An accurate estimate of the gasturbine inlet air temperature is essential to the stability of the engine since its control depends on it. Most supersonic military aircrafts have a design with the engine integrated in the fuselage which requires a rather long inlet duct from the inlet opening to the engine face. Such duct can affect the temperature measurement because of the heat flow between the inlet air and the duct skin. This is especially true when the temperature sensor is mounted close to the duct skin, which is the case for most engines. This master thesis project therefore revolved around developing a method to better estimate the engine inlet temperature and to compensate for the disturbances which a temperature sensor near the duct skin can be exposed to. A grey box model of the system was developed based on heat transfer equations between different components in the inlet, as well as predictions of temperature changes based on a temperature model of the atmosphere and thermodynamic laws. The unknown parameters of the grey box model were estimated using flight data and tuned to minimize the mean square of the prediction error. The numerical optimization of the parameters was performed using the Matlab implementations of the BFGS and SQP algorithms. An extended Kalman filter based on the model was also implemented. The two models were then evaluated in terms of how much the mean squared error was reduced compared to just using the sensor measurement to estimate the inlet air temperature. It was also analyzed how much the models reduced the prediction errors. A cross-correlation analysis was also done to see how well the model utilized the input signals. The results show that the engine inlet temperature can be estimated with good accuracy. The two models were shown to reduce the mean square of the prediction error by between 84 % and 89 % if you compare with just using the temperature sensor to estimate the temperature. The model which utilized the Kalman filtering was shown to perform slightly better than the other model. The relevance of different subcomponents of the model were investigated in order to see if the model could be simplified and maintain similar accuracy. Some investigations were also done with the relationship between different temperatures of the inlet to further understand the flow patterns of the inlet and to perhaps improve the model even more in the future. / En korrekt uppskattning av lufttemperaturen vid inloppet till turbofläktmotorer är väsentlig för stabil motorfunktion eftersom den direkt påverkar motorregleringen. För militära flygplan där motorn är integrerad i flygplansskrovet krävs ofta en relativt lång luftkanal för att leda luften till motorn. En sådan kanal kan påverka temperaturmätningen på grund av det värmeutbyte som sker mellan luften i kanalen och kanalväggen, speciellt då temperaturgivaren placeras nära kanalväggen eftersom den då kan påverkas av temperaturgränsskiktet nära kanalväggen. Det här examensarbetet handlade därför om att utveckla en metod för att bättre skatta temperaturen i motorinloppet och kompensera för de störningar som en temperaturgivare nära kanalväggen kan utsättas för. En fysikalisk model av systemet togs fram baserat på värmeöverföringen mellan olika komponenter i luftintagskanalen, samt ett sätt att förutse temperaturändringar baserat på en generell temperaturmodell för atmosfären och termodynamiska lagar. Många parametrar i den fysikaliska modellen av systemet var dock okända så dessa skattades baserat på flygdata. Parametrarna anpassades till modellen på ett sådant sätt att den genomsnittliga kvadraten av modellens skattningsfel minimerades. Den numeriska optimeringen av parametrarna utfördes med hjälp av Matlabs implementation av BFGS- och SQP-algoritmerna. Ett utökat kalmanfilter baserat på modellen implementerades också. De två modellerna utvärderades i termer av hur mycket de reducerade kvadraten av skattningsfelet och jämfördes med att endast använda temperaturmätningarna för att skatta temperaturen. Det undersöktes även hur mycket skattningsfelen reducerades. Korskorrelationen mellan skattningsfelet och insignalerna undersöktes även för att se om modellen hade utnyttjat insignalerna på ett bra sätt. Resultaten visar att det går att skatta temperaturen i motorinloppet med god noggrannhet. De två modellerna visade sig reducera den genomsnittliga kvadraten av skattningsfelet med mellan 84 % och 89 % om man jämför med att bara använda temperaturgivaren för att skatta temperaturen. Den modell som utnyttjade kalmanfiltrering visade sig ge något bättre resultat än den andra modellen. Olika delmodellers relevans undersöktes för att se om modellen kunde förenklas utan att modellens noggrannhet äventyrades. Några tester utfördes även för att undersöka förhållandet mellan olika temperaturer i intaget. Detta för att få en bättre förståelse för strömningen i intaget och resultatet skulle eventuellt kunna användas för att förbättra modellen ytterligare i framtiden.

Ce travail de thèse concerne l'étude de l'influence des ultrasons sur les transferts de chaleur. Il a été réalisé à partir de la conception d'un échangeur de chaleur dont la structure peut être mise en vibration à sa fréquence de résonance dans la gamme des ondes ultrasonores : 35 kHz. L'influence des ultrasons sur l'augmentation des transferts thermiques a ainsi pu être mise en évidence directement au sein du système. L'étude bibliographique a mis en avant l'originalité de ce travail, qui correspond à une première approche relative à un échangeur fluide-fluide. La conception de l'échangeur, du banc d'essais et du système d'acquisition dédiés a fait l'objet de la première partie de ce travail. Ensuite, la mise au point de méthodes pour l'analyse des performances énergétiques et leur implémentation ont constitué une deuxième partie. Enfin, des configurations opératoires variées (régimes d'écoulement, configurations hydrauliques, matériaux constitutifs, …) ont pu être étudiées. De plus, le potentiel des ultrasons quant à la réduction de l'encrassement au sein de l'échangeur a aussi été mis en évidence. / This work deals with the influence of ultrasound on heat transfer. It relies on the conception of a new kind of heat exchanger, whose structure can be set into vibration at its resonance frequency in the ultrasonic range : 35 kHz. The influence of ultrasound on heat transfer enhancement was thus directly observed within the system. The literature survey showed the originality of this work, corresponding to a first approach of a fluid-fluid heat exchanger. The conception of the heat exchanger, of the test rig and acquisition system both especially dedicated was the main object of the first part of this work. Then, the development of methods for the analysis of energetic performances and their implementation constituted the second part. Finally, various operating configurations (flow regimes, hydraulic configurations, constitutive materials, …) have been studied. Besides, the potential of ultrasound concerning fouling reduction inside the structure was also highlighted.

Lors d'un accident grave dans un réacteur à neutrons rapides refroidi au sodium, le combustible fondu peut entrer en contact avec le sodium environnant, conduisant alors à une interaction communément appelée Interaction Combustible-Réfrigérant. L'objectif de ce travail est d'améliorer la connaissance relative aux transferts thermiques en régime d'ébullition en film du sodium, essentielle pour étudier les risques liés à une éventuelle explosion de vapeur. Peu d'études, tant expérimentales que théoriques, ont été menées sur l'ébullition en film du sodium. Une unique expérience permet d'étudier l'ébullition en film du sodium en convection naturelle. Lors de l'analyse de ces essais, deux sous-régimes d'ébullition en film, non identifiés par l'auteur mais déjà observés pour l'eau, ont été mis en évidence : un régime de film qualifié de stable, sans contact liquide-solide, et un régime de film qualifié d'instable, avec contacts. D'un point de vue théorique, un seul modèle dédié à l'ébullition en film du sodium est proposé dans la littérature, dont l'analyse a révélé de nombreux défauts. Dans un premier temps, une analyse d'échelles du problème a été effectuée en convection naturelle et en convection forcée, en distinguant les cas d'un fort et d'un faible sous-refroidissement. Cette approche simplifiée, cohérente avec les résultats expérimentaux, a permis de définir les nombres adimensionnels pertinents pour l'établissement de corrélations. Un modèle a ensuite été développé pour traiter l'ébullition en film du sodium autour d'une sphère dans le cas le plus général - en convection naturelle ou forcée, pour un métal liquide saturé ou sous-refroidi. Ce modèle est basé sur l'approximation de double couche limite et met en œuvre une méthode intégrale en considérant les termes inertiels et convectifs, classiquement négligés, dans les équations de bilan de l'écoulement de vapeur. Par ailleurs, le rayonnement est pris en compte de manière couplée à l'interface liquide-vapeur et contribue directement à la production de vapeur. Ce modèle permet d'évaluer correctement le flux de chaleur perdu par un corps chaud en comparaison aux résultats des essais, en particulier lorsque ceux-ci sont corrigés des biais expérimentaux. La partition du flux de chaleur, entre chauffage et vaporisation, est également estimée : il s'agit d'une information indispensable à la description d'une explosion de vapeur et non accessible expérimentalement. En outre, l'influence de différents paramètres - sous-refroidissement du sodium, surchauffe et diamètre de la sphère, vitesse de l'écoulement externe, pression du système - dans les conditions pouvant être celles d'un accident grave a été étudiée. Enfin, un modèle simplifié a été utilisé pour étudier la transition entre les deux sous-régimes d'ébullition en film identifiés dans l'expérience. Les tendances obtenues par cette approche sont analogues à celles observées expérimentalement. / During a severe accident in a sodium-cooled fast reactor, molten fuel may come into contact with the surrounding liquid sodium, resulting in a so-called Fuel-Coolant Interaction. This work aims at providing a better understanding and knowledge of the associated heat transfer, likely to be in the film-boiling regime and required to study the risks related to a vapor explosion. Scarce literature has been found on sodium film boiling, both from an experimental and a theoretical point of view. Only one experiment has been conducted to investigate sodium pool film-boiling heat transfer. In our analysis of the experiment, two film-boiling regimes have been identified: a stable film boiling regime, without liquid-solid contact, and an unstable film-boiling regime, with contacts. Besides, the only theoretical model dedicated to sodium film boiling has shown some weaknesses. First, a scaling analysis of the problem has been proposed for free and forced convection, considering the two extreme cases of saturated and highly subcooled liquid. This simplified approach, which shows a good agreement with the experimental data, provides the dimensionless numbers which should be used to build correlations. A theoretical model has been developed to describe sodium film-boiling heat transfer from a hot sphere in free and forced convection, whatever the liquid subcooling. It is based on a two-phase laminar boundary layer integral method and includes the inertial and convective terms in the vapor momentum and energy equations, usually neglected. The radiation has been taken into account in the interfacial energy balance and contributes directly to produce vapor. This model enables to predict the heat lost from a hot body within an acceptable error compared to the tests results especially when the experimental uncertainties are considered. The heat partition between liquid heating and vaporization, essential to study the vapor explosion phenomenon, is also estimated. The influence of different parameters - sodium subcooling, sphere superheat and diameter, external flow velocity, system pressure - under accident conditions has been studied. Eventually, a simplified model has been used to investigate the transition between the two film boiling regimes identified in the experiment. The trends obtained with this approach are similar to those observed experimentally.

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Submitted by IGOR SEICHO KIYOMURA null (igorseicho@gmail.com) on 2016-09-12T14:07:49Z No. of bitstreams: 1 Dissertação_Igor Seicho Kiyomura.pdf: 3224196 bytes, checksum: d71f4ad45145d3dc7f441a0090d3b373 (MD5) / Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-09-14T19:13:44Z (GMT) No. of bitstreams: 1 kiyomura_is_me_ilha.pdf: 3224196 bytes, checksum: d71f4ad45145d3dc7f441a0090d3b373 (MD5) / Made available in DSpace on 2016-09-14T19:13:44Z (GMT). No. of bitstreams: 1 kiyomura_is_me_ilha.pdf: 3224196 bytes, checksum: d71f4ad45145d3dc7f441a0090d3b373 (MD5) Previous issue date: 2016-07-29 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Nas últimas décadas surgiu a necessidade de dissipar maiores quantidades de energia térmica, fato que acarretou no aumento do número de estudos em ebulição nucleada e convectiva com o objetivo de produzir trocadores de calor cada vez mais eficientes e compactos. A busca de produtos cada vez mais eficientes e compactos e a procura de novas técnicas para melhorar a transferência de calor, garantindo a integridade física do equipamento, continuam crescendo e a tendência é que continuará assim nos próximos anos. Uma das técnicas que está sendo amplamente pesquisada na comunidade cientifica é o uso de nanofluidos. Os nanofluidos foram desenvolvidos com o intuito de melhorar a condutividade e a difusividade térmica em relação aos fluidos tradicionais. Muitos experimentos com nanofluidos têm sido desenvolvidos nos últimos anos, mas ainda existem muitas divergências a respeito do efeito desses fluidos sobre o fenômeno de ebulição. Dentro deste contexto, o presente trabalho tem como objetivo a análise teórico-experimental do efeito de superfícies nanoestruturadas e da concentração do nanofluido, a ser depositado sobre a superfície aquecedora, sobre o coeficiente de transferência de calor em regime de ebulição nucleada. Para tanto, testes foram realizados para fluxos de calor que correspondem ao regime de ebulição nucleada da água deionizada, à temperatura de saturação (Tsat = 99 °C) e à pressão atmosférica (patm = 98 kPa), sobre superfícies aquecedoras de cobre com diferentes rugosidades. As superfícies nanoestruturadas foram produzidas por deposição de nanopartículas de maguemita, por meio do processo de ebulição da solução Fe2O3-água deionizada para diferentes concentrações mássicas previamente estabelecidas. As superfícies foram submetidas a ensaios metalográficos, de molhabilidade e de rugosidade permitindo a avaliação das modificações estruturais, topográficas e químicas das superfícies, antes e após os testes no regime de ebulição nucleada. Os resultados para o coeficiente de transferência de calor foram relacionados com as características geométricas e morfológicas das superfícies de teste, levando em consideração os aspectos relacionados à interação fluido/superfície, como, o ângulo de contato e a molhabilidade. / In the last decade, the necessity to dissipate large quantities of heat energy increased, thus leading to an increase on the number of studies in nucleate pool boiling and flow boiling with the aim of producing more compact and efficient heat exchangers. The search for increasingly efficient and compact products and for new techniques to improve the heat transfer, ensuring the physical integrity of the equipment, keep growing and it will remain so in the next years. One of the techniques being widely researched in the scientific community is the use of nanofluids. The nanofluids have been developed in order to improve the thermal conductivity and diffusivity compared to traditional fluids. Although many experiments with nanofluids have been developed in recent years, there are still many differences related to the effects of these fluids on the pool boiling phenomenon. In this context, this work aims to analyze the effects of nanostructured surfaces and different nanofluid concentrations, which are deposited on the heating surface, on the heat transfer coefficient during the nucleate boiling regime. Therefore, tests were performed to heat fluxes values corresponding to the nucleate boiling regime for deionized water, at saturation temperature (Tsat = 99 °C) and atmospheric pressure (patm = 98 kPa), on copper heating surfaces with different roughness values. The nanostructured surfaces were produced by maghemite nanoparticle deposition, which is achieved by boiling selected mass concentrations of a Fe2O3-deionized water nanofluid. Prior and after each boiling test, the characteristics of the test surfaces were evaluated by applying the metallographic, wettability and surface roughness tests. The results for the heat transfer coefficient were related to the geometrical and morphological characteristics of the test surfaces, taking into account the aspects of the flu-id/surface interaction such as, the contact angle and wettability. / FAPESP: 2014/07949-9

Orientador: Elaine Maria Cardoso / Resumo: Nas últimas décadas surgiu a necessidade de dissipar maiores quantidades de energiatérmica, fato que acarretou no aumento do número de estudos em ebulição nucleada e convectivacom o objetivo de produzir trocadores de calor cada vez mais eficientes e compactos. Abusca de produtos cada vez mais eficientes e compactos e a procura de novas técnicas paramelhorar a transferência de calor, garantindo a integridade física do equipamento, continuamcrescendo e a tendência é que continuará assim nos próximos anos. Uma das técnicas que estásendo amplamente pesquisada na comunidade cientifica é o uso de nanofluidos. Os nanofluidosforam desenvolvidos com o intuito de melhorar a condutividade e a difusividade térmicaem relação aos fluidos tradicionais. Muitos experimentos com nanofluidos têm sido desenvolvidosnos últimos anos, mas ainda existem muitas divergências a respeito do efeito dessesfluidos sobre o fenômeno de ebulição. Dentro deste contexto, o presente trabalho tem comoobjetivo a análise teórico-experimental do efeito de superfícies nanoestruturadas e da concentraçãodo nanofluido, a ser depositado sobre a superfície aquecedora, sobre o coeficiente detransferência de calor em regime de ebulição nucleada. Para tanto, testes foram realizadospara fluxos de calor que correspondem ao regime de ebulição nucleada da água deionizada, àtemperatura de saturação (Tsat = 99 °C) e à pressão atmosférica (patm = 98 kPa), sobre superfíciesaquecedoras de cobre com dif... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In the last decade, the necessity to dissipate large quantities of heat energy increased,thus leading to an increase on the number of studies in nucleate pool boiling and flow boilingwith the aim of producing more compact and efficient heat exchangers. The search for increasinglyefficient and compact products and for new techniques to improve the heat transfer,ensuring the physical integrity of the equipment, keep growing and it will remain so in thenext years. One of the techniques being widely researched in the scientific community is theuse of nanofluids. The nanofluids have been developed in order to improve the thermal conductivityand diffusivity compared to traditional fluids. Although many experiments withnanofluids have been developed in recent years, there are still many differences related to theeffects of these fluids on the pool boiling phenomenon. In this context, this work aims to analyzethe effects of nanostructured surfaces and different nanofluid concentrations, which aredeposited on the heating surface, on the heat transfer coefficient during the nucleate boilingregime. Therefore, tests were performed to heat fluxes values corresponding to the nucleateboiling regime for deionized water, at saturation temperature (Tsat = 99 °C) and atmosphericpressure (patm = 98 kPa), on copper heating surfaces with different roughness values. Thenanostructured surfaces were produced by maghemite nanoparticle deposition, which isachieved by boi... (Complete abstract click electronic access below) / Mestre

Resumo: Foi estudado processo de transferência de calor transiente por agitação intermitente em embalagens, visando a conservação de alimentos por tratamento térmico com processo mais econômico e que mantivesse a qualidade de alimentícios. Objetivou-se o desenvolvimento de um processo baseado em agitação intermitente de embalagens para aplicação em pasteurização ou esterilização. O estudo da transferência de calor transiente em sistema com movimento linear alternado foi realizado em embalagens metálicas, em 4 meios simulantes de diferentes viscosidades e massas específicas: 3 óleos orgânicos e água. Foram combinados efeitos de 5 tratamentos, sendo: meio simulante (4 níveis), espaços livres (3 níveis), freqüência de agitação (4 níveis), amplitude de agitação (2 níveis) e posições das latas (4 níveis). Os ensaios de aquecimento e resfriamento foram feitos em tanque com água a temperatura de 98°C e 17 a 20°C, respectivamente. Com os dados de penetração de calor em cada experimento foram calculados os parâmetros de penetração de calor fh, jh, fc e jc. Os resultados foram modelados utilizando-se grupos de números adimensionais e foram expressos em Nusselt, Prandtl, Reynolds e...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Transient heat transfer was studied by intermittent shake in cans with linear system, in order to preserve food by heat thermally processed, applying process more economic, and keeping high food quality. The objective was developing a process based on intermittent shake in cans to applying in pasteurisation or sterilisation process. Heat transfer was carried out in metallic cans filled four different simulate medium: water, Neutral oil 150 and 500 and Bright stock oil. It was arranged five treatments: simulate media (4 levels), head space (3 levels), agitation frequency (4 levels), length of agitation (2 levels) and cans positions (4 levels). The tests were carried out in hot water tank at temperature 98°C and cool at 17~20°C. Heat transfer parameters (fh, jh, fc and jc) for each test was calculated. Results were expressed applying dimensionless numbers equations for heat and cool. Data were computed pplying dimensionless numbers and were assign as Nusselt, Prandtl, Reynolds and trigonometric functions. Results obtained from linear shake system were compared with end-over-end agitation, and shake linear system showed more efficient. Shake linear system can be applied in pasteurisation or static retorts with simple internal structure fits...(Complete abstract, click electronic access below) / Orientador: José Santo Goldoni / Coorientador: Flávio Luís Schmidt / Banca: Jayme de Toledo Piza e Almeida Neto / Banca: Marco Antonio M. Biaggioni / Banca: Alfredo de Almeida Vitali / Banca: Flávio Luis Schimidt / Doutor