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Book Description
LES DEVELOPPEMENTS TECHNOLOGIQUES CONSTANTS DE CES DERNIERES ANNEES IMPOSENT LES TURBOMACHINES A FONCTIONNER DANS DES CONDITIONS DE PLUS EN PLUS SEVERES. EN PARTICULIER, LES PUISSANCES ELEVEES ENTRAINENT AU NIVEAU DES PALIERS HYDRODYNAMIQUES, DES TEMPERATURES DE REGULE PROCHES DES TEMPERATURES MAXIMALES COMMUNEMENT ADMISES. AFIN DE PREVENIR TOUT PROBLEME D'AVARIES, CES ORGANES DE SUPPORT DE MACHINES TOURNANTES DOIVENT DONC ETRE CONVENABLEMENT CONCUS TANT DU POINT DE VUE DES MATERIAUX QUE DU POINT DE VUE GEOMETRIQUE. AINSI, UNE METHODE BASEE SUR LA TECHNIQUE DES PLANS D'EXPERIENCES A ETE PROPOSEE: ELLE PERMET D'AIDER LE CONCEPTEUR DANS LE DIMENSIONNEMENT D'UN PALIER. UN DISPOSITIF D'ESSAI ORIGINAL DE TYPE INDUSTRIEL, RECREANT DES CONDITIONS REELLES DE FONCTIONNEMENT A PERMIS DE RECUEILLIR DE NOMBREUSES MESURES TELLES QUE LES TEMPERATURES A L'INTERFACE FILM/SOLIDE ET DANS LES COUSSINETS, LES DEBITS ET LES VIBRATIONS D'ARBRES. LES RESULTATS EXPERIMENTAUX OBTENUS POUR DES PALIERS A PATINS OSCILLANTS ET A GEOMETRIE FIXE MONTRENT QUE LES CONDITIONS DE FONCTIONNEMENT ONT UNE NETTE INFLUENCE SUR LES TEMPERATURES ET LES PUISSANCES DISSIPEES. POUR DE GRANDES VITESSES PERIPHERIQUES, UNE CHUTE DES TEMPERATURES MAXIMALES EST ENREGISTREE. CE PHENOMENE MONTRE QUE L'APPARITION D'UN REGIME D'ECOULEMENT DE TRANSITION LAMINAIRE-TURBULENT SE TRADUIT PAR UNE DIMINUTION DE LA TEMPERATURE MAXIMALE MESUREE AU NIVEAU DU REGULE. TOUTEFOIS, CE CHANGEMENT DE REGIME D'ECOULEMENT ENTRAINE UNE AUGMENTATION IMPORTANTE DE LA PUISSANCE DISSIPEE DANS LE PALIER. LES RESULTATS EXPERIMENTAUX ONT ETE COMPARES AUX RESULTATS THEORIQUES, OBTENUS A PARTIR DE CODES DE CALCULS THERMOHYDRODYNAMIQUES ET THERMOELASTOHYDRODYNAMIQUES. CETTE CONFRONTATION A PERMIS D'APPRECIER LA VALIDITE DES HYPOTHESES FAITES LORS DES ETUDES THEORIQUES. ELLE A EGALEMENT PERMIS DE MONTRER L'IMPORTANCE DE LA PRISE EN COMPTE DES DEFORMATIONS THERMOELASTIQUES DANS LE CALCUL DES PERFORMANCES DES PALIERS HYDRODYNAMIQUES
Book Description
LES DEVELOPPEMENTS TECHNOLOGIQUES CONSTANTS DE CES DERNIERES ANNEES IMPOSENT LES TURBOMACHINES A FONCTIONNER DANS DES CONDITIONS DE PLUS EN PLUS SEVERES. EN PARTICULIER, LES PUISSANCES ELEVEES ENTRAINENT AU NIVEAU DES PALIERS HYDRODYNAMIQUES, DES TEMPERATURES DE REGULE PROCHES DES TEMPERATURES MAXIMALES COMMUNEMENT ADMISES. AFIN DE PREVENIR TOUT PROBLEME D'AVARIES, CES ORGANES DE SUPPORT DE MACHINES TOURNANTES DOIVENT DONC ETRE CONVENABLEMENT CONCUS TANT DU POINT DE VUE DES MATERIAUX QUE DU POINT DE VUE GEOMETRIQUE. AINSI, UNE METHODE BASEE SUR LA TECHNIQUE DES PLANS D'EXPERIENCES A ETE PROPOSEE: ELLE PERMET D'AIDER LE CONCEPTEUR DANS LE DIMENSIONNEMENT D'UN PALIER. UN DISPOSITIF D'ESSAI ORIGINAL DE TYPE INDUSTRIEL, RECREANT DES CONDITIONS REELLES DE FONCTIONNEMENT A PERMIS DE RECUEILLIR DE NOMBREUSES MESURES TELLES QUE LES TEMPERATURES A L'INTERFACE FILM/SOLIDE ET DANS LES COUSSINETS, LES DEBITS ET LES VIBRATIONS D'ARBRES. LES RESULTATS EXPERIMENTAUX OBTENUS POUR DES PALIERS A PATINS OSCILLANTS ET A GEOMETRIE FIXE MONTRENT QUE LES CONDITIONS DE FONCTIONNEMENT ONT UNE NETTE INFLUENCE SUR LES TEMPERATURES ET LES PUISSANCES DISSIPEES. POUR DE GRANDES VITESSES PERIPHERIQUES, UNE CHUTE DES TEMPERATURES MAXIMALES EST ENREGISTREE. CE PHENOMENE MONTRE QUE L'APPARITION D'UN REGIME D'ECOULEMENT DE TRANSITION LAMINAIRE-TURBULENT SE TRADUIT PAR UNE DIMINUTION DE LA TEMPERATURE MAXIMALE MESUREE AU NIVEAU DU REGULE. TOUTEFOIS, CE CHANGEMENT DE REGIME D'ECOULEMENT ENTRAINE UNE AUGMENTATION IMPORTANTE DE LA PUISSANCE DISSIPEE DANS LE PALIER. LES RESULTATS EXPERIMENTAUX ONT ETE COMPARES AUX RESULTATS THEORIQUES, OBTENUS A PARTIR DE CODES DE CALCULS THERMOHYDRODYNAMIQUES ET THERMOELASTOHYDRODYNAMIQUES. CETTE CONFRONTATION A PERMIS D'APPRECIER LA VALIDITE DES HYPOTHESES FAITES LORS DES ETUDES THEORIQUES. ELLE A EGALEMENT PERMIS DE MONTRER L'IMPORTANCE DE LA PRISE EN COMPTE DES DEFORMATIONS THERMOELASTIQUES DANS LE CALCUL DES PERFORMANCES DES PALIERS HYDRODYNAMIQUES
Author: René Boncompain Publisher: ISBN: Category : Languages : fr Pages : 217
Book Description
RESOLUTION DE L'EQUATION DE REYNOLDS GENERALISEE ET DE L'EQUATION DE L'ENERGIE D'UN FILM MINCE VISQUEUX. COMPARAISON DES RESULTATS OBTENUS AVEC CEUX DE L'EXPERIENCE
Book Description
LES MACHINES ETANT DE PLUS EN PLUS SOLLICITEES A GRANDES VITESSES, LE REGIME D'ECOULEMENT DU FILM LUBRIFIANT DANS LES PALIERS DEVIENT TURBULENT ET L'ECHAUFFEMENT DANS LE FILM IMPORTANT ET IL EST INDISPENSABLE DE TENIR COMPTE DE LA NATURE DE L'ECOULEMENT DANS LES MODELISATIONS THEORIQUES. NOUS AVONS DONC EFFECTUE UNE ANALYSE THERMOHYDRODYNAMIQUE DES PALIERS A PATINS OSCILLANTS EN REGIME TURBULENT. DEUX MODELES (ELROD ET NG, CONSTANTINESCU) BASES SUR LE CONCEPT DE VISCOSITE TURBULENTE ONT ETE UTILISES AINSI QUE LA MODELISATION LINEAIRE DE NG ET PAN. L'ETUDE THEORIQUE PERMET DE TENIR COMPTE DES EFFETS THERMIQUES LOCAUX ET DES TRANSFERTS DE CHALEUR DANS LES SOLIDES. L'INFLUENCE DES CARACTERISTIQUES DU LUBRIFIANT ET DES MATERIAUX AINSI QUE LE PROFIL DE TEMPERATURE A L'ENTREE DU FILM SUR LES PERFORMANCES DES PALIERS EST TRAITEE. CETTE ETUDE PERMET D'EXPLIQUER LE PARADOXE CONSTATE EXPERIMENTALEMENT LORS DU CHANGEMENT DE REGIME D'ECOULEMENT: L'AUGMENTATION DE LA VITESSE DE ROTATION DE L'ARBRE ENTRAINE UNE DIMINUTION DE LA TEMPERATURE MAXIMALE DU PALIER ALORS QUE LA PUISSANCE DISSIPEE AUGMENTE TRES SENSIBLEMENT. CECI EST DU A L'ECOULEMENT NON LAMINAIRE QUI TEND A HOMOGENEISER LA TEMPERATURE DANS LE FILM ET A FAVORISER LES ECHANGES THERMIQUES DANS LES SOLIDES. AINSI, LA TEMPERATURE MAXIMALE DIMINUE ALORS QUE LA TEMPERATURE MOYENNE AUGMENTE. DIFFERENTS EXEMPLES ISSUS DE LA LITTERATURE ONT PERMIS DE CONFRONTER NOS RESULTATS THEORIQUES AUX RESULTATS EXPERIMENTAUX PUBLIES
Author: Isabelle Pierre Publisher: ISBN: Category : Languages : fr Pages : 210
Book Description
LES DIVERS TRAVAUX SUR LA LUBRIFICATION DES PALIERS HYDRODYNAMIQUES SOULIGNENT L'INFLUENCE PREPONDERANTE DES PHENOMENES THERMIQUES SUR LE FONCTIONNEMENT DES PALIERS. LE TRAVAIL PRESENTE DANS CE MEMOIRE PROPOSE DONC UNE ETUDE DES EFFETS THERMIQUES DANS LES PALIERS LISSES SOUMIS A UNE CHARGE STATIQUE ET FONCTIONNANT EN REGIME ETABLI. UNE APPROCHE THERMOHYDRODYNAMIQUE (THD) DU PROBLEME TRADUISANT LA CONTINUITE DES FLUX DE CHALEUR, EST ADOPTEE AFIN D'OBTENIR UNE ESTIMATION REALISTE DES PERFORMANCES D'UN PALIER. UN MODELE NUMERIQUE EST DEVELOPPE EN RESPECTANT LE PRINCIPE DE CONSERVATION DE LA MASSE LORS DE LA RUPTURE ET DE LA REFORMATION DU FILM LUBRIFIANT. L'ALGORITHME D'ELROD EST APPLIQUE ET UNE MODELISATION DES CARACTERISTIQUES DU LUBRIFIANT EST PROPOSEE DANS LA ZONE INACTIVE DU FILM. LA PLUPART DES ETUDES PUBLIEES UTILISENT DES MODELISATIONS THERMIQUES SOIT BIDIMENSIONNELLES (2D), SOIT TRIDIMENSIONNELLES (3D) AVEC UN PLAN DE SYMETRIE. LA MODELISATION NUMERIQUE PROPOSEE EST MOINS RESTRICTIVE CAR ELLE ADOPTE UNE APPROCHE 3D COMPLETE, AFIN D'ETUDIER LE COMPORTEMENT THD DE PALIERS ALIGNES ET MESALIGNES. UNE METHODE NUMERIQUE EST D'AILLEURS MISE AU POINT POUR RESOUDRE L'EQUATION DE L'ENERGIE EN TENANT COMPTE DE L'ECOULEMENT INVERSE AXIAL. APRES VALIDATION DU MODELE NUMERIQUE, DES ETUDES PARAMETRIQUES PRECISENT L'INFLUENCE DES PARAMETRES GEOMETRIQUES ET DES CONDITIONS DE FONCTIONNEMENT SUR LE COMPORTEMENT THD D'UN PALIER ALIGNE. DE PLUS, NOUS CONSTATONS QUE LA MODELISATION 2D FOURNIT DES RESULTATS ANALOGUES A CEUX DE LA MODELISATION 3D DANS LA PLUPART DES CONFIGURATIONS DE PALIERS ALIGNES. LES DIVERS TRAVAUX PUBLIES SUR LE MESALIGNEMENT, SONT POUR LA PLUPART INEXPLOITABLES DU POINT DE VUE THERMIQUE. UN DISPOSITIF EXPERIMENTAL MIS
Author: Robert K. Flitney Publisher: Elsevier ISBN: 008099413X Category : Science Languages : en Pages : 648
Book Description
Seals and Sealing Handbook, Sixth Edition provides comprehensive coverage of sealing technology, bringing together information on all aspects of this area to enable you to make the right sealing choice. This includes detailed coverage on the seals applicable to static, rotary and reciprocating applications, the best materials to use in your sealing systems, and the legislature and regulations that may impact your sealing choices.Updated in line with current trends this updated reference provides the theory necessary for you to select the most appropriate seals for the job and with its 'Failure Guide', the factors to consider should anything go wrong. Building on the practical, stepped approach of its predecessor, Seals and Sealing Handbook, 6th Edition remains an essential reference for any engineer or designer who uses seals in their work. - A comprehensive reference covering a broad range of seal types for all situations, to ensure that you are able to select the most appropriate seal for any given task - Includes supporting case studies and a unique 'Failure Guide' to help you troubleshoot if things go wrong - New edition includes the most up-to-date information on sealing technology, making it an essential reference for anyone who uses seals in their work
Author: A. Sethuramiah Publisher: Elsevier ISBN: 0128007842 Category : Technology & Engineering Languages : en Pages : 242
Book Description
Modeling of Chemical Wear is a one-stop resource for students, researchers and professionals seeking quick and effective tribological evaluations of environmentally friendly and energy efficient products.This book considers optimizing additive combinations by proper methodology, bridging the gap between theory and practice. It defines effective approaches to evaluate antiwear chemical additives commonly used in industry, enhancing the mapping ability of their performance to reduce the extent of full scale evaluations. - Provides full coverage of tribology in four concise chapters, including lubricants and additives and up-and-coming nano-level tribology - Offers effective empirical modelling of chemical wear, along with computer programs relevant to industry standards to help you improve your test methods - Outlines effective methodology for optimization of additive packages, relevant to the present search for eco-friendly combinations
Author: Viktor P. Astakhov Publisher: Elsevier ISBN: 0080466850 Category : Technology & Engineering Languages : en Pages : 451
Book Description
Tribology of Metal Cutting deals with the emerging field of studies known as Metal Cutting Tribology. Tribology is defined as the science and technology of interactive surfaces moving relative each other. It concentrates on contact physics and mechanics of moving interfaces that generally involve energy dissipation. This book summarizes the available information on metal cutting tribology with a critical review of work done in the past. The book covers the complete system of metal cutting testing. In particular, it presents, explains and exemplifies a breakthrough concept of the physical resource of the cutting tool. It also describes the cutting system physical efficiency and its practical assessment via analysis of the energy partition in the cutting system. Specialists in the field of metal cutting will find information on how to apply the major principles of metal cutting tribology, or, in other words, how to make the metal cutting tribology to be useful at various levels of applications. The book discusses other novel concepts and principles in the tribology of metal cutting such as the energy partition in the cutting system; versatile metrics of cutting tool wear; optimal cutting temperature and its use in the optimization of the cutting process; the physical concept of cutting tool resource; and embrittlement action. This book is intended for a broad range of readers such as metal cutting tool, cutting insert, and process designers; manufacturing engineers involved in continuous process improvement; research workers who are active or intend to become active in the field; and senior undergraduate and graduate students of manufacturing. · Introduces the cutting system physical efficiency and its practical assessment via analysis of the energy partition in the cutting system.· Presents, explains and exemplifies a breakthrough concept of the physical resource of the cutting tool.· Covers the complete system of metal cutting testing.
Author: George K. Nikas Publisher: ISBN: 9788130803777 Category : Languages : en Pages : 314
Book Description
The knowledge gained from studies on friction, lubrication and wear of contacting surfaces (three terms collectively known as tribology) is met in every branch of engineering. Tribology is a multidisciplinary science involving mechanical engineering, materials and lubrication science, physics, and chemistry. Tribological principles are normally used in characterising the mechanical behaviour of surfaces in relative motion. This involves a very large number of applications ranging in size from the nano-scale (molecular and nano-tribology) to the macro-scale (bearings, tyres, rock drills, etc.). Friction, lubrication and wear are inherent characteristics of the physical world regardless of scale. From the intermolecular forces holding a gecko s feet on a vertical wall to the tractive forces at the contact patches of aircraft tyres; from the lubricating film at the rolling contact of a ball on a rolling-bearing raceway to the soft magma supporting tectonic plates of the earth; from the erosion of human teeth from toothpaste particles to the particle erosion of turbine blades; such diverse phenomena can be described and analysed in tribological terms. Every type of machinery includes parts affected by friction, lubrication, and wear. Therefore, the role of tribology in machine operation and reliability is a major one. As a result, the effect of tribology to modern world economy, even though unknown to the majority of the population, is crucial. Although the effect on the economy has been quantified and found to represent a significant proportion of the gross domestic product of economically advanced countries, the true effect pertaining to the development of technologically advanced products is far greater and not immediately obvious. There are several good books on tribology covering the fundamental theory and various applications. However, technology is progressing at an immense pace and engineering norms are quickly outdated. This book is based on the collective experience of some of the world s top experts on friction, lubrication and wear. It presents recent developments in the field of tribology and its contributors are equally divided among theoreticians and experimentalists. Furthermore, some chapters contain new theory and results, which, in the editor s experience, is at the frontier of research. The topics covered in the eight chapters of this book include thin-film lubrication from a theoretical perspective, a critical review of rolling-bearing life-prediction models, a review of Laser Surface Texturing, a proposed unification of friction and wear via thermodynamic principles, the role of tribofilms in concentrated contacts from a materials-science perspective, transient phenomena in elastohydrodynamic lubrication from an experimental point of view, a theoretical assessment of the Stribeck curve in lubricated contacts, and, finally, a thorough presentation of modelling and adhesion problems of microelectromechanical systems (MEMS) and miniature devices. Chapter 1 by Professor Szeri is an in-depth discussion of the thin-film lubrication theory referring to hydrodynamic and elastohydrodynamic lubrication. Professor Szeri (University of Delaware, USA), a well-known author with many decades of research experience, attempts to define the limits of the classical Reynolds theory of lubrication in both laminar and turbulent flows of liquids and gases. He discusses the continuity limitation of the classical theory in terms of film thickness, wall slip, and the Reynolds number. He reaches to quantitative conclusions on the validity of the film continuity assumption and the necessity to use the full Navier-Stokes equations or first principles in some applications for which the Reynolds theory is inaccurate. Chapter 2 by Dr. Zaretsky is a critical evaluation of the main models proposed for the prediction of the fatigue lives of rolling-element bearings, comprising the past and present ISO standards. Those models have been adopted by major bearing manufacturers such as SKF and include the classical work of Palmgren, Weibull, Lundberg, Ioannides, Harris, and Zaretsky. Dr Zaretsky, a Chief Engineer of NASA and Adjunct Professor at Case Western Reserve University (USA), is an authority on bearing life prediction. In his comprehensive tutorial, which is suitable both to experts and non-experts on this topic, he explains the advantages and disadvantages of the various models from a theoretical point of view, and includes a selection of endurance test results to compare the relative accuracy of the theoretical models. Among Dr Zaretsky s conclusions is that the load-life exponent (10/3) used in the ANSI/ABMA and ISO standards to predict rolling bearing life is not reflective of modern rolling bearings and actually underestimates bearing lives. Chapter 3 by Professor Etsion is a review of Laser Surface Texturing (LST). Surface texturing of tribological, mechanical components, has emerged in the last decade as a viable option of surface engineering resulting in significant improvements in load capacity, wear resistance, reduction of friction etc. Professor Etsion (Chair in Fluid Mechanics and Heat Transfer, Technion Israel Institute of Technology) is one of the most recognised experts on the topic of surface texturing. In his review of the LST, he outlines the technique and discusses the potential of this technology in various engineering applications, including automotive (piston rings), bearings, seals, magnetic storage devices (hard disk sliders and magnetic tapes), and others. Chapter 4 by Professor Bryant is rather unique in the literature. Professor Bryant, a professor in the University of Texas at Austin (USA) and the Editor of the Journal of Tribology of the American Society of Mechanical Engineers, attempts to unify friction and wear via thermodynamic principles, focusing on the dissipative processes found at sliding interfaces. He presents a review of friction and wear mechanisms, and relates them in terms of their associated thermodynamics, energy losses and entropy produced by common dissipative processes. He shows that the expressions for entropy generation in dissipative processes operative at a sliding interface, which are common to both friction and wear, could result in unified friction and wear models. Chapter 5 by Professors Jacobson and Hogmark provides an overview of the role of tribofilms on surfaces in sliding contacts. The authors, both professors of materials science and tribology at Uppsala University in Sweden, have several decades of research experience on such topics. Through illustrative examples based on real applications, they show that tribologically induced surface modifications result in the creation of surface layers or tribofilms ranging in thickness from a few nanometres to tens of micrometres. The surface modifications include topographical changes, formation of micro-cracks, material phase transformations, formation of oxides, formation of solid films by reaction with lubricant additives, material transfer from the counter surface, etc. It is such tribofilms that actually dominate the contact properties between sliding solids in terms of friction and wear and not the original materials. Chapter 6 by Dr. Glovnea, Reader in the School of Engineering and Design at Sussex University in England, presents a review of recent experimental research on non-steady-state elastohydrodynamic lubrication, including transient loading, sudden variation of entrainment speed and variation of micro-geometry. His study is relevant to all industrial machinery involving lubricated contacts and susceptible to vibrations or normal operation involving load and speed variations. Dr Glovnea, who has spent several years studying such phenomena in the Tribology Group of Imperial College London, shows how transient conditions and various parameters affect (normally sub-micrometre) elastohydrodynamic films, their thickness distribution and overall cohesion. It is thus possible to assess the risk of contact damage from film thinning or collapse. Chapter 7 by Professor Khonsari (Louisiana State University, USA) and Dr. Booser, both well-respected researchers in the tribology community and authors of best-selling tribology books, deals with the different lubrication regimes met in contacts at relatively low sliding speeds. These are related via the so-called Stribeck curve, which demonstrates the transition from boundary lubrication at the start-up of motion to mixed lubrication as the speed is increased, and on to full-film lubrication at higher speeds. The review covers issues pertaining to roughness asperity interactions (particularly in the mixed lubrication regime), wear, stick-slip phenomena, and the effects of lubricant additives. Chapter 8 by Dr. Xue (Analog Devices, Inc., USA) and Professor Polycarpou (University of Illinois at Urbana-Champaign, USA) covers microelectromechanical systems (MEMS) from an experimental and theoretical point of view. The authors have extensive experience in this research field and are focused on the problem of adhesion or stiction of MEMS and miniature devices, which reduces their reliability and hinders their advancement and wider commercialisation. They develop an experimentally validated, adhesive-contact model, which is valid for a wide range of adhesion parameter values, covering the practical range of application of MEMS and other miniature devices. The editor embarked on this project in June 2007 and invited eminent tribologists to make contributions on specific topics based on the editor s plans for the book. The project was completed in about 18 months before the manuscripts were sent to the publisher. The editor is grateful to the authors/contributors of this book for their cooperation and patience throughout the lengthy process of communication, chapter editing, and book compilation. The editor is also grateful to the expert reviewers (see the list of reviewers) who kindly reviewed the chapters, one chapter each reviewer. Finally, the editor would like to thank the publisher, Research Signpost, for the original invitation and kind assistance.
Author: International Institute of Refrigeration Publisher: ISBN: Category : Refrigeration and refrigerating machinery Languages : fr Pages : 750
Book Description
Some numbers called Special issue and consist of summaries of papers to be presented at the International Congresses of Refrigeration.
Author: Christophe Bouchoule
Author: Christophe Bouchoule
Author: René Boncompain
Author: Ludovic Bouard
Author: Isabelle Pierre
Author: Robert K. Flitney
Author: A. Sethuramiah
Author: Viktor P. Astakhov
Author: George K. Nikas
Author: International Institute of Refrigeration
Author: