Approved for public release, distribution is unlimited / This study concentrates on the empirical characterization of a staggered pin-fin array heat exchanger placed in a modular, rectangular wind tunnel. A full analysis of the heat transfer and pressure drop behavior was conducted on various pin-fin shapes, sizes, and configurations. The study was based on airflow over a wide range of Reynolds numbers in the laminar regime. The empirical data gathered can be used to corroborate and develop better numerical models to characterize the performance of such heat exchangers as well as scale down to the micro level for comparison with micro-heat exchangers. / Lieutenant, United States Navy

The mechanical pitching characteristic of the NPS flapping-wing Micro Air Vehicle (MAV) developed by Professor Kevin D. Jones are studied experimentally through the use of constant temperature anemometry and force balance techniques. The MAV without the main fixed-wing is placed in a laminar flow field within a low speed wind tunnel with the wake after the flapping wings characterized with a constant temperature anemometer and thrust generation measured by a load cell at various neutral angles, flapping frequencies and free stream velocities. The experiments seek to determine the effects on the MAV propulsion when the neutral angle of attack of the flapping wings is varied. Flow visualization is also performed to better enhance understanding of the flow field across the pitched flapping wings.

This thesis deals with the instabilities of the incompressible boundary-layer flow thatis induced by a disk rotating in otherwise still fluid. The results presented include bothwork in the linear and nonlinear regime and are derived from direct numerical sim-ulations (DNS). Comparisons are made both to theoretical and experimental resultsproviding new insights into the transition route to turbulence. The simulation codeNek5000 has been chosen for the DNS using a spectral-element method (SEM) witha high-order discretization, and the results were obtained through large-scale paral-lel simulations. The known similarity solution of the Navier–Stokes equations for therotating-disk flow, also called the von K ́arm ́an rotating-disk flow, is reproduced by theDNS. With the addition of modelled small simulated roughnesses on the disk surface,convective instabilities appear and data from the linear region in the DNS are anal-ysed and compared with experimental and theoretical data, all corresponding verywell. A theoretical analysis is also presented using a local linear-stability approach,where two stability solvers have been developed based on earlier work. Furthermore,the impulse response of the rotating-disk boundary layer is investigated using DNS.The local response is known to be absolutely unstable and the global response, onthe contrary, is stable if the edge of the disk is assumed to be at radius infinity. Herecomparisons with a finite domain using various boundary conditions give a globalbehaviour that can be both linearly stable and unstable, however always nonlinearlyunstable. The global frequency of the flow is found to be determined by the Rey-nolds number at the confinement of the domain, either by the edge (linear case) or bythe turbulence appearance (nonlinear case). Moreover, secondary instabilities on topof the convective instabilities induced by roughness elements were investigated andfound to be globally unstable. This behaviour agrees well with the experimental flowand acts at a smaller radial distance than the primary global instability. The sharpline corresponding to transition to turbulence seen in experiments of the rotating diskcan thus be explained by the secondary global instability. Finally, turbulence datawere compared with experiments and investigated thoroughly. / <p>QC 20170203</p>

Reflux condensation occurs in a vertical tube when there is an upward core flow of vapour (or gas-vapour mixture) and a downward flow of the liquid film. The understanding of this condensation configuration is crucial in the design of reflux condensers and in loss-of-coolant safety analyses in nuclear power plant steam generators. A range of modelling approaches exists for co-current film condensation from gas-vapour mixtures in parallel-plate channels and tubes. These methods are based on marching from the inlet down the tube and do not apply to the reflux condensation. In this research, however, a two-dimensional two-phase model was developed that solves the steady, full elliptic governing equations in both the film and the gas-vapour core flow on a non-orthogonal mesh that dynamically adapts to the phase interface. Gas-vapour shear and heat and mass transfer at the interface were accounted for fundamentally. This modelling is a big step ahead of current capabilities by removing the limitations of previous reflux condensation models which inherently cannot account for the detailed local balances of shear, mass, and heat transfer at the phase interface. The model was developed and applied for co-current and counter-current flows in vertical parallel-plate channels, followed by vertical tubes. In each stage, the model results were compared against the available experimental and numerical data for validation purposes. A wide range of boundary conditions and geometries have been studied to examine the details of co-current and counter-current condensation phenomena. Velocity, temperature, pressure, and gas mass fraction profiles along with the axial variation of various parameters such as local Nusselt number, film thickness, interface and centre-line temperature and gas mass fraction are presented in parametric studies. / February 2017

La vitesse de flamme adiabatique est un paramètre clé dans l'étude de la combustion d'hydrocarbures. Elle joue en effet un rôle essentiel dans le domaine de la combustion, dans la mesure où elle est utilisée pour valider des modèles numériques, pour construire des brûleurs, ou encore pour prédire d'éventuels retours de flamme ou souffles de la flamme. Le but de cette thèse a été d'étudier les vitesses de flammes laminaires d'un grand nombre d'hydrocarbures présents dans les gaz naturels, les essences et les gazoles. Ce travail comprend une partie expérimentale et une partie de modélisation. La partie expérimentale a permis d'enrichir les bases de données de la littérature pour différentes compositions de mélanges air/hydrocarbures. Les travaux ont été effectués sur un nouveau montage mis au point au LRGP (Laboratoire Réactions et Génie des Procédés) pour la mesure de vitesses de flammes laminaires par la méthode du flux de chaleur à l'aide d'un brûleur adiabatique à flamme plate. Cette méthode est basée sur l'équilibre des pertes thermiques nécessaires pour stabiliser la flamme par le flux de chaleur convectif allant de la surface du brûleur vers le front de flamme. Le brûleur est constitué d'une plaque perforée montée sur une chambre de mélange des gaz et la mesure de la distribution radiale de la température est réalisée grâce à une série de thermocouples. Ce montage a d'abord été utilisé à pression atmosphérique et plusieurs températures pour la mesure de vitesses de flammes de composés gazeux (alcanes, alcènes, méthane enrichi en hydrogène ou oxygène, gaz naturels, mélanges méthane-éthane et méthane-propane) et de composés liquides (alcanes, éthanol, essences commerciale et modèle additionnées ou non d'éthanol, alkylcyclohexanes, alkylbenzènes). Le montage a ensuite été placé dans une enceinte pour pouvoir travailler avec des pressions pouvant théoriquement aller jusqu'à 10 atm. Les vitesses de flammes de deux composés ont été étudiées à température ambiante et à haute pression : un composé gazeux, le méthane, jusqu'à une pression de 6 atm et un composé liquide, le n-pentane, jusqu'à une pression de 4 atm. Une étude de modélisation a complété ce travail par l'utilisation de modèles cinétiques détaillés pour la combustion des composés étudiés. Ces modèles ont été testés par la simulation des résultats expérimentaux précédemment obtenus, dans des conditions de richesse, température et pression variées / The laminar burning velocity is a key parameter in the combustion of hydrocarbons study. It plays an essential role in the combustion science area since it is used for the validation of numerical models, the design of burners or to predict potential flashback or blow off of the flame. The goal of the thesis was the study of laminar burning velocities of many hydrocarbons found in natural gases, gasolines or diesel fuels. This work includes an experimental part and a modeling part. The experimental part allowed the implementation of the literature database for different air/hydrocarbons mixtures. The experiments were performed with a new apparatus developed at LRGP (Laboratoire Réactions et Génie des Procédés) for the measurement of laminar burning velocities by the heat flux method thanks to a flat flame adiabatic burner. This method is based on balancing of the heat loss required for the flame stabilization by the convective heat flux from the burner surface to the flame front. The burner head is a thick perforated plate included in a plenum mixing chamber and the measurement of the radial distribution of the temperature is performed with a thermocouples series. This apparatus was first used at atmospheric pressure and several temperatures to measure laminar burning velocities of gaseous compounds (alkanes, alkenes, hydrogen-enriched or oxygen-enriched methane, natural gases, methane-ethane and methane-propane mixtures) and liquid compounds (alkanes, ethanol, commercial gasoline and model fuel with addition of ethanol or not, alkylcyclohexanes, alkylbenzènes). The apparatus was then placed in a chamber in order to work under pressures theoretically up to 10 atm. Laminar burning velocities of two compounds were studied at room temperature and high pressure : a gaseous compound, methane, for pressures up to 6 atm and a liquid compound, n-pentane, for pressures up to 4 atm. A modelling study completed this work by using detailed kinetic models for the combustion of studied compounds. These models were tested by the simulation of experimental results previously obtained, in various equivalence ratio, temperature and pressure conditions

Orientador: Antonio Riul Júnior / Banca: Osvaldo Novais de Oliveira Júnior / Banca: José Alberto Giacometti / Banca: Daniel Souza Correa / Banca: Leonardo Giordano Paterno / O Programa de Pós Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi da Unesp / Resumo: Este trabalho de doutorado dá continuidade aos esforços iniciados no mestrado, apresentando os principais resultados obtidos na integração de uma "língua eletrônica" com recursos de microfluídica. Brevemente, trata-se de uma "língua eletrônica" utilizando microlitros para análise e descarte de amostras, visando desenvolvimentos que, possibilitem posteriormente a fabricação de dispositivos "lab-on-a-chip", abrindo fronteiras para possibilidades múltiplas de integração na análise de bebidas, desenvolvimento de formulações na indústria farmacêutica, biossensores, análises clínicas, etc. Para viabilizá-las, fez-se necessário depositar filmes ultrafinos nanoestruturados no interior de microcanais, previamente selados sobre eletrodos interdigitados (IDEs) de ouro, através de uma adaptação da técnica de automontagem (LbL, do inglês Layer-by-Layer), o que resultou em boa reprodutibilidade na fabricação dos dispositivos. Os filmes nanoestruturados no interior dos microcanais foram caracterizados insitu durante o processo de deposição através de medidas de espectroscopia de impedância elétrica, que indicaram alterações nos padrões observados em função da nanoestruturação de materiais sobre os IDEs, principalmente confirmado pela análise Raman. Completamente, para melhor compreensão das alterações causadas pelos filmes automontados no interior dos microcanais, as medidas elétricas foram analisadas através e circuitos elétricos equivalentes, implicando em uma simplificação no modelo que utilizamos por mais de uma década. Na sequência, o desempenho da "língua eletrônica microfluídica" aqui desenvolvida foi confrontado com os resultados por uma "língua eletrônica convencional", na qual os eletrodos interdigitados são imersos em um béquer contendo as amostras líquidas. A partir das respostas elétricas apresentadas por tais... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This PhD work continues the efforts initiated a our Master degree, presenting the main results obtained in the integration of an electronic tonque system using microfluidics. Briefly, it is an e-tongue device using microliters for sampling and discharge analysis, envissaging developments that might later enable the fabrication of lab-on-a-chip, devices, opening frontiers to multiple possibilities of integration in the analysis of beverages, developments of pharmaceutical formulations, biosensors, clinical analysis, etc. To get it into reality it was required the deposition of nanostructured ultrathin films inside microchannels, previously sealed onto gold interdigitated electrodes (IDEs), throughout and adaptation of the layer-by-layer (LbL0 technique, completely eliminating leakages, resulting in good reproducibility in the fabrication of the devices. The nanostructured thin films inside microchannels were characterized in-situ during the deposition process throughout impedance spectroscopy, indicating changes in the observed electric patterns due to the nanostructuration of materials onto the IDEs, further corroborated by Raman analysis. Complementarily, to better understand changes caused by the layer-by-layer films inside a microchannel, the impedance data were analyzed using equivalent electric circuits, resulting in a simplification of the model used by us for more than a decade. Sequentially, the performance of the microfluidic e-tongue developed here was confronted with data acquired in a conventional e-tongue, in which the IDEs were left soaking in a beaker having liquid samples. Principal Component Analysis was applied in the data from the electrical responses presented by these e-tongues, indicating that the microchannel system has a similar performance when compared to the conventional system of IDEs immersed in a liquid sample... (Complete abstract click electronic access below) / Doutor

Orientador: João Antonio Galbiatti / Banca: Teresa Cristina Tarlé Pissarra / Banca: Marcílio Vieira Martins Filho / Banca: David Luciano Rosalen / Banca: Raimundo Leite Cruz / Resumo: A expansão territorial do agronegócio, em especial o plantio de cana de açúcar e uso de pastagens degradadas, na bacia do rio Uberaba impacta a preservação dos recursos naturais, sendo que a ocorrência da erosão correlaciona-se diretamente com o uso e ocupação do solo. Este trabalho teve por objetivo identificar qualitativamente as áreas susceptíveis à erosão laminar na bacia do rio Uberaba, apoiado no modelo da Equação Universal de Perda de Solos (EUPS), e a partir do coeficiente morfométrico de rugosidade (RN) diagnosticar o uso potencial das terras, caracterizando áreas potenciais à degradação e conflito ambiental. A espacialização do potencial de erosão só foi possível a partir da estimativa da tolerância às perdas laminares para cada tipo de solo da bacia, e da profundidade dos solos, por entender que as perdas são mais significativas em solos mais rasos do que em solos muito profundos. Na análise dos resultados, verificou-se que 37,42% da área total da bacia do rio Uberaba (905,24 km2) sofre perdas de solos acima do limite de tolerância sendo, sendo 12,15% em solos profundos e 25,27% em muito profundos, e a espacialização deste evento, favorece a adoção de ações efetivas quanto à conservação dos solos da bacia. Na avaliação da classificação do uso potencial do solo, constatou-se que 47,12% das microbacias pertencentes à bacia do rio Uberaba apresenta-se apropriada para a pratica agrícola, enquanto 36,37% para pecuária, 11,86% para pecuária/reflorestamento e 1,40% para reflorestamento. De toda área da bacia, 17,07% (413,13 km2) encontra-se em conflito quanto ao uso e ocupação, necessitando de adequações que diminuam a degradação ambiental. / Abstract: The territorial expansion of the agribusiness, in special the plantation of cane of sugar and use of degraded pastures, in the basin of the river Uberaba impact the preservation of the natural resources, being that the occurrence of the erosion directly correlates with the use and occupation of the ground. This work had for objective qualitatively to identify the susceptive areas to the laminar erosion in the basin of the river Uberaba, supported in the model of the Universal Equation of Loss of Solo (USLE), and from the morphometric rugosity coefficient (Ruggdeness Number -RN) to diagnosis the potential use of lands, characterizing potential areas to the degradation and ambient conflict. The spatialization of the erosion potential alone was possible from the estimate of the tolerance to the laminar losses for each type of ground of the basin, and the depth of ground, for understanding that the losses are more significant in flatter ground of what in very deep ground. In the analysis of the results, it was verified that 37,42% of the total area of the basin of the river Uberaba (905,24 km2) it suffers losses of ground above from the tolerance limit being, being 12,15% in deep ground and 25,27% in very deep, and the spatialization of this event, favors the action adoption effective how much to the conservation of ground of the basin. In the evaluation of the classification of the potential use of the ground, one evidenced that 47,12% of the pertaining microbasins to the basin of the river Uberaba are presented appropriate for practice agriculturist, while 36,37% for cattle, cattle 11,86% for/reforestation and 1,40% for reforestation. Of all area of the basin, 17,07% (413,13 km2) one meets in conflict how much to the use and occupation, needing adequacies that they diminish of the ambient degradation. / Doutor

Orientador: Analice Costacurta Brandi / Banca: Gilcilene Sanchez de Paulo / Banca: Marcio Teixeira Mendonça / Resumo: O presente trabalho investiga a transição laminar-turbulenta devido a ondas de Tollmien-Schlichting para o escoamento de Poiseuille incompressível, bidimensional, de um uido viscoelástico, utilizando a equação constitutiva Giesekus. A Teoria de Estabilidade Linear e a Simulação Numérica Direta são utilizadas para veri car a estabilidade de escoamentos de uidos viscoelásticos a perturbações não estacionárias. Na análise LST a equação de Orr-Sommerfeld é modi cada para um uido viscoelástico e resolvida pelo método da estimativa (Shooting). Enquanto que, na formulação DNS, as equações de Navier-Stokes, juntamente com a equação constitutiva Giesekus, são resolvidas utilizando métodos de diferenças nitas compactas de alta ordem. Com o objetivo de avaliar as curvas neutras de estabilidade e as taxas de ampli cação, diferentes simulações numéricas são realizadas variando-se os parâmetros adimensionais no modelo Giesekus e comparando com o uido Newtoniano. As técnicas LST e DNS mostraram-se ferramentas e cientes na análise espacial da estabilidade de escoamentos viscoelásticos do tipo Giesekus, permitindo uma melhor compreensão da in uência dos parâmetros adimensionais desses escoamentos e contribuindo com resultados originais na veri cação da estabilidade de escoamentos viscoelásticos utilizando o uido Giesekus. / Abstract: The present work investigates the laminar-turbulent transition due to Tollmien-Schlichting waves for the incompressible two-dimensional Poiseuille ow of a viscoelastic uid, using the Giesekus constitutive equation. Linear Stability Theory and Direct Numerical Simulation are used to verify the stability of viscoelastic uid ows to unsteady disturbances. In the LST analysis, the Orr-Sommerfeld equation is modi ed to a viscoelastic uid and solved by Shooting method. Whereas, in the DNS formulation, the Navier-Stokes equations with the Giesekus constitutive equation are solved using high-order compact nite di erence methods. In order to evaluate the neutral stability curves and the ampli- cation rates, di erent numerical simulations are performed by varying the dimensionless parameters in the Giesekus model and their results are compared with the Newtonian uid. The LST and DNS techniques proved to be e cient tools to the spatial stability analysis of viscoelastic uid ows of the Giesekus type, allowing a better comprehension of the dimensionless parameters in uence of those ows, contributing with originals results to veri cation of the viscoelastics uid ows stability using Giesekus uid. / Mestre

Neste trabalho é analisado o transporte de massa em meios porosos rígidos, homogêneos e saturados com um fluido incompressível e monofásico, para os regimes de escoamento laminar e turbulento. A equação de transporte de massa macroscópica para o fluido é obtida com o auxílio do conceito de dupla decomposição, donde surge o termo de "dispersão mássica turbulenta". Os fluxos mássicos devido à dispersão, que aparece no processo de aplicação das médias temporal e volumétrica, são representados por um modelo de difusão proporcional ao gradiente da média intrínseca da fração mássica média no tempo. Os tensores de difusidade mássica resultantes desse modelo são obtidos de dois modos: a) para as componentes turbulentas, devidas às flutuações temporais da velocidade e fração mássica, é utilizado o modelo de difusividade mássica turbulenta onde a viscosidade turbulenta macroscópica é obtida através do modelo macroscópico, e b) para as componentes de dispersão, devido aos desvios espaciais da velocidade e fração mássica, são utilizados os resultados obtidos para os campos microscópicos de velocidade e fração mássica em uma célula unitária com condições de contorno periódicas para o escoamento e um gradiente de fração mássica imposto.

This work focuses on the study of flow and heat transfer in a parallel plate channel with solid and porous baffles, in both laminar and turbulent regimes by using numerical simulations. The main concern is to validate results by using a unique set of equations (for porous, solid and clear domain) for channels with solid baffles, after that change solid to porous baffles and study the effects on flow and heat transfer. Porous medium is treated as rigid, homogeneous and isotropic. The macroscopic transport equations are written for an elementary representative volume, yielding a set of equation valid for the entire computational domain. These equations are discretized using the control volume method, and the resulting system of algebraic equations is solved by the SIP algorithm utilizing the SIMPLE method for the pressure-velocity coupling. Initially, the laminar flow regime is analyzed, followed by turbulent flow simulations, utilizing both Low and High Reynolds turbulence models. Three different baffles heights were chosen for laminar and turbulent flow, aiming for further comparisons to literature data. Derivations are carried out under the recently established double-decomposition concept. Results show good qualitative agreement with literature data, for both laminar and turbulent cases, and good quantitative agreement with literature data, for laminar and some turbulent results.