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Multidisziplinäre Formoptimierung modularer Grundgeometrien für Druckgussbauteile mit strömungs- und strukturmechanischen Zielfunktionen / Multidisciplinary shape optimization of modular basic geometries for high pressure die castings with fluid dynamic and structural mechanic objective functionsMaurer, Simon Alexander 18 February 2016 (has links) (PDF)
Am Anfang des Entwicklungsprozesses eines Gussbauteils für die Automobilbranche steht klassischerweise die konstruktive Ausarbeitung und die Auslegung auf Zielgrößen, wie Festigkeit, Steifigkeit bzw. die Erfüllung der Crashlasten. Im nächsten Entwicklungsschritt wird, oftmals in Zusammenarbeit mit externen Lieferanten, das Werkzeugkonzept entwickelt und die Herstellbarkeit mit Hilfe von Gießsimulationen abgesichert. Bei der Fertigung verursachen streuende Prozessgrößen, wie etwa Geschwindigkeits- oder Temperaturniveaus, Schwankungen in der Leistungsfähigkeit des Endprodukts (z. B. lokale Bruchdehnung oder Zugfestigkeit). Maßnahmen zur Erhöhung der Prozessstabilität und zur Reduktion des Verschleißes konzentrieren sich oftmals auf die erfahrungsbasierte Verbesserung des Fertigungsprozesses und Anpassungen des Anguss- und Überlaufsystems. Größere Änderungen der Bauteilgeometrie sind häufig aus zeitlichen Gründen nicht mehr möglich.
Das Ziel dieser Arbeit ist es daher, optimierte modularisierte Grundgeometrien, wie Rippen oder Umlenkungen, mit Hilfe von numerischen Formoptimierungen zu entwickeln, um diese schon von Anfang an in der Bauteilentwicklung zu berücksichtigen. Als Zielfunktionen dienen strömungs- und strukturmechanische Kenngrößen, um einerseits verschleißfördernde Mechanismen und füllungsbedingte Defekte zu reduzieren und andererseits die Beanspruchbarkeit zu erhöhen. Bei den Untersuchungen wird zusätzlich die Robustheit des Ergebnisses analysiert, um Verbesserungspotenziale auch bei streuenden Randbedingungen realisieren zu können. / The virtual development process of an automotive casting part usually begins with classical design tasks and analyses of material strength, stiffness and crash load cases. In the next step, often in cooperation with external suppliers, the tooling concept is developed and casting simulations are used to ensure manufacturability. During manufacturing there is a scatter in process parameters, such as flow velocity or temperature levels, which in turn cause a scatter in the performance of the final product (e.g. local elongation at fracture or ultimate tensile strength). Means to increase process stability and yield are often limited to knowledge-based improvements of the manufacturing process parameters and adaptations of the gating and overflow system. Major changes to the part geometry are usually no longer possible due to project time constraints.
Therefore it is the goal of this thesis to optimize modularized basic geometries, like ribs or bends, by using numerical shape optimizations and employ them right from the beginning of the part development process. For the objective functions of the optimizations the disciplines of fluid dynamic filling and the resulting structural behaviour are considered. In addition, the resulting shape is analyzed with regards to robustness towards scatter in manufacturing operating conditions. By using these new modularized geometries the overall robustness of the final product is expected to be increased.
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Recherche de gaz/mélange gazeux sans hexafluorure de soufre pour des applications haute tensionNechmi, Houssem Eddine 12 December 2016 (has links)
Dans l’état actuel des techniques utilisées pour l’isolation gazeuse des systèmes d’énergie électrique à haute tension, l’hexafluorure de soufre (SF6) tient une place prépondérante en raison de ses performances diélectriques et chimiques (bonne tenue diélectrique, point d'ébullition bas, stabilité chimique, non toxicité, etc.) ; il est l’un des meilleurs isolants gazeux connus à ce jour. Il est principalement utilisé dans les appareils de coupure pour l’extinction de l’arc électrique, les lignes de transmission à isolation gazeuse et autres équipements de puissance. Cependant, de par sa taille excessive, sa durée de vie trop importante et son grand effet radiatif, la molécule de SF6 constitue un agent aggravant de l’effet de serre avec un potentiel de réchauffement global (PRG ou GWP en anglais) très élevé (23900 fois supérieur à celui du CO2). Ainsi, les recommandations internationales (COP3) et européennes (règlement (UE) n°517/2014) tendent à restreindre très fortement, voire interdire son utilisation pour préserver l’environnement. Depuis, une tâche importante a été engagée par les industriels pour trouver d’autres gaz ou mélanges de substitution avec moins d’impact sur l’environnement et des exigences diélectriques comparables ou supérieures à celles du SF6. Les candidats les plus prometteurs appartiennent tous au groupe des molécules poly-fluorées (CF3I, Perfluorinated Ketones, Octafluorotetra-hydrofuran, Hydrofluoroolefin (HFOs) ou heptafluoro-iso-butyronitrile(Fluoronitriles)), Ils offrent tous une tenue diélectrique entre 1.2 et 2.71 par rapport au SF6. Ces molécules candidates ouvrent des perspectives intéressantes pour la substitution de SF6 dans l’appareillage sous enveloppe métallique destiné pour le réseau T&D haute tension. Leur principal inconvénient réside dans leur masse moléculaire élevée, ce qui implique une température de fonctionnement plus élevée par rapport au SF6. Ce travail porte sur l’étude expérimentale des performances diélectriques des mélanges de Fluoronitriles-CO2. Les paramètres intrinsèques de l’avalanche électronique sont identifiés à partir des courants de la décharge stationnaire de Townsend. L’évaluation de ces courants a permis d’extraire le coefficient d’ionisation effectif pour différents mélanges de Fluoronitriles. Une comparaison du potentiel d’isolation de ces mélanges avec celui du SF6 pur, dans différentes géométries électrodes (sphère-plan, pointe-plan, sphère-sphère, système avec le profil de Bruce), sur une large gamme de pression et pour toutes les formes d'ondes de tension normalisées pour d'isolation est présentée. Les résultats de mesures de tensions de claquage de ces mélanges et du CO2 pur, pour comparaison, dans un système coaxial cylindrique de taille réelle, similaire à celui utilisé dans les postes à enveloppe métallique (GIS - Gas Insulated Switchgear), sont également présentés ; une étude de l’influence de la surface et de l’état de surface des électrodes sur la tenue diélectrique en fonction de différents paramètres (pression, rugosité, surface effective, forme de tension et polarité, température de gaz …) est faite. / SULPHUR hexafluoride, SF6, is the most common compressed gas used in high voltage power equipment since the 1950s and in HV transmissions and substations applications (GIS, GCB, GIL …), SF6 holds a prominent place because of its dielectric and chemical performance (high dielectric strength, non-toxicity, low condensation temperature, thermal stability, non-flammability, chemical inactivity with the other constituent materials of the apparatus, availability and moderate cost). It is one of the best insulators gas known today. Despite its excellent properties in both electrical insulation and current interruption performance, the excessive size, the radiative effect and atmospheric lifetime of SF6 molecule makes this gas an aggravating agent for the greenhouse gas effect, with a very high global warming potential (GWP) (23900 times higher than CO2). Thus, the international and European recommendations (COP 3) and (Regulation (EU) No 517/2014) respectively tend to strongly restrict or prohibit its use to preserve the environment. Since then, an important task was undertaken by manufacturers to find other gases or mixtures of substitution with less impact on the environment and dielectric performances comparable or superior to those of SF6. Naturally, the investigations were oriented towards halogenated products that have reduced GWP such as CF3I, Perfluorinated Ketones, Octafluorotetra-hydrofuran, Hydrofluoroolefin (HFOs) or heptafluoro-iso-butyronitrile (Fluoronitriles)), all offer a dielectric strength between 1.2 and 2.71 relative to SF6. These candidates open interesting perspectives for the substitution of SF6 in the GIS applications designed for high voltage T & D network. Their main disadvantage is their high molecular weight, which implies a higher operating temperature compared to SF6. This work deals with the experimental study of dielectric performance of Fluoronitriles CO2 mixtures. Intrinsic parameters of the measured steady state Townsend swarm currents are identified. The evaluation of the currents produce the effective ionization rate constant in different Fluoronitriles-CO2 mixtures. In addition, this work provides a conventional assessing of insulating performance with typical breakdown experiments, conducted for different field configurations over a wide pressure range and for all standard voltage waveforms. The experiments are conducted with different electrodes geometries namely plane-to-plane (Bruce profile), sphere-to-sphere, sphere-to-plane and rod-to-plane. AC and LI breakdown characteristics of CO2 and different Fluoronitriles /CO2 mixtures gas were experimentally analyzed in a real scale GIS coaxial test system. The main investigated parameters are the effect of roughness and effective surface area HV inner conductor on insulation performance, depending on various parameters (pressure, form and voltage polarity, gas temperature…).
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Experimental investigation of multi-component jets issuing from model pipeline geometries with application to hydrogen safetySoleimani nia, Majid 21 December 2018 (has links)
Development of modern safety standards for hydrogen storage infrastructure requires fundamental insight into the physics of buoyant gas dispersion into ambient air. Also, from a practical engineering stand-point, flow patterns and dispersion of gas originating from orifices in the side wall of circular pipe or storage tank need to be studied. In this thesis, novel configurations were considered to investigate the evolution of turbulent jets issuing from realistic pipeline geometries. First, the effect of jet densities and Reynolds numbers on vertical jets were investigated, as they emerged from the side wall of a circular pipe, through a round orifice. The resulting jet flow was thus issued through a curved surface from a source whose original velocity components were nearly perpendicular to the direction of the ensuing jets. Particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF) techniques were employed simultaneously to provide instantaneous and time-averaged flow fields of velocity and concentration. The realistic flow arrangement resulted in an asymmetric flow pattern and a significant deflection from the vertical axis of jets. The deflection was influenced by buoyancy, where heavier gases deflected more than lighter gases. These realistic jets experienced faster velocity decay, and asymmetric jet spreading compared to round jets due to significant turbulent mixing in their near field.
In addition to that, horizontal multi-component jets issuing from a round orifice on the side wall of a circular tube were also investigated experimentally by the means of simultaneous velocity and concentration measurements. A range of Reynolds numbers and gas densities were considered to study the effects of buoyancy and asymmetry on the resulting flow structure. The realistic pipeline jets were always exhibited an asymmetry structure and found to deflect about the jet's streamwise axis in the near field. In the far field, the buoyancy dominated much closer to the orifice than expected in the axisymmetric round jet due to the realistic leak geometry along with the pipeline orientation considered in this study. In general, significant differences were found between the centreline trajectory, spreading rate, and velocity decay of conventional horizontal round axisymmetric jets issuing through flat plates and the pipeline leak-representative jets considered in the present study.
Finally, the dispersion of turbulent multi-component jets issuing from high-aspect-ratio slots on the side wall of a circular tube were studies experimentally by employing simultaneous PIV and PLIF techniques. Two transversal & longitudinal oblong geometries in respect to the longitudinal axes of the tube , and with an aspect ratio of 10 were considered in this study. Both horizontal and vertical orientations along with broad range of Reynolds numbers and gas densities were considered to investigate the effects of buoyancy and asymmetry on the resulting flow structure. The ensuing jets were found to deflect along the jet streamwise axis, once more, due to the realistic pipeline leak-representative configuration. It was also found that increases in aspect ratio of these realistic jets caused a reduction in the angle of deflection, jet centreline decay rates and the width growth on both velocity and scalar fields compared to their round jets counterparts, most notably in the far field.
These findings indicate that conventional jets (those that are issuing through flat surfaces) assumptions are inadequate to predict gas concentration, entrainment rates and, consequently, the extent of the flammability envelope of realistic gas leaks. Thus, extreme caution is required when using conventional jet assumptions to describe the physics of a buoyant jet emitted from realistic geometries. / Graduate
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Enregistrement sédimentaire de l'activité diapirique associée à la ride du Jbel Azourki, Haut Atlas central, Maroc : impact sur la géométrie des dépôts et la distribution des faciès des systèmes carbonatés et mixtes du Jurassique inférieur / Synsedimentary record of diapiric activity related to the Jbel Azourki ridge, Central High Atlas, Morocco : Impact on depositional geometries and facies distribution of the Lower Jurassic carbonate and mixed systemsMalaval, Manon 09 September 2016 (has links)
L’évolution des systèmes sédimentaires jurassiques (Pliensbachien-Bajocien) dans le secteur de Zaouiat-Ahançal (Haut Atlas, Maroc) est localement influencée par des mouvements diapiriques associés à la ride du Jbel Azourki. Cette structure tectonique complexe suit un tracé en baïonnette d’orientation globale OSO-ENE sur près de 60 kilomètres, ponctué par six affleurements de matériel diapirique triasique. L’objectif de cette thèse est de caractériser l’impact du diapirisme sur la géométrie des dépôts et sur la distribution des faciès au sein de trois systèmes de dépôt successifs : (1) un système carbonaté de plate-forme peu profonde (Formations d’Aganane, de Jbel Choucht et d’Assemsouk) (2) des systèmes de rampe mixte silicoclastique et carbonatée (Formations de Tamadout, d’Amezraï, de Tafraout et d’Aguerd-n-Tazoult), (3) et un système carbonaté oolitique (Formation de Bin-El-Ouidane). Une cartographie détaillée des unités stratigraphiques et des unités de faciès, ainsi qu’une série de quatorze coupes géologiques de la ride diapirique du Jbel Azourki ont ainsi été réalisées. L’étude des interactions entre sédimentation et diapirisme révèle un enregistrement continu de la déformation diapirique sur l’ensemble de la série sédimentaire, et a permis d’établir une chronologie de l’activité diapirique dans le secteur de Zaouiat-Ahançal. L’unité des calcaires inférieurs (1) enregistre une déformation polyphasée marquée par le développement localisé, au sein de la plate-forme, de bassins d’extension kilométrique caractérisés par une sédimentation hémipélagique et gravitaire (rim basins). Ces bassins circonscrits aux diapirs sont limités par des bordures de plate-forme bioconstruites à Lithiotis, de type aggradant ou érosif. À partir du Pliensbachien terminal, les déformations syndiapiriques se manifestent dans les unités mixtes (2), d’une part à l’échelle plurikilométrique avec l’accumulation de plusieurs milliers de mètres de dépôts, contrôlée par la variation latérale du taux de subsidence entre et au sein des compartiments nord et sud de la ride, et d’autre part à l’échelle hectométrique de la bordure du diapir avec des géométries caractéristiques et des variations de faciès (micro plates-formes à oolites et coraux). La ride diapirique perce en surface pendant le dépôt des unités mixtes, puis est recouverte par l’unité transgressive peu déformée des calcaires supérieurs (3) à l’Aalénien terminal. Les paramètres de contrôle de la géométrie des dépôts et de la distribution des faciès autour de la ride diapirique du Jbel Azourki correspondent aux variations locales de subsidence liées aux mouvements de la couche de sel en profondeur, au taux de sédimentation et à leur rapport relatif. Ils s’inscrivent dans un contexte tectonique régional, et climatique global, qui définit l’accommodation générale et le type de remplissage sédimentaire du bassin atlasique. Le type de sédimentation, carbonatée ou mixte, joue un rôle prépondérant dans ces manifestations tectono-sédimentaires. / The evolution of the Jurassic sedimentary systems (Pliensbachian-Bajocian) in Zaouiat-Ahançal area (High Atlas, Morocco) is locally controlled by diapiric movements related to the Jbel Azourki ridge. This nearly-60-kilometer-long complex tectonic structure follows an overall WSW-ENE “bayonet-shape” outline, punctuated by six Triassic diapiric outcrops. The aim of this thesis is to characterize the role of diapirism on depositional geometries and facies distribution in three successive sedimentary systems: (1) a shallow-carbonate platform system, (2) mixed siliciclastic- and carbonate-ramp systems and (3) an oolitic-carbonate system. Therefore, a detailed geological map with the stratigraphic and facies units has been realized, as well as a set of fourteen geological sections across the Jbel Azourki diapiric ridge. The analysis of the interactions between sedimentation and diapirism has revealed a continuous recording of diapiric deformation by the entire sedimentary succession, allowing the establishment of a chronology of diapiric activity in the Zaouiat-Ahançal area. The lower-carbonate unit (1) records a polyphase deformation with the development of localized kilometer-scale basins within the platform, characterized by hemipelagic and gravity-flow deposits (rim basins). These basins are confined around the diapirs and bounded by Lithiotis-bioconstructed platform margins, which can be aggradational or erosional. From the late Pliensbachian, the mixed units (2) were affected firstly by syn-diapiric deformations at a pluri-kilometer scale, with the accumulation of several thousand-meter-thick deposits, controlled by lateral variations of the subsidence rate in and between the northern and southern flanks of the ridge, and secondly by syn-diapiric deformations at a hectometer- “diapir-edge” scale, with characteristic geometries and facies variations (oolite- and coral-rich micro platforms). The diapiric ridge reached the surface during the deposition of the mixed units and was finally capped by slightly deformed transgressive upper-carbonate unit (3) in the late Aalenian. The controlling factors on depositional geometries and facies distribution around the Jbel Azourki diapiric ridge are the local variations of the subsidence rate related to salt-movement, the sedimentation rate, and their relative ratio. They are part of the regional tectonic and global climate settings which defined the overall accommodation rate and the sedimentary filling of the atlasic basin. The type of sedimentation, carbonate- or mixed-dominated, played a major role in these tectonic-sedimentary responses.
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Přesné prostoročasy v modifikovaných teoriích gravitace / Exact spacetimes in modified theories of gravityKaramazov, Michal January 2017 (has links)
In the review part of the thesis we summarize various modified theories of gravity, especially those that are characterized by additional curvature invariants in the Lagrangian density. Further, we review non-twisting geometries, especially their Kundt subclass. Finally, from the principle of least action we derive field equations for the case with the Lagrangian density corresponding to an arbitrary function of the curvature invariants. In the original part of the thesis we explicitly express particular components of the field equations for non-gyratonic Kundt geometry in generic quadratic gravity in arbitrary dimension. Then we discuss how this, in general fourth order, field equations restrict the Kundt metric in selected geome- trically privileged situations. We also analyse the special case of Gauss-Bonnet theory. 1
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X-ray waveguide optics: Beyond straight channelsHoffmann-Urlaub, Sarah 18 October 2016 (has links)
No description available.
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Využití fraktální a harmonické analýzy k charakterizaci fyzikálně chemických dějů / Characterisation of the Physical Chemical Processes Using the Fractal and Harmonic AnalysisHaderka, Jan January 2010 (has links)
Existuje mnoho různých způsobů jak analyzovat disperzní systémy a fyzikálně chemické processy ke kterým v takových systémech dochází. Tato práce byla zaměřena na charakterizaci těchto procesů pomocí metod harmonické fraktální analýzy. Obrazová data sledovaných systémů byly analyzovány pomocí waveletové analýzy. V průběhu práce byly navrženy různé optimalizace samotné analýzy, převážně zaměřené na odstranění manuálních operací během analýzy a tyto optimalizace byly také inkorporovány do softérového vybavení pro Harmonickou Fraktální Analýzu HarFA, který je vyvíjen na Fakultě chemické, VUT Brno.
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Multidisziplinäre Formoptimierung modularer Grundgeometrien für Druckgussbauteile mit strömungs- und strukturmechanischen ZielfunktionenMaurer, Simon Alexander 10 December 2015 (has links)
Am Anfang des Entwicklungsprozesses eines Gussbauteils für die Automobilbranche steht klassischerweise die konstruktive Ausarbeitung und die Auslegung auf Zielgrößen, wie Festigkeit, Steifigkeit bzw. die Erfüllung der Crashlasten. Im nächsten Entwicklungsschritt wird, oftmals in Zusammenarbeit mit externen Lieferanten, das Werkzeugkonzept entwickelt und die Herstellbarkeit mit Hilfe von Gießsimulationen abgesichert. Bei der Fertigung verursachen streuende Prozessgrößen, wie etwa Geschwindigkeits- oder Temperaturniveaus, Schwankungen in der Leistungsfähigkeit des Endprodukts (z. B. lokale Bruchdehnung oder Zugfestigkeit). Maßnahmen zur Erhöhung der Prozessstabilität und zur Reduktion des Verschleißes konzentrieren sich oftmals auf die erfahrungsbasierte Verbesserung des Fertigungsprozesses und Anpassungen des Anguss- und Überlaufsystems. Größere Änderungen der Bauteilgeometrie sind häufig aus zeitlichen Gründen nicht mehr möglich.
Das Ziel dieser Arbeit ist es daher, optimierte modularisierte Grundgeometrien, wie Rippen oder Umlenkungen, mit Hilfe von numerischen Formoptimierungen zu entwickeln, um diese schon von Anfang an in der Bauteilentwicklung zu berücksichtigen. Als Zielfunktionen dienen strömungs- und strukturmechanische Kenngrößen, um einerseits verschleißfördernde Mechanismen und füllungsbedingte Defekte zu reduzieren und andererseits die Beanspruchbarkeit zu erhöhen. Bei den Untersuchungen wird zusätzlich die Robustheit des Ergebnisses analysiert, um Verbesserungspotenziale auch bei streuenden Randbedingungen realisieren zu können.:1 Einleitung
1.1 Motivation und Problemstellung
1.2 Zielsetzung und Vorgehensweise
1.3 Stand von Wissenschaft und Technik
2 Grundlagen
2.1 Leichtmetallgussbauteile im Automobil
2.2 Geometrische Gestaltung von Gussbauteilen
2.3 Modellierung gießtechnischer Fertigungsverfahren
2.4 Strukturmechanische Modellierung von Gussbauteilen
2.5 Numerische Optimierung
3 Modellaufbau und -analyse
3.1 Geometrische Entwurfsmodelle
3.2 Strömungsmodellbildung zur Abbildung der Fertigungseinflüsse
3.3 Strukturberechnungsmodell unter Berücksichtigung materieller Defekte
4 Optimierung der Umlenkung
4.1 Optimierungsstrategie und -prozesskette
4.2 Zielfunktionen
4.3 Optimierung mit Entwurfsmodell I
4.4 Optimierung mit Entwurfsmodell II
4.5 Diskussion der Ergebnisse
5 Optimierung der Rippe
5.1 Optimierungsstrategie und -prozesskette
5.2 Ziel- und Restriktionsfunktionen
5.3 Multidisziplinäre Optimierung
5.4 Diskussion der Ergebnisse
6 Zusammenfassung
7 Ausblick
Anhang
Abkürzungs- und Symbolverzeichnis
Literatur- und Quellenverzeichnis / The virtual development process of an automotive casting part usually begins with classical design tasks and analyses of material strength, stiffness and crash load cases. In the next step, often in cooperation with external suppliers, the tooling concept is developed and casting simulations are used to ensure manufacturability. During manufacturing there is a scatter in process parameters, such as flow velocity or temperature levels, which in turn cause a scatter in the performance of the final product (e.g. local elongation at fracture or ultimate tensile strength). Means to increase process stability and yield are often limited to knowledge-based improvements of the manufacturing process parameters and adaptations of the gating and overflow system. Major changes to the part geometry are usually no longer possible due to project time constraints.
Therefore it is the goal of this thesis to optimize modularized basic geometries, like ribs or bends, by using numerical shape optimizations and employ them right from the beginning of the part development process. For the objective functions of the optimizations the disciplines of fluid dynamic filling and the resulting structural behaviour are considered. In addition, the resulting shape is analyzed with regards to robustness towards scatter in manufacturing operating conditions. By using these new modularized geometries the overall robustness of the final product is expected to be increased.:1 Einleitung
1.1 Motivation und Problemstellung
1.2 Zielsetzung und Vorgehensweise
1.3 Stand von Wissenschaft und Technik
2 Grundlagen
2.1 Leichtmetallgussbauteile im Automobil
2.2 Geometrische Gestaltung von Gussbauteilen
2.3 Modellierung gießtechnischer Fertigungsverfahren
2.4 Strukturmechanische Modellierung von Gussbauteilen
2.5 Numerische Optimierung
3 Modellaufbau und -analyse
3.1 Geometrische Entwurfsmodelle
3.2 Strömungsmodellbildung zur Abbildung der Fertigungseinflüsse
3.3 Strukturberechnungsmodell unter Berücksichtigung materieller Defekte
4 Optimierung der Umlenkung
4.1 Optimierungsstrategie und -prozesskette
4.2 Zielfunktionen
4.3 Optimierung mit Entwurfsmodell I
4.4 Optimierung mit Entwurfsmodell II
4.5 Diskussion der Ergebnisse
5 Optimierung der Rippe
5.1 Optimierungsstrategie und -prozesskette
5.2 Ziel- und Restriktionsfunktionen
5.3 Multidisziplinäre Optimierung
5.4 Diskussion der Ergebnisse
6 Zusammenfassung
7 Ausblick
Anhang
Abkürzungs- und Symbolverzeichnis
Literatur- und Quellenverzeichnis
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[en] CFD SIMULATION OF THE FLOW IN THE HYDRAULIC CIRCUITS OF AN ONLINE HEAT EXCHANGER CLEANING DEVICE / [pt] SIMULAÇÃO CFD DO ESCOAMENTO NOS CIRCUITOS HIDRÁULICOS DE UM DISPOSITIVO DE LIMPEZA ONLINE DE TROCADORES DE CALORSERGIO LUIS DE LA HOZ TRUYOLL 09 July 2024 (has links)
[pt] Trocadores de calor são equipamentos essenciais do sistema de resfriamento de
equipamentos de processo, visando assegurar a sua eficácia e eficiência
operacional. O objetivo do trabalho é a simulação computacional do escoamento
do fluido de transporte dos artefatos de limpeza de uma alternativa tecnológica de
trocadores de calor que dispensa a interrupção do processo industrial. A motivação
resultou do potencial da ferramenta computacional CFD em gerar resultados
numéricos de interesse, complementando a base de dados experimentais em locais
críticos do escoamento difíceis de serem instrumentados. A simulação foi realizada
pelo Fluent/Ansys 2023 R2, utilizando-se o modelo de turbulência κ-ômega SST
(Transporte da tensão de cisalhamento), baseado na abordagem média de Reynolds
(RANS - Reynolds-Averaged Navier-Stokes). Os resultados da simulação (campos
de velocidade, pressão e estruturas da turbulência) orientaram ajustes e melhorias
localizadas no projeto construtivo da alternativa tecnológica de limpeza online
proposta, permitindo eliminar zonas de recirculação e uma redução de 62,2 por cento nas
perdas de carga localizadas, que tão drasticamente impactam nos custos de
bombeamento do fluido de transporte dos artefatos de limpeza. A pressão simulada
reproduziu o resultado da medição com 2,5 por cento de concordância. Como conclusão, a
ferramenta computacional provou ser estratégica para orientar a melhoria do projeto
construtivo do dispositivo inovador de limpeza online. Se por um lado os dados
experimentais provêm uma referência confiável fundamentada em medições
rastreáveis a padrões de referência, por outro, a simulação numérica provê
relevantes informações em todo o domínio do escoamento. / [en] Heat exchangers are essential equipment in the cooling system of various
process equipment, aiming to ensure its effectiveness and operational efficiency.
The objective of the work is the computational simulation of the fluid flow
transporting cleaning artifacts from a technological alternative for heat exchangers
that does not require interruption of the industrial process. The motivation resulted
from the potential of the CFD computational tool to generate numerical results of
interest, complementing the experimental database in critical flow locations that are
difficult to instrument. The simulation was carried out by Fluent/Ansys 2023 R2,
using the κ-omega SST (Shear Stress Transport) turbulence model based on the
Reynolds average approach (RANS - Reynolds-Averaged Navier-Stokes). The
simulation results (velocity, pressure fields, and turbulence structures) guided
adjustments and localized improvements in the constructive design of the proposed
online cleaning technological alternative, allowing the elimination of recirculation
zones and a 62.2 percent reduction in localized pressure losses that so drastically impact
the costs of pumping the fluid to transport cleaning artifacts. The simulated pressure
reproduced the measurement results with 2.5 percent agreement. In conclusion, the
computational tool proved to be strategic in guiding the improvement of the
constructive design of the innovative online cleaning device. If, on the one hand,
experimental data provides a reliable reference based on measurements traceable to
reference standards, numerical simulation provides relevant information across the
entire flow domain.
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Cohomologies on sympletic quotients of locally Euclidean Frolicher spacesTshilombo, Mukinayi Hermenegilde 08 1900 (has links)
This thesis deals with cohomologies on the symplectic quotient of a Frölicher space which is locally diffeomorphic to a Euclidean Frölicher subspace of Rn of constant dimension equal to n. The symplectic reduction under consideration in this thesis is an extension of the
Marsden-Weinstein quotient (also called, the reduced space) well-known from the finite-dimensional smooth manifold case. That is, starting with a proper and free action of a Frölicher-Lie-group on a locally Euclidean Frölicher space of finite constant dimension, we
study the smooth structure and the topology induced on a small subspace of the orbit space. It is on this topological space that we will construct selected cohomologies such as : sheaf cohomology, Alexander-Spanier cohomology, singular cohomology, ~Cech cohomology and de Rham cohomology. Some natural questions that will be investigated are for instance: the impact of the symplectic structure on these di erent cohomologies; the cohomology that will
give a good description of the topology on the objects of category of Frölicher spaces; the extension of the de Rham cohomology theorem in order to establish an isomorphism between the five cohomologies.
Beside the algebraic, topological and geometric study of these new objects, the thesis contains a modern formalism of Hamiltonian mechanics on the reduced space under symplectic and Poisson structures. / Mathematical Sciences / D. Phil. (Mathematics)
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