Download or read book Mod lisation du bruit de m lange des coulements turbulents libres supersoniques written by C. Bailly and published by . This book was released on 1993 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mod lisation du bruit de m lange turbulent d un jet libre supersonique chaud written by Wilfrid Raguenet and published by . This book was released on 1998 with total page 165 pages. Available in PDF, EPUB and Kindle. Book excerpt: L'OBJECTIF DE LA THESE CONSISTE EN LA MODELISATION DU BRUIT DE MELANGE D'UN JET SUPERSONIQUE CHAUD. ON REALISE LE CALCUL ACOUSTIQUE A PARTIR DE L'ESTIMATION DU CHAMP AERODYNAMIQUE ET D'UNE ANALOGIE ACOUSTIQUE. LE CHAMP AERODYNAMIQUE EST ESTIME A PARTIR DES RESULTATS FOURNIS PAR UN CODE DE MECANIQUE DES FLUIDES FERME PAR UN MODELE DE TURBULENCE K-. L'ANALOGIE ACOUSTIQUE EST FONDEE SUR LA RESOLUTION DE L'EQUATION DE LILLEY. CETTE APPROCHE SE HEURTE A DEUX DIFFICULTES MAJEURES. LA PREMIERE DIFFICULTE APPARAIT LORS DU CALCUL DE LA FONCTION DE GREEN ASSOCIEE A L'EQUATION DE LILLEY. POUR DES VITESSES SUPERSONIQUES, L'EQUATION DEFINISSANT LA FONCTION DE GREEN DEVIENT SINGULIERE AU POINT OU LE FACTEUR DOPPLER S'ANNULE ; SA RESOLUTION EST IMPOSSIBLE PAR DES METHODES NUMERIQUES CLASSIQUES. ON DEVELOPPE DONC DEUX METHODES POUR S'AFFRANCHIR DE CETTE SINGULARITE. L'UNE FAIT INTERVENIR LES PREMIERS TERMES DU DEVELOPPEMENT LIMITE DE LA SOLUTION AU VOISINAGE DU ZERO, L'AUTRE EST UNE SOLUTION ANALYTIQUE EXACTE. LA MODELISATION STATISTIQUE DU TERME SOURCE CONSTITUE LA SECONDE DIFFICULTE DE L'APPROCHE CHOISIE. ON RETIENT LA GRANDEUR DEPLACEMENT POUR REPRODUIRE L'ORIGINE DU CHAMP ACOUSTIQUE, QUI APPARAIT COMME PLUS NATURELLE DANS LE FORMALISME DEVELOPPE. LES PROPRIETES STATISTIQUES DU DEPLACEMENT SONT MODELISEES DE MANIERE CLASSIQUE. LE CALCUL DE LA FONCTION DE GREEN ASSOCIEE A L'EQUATION DE LILLEY ET LA MODELISATION DU TERME SOURCE NOUS PERMETTENT D'ELABORER UN MODELE DE PREVISION ACOUSTIQUE (CODE DUNE) INDEPENDANT DU REGIME DE VITESSE ET DE TEMPERATURE DE L'ECOULEMENT. LA VALIDATION DE LA MODELISATION EST REALISEE AU TRAVERS DE JETS LIBRES CIRCULAIRES SUPERSONIQUES CHAUDS EXPERIMENTES DANS LA SOUFFLERIE ANECHOIQUE CEPRA 19 (U#J#E#T/C#J#E#T = 1,4 ; T#J#E#T/T#0 = 2) D'UNE PART, D'AUTRE PART DANS LE BANC MARTEL (U#J#E#T/C#J#E#T = 2,8 ; T#J#E#T/T#0 = 2,7). LES SIMULATIONS SEMBLENT CONFIRMER, PAR LEUR QUALITE, LE BIEN-FONDE DU MODELE ADOPTE. ON PEUT ESTIMER, AU VU DES RESULTATS, QUE LE CODE DUNE PREVOIT CORRECTEMENT LA DIRECTIVITE ET LE SPECTRE DE PUISSANCE ACOUSTIQUE D'UN JET LIBRE SUPERSONIQUE. LES SIMULATIONS METTENT EN EVIDENCE L'IMPORTANCE DU RAYONNEMENT DES ONDES DE MACH SUR LE CHAMP ACOUSTIQUE.

Download or read book Mod lisation du bruit de m lange des coulements turbulents libres supersoniques written by Electricité de France. Direction des études et recherches and published by . This book was released on 1993 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mod lisation du rayonnement acoustique des coulements turbulents libres subsoniques et supersoniques written by Christophe Bailly and published by . This book was released on 1994 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: On s'intéresse dans ce travail à la prévision numérique du bruit rayonné par des écoulements turbulents libres subsoniques et supersoniques. Dans une première partie, on présente une modélisation statistique avec une résolution intégrale de l'équation de Lighthill. On développe deux modélisations pour des écoulements turbulents libres possédant un nombre de mach convectif soit subsonique, soit supersonique. Le calcul du champ moyen est effectué par résolution des équations de Navier-Stokes moyennées, avec un modèle de turbulence compressible k-epsilon. Dans une seconde partie, on utilise les équations d'Euler linéarisées autour d'un écoulement moyen stationnaire pour calculer le rayonnement acoustique. Le champ moyen est déterminé par résolution des équations de Navier-Stokes moyennées, alors que l'on utilise un champ spatio-temporel synthétique pour la turbulence. Le système forme par les équations d'Euler linéarisées et leurs termes sources est résolu numériquement. Sur un plan pratique, les développements réalisés ici sont déjà utilisés pour la prévision aéroacoustique dans des systèmes industriels

Download or read book Granular Materials written by S Joseph Antony and published by Royal Society of Chemistry. This book was released on 2007-10-31 with total page 385 pages. Available in PDF, EPUB and Kindle. Book excerpt: Granular materials play an important role in many industries. Continuous ingenuity and advancement in these industries necessitates the ability to predict the fundamental behaviour of granular materials under different working environments. With contributions from international experts in the field Granular Materials; Fundamentals and Applications details recent advances made in theoretical computational and experimental approaches in understanding the behaviour of granular materials including industrial applications. Topics covered include: * key features of granular plasticity * high temperature particle interactions * influence of polymers on particulate dispersion stability: scanning probe microscopy investigations * in-process measurement of particulate systems Presented by world renowned researchers this book will be welcomed by scientists and engineers working across a wide spectrum of engineering disciplines.

Download or read book Combustion and Flames written by Roland Borghi and published by Editions Technips. This book was released on 1998 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Professionals working in the field of combustion may well find many points of interest, highlighted by the book's logical and global approach to phenomena, which considers mechanical, thermal and chemical aspects simultaneously. The book prioritises an understanding of the physical and chemical aspects of the phenomena, and lays particular emphasis on experimental analyses and modern numerical simulations, and on the way in which these phenomena are translated into equations.Contents: Introduction: Discovering combustion and flames. 1. Combustion thermodynamics. 2. Chemical kinetics applied to combustion. 3. Mass and energy transport by convection and diffusion. 4. Self-ignitions in closed systems. 5. Laminar flames and deflagrations. 6. Turbulent flames and deflagrations. 7. Detonation and supersonic combustion. 8. Flame ignition. 9. Combustion of liquids and sprays. 10. Pollutant emissions in combustion reactions. Index.

Download or read book Unidentified written by Robert Salas and published by Career Press. This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In 1969 the U.S. Air Force issued a statement that read' "No UFO reported, investigated and evaluated by the Air Force was ever an indication of threat to our national security." This statement is patently false. It has been proven untrue by the testimony of many military officers and airmen and documentation of incidents involving UFOs and nuclear weapons, testimonies of which the U.S. Air Force was fully aware. Unidentified details many of these testimonies, some for the first time. As partial justification for its position, the Air Force cites a University of Colorado study that was contracted and paid for by federal funds. Unidentified reveals how this study was actually just another part of the plan to cover up the reality of the UFO phenomenon. For the first time, Unidentified publishes evidence that the investigators for the Colorado study knew about the UFO-related missile shutdown incidents but did not investigate them or include them in their final report.

Download or read book Lost Secrets of the Sacred Ark written by Laurence Gardner and published by HarperCollins UK. This book was released on 2004 with total page 466 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Ark of the Covenant is the source of one of the deepest mysteries of the Western world. Laurence Gardner has accessed Rosicrucian archives to reveal where the Ark is, what it is and how this lost secret of the distant past has led to the phenomenal new science of space-time manipulation.

Download or read book UFOs are Real written by Clifford E. Stone and published by S.P.I. Books. This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Encounter with Tiber written by Buzz Aldrin and published by Open Road Media. This book was released on 2013-05-28 with total page 802 pages. Available in PDF, EPUB and Kindle. Book excerpt: An Apollo 11 astronaut and the Nebula Award–nominated author of Directive 51 present a novel that “conveys the wonder and promise of space” (Publishers Weekly). Born the year of the Moon landing, Chris Terence spends his life fighting to return humanity to that pinnacle. An engineering student with dreams of spaceflight, he finds upon graduation that the United States no longer has need for astronauts. Years of bureaucratic meddling have reduced the space program to a shell of itself, and it will take the greatest scientific find in history to send humanity skyward once more. After years battling budget hawks, Chris finally gets his chance to walk on the Moon. While there, he finds evidence of an ancient alien civilization, the Tiberians, who visited Earth’s satellite eight thousand years before. Understanding what happened to those long-forgotten travelers will define the lives of Chris and his son, as they fight against all odds to unlock the secrets of the universe. “The collaboration of the first man to pilot a moon lander (Aldrin) with a major voice in contemporary science fiction (Barnes) has produced a fascinating chronicle of man’s first encounter with alien intelligence” (Booklist).