Braisted and published by . This book was released on 1980 with total page 177 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Simulation num rique d coulements 2D 3D cavitants stationnaires et instationnaires written by Benoît Pouffary and published by . This book was released on 2004 with total page 241 pages. Available in PDF, EPUB and Kindle. Book excerpt: Les travaux présentés concernent la simulation numérique d'écoulements cavitants à l'aide d'une loi barotrope pour modéliser le phénomène de cavitation. Ce modèle a été intégré dans le code commercial Fine/Turbo développé et commercialisé par la société Numeca Int. Du point de vue numérique, l'essentiel du travail a porté sur l'amélioration de la stabilité numérique et sur la fiabilisation de l'algorithme ; ces recherches ont débouché notamment sur la modification du calcul des paramètres de préconditionnement. La faisabilité de calculs cavitants instationnaires a été démontrée pour deux configurations bidimensionnelles : un canal venturi et un hydrofoil. Dans les deux cas, le lâcher de structures de vapeur à l'aval des poches a été simulé et l'écoulement dans ces conditions a été étudié. Une étude de l'influence des principaux paramètres numériques a été menée dans le cas du venturi. L'autre aspect du travail concerne les calculs en turbomachines. Une méthodologie permettant de reproduire numériquement la chute de performance en cavitation a été proposée et mise en oeuvre sur deux géométries d'inducteur, deux géométries de rouet et une grille d'aubes. Ces calculs ont permis de caractériser les mécanismes conduisant à la chute de performance et à observer les modifications induites par la cavitation sur les écoulements internes. Enfin, la faisabilité de la simulation d'instabilités de cavitation a été démontrée à partir des calculs dans une grille d'aubes. Les régimes sub synchrone et super synchrone ont été reproduits et un mécanisme de propagation de ces instabilités a été proposé.

Download or read book Etude de la dynamique d une poche de cavitation partielle en vue de la pr diction de l rosion dans les turbomachines hydrauliques written by Philippe Dupont and published by . This book was released on 1993 with total page 267 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Centrifugal Pumps written by Johann Friedrich Gülich and published by Springer. This book was released on 2014-10-24 with total page 1146 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gives an unparalleled, up-to-date, in-depth treatment of all kinds of flow phenomena encountered in centrifugal pumps including the complex interactions of fluid flow with vibrations and wear of materials. The scope includes all aspects of hydraulic design, 3D-flow phenomena and partload operation, cavitation, numerical flow calculations, hydraulic forces, pressure pulsations, noise, pump vibrations (notably bearing housing vibration diagnostics and remedies), pipe vibrations, pump characteristics and pump operation, design of intake structures, the effects of highly viscous flows, pumping of gas-liquid mixtures, hydraulic transport of solids, fatigue damage to impellers or diffusers, material selection under the aspects of fatigue, corrosion, erosion-corrosion or hydro-abrasive wear, pump selection, and hydraulic quality criteria. As a novelty, the 3rd ed. brings a fully analytical design method for radial impellers, which eliminates the arbitrary choices inherent to former design procedures. The discussions of vibrations, noise, unsteady flow phenomena, stability, hydraulic excitation forces and cavitation have been significantly enhanced. To ease the use of the information, the methods and procedures for the various calculations and failure diagnostics discussed in the text are gathered in about 150 pages of tables which may be considered as almost unique in the open literature. The text focuses on practical application in the industry and is free of mathematical or theoretical ballast. In order to find viable solutions in practice, the physical mechanisms involved should be thoroughly understood. The book is focused on fostering this understanding which will benefit the pump engineer in industry as well as academia and students.

Download or read book Cavitation partielle dans les pompes cryog niques written by Olivier Blottiaux and published by . This book was released on 1988 with total page 241 pages. Available in PDF, EPUB and Kindle. Book excerpt: L'ETUDE DE LA CAVITATION PARTIELLE DANS LES POMPES EST DEVELOPPEE EN TROIS PARTIES. EN VUE D'UNE ETUDE EXPERIMENTALE DE LA CAVITATION SUR UN INDUCTEUR DE POMPE CRYOGENIQUE, ON DEFINIT UNE VEINE D'ESSAI PERMETTANT DE RESTITUER AUTOUR D'UN PROFIL FIXE L'ECOULEMENT DANS L'INDUCTEUR. DANS LA DEUXIEME PARTIE, DIFFERENTS MODELES NUMERIQUES DE CAVITATION PARTIELLE SONT COMPARES. UNE ATTENTION PARTICULIERE EST PORTEE SUR LA REPRESENTATION DU SILLAGE DE LA CAVITE. DANS LA DERNIERE PARTIE, ON ABORDE L'ETUDE DES EFFETS THERMODYNAMIQUES AFFECTANT LES CARACTERISTIQUES DE LA CAVITATION DANS LE CAS DES FLUIDES THERMOSENSIBLES. CONTRAIREMENT AUX ETUDES REALISEES JUSQU'A PRESENT, ON S'EFFORCE DE QUANTIFIER LES PHENOMENES LOCAUX DE TRANSFERT A LA FRONTIERE DE LA CAVITE

Download or read book Advances in Hydroinformatics written by Philippe Gourbesville and published by Springer. This book was released on 2015-08-21 with total page 616 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a collection of extended papers based on presentations given during the SIMHYDRO 2014 conference, held in Sophia Antipolis in June 2014. It focuses on the modeling and simulation of fast hydraulic transients, on 3D modeling, and on uncertainties and multiphase flows. The book explores both the limitations and performance of current models and presents the latest developments based on new numerical schemes, high-performance computing, multiphysics and multiscale methods, and better interaction with field or scale model data. It addresses the interests of practitioners, stakeholders, researchers and engineers active in this field.

Download or read book Turbulence in Porous Media written by Marcelo J.S. de Lemos and published by Elsevier. This book was released on 2012-06-25 with total page 411 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulence in Porous Media introduces the reader to the characterisation of turbulent flow, heat and mass transfer in permeable media, including analytical data and a review of available experimental data. Such transport processes occurring a relatively high velocity in permeable media are present in a number of engineering and natural flows. This new edition features a completely updated text including two new chapters exploring Turbulent Combustion and Moving Porous Media. De Lemos has expertly brought together a text that compiles, details, compares and evaluates available methodologies for modelling and simulating flow, providing an essential tour for engineering students working within the field as well as those working in chemistry, physics, applied mathematics, and geological and environmental sciences. Brings together groundbreaking and complex research on turbulence in porous media Extends the original model to situations including reactive systems Now discusses movement of the porous matrix

Download or read book Model Based Systems Engineering with OPM and SysML written by Dov Dori and published by Springer. This book was released on 2016-06-01 with total page 419 pages. Available in PDF, EPUB and Kindle. Book excerpt: Model-Based Systems Engineering (MBSE), which tackles architecting and design of complex systems through the use of formal models, is emerging as the most critical component of systems engineering. This textbook specifies the two leading conceptual modeling languages, OPM—the new ISO 19450, composed primarily by the author of this book, and OMG SysML. It provides essential insights into a domain-independent, discipline-crossing methodology of developing or researching complex systems of any conceivable kind and size. Combining theory with a host of industrial, biological, and daily life examples, the book explains principles and provides guidelines for architecting complex, multidisciplinary systems, making it an indispensable resource for systems architects and designers, engineers of any discipline, executives at all levels, project managers, IT professional, systems scientists, and engineering students.

Download or read book Nonlinear Programming written by Dimitri P. Bertsekas and published by Goodman Publishers. This book was released on 1999 with total page 808 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Ungovernable Society written by Grégoire Chamayou and published by Polity. This book was released on 2021-05-03 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rebellion was in the air. Workers were on strike, students were demonstrating on campuses, discipline was breaking down. No relation of domination was left untouched – the relation between the sexes, the racial order, the hierarchies of class, relationships in families, workplaces and colleges. The upheavals of the late 1960s and early 1970s quickly spread through all sectors of social and economic life, threatening to make society ungovernable in the eyes of ruling elites. This crisis was also the birthplace of the authoritarian liberalism which continues to cast its shadow across the world in which we now live. To ward off the threat, new arts of government were devised in business-related circles, which included a war against the trade unions, the primacy of shareholder value and a dethroning of politics. The neoliberalism that thus began its triumphal march was not, however, determined by a simple ‘state phobia’ and a desire to free up the economy from government interference. On the contrary, the strategy for overcoming the crisis of governability consisted in an authoritarian liberalism in which the liberalization of society went hand-in-hand with new forms of power imposed from above: a ‘strong state’ for a ‘free economy’ became the new magic formula of our capitalist societies. Grégoire Chamayou analyses this crisis as it was perceived and theorized in the 1970s by those who strove to defend the interests of business – that is, the ruling elites, especially in the United States, from which a far-reaching intellectual and political movement spread. The new arts of government they devised are still with us today and we can understand their nature and lasting influence only by re-examining the history of the conflicts that brought them into being.

Download or read book Practical Centrifugal Pumps written by Paresh Girdhar and published by Elsevier. This book was released on 2011-04-18 with total page 257 pages. Available in PDF, EPUB and Kindle. Book excerpt: Practical Centrifugal Pumps is a comprehensive guide to pump construction, application, operation, maintenance and management issues. Coverage includes pump classifications, types and criteria for selection, as well as practical information on the use of pumps, such as how to read pump curves and cross reference. Throughout the book the focus is on best practice and developing the skills and knowledge required to recognise and solve pump problems in a structured and confident manner. Case studies provide real-world scenarios covering the design, set up, troubleshooting and maintenance of pumps.· A comprehensive guide to pump construction, design, installation, operation, troubleshooting and maintenance.· Develop real-world knowhow and practical skills through seven real-world case studies· Coverage includes pump classifications, types and criteria for selection, as well as practical information on the use of pumps