Mathematical models of a nitritation: anaerobic ammonia oxidation (anammox)-coupled biofilm in a counter-diffusion hollow fiber membrane bioreactor (HFMBR) and a nitritation: anammox-coupled biofilm in a co-diffusion rotating biological contactor (RBC) were developed and implemented using AQUASIM. Four different start-up scenarios on the nitritation: anammox-coupled biofilm in an HFMBR were investigated. The supply of oxygen was simulated with the flow through the lumen of the hollow fiber membrane. For the four scenarios, two scenarios investigated the start-up when nitrite was supplied in the feed while the other two scenarios investigated when the source of nitrite was through nitritation only. The results showed that the presence of nitrite in the feed facilitated the start-up of the reactor. In addition, the results also showed that increasing oxygen flux through the membrane up to a certain ratio of ammonia flux with oxygen flux affected reactor performance by improving nitrogen removal and reducing start up time. For the nitritation: anammox-coupled biofilm in an RBC, four different process options were investigated: the number of reactors, the initial anammox (AnAOB) biomass fraction, the bulk oxygen concentration and the maximum biofilm thickness. Modeling results revealed that the steady state total nitrogen removal in RBC reactors in series occurred primarily in the first and second reactors. It is concluded that the number of reactors in series dictates the effluent performance and, therefore, this number can be selected depending upon the desired total nitrogen removal. Simulation results also revealed that increasing the initial AnAOB biomass fraction from 0.01% to 1.0% had no effect in the steady state nitrogen removal but had an effect in the required time to reach the steady state total nitrogen removal and the maximum biofilm thickness. Modeling results of the third process option showed that increasing the bulk oxygen concentration in the reactor from 0.2 g/m3 to 5 g/m3 linearly increased the steady state total nitrogen removal and reduced the time to reach the maximum biofilm thickness. Beyond 5 g/m3, steady state total nitrogen removal decreased. In addition, simulation results revealed that the thicker biofilm clearly showed a more linear correlation between the increase in bulk oxygen concentration and the increase in the steady state total nitrogen removal within a range of bulk oxygen concentrations. The results showed that RBC performance could be controlled by several process options: the number of reactors in series, initial biomass fraction, the bulk oxygen concentration and the maximum biofilm thickness. The mathematical modeling results for the HFMBR and RBC have shown that both have potential as carriers for nitritation: anammox-coupled biofilms targeted at the removal of nitrogen in the wastewater. / Master of Science

This thesis presents a novel, cost-effective method for mapping the pressure distribution on a rotating cylinder in cross flow, a phenomenon central to the Magnus effect. Utilizing commercial-off-the-shelf (COTS) micro-electromechanical system (MEMS) pressure sensors, a high-resolution data acquisition system was developed and integrated into a rotating cylinder model. Compared to traditional approaches, such as slip rings or one-off designs, this method proved significantly cheaper and faster while achieving comparable or superior resolution. The experimental setup, including a modified continuous rotation technique and adaptable model design, facilitated rapid testing across a broad range of Reynolds numbers and reduced frequencies, exceeding the scope of existing literature. This provided an unprecedentedly detailed view of pressure distributions under both steady and unsteady flow conditions. The validated experimental methodology, applicable to arbitrary bluff body shapes and attitudes, has the potential to significantly accelerate research into unsteady aerodynamics. Moreover, the low-cost, adaptable nature of the setup allows its integration into educational settings, providing students with hands-on experience in experimental fluid mechanics and data acquisition.

This thesis deals with the modeling, analysis and control of a novel brushlessgenerator for wind power application. The generator is named as rotatingpower electronic brushless doubly-fed induction machine/generator (RPEBDFIM/G). A great advantage of the RPE-BDFIG is that the slip power recoveryis realized in a brushless manner. This is achieved by introducing an additionalmachine termed as exciter together with the rotating power electronicconverters, which are mounted on the shaft of a DFIG. It is shown that theexciter recovers the slip power in a mechanical manner, and delivers it backto the grid. As a result, slip rings and carbon brushes can be eliminated,increasing the robustness of the system, and reducing the maintenance costsand down-time of the turbine. To begin with, the dynamic model of the RPE-BDFIG is developed andanalyzed. Using the dynamic model, the working principle of the generatoris understood and its operation explained. The analysis is carried out atspeeds, ±20% around the synchronous speed of the generator. Moreover, thedynamics of the generator due to external load-torque disturbances are investigated.Additionally, the steady-state model is also derived and analyzed forthe machine, when operating in motor mode. As a next step, the closed-loop control of the generator is considered indetail. The power and speed control of the two machines of the generator andthe dc-link voltage control is designed using internal model control (IMC)principles. It is found that it is possible to maintain the stability of thegenerator against load-torque disturbances from the turbine and the exciter,at the same time maintain a constant dc-link voltage of the rotor converter.The closed-loop control is also implemented and the operation of the generatorwith the control theory is confirmed through experiments.In the third part of the thesis, the impact of grid faults on the behaviourof the generator is investigated. The operation of the generator and its responseis studied during symmetrical and unsymmetrical faults. An approachto successful ride through of the symmetrical faults is presented, using passiveresistive network (PRN). Moreover, in order to limit the electrical and mechanicaloscillations in the generator during unsymmetrical faults, the dualvector control (DVC) is implemented. It is found that DVC to a certain extentcan be used to safeguard the converter against large oscillations in rotorcurrents. Finally, for completeness of the thesis, a preliminary physical design ofthe rotating power electronic converter has been done in a finite elementsoftware called ANSYS. The thermal footprint and the cooling capability,with estimates of the heatsink and fan sizes, are presented. Besides, another variant of a rotating electronic induction machine whichis based on the Lindmark concept and operating in a single-fed mode is also investigated. It’s steady-state model is developed and verified through experiments. / <p>QC 20151006</p>

This thesis deals with the steady-state, dynamic and control aspects of new type of brushless configuration of a doubly-fed induction machine in which the slip rings and carbon brushes are replaced by rotating power electronics and a rotating exciter. The aim is to study the stability of this novel configuration of the generator under mechanical and grid disturbances for wind power applications. The derivation, development and analysis of the steady-state model of the brushless doubly-fed induction machine with a rotating excitor and the power electronic converters mounted on the shaft and rotating with it, is studied. The study is performed at rated power of the generator between ±20% slip range. Moreover unity power factor operation between ±20% speed range is also discussed. Furthermore dynamic modeling and control aspects of the generator are also analyzed. The controllers were designed using Internal Model Control principles and vector control methods were used in order to control the generator in a closed-loop system. It is shown that through the use of proper feedback control, the generator behaves in a stable state both at super-synchronous and sub-synchronous speeds. Moreover Low Voltage Ride Through of the generator during symmetrical and unsymmetrical voltage dips is also investigated. Passive Resistive Network strategy is employed for Low Voltage Ride Through of the generator during symmetrical voltage dips. On the other hand, Extended Vector Control is used in order to control the negative sequence currents during unsymmetrical voltage dips. Suppression of negative sequence currents is important as they cause extra heating in the windings and affects the lifetime of the mechanical and electrical components of the generator and system due to oscillations in power and torque. In addition to the above studies a steady-state model of a single-fed induction machine is also developed and investigated where the rotating exciter is removed and the rotor windings are short-circuited through the two rotating power electronic converters. In this way the slip power circulates in the rotor and with the help of the two rotating electronic converters, rotor current is used to magnetize the induction machine thereby improving the power factor. The steady state model is verified through experimental results. / <p>20120914</p> / Brushless Wind Generator with Rotating Power Electronic Converters

Large amplitude internal solitary waves in the coastal ocean are commonly modelled with the Korteweg-de Vries (KdV) equation or a closely related evolution equation. The characteristic feature of these models is the solitary wave solution, and it is well documented that these provide the basic paradigm for the interpretation of oceanic observations. However, often internal waves in the ocean survive for several inertial periods, and in that case, the KdV equation is supplemented with a linear non-local term representing the effects of background rotation, commonly called the Ostrovsky equation. This equation does not support solitary wave solutions, and instead a solitary-like initial condition collapses due to radiation of inertia-gravity waves, with instead the long-time outcome typically being an unsteady nonlinear wave packet. The KdV equation and the Ostrovsky equation are formulated on the assumption that only a single vertical mode is used. In this thesis we consider the situation when two vertical modes are used, due to a near-resonance between their respective linear long wave phase speeds. This phenomenon can be described by a pair of coupled Ostrovsky equations, which is derived asymptotically from the full set of Euler equations and solved numerically using a pseudo-spectral method. The derivation of a system of coupled Ostrovsky equations is an important extension of coupled KdV equations on the one hand, and a single Ostrovsky equation on the other hand. The analytic structure and dynamical behaviour of the system have been elucidated in two main cases. The first case is when there is no background shear flow, while the second case is when the background state contains current shear, and both cases lead to new solution types with rich dynamical behaviour. We demonstrate that solitary-like initial conditions typically collapse into two unsteady nonlinear wave packets, propagating with distinct speeds corresponding to the extremum value in the group velocities. However, a background shear flow allows for several types of dynamical behaviour, supporting both unsteady and steady nonlinear wave packets, propagating with the speeds which can be predicted from the linear dispersion relation. In addition, in some cases secondary wave packets are formed associated with certain resonances which also can be identified from the linear dispersion relation. Finally, as a by-product of this study it was shown that a background shear flow can lead to the anomalous version of the single Ostrovsky equation, which supports a steady wave packet.

Le développement de biofilms est étudié sur de longues périodes (de deux à sept mois) dans des réacteurs à disque tournant (RBC) et à lit fixe alimentés par des eaux résiduaires domestiques ou des substrats synthétiques en continu à l’échelle du laboratoire. Deux réacteurs ont été spécialement conçus pour des expériences. Les biofilms ont été soumis à des stress physiques (forces hydrodynamiques) ou chimiques (antibiotique). L’activité biologique des réacteurs a été suivie au cours du temps (dégradation de la pollution carbonée et azotée). Les phénomènes de détachement et de redéveloppement des biofilms ont été caractérisés sur des surfaces lisses ou structurées par des techniques d’analyse d’images non destructives. La quantité globale de biomasse présente est évaluée par l’opacité du biofilm et cette méthode d’évaluation a été validée par comparaison avec des méthodes classiques destructives (coloration au Cristal Violet, matières sèches). La macrostructure du biofilm, liées aux phénomènes de croissance, détachement et recroissance, a été évaluée à l’aide de deux méthodes de caractérisation de la texture visuelle : la méthode de cooccurrence de niveaux de gris (SGLDM) et la longueur des segments (GLRLM). Le travail montre l’efficacité de l’analyse d’images comme une méthode rapide et peu onéreuse dans l’étude des biofilms sur le long terme. / The development of biofilm has been studied over long periods of time (two to seven months) in laboratory-scale rotating biological contactors and fixed bed reactors continuously fed with municipal wastewater or synthetic growth media. Two reactors have been specifically designed for this purpose. The biofilms have been subject to hydrodynamic and chemical (antibiotics) stresses. The overall biological activity of the reactors have been monitored, in terms of carbon and nitrogen removal. The phenomena of sloughing and re-growth have been characterized on smooth and rough surfaces using image analysis non-destructive techniques. The amount of biomass present on the substratum has been evaluated by the biofilm opacity and this monitoring method has been validated by comparison with destructive methods such as crystal violet staining and dry weight. The biofilm macrostructure, related to growth, sloughing and re-growth phenomena, has been evaluated through visual texture characterization of the scanning gray level co-occurrence matrix (SGLDM) and the gray level run length method (GLRLM). The results shows the efficiency of image analysis as a rapid and cheap method to monitor biofilm development on the long term.

<p>U radu su predstavljeni rezultati&nbsp; ispitivanja biolo&scaron;ke&nbsp;<br />stabilnosti vode za piće primenom rotirajućih prstenastih reaktora (eng.&nbsp;<br />rotating annular reactor, RAR). Pomoću RAR praćen je uticaj odabranih&nbsp;<br />faktora na suspendovani i pričvr&scaron;ćeni mikrobni rast pri kontrolisanim&nbsp;<br />laboratorijskim uslovima koji su simulirali distributivne sisteme. Pored&nbsp;<br />toga, u cilju potpunog razumevanja biolo&scaron;ke stabilnosti vode za piće&nbsp;<br />izvr&scaron;eno je ispitivanje metoda za određivanje biodegradabilne frakcije<br />organske materije, BDOC i AOC test.</p><p>Poređenjem BDOC testova sa nativnom populacijom bakterija&nbsp;<br />pričvr&scaron;ćenom za pesak iantracit utvrđena je efikasnija primena biolo&scaron;kog&nbsp;<br />aktivnog peska. Primenom peska za inokulaciju uzorka, vrednost BDOC&nbsp;<br />u podzemnoj vodi sa teritorije srednjeg Banata iznosila je 1,27 mgC/l. U<br />ispitivanju AOC testa sa suspendovanim standardnim kulturama&nbsp;<br />Pseudomonas fluorescens P17 (ATCC 49642) i Spirillum sp. NOX&nbsp;<br />(ATCC 49643), AOC iskori&scaron;ćen od strane NOX je imao veću vrednost u&nbsp;<br />odnosu na P17, &scaron;to pokazuje da su karboksilne kiseline dominantan&nbsp;<br />supstrat za rast. Vrednost AOC u tretiranoj podzemnoj vodi iznosila 32&nbsp;<br />&mu;g acetat-C/l. Veće vrednosti BDOC ukazuju na prisustvo jedinjenja&nbsp;<br />veće molekulske mase u ovoj frakciji u odnosu na AOC frakciju&nbsp;<br />biodegradabilne organske materije.</p><p>U ispitivanju biostabilnosti podzemne vode sa teritorije srednjeg&nbsp;<br />Banatatokom tretmana, najveća količina biofilma je razvijena u RAR sa&nbsp;<br />ozoniranom vodom (13,30 CFU/cm²), &scaron;to potvrđuje efekte ozonizacije na&nbsp;<br />biodegradabilnost organske materije i ponovni rast mikroorganizama.&nbsp;<br />Tokom tretmana zabeleženo je variranje razvoja biofilma, pri čemu je&nbsp;<br />najmanji stepen rasta biofilma uočen u RAR sa vodom nakon GAC&nbsp;<br />filtracije (1,10 CFU/cm²).</p><p>Tokom mikrobne kolonizacije test-pločica RAR pri laminarnom i&nbsp;<br />turbulentnom protoku uočen je sličan trend rasta bakterija u biofilmu u sintetičkoj sme&scaron;i organskih i neorganskih nutrijenata. Međutim, tokom dominacije suspendovanog rasta u sistemu voda-biofilm pri neprotocnim uslovima, pona&scaron;anje biofilmova razvijenih pri protočnim (laminarnim i turbulentnim) uslovima je bilo različto. Uočen je manji udeo bakterija prisutnih u vodenoj fazi kod biofilma nastalim pri turbulentnom protoku u odnosu na veće oslobađanje ćelija iz biofilma nastalim pri laminarnim uslovima, nakon 48h 78% i 89% suspendovanih bakterija, redom. Ovi rezultati pokazuju da su biofilmovi razvijeni pri turbulentnom protoku snažniji, stabilniji &nbsp; i jače pričvr&scaron;ćeni nego pri laminarnom protoku.</p><p>Tokom praćenja sekundarne kolonizacije odvojenih ćelija biofilma&nbsp;<br />uočeno je da se primarni biofilm pona&scaron;a kao stalni rezervoar ćelija koje&nbsp;<br />su sposobne da zauzmu nove povr&scaron;ine vrlo brzo pri različitim&nbsp;<br />hidrodinamičkim uslovima. Brojnost bakterija u biofilmu razvijenom na&nbsp;<br />sekundarnim test-pločicama nakon 24 h iznosila je 32000&plusmn;1200&nbsp;CFU/cm^2&nbsp;<br />u odnosu na 16&plusmn;1 CFU/cm^2&nbsp;primarne test-pločice. Ustanovljen&nbsp;<br />je izraženiji potencijal kolonizacije novih povr&scaron;ina odvojenim želijama iz&nbsp;<br />primarnog biofilma koji je formiran pri turbulentnim uslovima u odnosu&nbsp;<br />na laminarne uslove.</p><p>Proces stvaranja biofilma na test-pločicama od nerđajućeg čelika&nbsp;<br />(SS), polivinilhlorida(PVC) i polietilena(PE) je bio vrlo sličan. Samo&nbsp;<br />debljina biofilma je bila veća na PE (4,0-5,5 kg/m³) nego na SS i PVC&nbsp;<br />test-pločicama (2,7-3,6 kg/m^3&nbsp;i 2,8-3,9 kg/m³, redom). Ustanovljen je&nbsp;<br />uticaj materijala cevi na rast biofilma u RAR snabdevanim vodom iz&nbsp;<br />distributivnog sistema grada Novog Sada, naročito za vreme početne faze&nbsp;<br />procesa. Biofilmovi formirani na različitim materijalima u RAR su uticali&nbsp;<br />na mikrobiolo&scaron;ki kvalitet vode, zavisno od njihove bakterijske gustine.&nbsp;</p><p>SEM analiza potvrdila je prisustvo biofilma na test-pločicama u&nbsp;<br />eksperimentima, ukazujući na uspe!nu primenu RAR u ispitivanju&nbsp;<br />biofilma i biostabilnosti vode za piće.</p><p>Rezultati dobijeni tokom ispitivanja ukazuju da se primenom&nbsp;<br />odabranih i optimizovanih, zavisno od cilja ispitivanja i vrste uzorka,&nbsp;<br />BDOC i AOC testova može efikasno definisati biolo!ka stabilnost vode&nbsp;<br />za piće. Pored toga, sistematski pristup odabiru odgovarajućih materijala&nbsp;<br />cevi, koji je zasnovan na pouzdanim testovima i definisanim&nbsp;<br />kriterijumima, može se primeniti u cilju osiguravanja kvaliteta vode sa&nbsp;<br />mikrobiolo&scaron;kog aspekta.</p><p>Ispitivanja su pokazala uspe&scaron;nu primenuRAR u simulaciji&nbsp;<br />mikrobnog rasta u cevima pri kontrolisanim laboratorijskim uslovima i&nbsp;<br />značaj istovremenog ispitivanja imobilisanog i suspendovanog rasta u&nbsp;<br />definisanom hidrodinamičkom sistemu.&nbsp; Primena RAR kao model biofilma je ukazala na njegov značaj u ispitivanju potencijala ponovnog naseljavanja povr&scaron;ina otkinutih delova i/ili pojedinačnih ćelija biofilma za uspostavljanje efikasne kontrole mikrobnih problema u distributivnim sitemima vode za piće.</p> / <p>This thesis presents theresults of investigation of drinking water biostability using the&nbsp; rotating annular reactor (RAR). The effects of selected factors on the suspended and attached microbial growth under controlled laboratory conditions that simulated the&nbsp;distribution systems were monitored using RAR. In addition, in order to completeunderstanding of the drinking water biological stability,&nbsp;methods for determining biodegradable organic matter fractions, BDOC&nbsp;and AOC methods were tested.</p><p>Comparing the BDOC tests with the native population of bacteria&nbsp;attached to sand and anthracite, a better application of biologically active&nbsp;sand was established. Using BDOC test with sand, the BDOC value in&nbsp;groundwater from the territory of the Central Banat (Republic of Serbia)&nbsp;was 1.27 mgC/L. In the investigation of AOC tests with standard&nbsp;<br />suspended culture of Pseudomonas fluorescens P17(ATCC 49642) and&nbsp;Sprillumsp. NOX (ATCC 49643), AOC utilized by NOX had a higher&nbsp;value compared to the P17, which shows that the carboxylic acid are&nbsp;dominant substrate for growth. The AOC value in the treated ground&nbsp;water was 32 &mu;g acetate-C/L. The higher BDOC values indicate the&nbsp;presence of higher molecular weight compounds in this fraction&nbsp;compared to the AOC biodegradable fraction of organic matter.&nbsp;</p><p>In the investigation of biostability during treatment of&nbsp;groundwater from the territory of the Central Banat (Republic of Serbia),&nbsp;the largest amount of biofilm was developed in the RAR with ozonated&nbsp;water (13.30 CFU/cm²), confirming the effects of ozonation on organic&nbsp;matter biodegradability and microbial regrowth. During treatment the&nbsp;<br />variation of biofilm development was detected and in the RAR with water after GAC filtration the lowest level of biofilm growth (1.10 CFU/cm²) was observed.&nbsp;</p><p><span style="font-size: 12px;">During the microbial colonization of the RAR test-coupons under&nbsp;</span><span style="font-size: 12px;">laminar and turbulent flow, the similar trend of growth of bacteria in the&nbsp;</span><span style="font-size: 12px;">biofilm in synthetic mixture of organic &nbsp;and inorganic nutrients was&nbsp;</span><span style="font-size: 12px;">observed. However, the higher numbers of immobilized bacteria under&nbsp;</span><span style="font-size: 12px;">the turbulent conditions in the same growth period (16 days) were&nbsp;</span><span style="font-size: 12px;">recorded. During the domination of suspended growth in water-biofilm system under &nbsp;non-flow conditions, the behavior of biofilms developed under flow (laminar and turbulent) conditions were different. There was a smaller proportion of bacteria present inthe aqueous phase of the biofilm formed under the turbulent flow over a larger release of cells &nbsp;from biofilms formed under laminar conditions, after 48h 78% and 89% of the suspended &nbsp;bacteria, respectively. These results indicate that biofilms developed under turbulent flow &nbsp;were stronger, more stable and more strongly attached than the ones under laminar flow.</span></p><p>During monitoring of the secondary colonization of the dettached&nbsp;biofilm cells, it was noted that the primary biofilm was a constant&nbsp;reservoir of cells that are able to occupy the new areas very quickly&nbsp;under different hydrodynamic conditions. The abundance of bacteria in&nbsp;the biofilm developed on the secondary test-coupons after 24 h was 32&nbsp;<br />000&plusmn;1200 CFU/cm² compared to 16&plusmn;1 CFU/cm²on the primary test-coupons. A stronger potential for colonization of new areas by dettached&nbsp;cells from the primary biofilm formed under the turbulent conditions in&nbsp;comparison to laminar conditions was found.&nbsp;</p><p>The biofilm formation processes on SS, PVC and PE test-coupons&nbsp;werevery similar. Only biofilm thickness was greater on the PE (4.0 to&nbsp;5.5 kg/m³) than the SS and PVC &nbsp;test-coupons (2.7 to 3.6 kg/m³ and 2.8 to&nbsp;3.9 kg/m³, respectively). There was a slight influence of pipe material on&nbsp;the biofilm growth, especially during the initial stages of the process.&nbsp;Biofilms formed on different materials in the RAR with water from the&nbsp;distribution system of the city of Novi Sad (Vojvodina, Republic of&nbsp;Serbia) have showed the influence on the microbiological quality of&nbsp;water, depending on their bacterial density.</p><p>SEM analysis confirmed the biofilm presence on test-coupons in&nbsp;the experiments, indicating the successful implementation of RAR in the&nbsp;examination of biofilm and drinking water biostability.&nbsp;</p><p><span style="font-size: 12px;">The results obtained during the investigations indicate that the&nbsp;</span><span style="font-size: 12px;">application of selected and optimized, depending on the test objective&nbsp;</span><span style="font-size: 12px;">and sample types, BDOC and AOC tests can effectively define the&nbsp; biological stability. In addition, a systematic approach for &nbsp;electing appropriate pipe materials, which is based on reliable tests and defined criteria, specific for the investigated drinking water distribution system can be applied to ensure &nbsp;he water quality from a microbiological point of view.</span></p><p>The investigations have shown the successful application of RAR&nbsp;in the simulation of microbial growth in the pipes under controlled&nbsp;laboratory conditions as well as the importance of simultaneous&nbsp;examination of immobilized and suspended growth under defined&nbsp;hydrodynamic system. Implementation of RAR as amodel biofilm&nbsp;indicated its importance in examining the potential resettlement area by&nbsp;dettached parts and/or individual biofilm cells to establish effective&nbsp;control of microbial problems in the drinking water distribution system.&nbsp;</p>

Une grande quantité d'énergie est présente dans les mouvements de rotations propre et orbitale des planètes. Des forçages harmoniques tels que les déformations de marées, la précession ou la libration peuvent en convertir une partie pour générer des écoulements dans les couches fluides d'une planète. Ces écoulements restent largement méconnus même s'ils sont importants pour contraindre des modèles d'intérieur planétaire ou expliquer la présence de champs magnétiques dans certains astres.Dans cette thèse, nous étudions les mécanismes engendrés par ces forçages en combinant une approche théorique, expérimentale et numérique et soulignons la généricité des phénomènes observés. L'étude d'un forçage de libration longitudinale, i.e. des oscillations de la vitesse de rotation d'un astre, montre la présence d'un écoulement zonal généré par des interactions non-linéaires dans les couches visqueuses. Nous étudions ensuite l'instabilité qui apparaît à la paroi pour des amplitudes de libration suffisantes et qui peut transférer de l'énergie vers le volume du fluide. Finalement, une étude expérimentale de forçage de marées dans une sphère met en évidence que l'excitation directe d'ondes inertielles induit un écoulement zonal intense et localisé. Cet écoulement peut se déstabiliser par une instabilité de cisaillement et générer un écoulement turbulent dans tout le volume.Pour finir, nous considérons la pertinence de ces résultats pour des applications géo-/astrophysiques, telles que l'étude des océans internes sous la surface de glace des satellites joviens Ganymède, Encelade et Europe. / A huge amount of energy is stored in the spin and orbital motions of any planet. Harmonic forcings such as libration, precession and tides are capable of conveying a portion of this energy to drive intense three-dimensional flows in liquid layers of planetary bodies. The generated flows remain largely unknown even if they are important to constraint model of planetary interior or to explain the presence of magnetic fields in some astrophysical bodies.In this thesis, we study the mechanisms induced by these forcings by combining theoretical, experimental and numerical approaches and we highlight the genericity of the observed phenomena. The study of a longitudinal libration forcing, corresponding to oscillations of the rotation rate of a planet, shows the presence of a mean zonal flow generated by non-linear interactions in the viscous layers. We then study the instability which appears at the outer boundary at sufficiently large libration amplitude or small Ekman number and which can transfer energy to the bulk of the fluid. Finally, an experimental study of tidal forcing in a sphere shows that the nonlinear self-interaction of excited inertial waves may drive an intense and localised axisymmetric jet, which becomes unstable at low Ekman number following a shear instability, generating space-filling turbulence.To conclude, we consider the relevance of these results to geo-/astrophysical applications, such as the subsurface oceans of the icy satellites Ganymede, Enceladus or Europa.

[pt] O presente trabalho apresenta um modelo simplificado baseado na teoria de lubrificação e conceito de viscosidade equivalente para estudar o escoamento dos fluidos de perfuração através de um espaço anular excêntrico com rotação da coluna de perfuração. Em razão do comportamento não Newtoniano destes fluidos, é significativa a influência da rotação da coluna na perda de carga, já que a viscosidade dos fluidos varia com a taxa de deformação imposta. Uma completa análise deste problema requer uma solução tridimensional da equação de conservação de quantidade de movimento de fluidos não Newtonianos, cuja solução é extremamente cara computacionalmente, tornando necessário o desenvolvimento de modelos simplificados que descrevam bem os principais fenômenos observados nestes escoamentos. No modelo proposto, as equações que governam o escoamento são simplificadas pela teoria da lubrificação em coordenadas cilíndricas. Desta forma, o escoamento tridimensional é descrito por uma única equação diferencial bidimensional para o campo de pressão. O comportamento mecânico do fluido é avaliado através do método da Viscosidade Newtoniana Equivalente. O modelo proposto foi validado a partir de soluções numéricas para o modelo completo, disponíveis na literatura, avaliando a precisão das simplificações adotadas. Os resultados mostram o intervalo no qual o modelo simplificado é preciso e apresentam o efeito das propriedades dos fluidos, da geometria do poço e da rotação da coluna na perda de carga do escoamento.O presente trabalho apresenta um modelo simplificado baseado na teoria de lubrificação e conceito de viscosidade equivalente para estudar o escoamento dos fluidos de perfuração através de um espaço anular excêntrico com rotação da coluna de perfuração. Em razão do comportamento não Newtoniano destes fluidos, é significativa a influência da rotação da coluna na perda de carga, já que a viscosidade dos fluidos varia com a taxa de deformação imposta. Uma completa análise deste problema requer uma solução tridimensional da equação de conservação de quantidade de movimento de fluidos não Newtonianos, cuja solução é extremamente cara computacionalmente, tornando necessário o desenvolvimento de modelos simplificados que descrevam bem os principais fenômenos observados nestes escoamentos. No modelo proposto, as equações que governam o escoamento são simplificadas pela teoria da lubrificação em coordenadas cilíndricas. Desta forma, o escoamento tridimensional é descrito por uma única equação diferencial bidimensional para o campo de pressão. O comportamento mecânico do fluido é avaliado através do método da Viscosidade Newtoniana Equivalente. O modelo proposto foi validado a partir de soluções numéricas para o modelo completo, disponíveis na literatura, avaliando a precisão das simplificações adotadas. Os resultados mostram o intervalo no qual o modelo simplificado é preciso e apresentam o efeito das propriedades dos fluidos, da geometria do poço e da rotação da coluna na perda de carga do escoamento.O presente trabalho apresenta um modelo simplificado baseado na teoria de lubrificação e conceito de viscosidade equivalente para estudar o escoamento dos fluidos de perfuração através de um espaço anular excêntrico com rotação da coluna de perfuração. Em razão do comportamento não Newtoniano destes fluidos, é significativa a influência da rotação da coluna na perda de carga, já que a viscosidade dos fluidos varia com a taxa de deformação imposta. Uma completa análise deste problema requer uma solução tridimensional da equação de conservação de quantidade de movimento de fluidos não Newtonianos, cuja solução é extremamente cara computacionalmente, tornando necessário o desenvolvimento de modelos simplificados que descrevam bem os principais fenômenos observados nestes escoamentos. No modelo proposto, as equações que governam o escoamento são simplificadas pela teoria da lubrificação em coordenadas cilíndricas. Desta forma, o escoamento tridimensional é descrito por uma única equação diferencial bidimensional para o campo de pressão. O comportamento mecânico do fluido é avaliado através do método da Viscosidade Newtoniana Equivalente. O modelo proposto foi validado a partir de soluções numéricas para o modelo completo, disponíveis na literatura, avaliando a precisão das simplificações adotadas. Os resultados mostram o intervalo no qual o modelo simplificado é preciso e apresentam o efeito das propriedades dos fluidos, da geometria do poço e da rotação da coluna na perda de carga do escoamento. / [en] In this work a simplified model based on the Lubrication Theory and on the equivalent viscosity is presented to study the drilling fluid flow dynamics through an eccentric annular space with rotation of the drilling column. As a result of the non-Newtonian behavior of the fluid, the rotation of the column has a significant impact on the pressure drop since the viscosity of the fluids is a function of the strain rate applied. A complete analysis of this problem requires a tridimensional solution of the equation of momentum conservation, which makes the solution computationally expensive. For such, simplified accurate models that describe the main phenomena observed have to be developed. On the proposed model, the flow dynamics equations are simplified by the Lubrication Theory in cylindrical coordinates. Therefore, the tridimensional flow is described by one single two dimensional equation for the pressure field. The mechanical behaviour of the fluid is evaluated through the Equivalent Newtonian Viscosity method. The proposed model, as well as the accuracy of the simplifications used, was validated by comparison with numerical solutions of the complete set of equations available on the literature. The results show the range in which the proposed simplified model is accurate and presents the effects of the fluids properties, well geometry and column rotation on the pressure loss.

EDF exploite sur son parc de production de nombreuses machines électriques tournantes. Les contraintes thermiques subies par celles-ci engendrent des échauffements locaux qui nuisent à leur intégrité. Le présent travail contribue à fournir des méthodes de calcul adaptées à la détection et à la localisation des points chauds. Il participe à améliorer la compréhension des écoulements en rotation et leurs effets sur les transferts thermiques. Plusieurs dispositifs expérimentaux, de complexité ascendante, ont été utilisés pour comprendre et valider les simulations numériques. Une première étude sur une marche descendante (demi-pôle) parcourue par un jet de paroi non-confiné a mis en avant des différences par rapport à un jet confiné ; ces deux cas existent dans un alternateur. Une seconde étude menée sur une cavité tournante confinée a analysé l’impact d’un écoulement de Taylor-Couette-Poiseuille sur la température et la position des points chauds créés, en balayant l’ensemble des régimes d’écoulement. Ces études ont mis en exergue une première méthode de calcul fiable, fondée sur l’étude numérique CHT. Une autre méthode, basée sur la FEM couplée à une méthode inverse, a été testée sur une maquette d’alternateur hydraulique afin de pallier aux temps de calcul longs de la première. Cette méthodologie remonte aux coefficients d’échanges convectifs numériques à partir des mesures du champ thermique du rotor, mais n’est envisageable que lorsque l’on dispose de données expérimentales suffisantes. Ces travaux ont aussi mis en évidence de nouvelles techniques de mesures sans contact, comme l’utilisation d’un pyromètre à haute fréquence pour la mesure de température sur des machines tournantes. / EDF operates a large number of electrical rotating machines in its electricity generation capacity. Thermal stresses which affect them can cause local heating, sufficient to damage their integrity. The present work contributes to provide methodologies for detecting hot spots in these machines, better understanding the topology of rotating flows and identifying their effects on heat transfer. Several experimental scale model were used by increasing their complexity to understand and validate the numerical simulations. A first study on a turbulent wall jet over a non-confined backward-facing step (half-pole hydrogenerator) notes significant differences compared to results from confined case : both of them are present in an hydrogenerator. A second study was done on a small confined rotating scale model to determinate the effects of a Taylor-Couette-Poiseuille on temperature distribution and position of hot spots on the heated rotor, by studying the overall flow regimes flow. These studies have helped to obtain a reliable method based on conjugate heat transfer (CHT) simulations. Another method, based on FEM coupled with the use of an inverse method, has been studied on a large model of hydraulic generator so as to solve the computation time issue of the first methodology. It numerically calculates the convective heat transfer from temperature measurements, but depends on the availability of experimental data. This work has also developped new no-contact measurement techniques as the use of a high-frequency pyrometer which can be applied on rotating machines for monitoring temperature.