Dissertations / Theses on the topic 'Propulsione navale'
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Iannaccone, Tommaso. "Analisi del comportamento di serbatoi di gas naturale liquefatto per applicazioni di propulsione navale in scenari di incendio." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
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Il presente lavoro di tesi vuole focalizzare l’attenzione sull’impiego del GNL per la propulsione navale, analizzando aspetti legati alla sicurezza delle infrastrutture necessarie a tale scopo.
Si sono considerati due diversi casi di studio: il primo riguarda un deposito costiero attrezzato per poter svolgere attività di rifornimento per imbarcazioni, mentre il secondo caso interessa una nave da trasporto passeggeri alimentata a GNL.
È stata condotta un’analisi del rischio: l’identificazione dei pericoli ha seguito le linee guida proposte dalla metodologia MIMAH, oltre a sfruttare risultati di analisi HAZOP e HAZID. La stima delle frequenze di rilascio è stata effettuata con la tecnica della parts count, sulla base di valori ottenuti da database affidabilistici. La valutazione delle conseguenze è stata realizzata con il supporto del software DNV PHAST, utilizzando come riferimento i valori soglia proposti dal D.M. 9/5/2001.
È stata infine impostata una modellazione fluidodinamica con lo scopo di valutare la possibilità di rottura catastrofica dei serbatoi di stoccaggio dovuta ad un’eccessiva pressurizzazione causata da una situazione di incendio esterno. Le simulazioni sono state condotte con il supporto del software CFD ANSYS® FLUENT® 17.2.
Si è modellata una situazione di completo avvolgimento dalle fiamme considerando due geometrie di serbatoio diverse, nel caso di materiale isolante integro o danneggiato.
I risultati ottenuti dall’analisi del rischio mostrano come i danni derivanti da un ipotetico scenario incidentale possano avere conseguenze anche significative, ma con valori di frequenze di accadimento tipici di situazioni rare.
Lo studio fluidodinamico del comportamento di serbatoi di stoccaggio avvolti dalle fiamme ha evidenziato come questi siano capaci di resistere a condizioni gravose di incendio per tempi prolungati senza che si abbia una pressurizzazione tale da destare preoccupazione per l’integrità strutturale delle apparecchiature.
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Aizza, Marco. "Modelli per la simulazione di azionamenti elettrici di propulsione e sistemi di generazione navali." Doctoral thesis, Università degli studi di Trieste, 2013. http://hdl.handle.net/10077/8532.
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2011/2012La propulsione elettrica navale è una soluzione che riscuote notevole interesse per le navi di nuova generazione. La sua versatilità permette di ottimizzare gli spazi ed i pesi del sistema elettrico di propulsione. Questo sistema garantisce una riduzione dei consumi specifici del motore primo che, al variare della velocità di rotazione dell’elica connessa alla macchina elettrica, lavora costantemente alla velocità nominale, dove i consumi sono ottimizzati. Il presente elaborato si pone come obiettivo lo studio di un sistema di propulsione ibrida, composto da una turbina a gas e due azionamenti elettrici, installato su navi militari di nuova concezione. Il sistema è in grado di funzionare anche come generatore asse. Lo studio si focalizzerà principalmente sugli azionamenti elettrici del sistema di propulsione e sulla loro interazione con il sistema elettrico integrato di bordo. L’obiettivo principale è quello di realizzare un simulatore dettagliato dell’azionamento elettrico di propulsione, permettendo di studiare il funzionamento dello stesso in regime stazionario e in regime dinamico. Viene quindi eseguita una modellizzazione matematica dettagliata dell’azionamento di propulsione oggetto di studio, dalla macchina elettrica ai convertitori di propulsione. Lo studio è condotto allo scopo di ottenere informazioni riguardanti il comportamento dell’azionamento, in determinate condizioni di funzionamento, e gli effetti da esso causati sulla rete elettrica di bordo. Viene poi descritto il modello del sistema funzionante in modalità di “generatore asse”, dalla trattazione fatta sul sistema di propulsione, effettuando una validazione del relativo simulatore implementato, attraverso la comparazione tra i risultati ottenuti e le prove di collaudo fornite dai produttori del sistema oggetto di studio. Viene infine trattato uno degli argomenti più promettenti nell’ambito della propulsione elettrica navale, il sistema di distribuzione in media tensione continua (MVDC). Il sistema MVDC è una soluzione che riscuote notevole interesse nell’ambito delle “all-electric ship” di nuova generazione, grazie ai vantaggi offerti in termini di riduzione di pesi e dimensioni del sistema di generazione e di consumo di energia.
XXV Ciclo
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BONO, ANDREA. "Criticità nelle esigenze e nelle offerte energetiche: il ruolo rilevante della progettazione e della gestione ottimizzata delle macchine a fluido e dei sistemi per la conversione di energia. Aspetti applicativi nella piccola fornitura di energia e nella propulsione navale." Doctoral thesis, Università degli studi di Genova, 2021. http://hdl.handle.net/11567/1046981.
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The present work deals with environmental sustainability and specific engineering solutions able to cope with such a global issue. Attention is focused on renewable energy and innovative fuels as effective strategies in contributing valuable techniques in order to face the need of mitigating environmental problems concerning climate change and global warming.
The research study is targeted on optimized design and management of fluid machinery, and extensively on optimized energy conversion systems, conceptualized in accordance with current standards and regulations, governing the reference sector. The analysis investigates small energy supply from renewables (wind power) and innovative marine propulsion (alternative fuels and unconventional propulsion systems). Regulations and technical design are constantly focused for the study.
The work proposes case solutions for energy design and management actions dealing with the theme of environmental sustainability: engineering analyses (design, technical-economical evaluation, performance results) for hybrid wind powered plants empowering SWRO (Sea Water Reverse Osmosis) desalination processes; engineering analyses (design, technical evaluation, performance results) for wind turbine rotors operating in sites characterized by a small wind resource; engineering analyses (design, technical evaluation, performance results) for marine ship propulsion empowered by LNG as an alternative sustainable fuel and by gas turbines as prime movers coupled to combined cycles as an innovative propulsion system (COGES configuration).
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Convert, Damien. "Propulsion magnétohydrodynamique en eau de mer." Université Joseph Fourier (Grenoble), 1995. http://www.theses.fr/1995GRE10002.
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L'idee simple d'utiliser les forces de laplace pour propulser en eau de mer un navire est apparue des les annees 1960. Les performances etaient alors trop limitees par les inductions des aimants a bobinage classique. Le developpement d'aimants supraconducteurs de grand volume et a forte induction, jusqu'a 10 tesla, relance l'interet de cette propulsion magnetohydrodynamique qui, en supprimant toute piece mecanique mobile, presente une grande furtivite. Cette etude concerne les propulseurs a conduction, c'est a dire que le champ electrique et le courant qui interagissent avec le champ magnetique sont appliques dans le fluide par des electrodes. Une approche globale du systeme propulsif montre que les couplages entre les aspects hydrodynamiques, electromagnetiques et electrochimiques sont faibles. L'etablissement detaille du bilan de quantite de mouvement, conjugue avec diverses expressions de l'equation de bernoulli et de la loi d'ohm, permet de construire un modele unidimensionnel simple. Une demarche d'optimisation des performances amene a considerer une geometrie annulaire s'integrant bien au navire. Dans une seconde partie, les limitations de la modelisation unidimensionnelle sont mises en evidence en plusieurs points. Tout d'abord, l'ecoulement amont est aborde par un calcul en fluide parfait qui montre la non uniformite des vitesses en entree du propulseur, et ces consequences possibles. D'autre part, le couplage entre un modele mecanique et un modele electromagnetique dans deux plans distincts est applique a la propulsion en mode externe. Ce systeme apparait moins performant que ceux envisages precedemment mais il presente de grands avantages par la simplicite du bobinage supraconducteur. Le couplage entre electrochimie et mecanique des fluides est aborde grace a un pilote experimental d'electrolyse en ecoulement realise lors de ce travail. L'etude des reactions aux electrodes montre la difficulte a privilegier un type de degagement. La validation de methodes video sous microscope permet l'analyse des microbulles d'electrolyse
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Papale, Davide. "High performance waterjets: study of an innovative scoop inlet and development of a novel method to design ducted propellers." Doctoral thesis, Università degli studi di Padova, 2015. http://hdl.handle.net/11577/3424758.
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In the last decades the diffusion of waterjet systems for commercial applications in the high speed field is on the increase. These marine propulsors show remarkable qualities in terms of fuel consumption, noise, vibrations and manoeuvrability but they have some disadvantages which make their use optimal only for a limited speed range and which limit the overall propulsive efficiency. In the present document is described a way to modify a conventional waterjet with the aim of reducing these problems, increasing the overall efficiency.
Many problems are dealt with. In chapter 3 it is shown how the substitution of a conventional flush inlet with a new scoop inlet could be an efficient way to minimise the total pressure losses and the non-uniformity velocity distribution upstream the pump, limiting in this way the influence of the boundary layer ingestion on the machine performance. In chapter 4 a novel method to study and design axial pumps is developed and explained. In chapter 5 a rim driven propeller is designed and tested numerically and experimentally demonstrating the good prediction capabilities of the method.Il documento riassume il progetto di dottorato sugli idrogetti ad alte prestazioni condotto dall'autore nel periodo che va dal 2012 al 2014. Durante il triennio sono stati affrontati due filoni principali di ricerca riguardo questi propulsori, focalizzandosi in particolare sullo studio dell'imbocco e del sistema pompante. Un idrogetto è una propulsore navale che riesce a produrre una forza propulsiva accelerando una massa d'acqua; durante questo processo la massa d'acqua, originariamente presente libera nell'ambiente marino o fluviale, attraversa quattro diversi componenti: l'imbocco, il sistema pompante, l'ugello e il sistema sterzante. Ogni componente possiede una sua funzionalità ma in generale massimizzando l'efficienza di questi componenti è possibile osservare un generico aumento delle prestazioni complessive. Il lavoro qui presentato si è focalizzato sullo studio dell'imbocco e del sistema pompante; volendo essere di carattere innovativo, le configurazioni e le idee qui presentate rappresentano delle alternative costruttive o metodologiche sostanzialmente differenti dalla comune prassi industriale. Lo studio dell'imbocco ha avuto come linea guida il confronto tra un imbocco commerciale di stampo tradizionale (i cosiddetti imbocchi flush) e un imbocco dinamico di derivazione aeronautica (imbocchi scoop). Lo studio, oltre a rappresentare forse l'unico caso in letteratura di studio specifico su imbocchi dinamici, mette in luce le criticità dell'imbocco tradizionale mostrando una via alternativa alla prassi industriale. Lo studio analizza le performance in termini di perdite di pressione totali e fattore di distorsione di questi due imbocchi, con e senza la presenza dell'albero di trasmissione, attraverso diverse analisi CFD. Interessante è la derivazione aeronautica dell'imbocco dinamico preso “in prestito” da studi NASA riguardanti un imbocco per un aereo sperimentale caratterizzato da importanti spessori dello strato limite. Lo studio dimostrerà, per il caso in analisi, la superiorità dell'imbocco dinamico rispetto a quello tradizionale nei termini di paragone sopra descritti, dimostrando la necessità di affrontare con critico approfondimento lo studio degli imbocchi sugli idrogetti in ambito industriale, rimettendo in discussione molti dogmi dati per scontati nella realtà industriale ma in verità mai dimostrati nella letteratura scientifica. Lo studio dell'apparato pompante è stato affrontato in due fasi, la prima squisitamente teorica , la seconda di carattere sperimentale. La fase teorica ha visto la definizione di un nuovo metodo per la progettazione di un apparato pompante assiale. Il metodo, che è stato successivamente implementato in un programma Matlab e validato, è un metodo di carattere generale frutto della combinazione di diversi metodi analitici già utilizzati in letteratura ma in maniera concettualmente differente; anche se sviluppato originariamente per una pompa di un idrogetto, è stato pensato per avere una validità generale e può essere utilizzato per lo studio di una qualsiasi pompa assiale intubata. Il metodo rappresenta una combinazione di un metodo BEM (Blade Element Momentum) con due teorie analitiche per il calcolo dei coefficienti di portanza e resistenza dei profili alari (Weinig e Lieblein) e dell'equazione di Eulero per le turbomacchine. Il metodo risultante è un metodo fortemente iterativo che permette di calcolare la geometria di una pompa assiale intubata e le sue prestazioni anche fuori dal punto di progetto senza la necessità di utilizzare fattori empirici di discutibile attendibilità; esso si dimostra quindi un metodo innovativo e flessibile per lo studio completo di un generico propulsore intubato. Il metodo è stato implementato e testato sia numericamente che sperimentalmente grazie alla collaborazione della “University of Southampton” e della ditta “TSL Technology” su un propulsore elettrico attuato in periferia. Il propulsore in questione fa parte di una classe di propulsori di nuova concezione meglio conosciuti come RDP (Rim Driven Propeller) che fra le varie caratteristiche hanno quella di abbandonare la necessità di un albero per la trasmissione della coppia motrice con la conseguente assenza delle perdite dovute alla presenza dell'albero immerso nel flusso dell'acqua. La realizzazione sperimentale di questo propulsore, oltre ad aver sensibilmente migliorato l'efficienza del propulsore rispetto a quelli sviluppati in passato dalla ditta coinvolta, ha dimostrato l'attendibilità del modello analitico sviluppato.
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Froidurot, Benoît. "Discrétion magnétique des machines électriques de propulsion navale." Grenoble INPG, 2002. http://www.theses.fr/2002INPG0074.
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Les machines électriques deviennent le mode principal de propulsion des navires civils depuis quelques années car elles présentent de nombreux avantages. Cependant, l'application aux bâtiments militaires pose des problèmes de discrétion magnétique, notamment pour la lutte anti-mines. Le but de cette thèse est par conséquent de déterminer les champs magnétiques émis par une machine électrique. L'étude et la connaissance de ces champs permettent alors de les compenser de manière à rendre la machine magnétiquement discrète. La solution réside dans un système de compensation externe composé de bobines alimentées judicieusement selon les champs rotorique et statorique de la machine
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Dadd, George M. "Kite dynamics for ship propulsion." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/351348/.
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Kite propulsion has emerged as an attractive means to harness wind power in a way that yields environmental and financial benefits. An understanding of the dynamics that affect kite motion and the resulting forces is required to facilitate the design and optimization of kite propulsion systems. In this thesis results from two line tension models are compared with experimentally recorded time histories for dynamic kite flight. New methodologies for investigating kite performance are established. The first zero mass model assumes that the kite and lines are weightless. The second, lumped mass model, considers the kites mass and thus makes use of the equations of motion. It is found that the two different models converge to the same result in the limit where the kite mass tends to zero. The zero mass model has been shown to compare favourably with experimental results. A method for parameterising figure of eight shape kite trajectories and for predicting kite velocity is presented. Results are shown for a variety of manoeuvre shapes, assuming realistic performance characteristics from an experimental test kite. Using a 320m2 kite, with 300m long flying lines in 6.18ms.
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Debbou, Mustapha. "Modélisation et commande d'un système innovant pour la propulsion navale." Thesis, Toulouse, INPT, 2014. http://www.theses.fr/2014INPT0028.
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Les travaux menés durant cette thèse s'intéressent principalement aux avantages que peut offrir la machine asynchrone à double alimentation (MADA) dans un système de propulsion navale. Ceci est obtenu à travers les degrés de libertés additionnels qu'elle apporte, d'une part, par l'exploitation de la redondance structurelle naturelle, et d'autre part , par les stratégies de contrôle qui lui sont appliquées. La première partie de ce mémoire, présente la modélisation du propulseur innovant. Ce dernier est conçu principalement autour de la MADA comme moteur de propulsion. Il est alimenté par deux onduleurs de tension à Modulation de Largeur d'Impulsion (MLI), et entrainant une hélice à trois pales fixes et symétriques. Plusieurs stratégies de commande ont été introduites pour piloter le système. En effet, des lois de contrôle de type linéaires et non linéaires, associées à des divers modulateurs MLI ont été validées et appliquées à cette structure de propulsion. L'innovation apportée dans le cadre de ces travaux consiste à associer à l'optimisation par conception (machine et convertisseurs d'alimentation), une optimisation par la commande et ce en évaluant l'influence de ces techniques pour deux critères de dimensionnement majeurs, à savoir, les pertes dans les convertisseurs de puissances, et les bruits acoustiques et vibratoires. La propulsion navale, comme tout système embarqué, possède des exigences en matière de qualité de service non seulement en termes de performances mais aussi de fiabilité et de disponibilité. En effet, les systèmes conçus pour ce type d'application doivent assurer et garantir une continuité de service en cas d'apparition de défauts au sein des constituants du système. L'utilisation de la MADA dans les systèmes de propulsion offre une redondance structurelle naturelle et analytique, introduite par la commande, qui permet d'assurer une continuité de service du système en présence d'une défaillance dans la structure. Deux défauts sont ainsi considérés dans cette étude, un défaut de semi-conducteur de puissance dans le convertisseur de puissance et un défaut de capteur vitesse/position. Les stratégies de contrôle proposées, les modèles de propulseur établis ainsi que les reconfigurations adoptées suite aux défauts ont été validées expérimentalement sur les bancs développés au LAPLACE dans le cadre de ces travauxThis study focuses on the benefits that can be induced by the use of the Double Fed Induction Machine (DFIM) operating in motor mode for marine propulsion systems. It can be achieved by the additional degree of freedom it provides, firstly, by exploiting the natural structural redundancy, and secondly, by the alytical redundancy introduced by applied control strategies. The first part of this thesis presents the modeling of a propeller architected mainly around the DFIM and its load such as a propeller with three fixed and symmetrical blades. Several control strategies have been introduced to control the system, in fact, linear and nonlinear control laws type associated with various modulators have been validated and applied to the propulsion structure. The objective was to evaluate the influence of these techniques for two major design criteria, namely, losses in power converters, and noise and vibration noise. Naval propulsion as any embedded system has requirements for the quality of service not only in performance but also reliability and availability. Indeed, the systems designed for these types of applications must ensure and guarantee continuity of service in response to the failures in system components. The use of MADA in propulsion systems provides a natural structural and analytical redundancies which ensure system service continuity in the presence of a fault in this structure. Two faults are considered in this study, a power semiconductor fault in the power converter and a speed sensor / position failure. Control strategies proposed, the propeller modeling established and reconfigurations adopted following settings have been validated by simulation and experimentally on the real laboratory or industrial benches developed in the context of this study
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Waller, Brian S. "Development of a Quantitative Methodology to Forecast Naval Warship Propulsion Architectures." ScholarWorks@UNO, 2015. http://scholarworks.uno.edu/td/2000.
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This paper is an investigation into a quantitative selection process of either a mechanical or electrical system architecture for the transmission of propulsion power in naval combatant vessels. A database of historical naval ship characteristics was statistically analyzed to determine if there were any predominant ship parameters that could be used to predict whether a ship should be designed with a mechanical power transmission system or an electric one. A Principal Component Analysis was performed to determine the minimum number of dimensions required to define the relationship between the propulsion transmission architecture and the independent variables. Combining the results of the statistical analysis and the PCA, neural networks were trained and tested to separately predict the transmission architecture or the installed electrical generation capacity of a given class of naval combatant.
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Man, S. "Aquatic flight inspired propulsion for autonomous underwater vehicles." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/385840/.
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Modern Autonomous Underwater Vehicle (AUV) technology has a number of limitations and one of these is vehicle manoeuvrability. Conventional flight style AUVs generally have turning circle diameters of five or more vehicle lengths, but most marine animals can turn in under one body length. This shows there is merit in looking at marine animals for inspiration to improve the manoeuvrability of AUVs. Aquatic flight propulsion is one marine animal propulsion strategy that was identified early in the research as having the potential to full fill this role. Aquatic flight propulsion has been studied experimentally in the past, but most of the past research focused in one or two axis aquatic flight (foil pitch and dorsoventral roll). However, marine animal literatures show animal aquatic flight is a three axis problem and there is an additional motion component in anteroposterior yaw. The effect of this yaw motion is not well understood and this will be the focus of this thesis’s research. The effect of aquatic flight yaw motion is investigated using a combination of computation modelling and experimental studies. It found two-axis aquatic flight is better for producing propulsive thrust for most scenarios, but three-axis aquatic flight is useful for producing additional off axis force. In particular, the three axis slanted foil actuation path can produce a sizeable vertical force with very little change to the horizontal thrust coefficient, which would be very useful for a positively buoyant AUV to control its depth. The experiment verified the model’s results and many of the experiment data points were within 30% of the model prediction. The experiment has a relatively large uncertainty due to turbulences in the recirculating water channel, so 30% is a reasonably good fit. Whilst there is room for improvement for both the model and the experiment, the current model is sufficient to produce provisional estimates for actuator and control system design as well as identification of various cases of interest for further in depth analysis.
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Guibert, Cédric. "MODELISATION ET COMMANDE EN POUSSEE DE MOTEURS A COURANTS ALTERNATIFS EN PROPULSION NAVALE." Phd thesis, Université de Nantes, 2005. http://tel.archives-ouvertes.fr/tel-00128368.
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L'objectif des travaux présentés dans ce mémoire concerne la commande en poussée de propulseurs électriques marins. Afin de simplifier le problème, l'étude se limite aux véhicules sous-marins autonomes (AUV) ou commandés à distance (ROV).La première partie de ce mémoire présente la modélisation des propulseurs ainsi que plusieurs commandes en poussée issues de la littérature. La majorité de ces commandes est basée sur l'inversion des modèles avec parfois une boucle de régulation
intermédiaire.
Dans une deuxième partie, une commande originale est proposée. Elle repose sur trois éléments : l'observation du couple hydrodynamique, l'estimation de la poussée par modèle inverse et l'utilisation de correcteurs de type PID. Une étude comparative avec les commandes existantes est menée en simulation.
Enfin, la dernière partie concerne la conception d'un banc d'essais. Ce banc d'essais permettra de valider les modèles et les lois de commande utilisés pour la commande en poussée des AUV et des ROV.
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Guibert, Cédric. "Modélisation et commande en poussée de moteurs à courants alternatifs en propulsion navale." Nantes, 2005. http://www.theses.fr/2005NANT2137.
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L'objectif des travaux présentés dans ce mémoire concerne la commande en poussée de propulseurs électriques marins. Afin de simplifier le problème, l'étude se limite aux véhicules sous-marins autonomes (AUV) ou commandés à distance (ROV). La première partie de ce mémoire présente la modélisation des propulseurs ainsi que plusieurs commandes en poussée issues de la littérature. La majorité de ces commandes est basée sur l'inversion des modèles avec parfois une boucle de régulation intermédiaire. Dans une deuxième partie, une commande originale est proposée. Elle repose sur trois éléments~: l'observation du couple hydrodynamique, l'estimation de la poussée par modèle inverse et l'utilisation de correcteurs de type PID. Une étude comparative avec les commandes existantes est menée en simulation. Enfin, la dernière partie concerne la conception d'un banc d'essais. Ce banc d'essais permettra de valider les modèles et les lois de commande utilisés pour la commande en poussée des AUV et des ROVThis work deals with the thrust control for marine electric thrusters. In order to simplify the problem, we consider the case of the thrusters which equip the Autonomous Underwater Vehicles (AUV) or Remotely Operated underwater Vehicles (ROV). The first part of this work presents the thruster modelling and several thrust controls find in the literature. The most of these controls are based on the inverse models, sometimes with a cascade regulation loop. In a second part an original control law is proposed. This one is based on three parts~: the observation of the hydrodynamic torque, the thrust estimation by the inverse model and the use of PID controllers. A comparative study with the existing control laws is undertaking in simulation. Finally, the last part relates to the design of a thruster test stand. This test will allow to validate the models and the control laws used for the thrust control of AUV and ROV
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Schmerber, Louis-Antoine. "Identification et caractérisation de sources électromagnétiques : application à la discrétion des moteurs de propulsion navale." Grenoble INPG, 2006. https://tel.archives-ouvertes.fr/tel-00128151v2.
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Cette thèse présente une méthode d'identification de sources électromagnétiques dynamiques ainsi qu'une méthode de calcul de dimensionnement de blindage électromagnétique. Elles reposent sur les développements harmoniques solutions des équations de Maxwell. L'identification électromagnétique permet de caractériser une source dynamique dans un milieu conducteur à partir de mesures de champs electromagnétiques proches. Elle permet l'extrapolation des signatures électromagnétiques d'une source et le diagnostic d'installations électriques par mesures de champs proches. Cette identification repose sur l'estimation bayésienne des paramètres du développement harmonique d'une source qui permet l'intervention d'information a priori. Le calcul de blindage repose sur l'écriture harmonique des conditions de passage sur les frontières d'un blindage. Il permet de dimensionner un blindage en distinguant l'effet d'atténuation et l'effet de forme en fonction des matériaux et des couches de ce dernierThis Ph. D. Thesis presents two methods : one to identify dynamic electromagnetic sources and another one to size an efficient magnetic shield. Both are based on harmonic expansion solutions of Maxwell's equations. The electromagnetic identification gives from near electromagnetic fields measurements the main characteristics of a dynamic source closed in a conducting media. Electromagnetic field extrapolation of the source and condition monitoring based on near field measurements are the applications of the identification method. It uses Bayesian estimation of the harmonic expansion parameters of a source. It allows the use of prior information. The magnetic shielding method is based on the harmonic expansion of boundary conditions and the distinction between the attenuation effect and the shape effect of the shield on the parameters of an electromagnetic source
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Trophime, Christophe. "Modélisation numérique du couplage magnétohydrodynamique (MHD) fort : application à la propulsion MHD navale." Grenoble INPG, 1995. https://hal.archives-ouvertes.fr/tel-01340645.
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Nous présentons un code numérique 3D de simulation des phénomènes magnétohydrodynamiques. Le problème électromagnétique est traité par la méthode des éléments finis. Les équations de Navier-Stokes pour les fluides incompressibles en régime permanent sont résolues à l’aide de la méthode des Volumes Finis. Le couplage de ces deux méthodes est réalisé par des procédures d’interpolation pour le calcul des forces de Laplace et du champ de vitesse. Le code est appliqué à différents problèmes M. H. D. Ces exemples permettent de valider et de mettre en évidence les situations de couplage M. H. D. Traitées par notre programme. Enfin la modélisation de la propulsion navale M. H. D. Est abordée. Elle concerne à la fois les systèmes à conduction et à induction. Une attention particulière est portée au couplage entre l’écoulement et les forces électromagnétiques dans les deux casWe present a 3D numerical simulation code for MHD phenomena. The electromagnetic problem is treated by the finite element method. Navier-Stokes equations for incompressible fluid in steady state are solved using the Finite Volumes method. The coupling of these two methods is performed by interpolation procedures for calculating the Laplace forces and the velocity field. The code is applied to different MHD problems. These examples validate and highlight coupling MHD situations, processed by our program. Finally the modeling of naval MHD propulsion is discussed. It relates to both systems conduction and induction. Particular attention is paid to the coupling between flow and electromagnetic forces in both cases
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Thomas, Mark W. "Evaluation and optimization of axial air gap propulsion motors for naval vessels." Thesis, Monterey, California. Naval Postgraduate School, 1996. http://hdl.handle.net/10945/8347.
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Thomas, Mark W. (Mark Wayne). "Evaluation and optimization of axial air gap propulsion motors for naval vessels." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/38167.
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Thesis (Nav. E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1996, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.Includes bibliographical references (leaves 89-90).
by Mark W. Thomas.
M.S.
Nav.E.
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Sarris, Emmanouil. "Naval ship propulsion and electric power systems selection for optimal fuel consumption." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/68573.
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Thesis (Nav. E.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and, (S.M. in Engineering and Management)--Massachusetts Institute of Technology, Engineering Systems Division, System Design and Management Program, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. [100]-102).
Although propulsion and electric power systems selection is an important part of naval ship design, respective decisions often have to be made without detailed ship knowledge (resistance, propulsors, etc.). Propulsion and electric power systems have always had to satisfy speed and ship-service power requirements. Nowadays, increasing fuel costs are moving such decisions towards more fuel-efficient solutions. Unlike commercial ships, naval ships operate in a variety of speeds and electric loads, making fuel consumption optimization challenging. This thesis develops a flexible decision support tool in Matlab® environment, which identifies the propulsion and ship-service power generation systems configuration that minimizes fuel consumption for any ship based on its operating profile. Mechanical-driven propulsion systems with or without propulsion derived ship-service power generation, separate ship-service systems and integrated power systems are analyzed. Modeling includes hull resistance using the Holtrop-Mennen method requiring only basic hull geometry information, propeller efficiencies using the Wageningen B series and transmission and prime movers fuel efficiencies. Propulsion and ship-service power generation systems configuration is optimized using the genetic algorithm. US Navy's Advanced Surface Ship Evaluation Tool (ASSET) model for the DDG-51 Flight I destroyer was used for modeling validation. Optimal fuel consumption results are compared against the existing configuration for the DDG-51 Flight I destroyer using a representative operating profile.
by Emmanouil Sarris.
S.M.in Engineering and Management
Nav.E.
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Boissonneau, Patrick. "Propulsion MHD en eau de mer : étude des couplages hydrodynamique-électrochimie-électromagnétisme." Université Joseph Fourier (Grenoble), 1997. http://www.theses.fr/1997GRE10079.
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La magnetohydrodynamique (mhd) permet de realiser des propulseurs a reaction fournissant des flux d'eau de mer a grande vitesse sans helice ni piece mecanique en mouvement. En appliquant a un ecoulement d'eau de mer des champs magnetique et electrique, on produit directement au sein de l'ecoulement des forces electromagnetiques (laplace) qui propulsent le navire. Malheureusement l'eau de mer est un electrolyte : le passage des courants amenes par des electrodes entraine une electrolyse non desiree. Le travail presente se consacre a l'etude des couplages suivants : - influence de l'hydrodynamique parietale sur l'electrochimie de l'eau de mer - influence du degagement de micro-bulles sur la couche limite turbulente - determination des courants et des forces au sein de l'ecoulement les parties experimentales reposent sur la confrontation des mesures sur electrodes de platine en cellule d'electrolyse avec des mesures sur electrodes de titane platine en ecoulement reel. Nous avons associe aux mesures traditionnelles electriques et electrochimiques, l'analyse de la production de bulles (electrolyse) et de ses consequences sur l'ecoulement (velocimetrie granulometrie laser doppler & visualisation). Les parties theoriques, touchant l'electrochimie, font une synthese des connaissances et permettent d'identifier les mecanismes dominants et d'expliquer les resultats experimentaux. La partie calcul numerique, concernant le couplage : ecoulement/champs electromagnetiques, repose sur la confrontation de resultats de modeles globaux dedies avec des simulations faites a l'aide de fluent, logiciel commercial (volumes finis 2d).
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Sigrist, Jean-François. "Modélisation et simulation numérique d'un problème couplé fluide/structure non linéaire : application au dimensionnement de structures nucléaires de propulsion navale." Nantes, 2004. http://www.theses.fr/2004NANT2088.
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Nous nous intéressons dans cette thèse à la modélisation et la simulation numérique d'un problème couplé fluide/structure non linéaire avec surface libre fluide. Nous définissons un cas générique d'étude pour lequel nous formulons un problème linéaire (problème aux valeurs propres du système couplé) et un problème non linéaire (problème d'évolution du système couplé, initialement au repos et soumis à une excitation dynamique). Le problème non linéaire est formulé en pression/déplacement avec les équations de la dynamique linéaire pour la structure et l'équation de Laplace pour le fluide. La résolution du problème aux valeurs propres est conduite avec une méthode de couplage fort éléments finis (structure) et éléments finis/équation intégrale (fluide). Les formulations du problème modal couplé sont écrites dans avec prise en compte ou non des modes de ballottement du fluide. Le problème aux valeurs propres ainsi obtenu est non symétrique : il est résolu avec l'algorithme de Lanczos non symétrique. Le problème non linéaire est formulé en pression-vitesse/déplacement avec les équations de la dynamique non linéaire pour la structure et les équations de Stokes pour le fluide. La résolution du problème d'évolution utilise une méthode de couplage faible. Le problème fluide est résolu avec une technique volumes finis, avec une représentation en maillage mobile, un algorithme temporel découplé en pression/vitesse et une méthode de capture d'interface pour la simulation de la surface libre. Le problème structure est résolu avec une technique éléments finis, un algorithme temporel mixte implicite/explicite. Le couplage des deux problèmes est détaillé pour les aspects de couplage en espace (gestion d'incompatibilité de maillage, projection des efforts et des déplacements, algorithme de remaillage du problème fluide) et en temps (approche explicite, gestion des oscillations numériques). Un travail de validation du code de calcul CFD utilisé pour l'étude est proposé en comparant les résultats de calcul pour deux problèmes fluides élémentaires avec les solutions analytiques correspondantes. Ce travail conduit à la définition d'un benchmark général de validation d'un code de calcul CFD. Une étude numérique est ensuite conduite et permet de mettre en évidence la physique des interactions fluide/structure sur ce cas d'étude (masse ajoutée, masse déplacée, couplage de modes, effets des non linéarités structure). Une application des techniques de calcul éléments finis/éléments finis à l'analyse modale de l'ensemble panier/cuve d'un réacteur nucléaire de propulsion navale permet de montrer l'importance des interactions fluide/structure dans le cas industriel.
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Uhlig, Robert Angus. "Preliminary design and integration procedures for gas turbine intercoolers on naval combatants." Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/80076.
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The methodology used in analyzing the feasibility of installing direct and indirect intercooling systems on naval gas turbines is presented. The indirect system is comprised of two types of heat exchangers; an air to ethylene glycol, plate fin heat exchanger, and an ethylene glycol to seawater shell and tube heat exchanger. The direct system utilizes an air to seawater shell and tube heat exchanger. The analysis requires, as input, air mass flow rates, compressor efficiencies and pressure ratios. The output, based on given environmental constraints and an assumed overall intercooler effectiveness, provides mass flow rates of seawater and ethylene glycol, heat exchanger effectiveness and size, intermediate fluid temperatures, and air and seawater outlet temperatures. The output provides preliminary data for specific heat exchanger design and pump and piping selections.Master of Science
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Palmer, Alistair Robin. "Analysis of the propulsion and manoeuvring characteristics of survey-style AUVs and the development of a multi-purpose AUV." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/72149/.
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Autonomous Underwater Vehicles (AUVs) are a developing technology with multiple applications including oceanographic research, military missions and commercial activities such as oil and gas field exploration. The reported research covers two main areas, namely, the assessment of the survey performance of AUVs and the development of the next generation of multi-purpose AUVs. The performance characteristics of long range survey-style AUVs are examined and improvements in performance are sought through the use of hybrid devices. Hybrid devices are defined as those that provide both propulsion and manoeuvring forces. Two devices were chosen for detailed investigation; a vectored thruster and a collective and cyclic pitch propeller. The manoeuvring performance of both devices was found to be insufficient to justify the additional engineering complexity associated with them. The aim of the next generation of AUVs is to be able to combine long range survey capabilities with low speed investigation of the environment encountered. An assessment of a likely mission profile and a review of the available design options demonstrate that maintaining the survey efficiency of the AUV is of principal importance. Therefore the investigation focuses on approaches to the addition of low speed control to an existing survey-style AUV design using propeller based thrusters. Externally mounted thrusters and through-body tunnel thrusters are reviewed and new experimental investigations are reported to provide insight into the performance characteristics on a survey-style AUV hull form. The main body of the experimental programme characterises forward and aft mounted tunnel thruster performance over a range of forward speeds and small yaw angles. The results are used to develop a new, simple modelling procedure representing the performance of tunnel thrusters on an AUV which facilitates the incorporation of the characteristics of tunnel thrusters into numerical simulations of AUV performance. Such a simulation is used to examine approaches to undertaking the transition phase between high speed survey and low speed manoeuvring operation. The results demonstrate the advantageous nature of undertaking a smooth interchange between control approaches considering both the vehicle performance and the energy demands.
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ODETTI, ANGELO. "Study of innovative autonomous marine vehicles for monitoring in remote areas and shallow waters The Shallow Water Autonomous Multipurpose Platform (SWAMP)." Doctoral thesis, Università degli studi di Genova, 2020. http://hdl.handle.net/11567/1003967.
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The main objective of the research activity covered by the present thesis is the design of an
Autonomous Surface Vehicle for the monitoring of environmental areas characterised by shallow
water, difficult access and harsh environment, namely the Wetlands.
Wetlands are those geographic areas where water meets the earth that cover between 5 and 8%
of the Earth’s surface. Wetlands include mangrove zones, swamps, bogs and marshes, rivers and
lakes, alluvial plains and flooded forests, shallow coasts and coral reefs. In recent years, their importance
is becoming more and more recognized and various international conventions, directives and
projects work on their protection. Their importance is related to the fact that these areas are essential
ecosystems considered among the world’s most productive environment. Classified as natural
purification systems and carbon resources for fauna, Wetlands provide the water and productivity
upon which biological diversity relies for the growth of an enormous amount of species of plants
and animals. Their importance is also related to human activities since Wetlands can be exploited
commercially for fishing but especially become important when thinking that the protection of these
areas can also help fighting the disasters resulting from human impact on the environment and its
role in the climate change.
The lack of a hydro-graphic vessels capable of performing shallow water measurements at depths of
less than 1m has led to unreliable maps and data, thus motivating research on innovative technical
approaches for executing the tasks of water sampling, limnological surveys, bathymetric analyses
and monitoring of water quality. In recent years a variety of robotic approaches to improve the
quality, speed, and accessibility of surveys have been explored by research groups using both commercial
and ad-hoc solutions.
In this thesis a prototype of Autonomous Surface Vehicle (ASV) named SWAMP (Shallow Water
Autonomous Multipurpose Platform) is proposed as the base for an innovative class of reliable modular
re-configurable lightweight ASVs for extremely shallow water applications. The vehicle was
studied to solve the problem of monitoring the water status in the Wetlands but the SWAMP class
ASV will also be able to support, as test-bed, the research on many aspects of marine engineering
and robotics like propulsion issues, structure issues, artificial intelligence, cooperative distributed
control, Guidance, Navigation and Control (GNC) systems as well as innovative technological solutions
in terms of communication, materials, sensors and actuators.
The heterogeneity of the themes treated by this thesis relies on the fact that the whole aspects of
design were taken into consideration.
In this thesis the description of the design, modeling, construction and testing of the new concept
of Autonomous Surface Vehicles (ASV) is illustrated. The motivations behind the necessity of a
new system are described in Chapter 1 and 2 while in Chapter 3 the general considerations on the
requirements that led to the definition of the specifications of a special layout are reported.
In Chapter 4 the design of the vehicle layout is illustrated together with the description of an innovative
soft-material hull structure on which extensive analyses in towing tank were performed. The
tests were carried out both in deep and shallow water to completely identify the surge motion of
the ASV.
The hardware, software and mechanical modularity represent some main ideas behind the conception
of SWAMP. The two hulls of SWAMP are two separate modules. Each hull can be composed
of more or less structural elements, actuation modules, powering elements, control units, sensors.
This can be done without constraints thanks to the novel communication architecture all based on
Wi-Fi modules.
In Chapter 5 the thrusters expressly studied for environmental monitoring in the extremely shallow
waters of the Wetlands (rivers, lakes swamps, marshes, mangroves..) are illustrated. These systems
were modeled, designed and constructed on the Pump-Jet concept. Four Pump-Jet Module s for a
class of small/medium size ASV were built and the description of the design and tests are reported
in the thesis. The extremely modular hardware control system of SWAMP is described in Chapter 6
where also the modules composing the vehicle are described. Once assembled, the vehicle was tested
at sea in various environments. A series of pioneering tests with the application of Machine Learning
and the citizen’s engagement in teaching to a robot to self-control are described in the Chapter 7,
together with more standard results. The algorithm for the training of a neural network for the
control of SWAMP was tested also by using the simulator described in Chapter 8.
The conclusions of this work, reported in Chapter 9, are correlated with a visionary analysis of the
possible applications of SWAMP in a series of futuristic research trends of marine robotics.
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Bourguet, Salvy. "Contribution à l'étude de l'influence du réseau de distribution d'un navire tout électrique sur sa signature électromagnétique." Nantes, 2004. http://www.theses.fr/2004NANT2104.
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Les installations électriques des navires à passagers et de marchandises ne cessent de se développer avec l'emploi généralisé de la propulsion électrique et l'introduction massive de convertisseurs de puissance. Dans le cas de navires militaires, cette augmentation de la puissance électrique installée ne doit pas compromettre sa " discrétion ", notamment par une signature électromagnétique non contrôlée. Tout en mettant en évidence la circulation de courants ainsi que la présence de tensions en basse fréquence sur le réseau de distribution, l'étude se concentre essentiellement sur les systèmes de propulsion et vise à déterminer les sources de telles perturbations. Une analyse à l'aide de fonctions de commutation permet de mettre en évidence des perturbations basses fréquences dans les différents éléments du système de propulsion. Deux types de convertisseurs sont abordés : commutateurs de courant et onduleurs de tension. Ces montages génèrent des perturbations interharmoniques liées au réseau et à la fréquence de pilotage du moteur de propulsion. Celles-ci sont prévisibles selon les convertisseurs la structure de propulsion (couplages des transformateurs, enroulements statoriques du moteur). Des mesures réalisées à bord de plusieurs navires tout électriques équipés de ces convertisseurs de propulsion valident cette approche. La simulation numérique est utilisée en vue d'avoir un outil de prévision des perturbations des systèmes de propulsion de navires. Toujours par une approche expérimentale, une description des différents courants de fuite provenant d'installations particulières est proposée. La mesure du rayonnement électromagnétique émis par un navire tout électrique de croisière est ensuite présentée et analysée, montrant l'influence des fréquences des sources d'alimentation à bordElectrical installations aboard passenger and goods vessels keep developing with a more and more frequent use of electric propulsion and the massive introduction of power converters. As far as military ships are concerned the increase of the aboard electrical power must not compromise its 'discretion', especially due to an uncontrolled electromagnetic signature. In enhancing the circulation of currents as well as the presence of voltage in a low frequency range within the distribution network, this study mainly focuses on propulsion systems and aims at finding the sources of such perturbations. A commutation functions based analysis allows to reveal low frequency perturbations in the different parts of the propulsion system. Two kinds of converters are dealt with: current source inverters and voltage source inverters. Both of these drives generate network and propulsion motor driving frequency dependent interharmonic perturbations. These ones are foreseeable according to the kind of converter and to propulsion structure (coupling of the transformers, propulsion motors stator windings). Some measures recorded aboard several all electric ships equipped with this kind of propulsion converters validate this approach. Numeric simulation is used and developed in order to have a tool to predict the perturbations within the propulsion systems and the distribution networks of the electrical ships. Subsequently, in an experimental approach, this work puts forward a description of the different leakage currents coming from several installations. The measure of the electromagnetic signature transmitted by an all electric cruise hip is presented and analysed, showing the influence of the frequencies of the electrical sources onboard
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Llinares, Sylviane. "Marine, propulsion et technique : l'evolution du systeme technologique du navire de guerre francais au xviiie siecle." Paris 4, 1993. http://www.theses.fr/1993PA040111.
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Le systeme propulsif apparait comme le point faible des batiments de guerre de la marine francaise au dix-huitieme siecle. Ce defaut majeur present sur toutes les composantes du greement (mats, voiles, cordages et poulies) est originel et perdure pendant toute la periode etudiee (1660-1789). D'une maniere generale, le progres des sciences et de la theorie juge indispensable a l'amelioration de la construction navale (mais qui demeure incomplet) et la politique de normalisation excessive suivie par les dirigeants de la marine, ont determine l'evolution du navire de guerre en france. La marine anglaise, au contraire, a toujours innove la premiere en matiere de greement et beneficie de tres nombreuses innovations qui lui assurent une superiorite technologique inegalee en europeThe propulsive system is the main weakness of french shipwar during the eighteenth century. This vulnerable point of rigging (including masting, ropes, blocks and sails) to the vessels and frigates is original, regular and will lasting up the end of the studied period (1660-1789). Generaly, the progress of science and theory esteemed essential to improve the shipbuilding (but tu stay incomplete) and the excessive political "standardization" to be continued by the naval administration are oriented the evolution of shipwar in french. By opposition, the english navy is more inventive for the rigging and she profit's by many innovations tested and prouved on there ships who give it to them a great technological superiority in europe
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VIGNA, VERONICA. "Modelling energy efficiency of complex ship propulsion systems, considering sludge recycling, exhaust gas recovery and Flettner rotors." Doctoral thesis, Università degli studi di Genova, 2022. http://hdl.handle.net/11567/1093175.
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Energy efficiency has become increasingly important during the recent years due to the negative effects of the anthropogenic activities on the environment; in the maritime field IMO is leading a steep slope down policy on Greenhouse gas emission reduction by enacting stricter rules at a fast pace. In addition to the environmental and legal aspects, a key driver for increasing energy efficiency is operational cost savings due to fuel consumption reduction.
In this framework, the thesis focuses on the improvement of the energy efficiency of the ship propulsion plant by analysing different kind of innovative technologies.
Modelling and simulation techniques and appropriate key parameter indicators have been extensively used to provide a suitable metric for bench-marking the different solutions.
The reason behind the choice to analyse different technologies is because a well defined solution does not exist. Different ship types and different operational conditions may trigger different options.
The first way investigated to improve energy efficiency was by means of an innovative technology to transform sludge into new recycled marine fuel oil through a pyrolysis process carried out in a small reactor onboard. A passenger ship was chosen as a case study due to the advantageous large amounts of waste oil involved and the space availability. The feasibility study and the analysis of fuel consumption reduction and EEOI criticalities are reported: the results showed an easy integration of the system inside the incinerator and a reduction of time and costs; about the environmental aspect, the EEOI formula is not suitable for this innovative technologies and the attempt made to calculate it was unsatisfactory. The results are interesting but not good enough to justify the necessary expenditure investment, also in lieu of the noncalculable impact on the efficiency index.
The second investigated solution to further improve the ship efficiency was an innovative flexible propulsion and power system with recovery technologies, studied in collaboration with an Italian shipping company. In the propulsion plant there are dual fuel engines coupled with waste heat recovery systems, innovative hybrid turbocharger and electric power shaft motor/generators. In addition to the description of the propulsion plant and its various modes of use, different configurations are analysed in terms of efficiency and costs and the plant was tested with and without the various recovery systems and with natural gas and HFO, referring to the routes currently travelled by the model ship (a Ro-Ro ferry). The results are expressed as a function of the ship speed: for a given speed and a chosen plant configuration (which recovery systems to consider), the best plant mode of use, among the main three described, is chosen, which means the one associated with the minimum fuel expense. The results showed that the Normal Navigation scenario is the one associated with the lowest fuel costs and highest plant efficiency, for all considered recovery systems. Moreover, they all allow considerable cost savings; in particular, the hybrid turbocharger is the more interesting because the low initial investment is paid off by considerable annual savings. On the other hand, the calculation of the EEDI for each plant configuration shows that only by combining WHRS and hybrid turbocharger together it is possible to respect the IMO limit.
After the analysis of said hybrid propulsion system, there was a need to go further to try to integrate renewable sources on board. Therefore the research moved to the wind assisted propulsion, which is gaining in popularity due to the expected benefit in emission reduction. A study was performed about the proper integration between the conventional diesel engine with controllable pitch propeller propulsion plant and the wind assisted plant with Flettner rotor. A mathematical model describing the behaviour of the rotor in terms of propulsive thrust and power is proposed; the rotor model was then integrated into a diesel propulsion model in order to evaluate the ship net fuel consumption for a given wind condition. The integrated propulsion model was written in parametric form. The methodology is intended to support the ship designer during the choice of the best possible propulsion diesel engine for a given rotor-propeller configuration, in addition it can be used to optimize the fuel consumption during the ship operation. A 3000 tons Ro-Ro/Pax ferry has been selected as case study; the results showed that a bigger rotor is always beneficial, that the best directions of incoming wind are from side to astern while the worst case is head wind, that the stronger the wind, the wider the range of suitable angle and that wind angle has a greater influence on the fuel consumption than the wind speed. With the optimized propulsion plant, remarkable double digit power savings can be observed in the whole range of ship speeds, while a 20% of fuel saving was achieved at the design ship speed.
The three developed numerical models allow to reduce the environmental impact of the ship and these simulators can be used as a tool to design or operate ships able to meet the present and future energy efficiency requirements. Decarbonisation and environmentally friendly innovations are the real challenges of our century. Therefore, the future of research is strongly linked to the improvement of the energy efficiency and the reduction of environmental impact.
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Lanfranchi, Jacques. "Études des résonances d'objets à symétrie cyclique : modes propres d'une hélice de navire." Le Havre, 1998. http://www.theses.fr/1998LEHA0015.
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Le sujet de cette étude concerne la détermination des modes de résonance de maquettes d'hélices de navire placées dans l'air et dans l'eau, l'hélice étant statique. Afin de comprendre les phénomènes physiques mis en jeu, et compte tenu de la géométrie complexe de l'hélice, les travaux ont été menés en commençant par l'étude de modelés très simplifiés. Dans le chapitre I, une étude et expérimentale est réalisée sur deux objets, chacun étant constitue d'une plaque soudée sur un moyeu. L'influence de la disposition des plaques dans l'excitation des modes de résonance est analysée. La comparaison entre les mesures faites dans l'air, et celles faites dans l'eau montre l'influence du liquide sur les résonances. Dans le chapitre II, il est établi que le comportement vibratoire des plaques soudées, déterminé théoriquement par le calcul en basse fréquence dans le chapitre I, peut également être interprète par la propagation d'ondes guidées. Il est montre que des ondes de Lamb effectuent des allers-retours dans la largeur de la plaque. Dans le chapitre II les principales propriétés des objets à symétrie cyclique sont présentées. Les modes de résonance de cibles à symétrie cyclique, composées de cinq plaques soudées sur un moyeu, sont mesures expérimentalement. Ces résultats sont comparés avec ceux obtenus au chapitre i sur une seule plaque. Le chapitre iv termine ces travaux par la détermination des modes de résonance dans l'air et dans l'eau de plusieurs maquettes d'hélice de navire. Les mesures expérimentales sont comparées aux valeurs théoriques calculées par la méthode des éléments finis.
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Gaudart, Louis. "Incidences des configurations de fonctionnement de navires militaires sur la suralimentation a deux etages de leurs moteurs diesel de propulsion pag btc." Nantes, 1987. http://www.theses.fr/1987NANT2061.
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Tauzia, Xavier. "Simulation de l'influence des parametres de fonctionnement des moteurs diesel suralimentes semi-rapides sur les emissions polluantes etude en regime stationnaire et dynamique application aux ensembles utilises en propulsion navale." Nantes, 1998. http://www.theses.fr/1998NANT2063.
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La reduction a la source des emissions polluantes devient un objectif primordial lors de la conception et de l'optimisation des moteurs diesel de forte puissance, notamment pour les ensembles utilises en propulsion navale. Le travail presente dans ce memoire est centre sur ce point important, et sur les consequences engendrees sur le fonctionnement general des moteurs. Compte tenu de la taille des ensembles consideres, la simulation apparait comme un moyen d'etude et d'analyse privilegie. L'etude bibliographique revele l'existence de deux modeles interessants (un modele deux-zones et un modele phenomenologique multizones) mais aussi la necessite de les adapter a l'etude des moteurs diesel de forte puissance, en considerant principalement deux polluants : les no#x et les fumees. La procedure de validation menee sur deux moteurs diesel semi-rapides presentant des niveaux de puissance distincts (320 kw/cyl et 615 kw/cyl) permet d'obtenir, pour les deux polluants retenus, un accord satisfaisant, sur toute l'etendue du domaine d'exploitation. La prise en compte de modifications visant a limiter les emissions de no#x, relatives a l'avance a injection, au diametre des trous des injecteurs, au taux de compression, et a l'adaptation de la suralimentation, traduit egalement un bon accord entre les calculs et les releves experimentaux. La simulation des principaux moyens de depollution a la source (diminution de l'avance a injection, diminution de la temperature d'admission, recyclage des gaz d'echappement, et injection d'eau) en regime stationnaire met en evidence le potentiel de chacune de ces techniques, notamment pour repondre aux imperatifs des reglementations en vigueur. Mais elle fait egalement ressortir les avantages et les inconvenients lies a leur mise en uvre, par rapport a d'autres aspects du fonctionnement du moteur (consommation et limites d'exploitation notamment). La comparaison des resultats fournis par les deux modeles avec ceux des travaux experimentaux disponibles dans la litterature, etablit une assez bonne correspondance. Enfin, le modele deux-zones est retenu, en raison de sa plus grande souplesse, pour etudier les emissions lors des phases de fonctionnement transitoires des moteurs diesel, et evaluer l'efficacite des techniques de depollution pour deux cas tests : echelon de charge et prise de charge suivant une loi helice. Les moyens de depollution habituellement utilises en regime stationnaire ont ici une efficacite limitee. En revanche, l'assistance pneumatique des turbocompresseurs, utilisee pour maintenir un exces d'air eleve, conduit a des reductions d'emissions significatives, et a une amelioration des performances du moteur en regime transitoire.
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LUZZI, MATTEO. "Small scale Cogenerative Energy Systems with low Environmental impact for Naval applications." Doctoral thesis, Università degli studi di Genova, 2022. http://hdl.handle.net/11567/1082823.
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Considering the recent introduction of restrictions on air pollutant onboard ships and the increasing interest towards more energy efficient naval transportation, an effort is made in the present thesis to assess the possible design of a novel engine unit. More specifically, in the current regulation context, Gas Turbines are a promising alternative to current diesel engines, thanks to lighter fuel requirements, low NOx pollutants and the potential to run in combined cycle architecture with cogeneration strategies. While their application has shown clear advantages and drawbacks on large ships, there seems to be little if no data concerning smaller units. The present work tries to assess the possible design of a radial turbine for an engine to be employed onboard ships as a Mini Gas Turbine, i.e. up to 5 MW output power, taking into account cycle, aerodynamic and structural design. To this purpose, a platform was built in Ansys Workbench to perform Computational Fluid Dynamics and thermo-mechanical Finite Element simulations aimed to design and optimize such a novel radial turbine.
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Behrel, Morgan. "Investigation of kites for auxiliary ship propulsion : experimental set-up, trials, data analysis and kite specs novel identification approach." Thesis, Brest, 2017. http://www.theses.fr/2017BRES0132.
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Cette thèse s’inscrit dans le programme de recherche beyond the sea® visant à développer la traction de navire de commerce par des kites géants. Le but est d’utiliser l’énergie du vent, et ainsi de réduire la consommation de carburant des navires et réduire les émissions polluantes. Un tel projet demande de nombreux développements et actions scientifiques, en particulier pour prédire le comportement des cerfs-volants géants et des navires associés. Pour cela des modèles sont développés, mais ces modèles doivent être confrontés à des mesures pour en estimer la validité. Cette thèse a donc pour objectif de mesurer les interactions entre le kite et le navire, à une échelle limitée par rapports aux navires visés par le programme global. Des mesures ont donc été réalisées sur un navire de pêche de 13 m, puis sur un bateau expérimental de 6 m spécialement conçu à cet effet. De plus, des mesures ont aussi été menées à terre pour évaluer uniquement les performances du kite. Chacune de ces campagnes expérimentales mettait en oeuvre un dispositif de mesure complexe, ainsi qu’un système automatique de contrôle du vol du kite. En plus de fournir des données de qualité à destination de la science, les outils développés au cours de cette étude peuvent être utilisés directement par les partenaires industriels du projet beyond the sea®This study is part of the research program beyond the sea® aiming to develop kites as auxiliary propulsion devices for ships. The goal is to use the energy of the wind to save fuel and reduce harmful emissions. Such a project needs numerous developments and scientific actions, particularly to model the behavior of giant kites and associated ships. However these models must be compared to measurements to assess their validity. This study is then focus on the measurements of the interaction between kites and ships, at a limited scale in comparison to the real scope of the project. Thus measurement campaigns were carried out on a 13-meter long trawler, and on a 6-meter long experimental platform specifically designed. Another experimental campaign was also carried out onshore to assess the aerodynamic specs of the kite. Each of these three campaigns was based on a complex experimental set-up, including an automatic kite control system. In addition to provide a valuable data set for further scientific analyses, this study provided also tools which can be used by the industrial partners of the beyond the sea project®
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Rolland, Yves. "Le transport de marchandises sur le Rhône et la Saône à l’époque romaine (Ier s. av. – IVe s. ap. J.-C.) : paramètres, conditions et possibilités de la navigation." Thesis, Lyon 2, 2014. http://www.theses.fr/2014LYO20132.
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Le Rhône, prolongé de la Saône, forme un axe de pénétration à l’intérieur de la Gaule emprunté à l’époque romaine pour mettre en relation la Méditerranée avec le nord de l’empire. De brèves connections terrestres (portages) permettaient de poursuivre les échanges vers les bassins de la Loire, de la Seine, du Rhin et les lacs alpins. Seul le quart sud-ouest semble avoir échappé à l’influence rhodanienne. Ce corridor formait très clairement l’artère majeure du réseau fluvial gaulois, et cela avant-même la conquête romaine. La voie fluviale était à l’époque le principal vecteur de transport de marchandises à l’intérieur des terres, et cela jusqu’à l’arrivée du chemin de fer. Le Rhône et la Saône auraient détenu à eux seuls près de la moitié du trafic fluvial de toute la Gaule. Ces cours ont par ailleurs clairement contribué au développement des villes riveraines correspondant souvent à des haltes fluviales et des nœuds de redistribution. L’intérêt du sujet est donc de toute première importance. Les intentions de ce travail sont triples. Tout d’abord, présenter une synthèse de la navigation du Rhône et de la Saône actualisée des grandes séries de découvertes des années 2000 (épaves lyonnaises et arlésiennes) ; ensuite réhabiliter l’image du « marin d’eau douce » antique qui souffre d’un double a priori, l’archaïsme technique antique, et la facilité de la navigation en milieu fluvial ; enfin, l’intention principale est de montrer les spécificités de la navigation sur le Rhône et la Saône à l’ époque romaine. Pour y parvenir nous procédons en trois temps. Une première partie consacrée aux paramètres de la navigation (marchandises, emballages, embarcations, corporations, milieu fluvial) permettant de cerner en détail les différentes variables de la question. Une seconde partie est dédiée aux conditions de la navigation (conditions climatiques, conditions morphologiques – tirant d’eau, tirant d’air – conditions dynamiques – modes de propulsion autorisés –, conditions juridiques, religieuses, risque d’attaque, etc.). La dernière partie est consacrée aux possibilités de la navigation. Il s’agit en fait d’un outil permettant de simuler des situations de transport. Le lecteur a la possibilité de « composer » un scénario de transport en sélectionnant les variables de la première partie, et en le confrontant aux conditions de navigation de l’axe fluvial défini en seconde partie. Ainsi, il est possible de prendre position sur un certain nombre de sujet comme la remonte du fleuve à la rame ou à la voile, les tirants d’eau autorisés, la présence des navires maritimes ou des navires à dolia en amont d’Arles, les moments propices à la navigation pour les chalands, les vitesses et les temps de transport, etcThe Rhone River, in conjunction with its tributary the Saone River, form an axis of penetration inside the Gaul used during the Roman period to link the Mediterranean sea to the north of the empire. Short land connections enabled the trades to flourish over the basins of the Loire, the Seine, the Rhine and the alpine lakes. Short land connections have allowed the pursuit of the trades over the basins of the Loire, the Seine, the Rhine and the alpine lakes. Only the southwest quarter seems to have escaped the influence of the Rhone. This corridor formed the major artery of the Gallic river network, even before the Roman conquest. The waterway at the time was the primary means for transporting goods inland, up until the arrival of the railway. The Rhône and Saone rivers alone would have conveyed nearly half of river traffic of all Gaul. These waterways have also clearly contributed to the development of riverside towns often corresponding to river stops and points of cargo redistribution. The interest of the subject is of paramount importance. The intention of this work is threefold. First, provide an overview of the navigation of the Rhone and the Saone as evidenced by series of discoveries of the 2000s (Lyon and Arles wrecks) ; then disprove two commonly held misconceptions of the Roman "landlubber": the use of archaic navigation technique and the ease of the river environment. Finally, the main intention is to show the specifics of navigation on the Rhone and Saone in Roman times. This will be covered in three parts. A first part related to the navigation parameters (goods, packaging, crafts, corporations, river environment) to identify in detail the characteristics and issues related to each of them. A second part is dedicated to given navigation conditions : weather, boat morphology (draft, air-draft), dynamic conditions (possible propulsions), legal and religious conditions, risk of attack, etc. Based on the navigation parameters and navigation conditions presented, the last part describes the possibilities of navigation that were offered at that period. It is a tool to simulate transport situations. The reader has the option to "compose" a transport scenario by selecting the parameters of the first part, and by confronting them to the navigation conditions of the fluvial axis defined in the second part. In the end, it is possible to to give answers to several questions such as the use of oar or sail against the current, the possible drafts that could be used, the presence of marine ships or dolia ships upstream of Arles, the most favorable conditions to barge navigation, the speed or travel time
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MIGNOTTE, DOMINIQUE. "Etude et evaluation de l'alteration des moteurs diesel suralimentes. Elaboration d'une procedure de diagnostic. Application aux moteurs de forte puissance a suralimentation monoetagee et bietagee, dans le cadre de la maintenance predictive et corrective de la propulsion navale militaire." Nantes, 1994. http://www.theses.fr/1994NANT2113.
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Cette etude s'inscrit dans le domaine de la maintenance des moteurs diesel suralimentes, exploites pour la propulsion navale militaire. L'objectif principal est l'elaboration d'une procedure de diagnostic capable de s'inserer dans une strategie de maintenance preventive, c'est a dire avant avarie. La demarche suivie, qui se veut la plus generale possible, s'inspire de quelques acquis partiels sur le sujet et fait appel aux grandeurs caracteristiques de l'alteration des phenomenes ou des composants mecaniques ainsi qu'a l'exploitation de l'informatique dans le cadre de la modelisation des avaries. L'accent est mis sur l'importance de la combustion dont les effets thermiques et vibratoires sont exploites dans un systeme informatise de diagnostic. La mesure de l'intensite de severite de combustion (isc) adaptee pour la circonstance a un moteur a prechambre et a geometrie variable, constitue pour le suivi des alterations un indicateur privilegie. Une validation du systeme de detection est obtenue par une correlation avec l'experience lors du reperage d'un cylindre defectueux et au cours du depistage d'une reduction de la section equivalente d'un refrigerant. Neanmoins des limitations ou des insuffisances existent, notamment au niveau des consequences liees a la tribologie de certains elements en particulier le piston, les segments, la chemise. Sur ce plan, le suivi de l'indice de frottement permet en partie de combler les deficiences du systeme de diagnostic, il apporte des renseignements interessants en particulier pour deceler les phenomenes de glacage et de grippage
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Larsson, Arvid. "Ecolometer - An environmental sales tool." Thesis, KTH, Marina system, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-286804.
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Sustainability thinking and environmental questions are often in the center of news today. Our planet is changing and us humans need to change our lifestyle in order to avoid potentially devastating events. New laws and regulations, along with new sustainability goals, are constantly arriving around the world. Within the maritime industry, multiple emission goals have recently been implemented which puts a lot of pressure on shipping companies around the world. This thesis introduces a new sales-tool, The Ecolometer, which purpose is to support sales-processes within Volvo Penta. The tool uses a Product Environmental Footprint methodology to quantify different environmental impact categories based on the Nine Planetary Boundaries model. Based on the Planetary Boundaries model, some focus categories have been selected which has been set as requirements for the new tool. The tool have been validated and tested on some cases, where different propulsion systems where investigated. The results shows that the method and tool is useful and applicable to the intended purpose. The tool provides an efficient and easy way to quantify and optimize environmental impact throughout the lifecycle of a vessel, while in the meantime making sustainability thinking accessible, and popular within the industry. The thesis also shows how necessary it is for Volvo Penta the implement this tool, in order to ensure that their sustainability investments is going in the right direction.Miljöfrågor ligger ofta i fokus i dagens debatt, och att tänka miljövänligt och hållbart blir allt mer ett socialt krav. Vår planet förändras, och vi människor måste göra stora förändringar i hur vi lever för att undvika att potentiella katastrofer uppstår. Nya lagar, regler och hållbarhetsmål är konstant uppsatta runt om i världen för hur vi ska leva. Inom den maritima industrin sattes nyligen stora mål upp i hur mycket utsläpp som tillåts för fartyg runt vilket sätter stor press på företag inom branschen runt om i världen. Denna uppsats introducerar ett nytt försäljningsverktyg, Ecolometern, vars syfte är att hjälpa och assistera Volvo Pentas säljprocesser. Verktyget använder sig av en Product Environmental Footprint metodologi för att kvantifiera miljöpåverkan utifrån olika kategorier i Nine Planetary Boundaries modellen. Baserat på modellen, har ett antal kategorier valts ut, som agerar kriterier för det nya verktyget. Verktyget har även blivit validerat och testa mot ett antal case, där olika drivlinor har blivit analyserade. Resultatet visar att metoden och verktyget är användbart för det uppsatta syftet. Verktyget ger ett effektivt men enkelt sätt att visa och optimera miljöpåverkan sett till hela livscykeln av ett fartyg, samtidigt som det gör hållbarhetstänk mer tillgängligt och populärt inom industrin. Uppsatsen visar också på nödvändigheten för Volvo Penta att implementera detta verktyg, för att försäkra sig om att deras hållbarhetssatsningar verkligen går åt rätt håll.
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Cadalen, Baptiste. "Modélisation et commande robuste d'une aile de kite en vol dynamique : application à la traction d'un navire." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0136.
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Les énergies renouvelables représentent aujourd'hui un domaine de développement de plus en plus important, au vu de la consommation énergétique mondiale et de ses conséquences désastreuses sur l'environnement. Les différents accords politiques, notamment l'accord de Paris, ne peuvent à eux seuls apporter une solution définitive au changement climatique actuel. Les contraintes imposées par la réduction des émissions de CO_2 et l’augmentation du prix du pétrole dans l’industrie maritime ont poussé Yves Parlier à lancer le projet « beyond the sea » dans le but de développer des cerfs-volants (kites) dédiés à la propulsion auxiliaire des navires. L'objectif principal de cette étude est donc la modélisation et la commande robuste d'une aile de kite en vol dynamique. Le but à terme étant l'élaboration d'un pilote automatique dédié à la traction d'un navire par kite. Un modèle « point-masse » du kite est proposé afin de comprendre et contrôler sa dynamique. Les différents paramètres du modèle sont estimés à partir de données expérimentales obtenues lors d’essais en conditions réelles. Des simulations en boucle ouverte sont proposées afin de valider la cohérence du modèle. Pour effectuer un vol dynamique, une trajectoire en forme de huit est définie dans la fenêtre de vol. La position, la taille et l’orientation de cette trajectoire sont des paramètres ajustables par l’utilisateur. Un algorithme de suivi de trajectoire est développé permettant ensuite de synthétiser une loi de commande robuste intégrant le modèle du kite. Ce pilote automatique permet donc d’effectuer une grande variété de trajectoires pour toute une gamme de vitesses de vent. Enfin, des simulations en boucle fermée montrant les performances théoriques du système mettent en évidence l’intérêt de la propulsion auxiliaire des navires par kiteThe need in reducing the CO_2 emissions and the increase of oil prices affect all transportation industries and especially the maritime industry. This has led to the search for more energy-saving ship propulsion systems. Taking advantage of wind energy by using tethered wings, or kites, as an alternative propulsion source can be an effective solution. The "beyond the sea" project, led by Yves Parlier, aims to provide ships an alternative green energy source. In most wind conditions, compared to a static flight, a dynamic motion of a tethered wing with an eight-shaped pattern can provide sufficient force through traction to tow a ship. Therefore, the main objective of this study is the modeling and robust control of a tethered kite in dynamic flight. To this end, a point mass model is first used to describe the kite dynamics. The model parameters are estimated from experimental data and the aerodynamic coefficients are identified using data from a quasi-static flight. Open loop simulations are conducted to verify the kite behavior and the overall coherence of the model. To ensure a dynamic flight, an eight-shaped trajectory is defined within the wind window. Its position, size, orientation and direction are all adjustable parameters. A path-following strategy is then developed in order to design a robust control law including the kite model. This allows the system to be used in different trajectories with a wide range of wind speeds. Closed-loop simulations are presented to show the efficiency of the path-following algorithm, and the various theoretical performances obtained shows the efficiency of a kite dedicated to vessels auxiliary propulsion
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Filho, Gilberto Dória do Valle. "Avaliação das instalações de máquinas em navios visando redução do uso de combustível fóssil." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/3/3135/tde-11082011-131221/.
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Este trabalho trata da questão da redução de consumo de combustível fóssil em instalações de máquinas de navios. É um tema de grande interesse no momento, devido ao alto custo operacional e à emissão de poluentes decorrentes do processo da combustão desses derivados de petróleo. Apresenta-se, inicialmente o cenário atual e tendências futuras das instalações propulsoras convencionais que usam óleo pesado ou Diesel. Em seguida, são examinadas alternativas propostas para redução de consumo de combustíveis fósseis nos navios, que são enquadradas em três categorias. A primeira delas envolve possíveis melhorias de projeto para redução da demanda de energia. As outras categorias se referem ao emprego de fontes alternativas de energia, que introduzem uma força propulsora adicional, reduzindo o empuxo requerido do hélice, ou uma potência suplementar no eixo propulsor. Em ambos os casos há também uma redução de demanda de potência requerida do motor Diesel. Na seqüência, são apresentados e discutidos fundamentos termodinâmicos, com ênfase nas análises energética e exergética, como ferramentas para avaliação das máquinas dos navios. A análise exergética, diferentemente do enfoque apenas energético, é a ferramenta mais apropriada para tratar as questões ligadas ao meio ambiente, pois a própria definição de exergia está relacionada com o ambiente de referência. Finalmente, utilizando dados de um navio porta contêineres da frota nacional, é exercitado um exemplo de aplicação com as análises termodinâmicas do motor de propulsão; são também avaliadas e simuladas as diversas alternativas de melhorias e novas fontes de energia, que visam a redução de consumo de combustível fóssil.This work addresses the issue of reduction of fossil fuel use on ship machinery. Presently it is an interesting topic due to high operational cost and the pollution emissions generated by the combustion process. Initially, it is introduced the present scenario and future trends regarding conventional ship machinery that use heavy or diesel fuel oil. In the sequence, the proposed alternatives for reducing the use of fossil fuel on ships are presented and examined. These alternatives are classified into three categories. The first category comprises possible improvements to the design of ships for reduction of total energy demand. The other categories refer to the use of alternative energy sources, that produce and additional force on the ship reducing the required propeller thrust; or a supplementary power added to the propulsion shaft. For both cases there is also a reduction in the power required from the Diesel engine. Afterwards, the pertaining thermodynamics theory is revised and discussed with focus on the energy and exergy analysis as aid tools for evaluation of ship machinery. The energetic analysis, different from the sole energetic focus, is the most applicable tool to be employed for environmental issues as the self definition of exergy relates to an environment reference. Finally, using data from a typical container ship belonging to the national fleet, an application example using the thermodynamic analysis is performed to the propulsion main engine; as well as it is also simulated several alternative conditions for improvements and new energy sources, aiming to the reduction of fossil fuel consumption.
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Froidurot, Benoît. "DISCRETION MAGNETIQUE DES MACHINES ELECTRIQUES DE PROPULSION NAVALE." Phd thesis, 2002. http://tel.archives-ouvertes.fr/tel-00473509.
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Les machines électriques deviennent le mode principal de propulsion des navires civils depuis quelques années car elles présentent de nombreux avantages. Cependant, l'application aux bâtiments militaires pose des problèmes de discrétion magnétique, notamment pour la lutte anti-mines. Le but de cette thèse est par conséquent de déterminer les champs magnétiques émis par une machine électrique. L'étude et la connaissance de ces champs permettent alors de les compenser de manière à rendre la machine magnétiquement discrète. La solution réside dans un système de compensation externe composé de bobines alimentées judicieusement selon les champs rotorique et statorique de la machine.
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YANG, LI-WEI, and 楊立瑋. "Naval Propulsion Shafting Design And Case Studies." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/9x6hm3.
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碩士國立高雄應用科技大學
模具系碩士在職專班
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This study concentrates on propulsion shafting design and parameters study for MIL-STD-2189 that is a document of design methods for naval shafting. The thesis gets relevant data results and performs case research analysis along with verification for naval propulsion shafting design. Bearing stress and shafting load are designed in the safety range to prevent the shaft and propeller with unnecessary vibration. The study provides reference data for future naval ship propulsion system design and configuration modification. The results for both submarines and surface ships shafting are validated by case studies and proven feasible after the validation. It should be noted that in addition to obtaining the required relevant parameters, boat and environmental conditions in paragraph should be the same as that of the document providing, otherwise the expression will not be validated.
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Schmerber, Louis. "Identification et caractérisation de sources électromagnétiques - Application à la discrétion des moteurs de propulsion navale." Phd thesis, 2006. http://tel.archives-ouvertes.fr/tel-00128151.
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Cette thèse présente une méthode d'identification de sources électromagnétiques dynamiques ainsi qu'une méthode de calcul de dimensionnement de blindage électromagnétique. Elles reposent sur les développements harmoniques solutions des équations de Maxwell. L'identification électromagnétique permet de caractériser une source dynamique dans un milieu conducteur à partir de mesures de champs electromagnétiques proches. Elle permet l'extrapolation des signatures électromagnétiques d'une source et le diagnostic d'installations électriques par mesures de champs proches. Cette identification repose sur l'estimation bayésienne des paramètres du développement harmonique d'une source qui permet l'intervention d'information a priori. Le calcul de blindage repose sur l'écriture harmonique des conditions de passage sur les frontières d'un blindage. Il permet de dimensionner un blindage en distinguant l'effet d'atténuation et l'effet de forme en fonction des matériaux et des couches de ce dernier.
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Gully, Benjamin Houston. "Hybrid powertrain performance analysis for naval and commercial ocean-going vessels." Thesis, 2012. http://hdl.handle.net/2152/ETD-UT-2012-08-6270.
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The need for a reduced dependence on fossil fuels is motivated by a wide range of factors: from increasing fuel costs, to national security implications of supply, to rising concern for environmental impact. Although much focus is given to terrestrial systems, over 90% of the world's freight is transported by ship. Likewise, naval warfighting systems are critical in supporting U.S. national interests abroad. Yet the vast majority of these vessels rely on fossil fuels for operation. The results of this thesis illustrate a common theme that hybrid mechanical-electrical marine propulsion systems produce substantially better fuel efficiency than other technologies that are typically emphasized to reduce fuel consumption. Naval and commercial powertrains in the 60-70 MW range are shown to benefit substantially from the utilization of mechanical drive for high speed propulsion; complemented by an efficient electric drive system for low speed operations. This hybrid architecture proves to be able to best meet the wide range of performance requirements for each of these systems, while also being the most easily integrated technology option. Naval analyses evaluate powertrain options for the DDG-51 Flight III. Simulation results using actual operational profile data show a CODLAG system produces a net fuel savings of up to 12% more than a comparable all-electric system, corresponding to a savings of 37% relative the existing DDG-51 powertrain. These results prove that a mechanical linkage for the main propulsion engine greatly reduces fuel consumption and that for power generation systems requiring redundancy, diesel generators represent a vastly superior option to gas turbines. For the commercial application it is shown that an augmented PTO/PTI hybrid system can better reduce cruise fuel consumption than modern sail systems, while also producing significant benefit with regard to CO2 emissions. In addition, using such a shaft mounted hybrid system for low speed electric drive in ports reduces NOx emissions by 29-43%, while CO is reduced 57-66% and PM may be reduced up to 25%, depending on the specific operating mode. As an added benefit, fuel consumption rates under these conditions are reduced 20-29%.text