Download or read book Simulation des coulements turbulents et des transferts thermiques en vue de l optimisation du refroidissement des pales de turbine written by Sacha Parneix and published by . This book was released on 1995 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt: DANS LE BUT D'AMELIORER LE RENDEMENT D'UNE TURBOMACHINE, LES PALES DE TURBINE SONT REFROIDIES PAR CONVECTION INTERNE D'AIR REFRIGERANT. POUR OPTIMISER CES TECHNIQUES, L'EXPERIMENTATION SE REVELE LONGUE, DIFFICILE ET COUTEUSE, ET L'INGENIEUR A DE PLUS EN PLUS RECOURS A LA SIMULATION NUMERIQUE. DANS CETTE OPTIQUE, L'ETUDE PROPOSEE INTRODUIT UNE METHODE ORIGINALE UTILISANT LA THEORIE DES MILIEUX POREUX ET LA TECHNOLOGIE MULTIGRILLE POUR MODELISER LES ECOULEMENTS TURBULENTS ET LES TRANSFERTS THERMIQUES DANS UN MILIEU HETEROGENE FLUIDE/SOLIDE. IL EN RESULTE UN LOGICIEL INTERACTIF D'OPTIMISATION PERMETTANT DE VISUALISER LES RESULTATS ET DE MODIFIER LA GEOMETRIE OU LES CONDITIONS GENERALES D'ECOULEMENT EN COURS DE CALCUL. EN CE QUI CONCERNE LA TURBULENCE, PLUSIEURS VOIES NUMERIQUES SONT EXPLOREES, DES METHODES STATISTIQUES CLASSIQUES A LA SIMULATION INSTATIONNAIRE DIRECTE DES EQUATIONS DE NAVIER-STOKES ET DE L'ENERGIE

Download or read book Simulations des grandes chelles pour la pr diction des coulements de refroidissement des pales de turbines written by Thomas Grosnickel and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Les concepteurs de moteurs aéronautiques sont constamment sujets à la demande d'augmentation de puissance de la part des constructeurs d'aéronefs. Pour satisfaire à cette exigence, la température de sortie de la chambre de combustion peut être augmentée pour améliorer le rendement et la puissance de sortie du moteur. Cette élévation de température peut toutefois dépasser le point de fusion du matériau et, pour éviter les pannes de moteur, l'intégrité des aubes de la turbine repose notamment sur des systèmes de refroidissement internes,prélevant de l'air froid du compresseur. La conception de ces systèmes revient donc à maximiser l'amélioration du transfert de chaleur tout en minimisant le débit d'air via les pertes de charge afin d'éviter des pénalités de puissance du moteur. Or ces écoulements en canaux internes sont encore largement incontrôlés et mal compris. Dans le but de mieux comprendre ces écoulements en rotation se développant spatialement, ce travail porte sur l'étude via simulations numériques d'un canal de refroidissement droit, perturbé, en rotation. La configuration consiste en un canal carré équipé de 8 perturbateurs placés avec un angle de 90 degrés par rapport à l'écoulement principal. Pour les cas étudiés, des mesures PIV temporelles ont été effectuées à l'Institut VanKarman (VKI). Les conditions adiabatiques et isothermes ont été étudiées pour évaluer l'impact dela température de la paroi sur l'écoulement, en particulier dans les configurations en rotation. Les canaux statiques ainsi qu'en rotation positive et négative sont comparés avec, dans chaque cas,une prédiction d'écoulement adiabatique ou isotherme. Dans ce travail, les résultats de simulations aux grandes échelles (SGE) montrent que le modèle CFD haute fidélité est capable de reproduire les différences induites par la flottabilité sur la topologie de l'écoulement dans la région proche. Le modèle parvient également à prévoir l'augmentation (la diminution) de la turbulence autour des perturbateurs en rotation déstabilisante (stabilisante). Enfin et grâce à la SGE spatiale et temporelle complète, le développement spatial et l'instationnarité des écoulements secondaires sont analysés pour mieux comprendre leur origine et leurs différences potentielles entre les cas. Cette étude montre que la topologie du flux thermique en parois est déterminée par la structure des écoulements secondaires alors que l'intensité du flux thermique aux parois est déterminée par le niveau de fluctuations de l'écoulement dans l'espace interperturbateur.

Download or read book Transferts thermiques des coulements turbulents compressibles en conduites written by Jérôme Hébrard and published by . This book was released on 2004 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dans de nombreux dispositifs industriels comme les conduites de refroidissement des moteurs de fusées, un écoulement turbulent est en contact avec une paroi solide chaude.L'instabilité due aux courbures ajoutée au confinement créent des courants orthogonaux au flux principal d'une intensité pouvant aller jusqu'à 20% de celui-ci. Pour comprendre les interactions entre ces courants secondaires et les transferts thermiques, des résultats de simulations numériques des grandes échelles sont obtenus dans des conduites pouvant présenter des courbures et des parois chauffées. Un écoulement pleinement développé est injecté à l'entrée du domaine par la simulation synchrone d'une conduite périodique. Un modèle de viscosité turbulente a été implanté dans le code de calcul et aucune loi de paroi n'est utilisée. Une température supérieure est d'abord appliquée sur une des quatre parois d'une conduite carrée rectiligne pour une validation du code de calcul. Les mécanismes d'éjections de fluide chaud de la paroi chauffée vers le coeur de la conduite sont bien représentés et on peut observer le développement progressif de la couche limite thermique. L'évolution spatiale de l'écoulement a ensuite permis d'appliquer un flux constant.Une conduite de section rectangulaire en forme de S a ensuite été simulée. A chaque courbure, apparaît un fort flux secondaire inhérent au gradient de pression normal aux parois courbes. Ceci implique la naissance d'une paire de tourbillons longitudinaux contra-rotatifs de type "Dean" ou "Ekman" évoluant au voisinage de la paroi convexe.L'interaction entre ces courants secondaires et le mélange turbulent est étudiée suivant les modes de chauffage.

Download or read book Etude th orique et num rique des coulements et des transferts de chaleur dans les canaux en rotation written by Gilles Chaineray and published by . This book was released on 1995 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: LE REFROIDISSEMENT DES AUBES DE TURBINES PEUT S'EFFECTUER PAR CONVECTION INTERNE PAR L'INTERMEDIAIRE DE CIRCUITS DE GEOMETRIE PLUS OU MOINS COMPLEXE. LA ROTATION DE L'ENSEMBLE ENGENDRE UN ECOULEMENT SECONDAIRE QUI MODIFIE DE MANIERE SIGNIFICATIVE LA DISTRIBUTION DES TRANSFERTS THERMIQUES. LA PRESENCE DE PERTURBATEURS DONT LA FONCTION EST D'AMPLIFIER LA TURBULENCE ET PAR DELA LES ECHANGES, COMPLIQUE LES MECANISMES MOTEURS DE L'ECOULEMENT. CES DERNIERS DEPENDENT, DANS CE CAS, D'UNE MULTITUDE DE PARAMETRES GEOMETRIQUES ET DYNAMIQUES. UNE APPROCHE NUMERIQUE, FAISANT APPEL AU CODE DE CALCUL MATHILDA DEVELOPPE A L'ONERA, A PERMIS DE DEGAGER, A PARTIR DE GRANDEURS PREPONDERANTES COMME LA DIRECTION DE ROTATION, LA VITESSE ANGULAIRE ET LE DEBIT, DES CONDITIONS DE REFROIDISSEMENT OPTIMALES. PAR AILLEURS, DES CALCULS SUR DES CONFIGURATIONS DE TYPE INDUSTRIEL ONT ETE MENES. GLOBALEMENT, SI LA ROTATION EST SUFFISANTE, IL EST MONTRE QUE LES ECHANGES SONT AUGMENTES PAR INTENSIFICATION DU BRASSAGE CONVECTIF. MAIS LE BIEN FONDE DE LA DEMARCHE REPOSE SUR UNE VALIDATION SYSTEMATIQUE DU CODE. POUR CE FAIRE, DES CONFRONTATIONS AVEC DES RESULTATS EXPERIMENTAUX ISSUS DE CONFIGURATIONS FIXES ONT ETE ENTREPRISES. ELLES ONT PERMIS D'ACQUERIR, AVANT D'ABORDER LA ROTATION, UNE BASE SOLIDE POUR LA COMPREHENSION DES PHENOMENES MIS EN JEU. LA QUALITE DE LA SIMULATION DEPEND INTIMEMENT DES MODELES DE TURBULENCE ET DES LOIS DE PAROI UTILISES. DANS CE GENRE DE CONFIGURATIONS, LES MODELES CLASSIQUES DE TYPE K- SOUFFRENT DES LIMITATIONS IMPOSEES PAR DES HYPOTHESES TROP RESTRICTIVES. SUR CE CONSTAT, UN MODELE PLUS ELABORE DE TYPE ASM, INTEGRANT LES EFFETS DE LA ROTATION, A ETE IMPLANTE DANS LE CODE. IL A FAIT L'OBJET DE VALIDATIONS ELEMENTAIRES SUR UN ENSEMBLE DE GEOMETRIES SIMPLES ET VARIEES

Download or read book Faecal Sludge Management written by Linda Strande and published by IWA Publishing. This book was released on 2014-08-15 with total page 428 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is estimated that literally billions of residents in urban and peri-urban areas of Africa, Asia, and Latin America are served by onsite sanitation systems (e.g. various types of latrines and septic tanks). Until recently, the management of faecal sludge from these onsite systems has been grossly neglected, partially as a result of them being considered temporary solutions until sewer-based systems could be implemented. However, the perception of onsite or decentralized sanitation technologies for urban areas is gradually changing, and is increasingly being considered as long-term, sustainable options in urban areas, especially in low- and middle-income countries that lack sewer infrastructures. This is the first book dedicated to faecal sludge management. It compiles the current state of knowledge of the rapidly evolving field of faecal sludge management, and presents an integrated approach that includes technology, management, and planning based on Sandecs 20 years of experience in the field. Faecal Sludge Management: Systems Approach for Implementation and Operation addresses the organization of the entire faecal sludge management service chain, from the collection and transport of sludge, and the current state of knowledge of treatment options, to the final end use or disposal of treated sludge. The book also presents important factors to consider when evaluating and upscaling new treatment technology options. The book is designed for undergraduate and graduate students, and engineers and practitioners in the field who have some basic knowledge of environmental and/or wastewater engineering.

Download or read book Acoustics Aeroacoustics and Vibrations written by Fabien Anselmet and published by John Wiley & Sons. This book was released on 2016-01-07 with total page 529 pages. Available in PDF, EPUB and Kindle. Book excerpt: This didactic book presents the main elements of acoustics, aeroacoustics and vibrations. Illustrated with numerous concrete examples linked to solid and fluid continua, Acoustics, Aeroacoustics and Vibrations proposes a selection of applications encountered in the three fields, whether in room acoustics, transport, energy production systems or environmental problems. Theoretical approaches enable us to analyze the different processes in play. Typical results, mostly from numerical simulations, are used to illustrate the main phenomena (fluid acoustics, radiation, diffraction, vibroacoustics, etc.).

Download or read book Gas cooled Nuclear Reactors written by France. Commissariat à l'énergie atomique and published by . This book was released on 2006 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book From Microphysics to Macrophysics written by Roger Balian and published by Springer Science & Business Media. This book was released on 2007-06-26 with total page 626 pages. Available in PDF, EPUB and Kindle. Book excerpt: This popular, often cited text returns in a softcover edition to provide a thorough introduction to statistical physics and thermodynamics, and to exhibit the universal chain of ideas leading from the laws of microphysics to the macroscopic behaviour of matter. A wide range of applications illustrates the concepts, and many exercises reinforce understanding. Volume II applies statistical methods to systems governed by quantum effects, in particular to solid state physics, explaining properties due to the crystal structure or to the lattice excitations or to the electrons. The last chapters are devoted to non-equilibrium processes and to kinetic equations, with many applications included.

Download or read book Four Laws That Drive the Universe written by Peter Atkins and published by OUP Oxford. This book was released on 2007-09-06 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: The laws of thermodynamics drive everything that happens in the universe. From the sudden expansion of a cloud of gas to the cooling of hot metal, and from the unfurling of a leaf to the course of life itself - everything is directed and constrained by four simple laws. They establish fundamental concepts such as temperature and heat, and reveal the arrow of time and even the nature of energy itself. Peter Atkins' powerful and compelling introduction explains what the laws are and how they work, using accessible language and virtually no mathematics. Guiding the reader from the Zeroth Law to the Third Law, he introduces the fascinating concept of entropy, and how it not only explains why your desk tends to get messier, but also how its unstoppable rise constitutes the engine of the universe.

Download or read book How to Design Wastewater Systems for Local Conditions in Developing Countries written by David M. Robbins and published by IWA Publishing. This book was released on 2014-03-15 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a practical handbook providing a step-by-step approach to the techniques used for characterizing wastewater sources and investigating sites where collection, treatment and reuse/disposal technologies will be installed. It is intended to help enable local implementation of on-site and decentralized wastewater management system (DWMS)for wide scale use in development settings. How to Design Wastewater Systems for Local Conditions in Developing Countries helps local service providers and regulatory officials make informed decisions through the use of tools, checklists and case studies. It includes a link to a web based community of on-site and decentralized wastewater professionals, which contains related tools and case studies. This handbook serves as a reference for training classes, certification programs, and higher education programs in civil and sanitary engineering. There is an increasing interest on the part of local government officials and private sector service providers to implement wastewater treatment systems to solve sanitation problems. The model presented in this handbook promotes activities that first generate data related to source and site conditions that represent critical inputs, and then applies this information to the technology selection process. Matching the most appropriate technologies to the specific needs of the wastewater project is the key that leads to long term sustainability. How to Design Wastewater Systems for Local Conditions in Developing Countries is an invaluable resource for public sector decision makers and private sector service providers in developing countries. It is also a useful text for students at engineering colleges in developing countries interested in taking a class that teaches the methods of decentralized wastewater management system (DWMS) development.

Download or read book Compendium of Sanitation Systems and Technologies written by Elizabeth Tilley and published by . This book was released on 2014 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Aircraft Fire Safety written by North Atlantic Treaty Organization. Advisory Group for Aerospace Research and Development. Propulsion and Energetics Panel. Symposium and published by . This book was released on 1997 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Basic Studies in the Field of High temperature Engineering written by Nihon Genshiryoku Kenkyūjo and published by Paris, France : Nuclear Energy Agency, Organisation for Economic Co-operation and Development. This book was released on 2002 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: In response to increasing interest in high-temperature, gas-cooled reactors (HTGRs) in many countries and the need for improved materials for nuclear applications in high-temperature environments, the NEA organised a Second Information Exchange Meeting on Basic Studies in the Field of High-temperature Engineering. These proceedings provide an overview of the activities being carried out in eight countries, the improvement of material properties for HTGR application, in-core monitoring methods and properties of irradiated graphite, and HTGR fuel fabrication and performance.

Download or read book Auxiliary power systems papers presented at the Propulsion and Energetics Panel 61st B specialists meeting held in Copenhagen Denmark 30 31 May 1983 written by AGARD. and published by . This book was released on with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Heat Transfer and Cooling in Gas Turbines written by and published by . This book was released on 1985 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Reacting Flows Combustion and Chemical Reactors written by G. S. S. Ludford and published by American Mathematical Soc.. This book was released on 1986 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt: Represents the culmination of the Special Year '84-'85 in Reacting Flows held at Cornell University. This work focuses on both mathematical and computational questions in combustion and chemical reactors. It is suitable for researchers and graduate students in the theory of reacting flows.

Download or read book Transonic and Supersonic Phenomena in Turbomachines written by and published by . This book was released on 1987 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: