Orientador: Isaias Vizotto / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-24T02:40:36Z (GMT). No. of bitstreams: 1 Ferreira_AntonioMario_D.pdf: 9010854 bytes, checksum: 0b548385f37faa810cae541ae265ec42 (MD5) Previous issue date: 2013 / Resumo: Este trabalho realiza uma análise numérica e experimental do comportamento de estruturas em cascas de formas livres sob a ação do vento. Inicialmente foram gerados modelos computacionais de formas otimizadas, sendo uma casca de planta pentagonal e outra hexagonal. Na sequência foram construídos modelos físicos reduzidos em laboratório e submetidos a uma série de ensaios em túnel de vento. E, finalmente foram realizadas simulações numéricas dessas estruturas submetidas à ação do vento utilizando o programa computacional ANSYS-CFX do Laboratório de Informática da FEC-UNICAMP. Os modelos físicos reduzidos analisados foram gerados utilizando o software ANSYS e o programa computacional desenvolvido por Vizotto (1993), e construídos no Laboratório de Automação e Prototipagem para Arquitetura e Construção (LaPAC) da FEC-UNICAMP, utilizando inicialmente isopor de alta densidade, que foi posteriormente empregado para execução de fôrmas de concreto armado para moldar os modelos finais em material composto por fibra de vidro e resina, para serem ensaiados no túnel de vento do Laboratório de Conforto Ambiental e Física Aplicada (LaCAF) da FEC-UNICAMP. Os testes no túnel de vento do LaCAF foram realizados em dezesseis fases, sendo compostas por análises para obtenção dos coeficientes de pressão externa e interna, com ventos em regime laminar e turbulento, a 0º e 36º para a casca com forma de planta pentagonal, e a 0º e 30º para a casca com forma de planta hexagonal. Para análises por meio de simulação fluidodinâmica computacional pelo ANSYS-CFX, foi realizada inicialmente uma análise comparativa para os resultados dos coeficientes de pressões externas de um modelo de cúpula sobre o terreno da NBR 6123:1988. O software ANSYS-CFX demonstrou ótima eficiência na configuração realizada, apresentando resultados muito próximos aos da norma brasileira, e essa configuração também foi utilizada na validação física entre os ensaios no túnel de vento e as simulações pelo ANSYS-CFX. É sugerida a utilização dos dados finais na elaboração de normas específicas e uma configuração adequada e segura dentro das características consideradas para a utilização do software ANSYS-CFX como ferramenta para obtenção de coeficientes de pressões / Abstract: This work performs a numerical and experimental analysis of behavior of structures in free form shells about wind action. At first, computational models were generated in optimized forms, being one shell of pentagonal shape and another one hexagonal. After this, reduced physical models were built in laboratory and subjected to several tests in the tunnel of wind. Finally, numerical analyzes of these structures subjected to wind action were achieved using ANSYS computational program from FEC-UNICAMP computer laboratory. Two reduced physical models were analyzed, using the software ANSYS and the computational program that was developed by VIZOTTO I. (1993), and built at the Laboratory of Automation and Prototyping for Architecture and Construction site (LaPAC) from FECUNICAMP. The techniques: one hexagonal and another pentagonal, both made, at first, with Styrofoam in large dense, that was applied to execution of forms of concrete to be sculptured and finalized as a material composed of glass fiber and resin for future test in the wind tunnel at (LaCAF) from FEC-UNICAMP Environmental Comfort and Applied Physics Laboratory. The tests at the wind tunnel from LaCAF were made into sixteen phases, composed by analysis to obtain the coefficients of outside and inside pressure with wind in turbulent and laminar state, at 0º and 30º for hexagonal shape and turbulent and laminar, at 0º and 36º for pentagonal shape. To analyze by simulation computational fluid dynamics by ANSYS-CFX, at first were achieved a comparative analysis to the results of coefficients of outside pressure from a model of dome on the land from NBR 6123:1980. The software ANSYS-CFX showed an excellent efficiency on the made configuration, showing results very closed to the Brazilian rule, and this configuration also was used in the physical validation between the tests at wind tunnel and the simulations by ANSYS-CFX. It is suggested the usage of final data on specific standard preparation and safe configuration for ANSYS software application as a tool to achieve pressure coefficients / Doutorado / Estruturas / Doutor em Engenharia Civil

Orientadores: Milton Mori, Marcos Akra D'Ávila / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-21T08:49:15Z (GMT). No. of bitstreams: 1 Mori_ErickDjin_M.pdf: 2359279 bytes, checksum: ee684b815a4962d2a25990de40b76d0a (MD5) Previous issue date: 2012 / Resumo: Escoamentos gás-líquido-sólido em colunas de bolhas ainda são pouco compreendidos pela comunidade científica. Conhecer melhor a hidrodinâmica em uma coluna de bolhas é condição primordial para o sucesso em seu dimensionamento. Se a natureza do escoamento multifásico por si só é complexa, a tarefa de estudá-lo se torna ainda mais desafiadora, tendo em vista que são poucos os trabalhos consistentes publicados na literatura que abordam a temática. No presente estudo, utiliza-se a técnica da fluidodinâmica computacional (CFD), para conduzir simulações tridimensionais e transientes, a fim de se descrever a hidrodinâmica de um sistema gás-líquido-sólido em uma coluna de bolhas com quantidade intermediária de sólidos. O problema é tratado por meio de uma abordagem Euleriana e a interação interfásica é descrita exclusivamente pelo arraste entre as fases gás-líquido e sólido-líquido. Os resultados numéricos obtidos são confrontados com resultados experimentais da literatura e comprovam a capacidade da ferramenta computacional em descrever o sistema em questão. A análise dos modelos de arraste para a interação sólido-líquido mostrou a relevância da escolha da lei de arraste para descrever corretamente a circulação de sólidos no leito. Para a interação gás-líquido sob as condições analisadas, os modelos que consideram distorções da fase gasosa mostraram melhor desempenho, frente os modelos que consideram apenas bolhas esféricas. A turbulência no meio contínuo foi descrita por modelos de duas equações, os modelos kepsilon e RNG k-epsilon. O último mostrou melhor desempenho em descrever o padrão de escoamento, possivelmente por ter sido concebido para escoamentos vorticiais / Abstract: Gas-liquid-solid flows inside bubble columns are not fully comprehended by scientific community yet. A better knowledge regarding the hidrodynamics of a bubble column is the first step towards reaching its sizing successfully. If the multiphase flow nature by itself presents great complexity, the task of studying it becomes even more challenging, since few are the consistent published work in the literature treating this subject. In the present study, the computational fluid dynamics (CFD) was used to capture the hidrodynamics of a gas-liquid-solid flow inside a bubble column with intermediate solid concentration. The Eulerian approach was used as frame of reference and for the interphase forces only the drag between gas-liquid and solid-liquid phases were considered. The numerical results were compared to experimental data of the literature, showing the ability of CFD in describing the multiphase flow. Furthermore, analysis of drag models for the solid-liquid interaction indicates that the drag law plays an important role in describing the solid circulating in the system. For the gas-liquid interaction under the analyzed conditions, it has been found that the drag laws considering the bubble distortion showed better agreement with experimental data in comparison to the ones that considered bubbles as rigid spheres. The turbulence in the continuous phase was described by a two equation model. Comparison between standard k-epsilon and RNG k-epsilon revealed that in this case, the latter represented better the flow pattern, since it was developed for swirling flows / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química

Orientador: Paulo Roberto Ribeiro / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica e Instituto de Geociência / Made available in DSpace on 2018-08-21T19:58:43Z (GMT). No. of bitstreams: 1 Paes_DiogoMelo_M.pdf: 2739943 bytes, checksum: 4213b100e22039aa35e9bbceb5f52418 (MD5) Previous issue date: 2012 / Resumo: Durante a produção de petróleo, partículas de asfalteno podem ser precipitadas da fase líquida devido a variações de pressão, temperatura e composição ao longo da trajetória do fluido do reservatório até a superfície. Uma vez precipitadas, essas partículas podem se depositar na parede de colunas de produção, reduzindo a área aberta ao escoamento e, consequentemente, a vazão. Apesar da importância do tema, a literatura sobre a deposição de asfaltenos em poços (incluindo modelos teóricos e dados experimentais) é escassa. Para superar as dificuldades inerentes a pouca literatura existente sobre o assunto, possibilitando um melhor entendimento desse complexo problema de transferência de massa, uma consistente metodologia foi proposta nesta dissertação. Essa metodologia envolveu uma revisão de literatura sobre conceitos fundamentais de transferência de quantidade de movimento e sobre a teoria da deposição de partículas, situando a deposição de asfaltenos em um contexto mais amplo, da deposição de partículas durante escoamentos turbulentos. Seis modelos de deposição (Lin et al. 1953; Friedlander e Johnstone 1957; Beal 1970; El-Shobokshy e Ismail 1980; Papavergos e Hedley 1984; Escobedo e Mansoori 1995) são estudados e validados com quatro conjuntos de dados experimentais de deposição de aerossol (Friedlander 1954; Wells e Chamberlain 1967; Liu e Agarwal 1974; Agarwal 1975). Com base nos resultados desse estudo, o modelo de Beal (1970) foi selecionado como sendo o mais adequado para prever a deposição de partículas, sendo considerado adequado também para prever a deposição de asfaltenos (limitando-se sua aplicação a intervalos similares de número de Reynolds, número de Schmidt e tempos de relaxação adimensionais em relação àqueles cobertos no estudo de validação). Por fim, esse modelo foi aplicado em uma análise de sensibilidade para se avaliar os parâmetros e mecanismos de transporte mais importantes para a deposição de asfaltenos em poços / Abstract: During petroleum production, asphaltene particles can precipitate from the crude oil due to pressure, temperature, and composition changes along the fluid path from the reservoir to the surface. Once precipitated, those particles can deposit in the inner surface of production tubings, restricting the available flow area and reducing flow rates. Despite the importance of the theme, the literature about asphaltene deposition in wellbores (including theoretical models and experimental data) is scarce. To overcome the difficulties inherent to that shortage of literature and enable a better understanding of that complex mass transfer problem, a consistent methodology is proposed in this work. That methodology involved a comprehensive review of fundamental concepts of the mass transfer and particle deposition theories, placing the asphaltene deposition within a more general context, of particle deposition during turbulent flow. Six published particle deposition models (Lin et al. 1953; Friedlander and Johnstone 1957; Beal 1970; El-Shobokshy and Ismail 1980; Papavergos and Hedley 1984; Escobedo and Mansoori 1995) are studied and validated with four published aerosol experimental data sets (Friedlander 1954; Wells and Chamberlain 1967; Liu and Agarwal 1974; Agarwal 1975). Based on the results of the study, Beal's (1970) model was selected as the most suitable to predict particle deposition and was considered adequate also to predict asphaltene deposition (limiting its application to similar ranges of Reynolds numbers, Schmidt numbers and dimensionless relaxation times in relation to those covered in the validation study). Finally, that model was applied in a sensitivity analysis to evaluate the most important parameters and transport mechanisms governing asphaltene deposition in wellbores / Mestrado / Explotação / Mestre em Ciências e Engenharia de Petróleo

No description available.

[pt] Determinou-se experimentalmente o coeficiente local de troca de calor, para o escoamento turbulento interno, em tubos de seção transversal elíptica. As condições de contorno impostas foram, temperatura constante na parede e entrada abrupta, com canto vivo, em uma placa plana. Foram obtidos resultados na região de entrada e na região desenvolvida, cobrindo a faixa de número de Reynolds de 7 000 a 60 000. Foram investigadas as razões de aspecto 0,12, 0,25 e 0,5 e os resultados, comparados com os encontrados na literatura para placa plana e tubo circular. Uma diferença máxima de 16 por cento, foi encontrada em relação aos resultados para tubo circular. Portanto, a utilização de tubos elípticos em trocadores de calor é, em geral, vantajosa do ponto de vista térmico. / [en] Experiments were performed to determine local heat transfer coefficients for the turbulent flow in a duct with elliptical cross section. The boundary conditions imposed were isothermal wall and abrupt-contraction at the entrance built into a large wall. Both entrance-region and fully-developed results were obtained, whereas the Reynolds number was varied in the overall range 7,000-60,000. The aspect ratios 0.12, 0.25 and 0.5 were investigated and the results compared with the ones for parallel planes and for circular tubes, found in the open literature. The measured heat transfer coefficients displayed a maximum deviation of 16 percent relative to the results for the circular tube. Therefore, using elliptical ducts in heat exchangers is in general advisable as far as heat transfer is concerned.

On se propose d’analyser le régime transitoire de décrochage à l’aide de la simulation numériqueinstationnaire de type DNS. Cette approche permet de reproduire avec fidélité l’écoulementdans la région critique de Bulbe de Décollement Laminaire au bord d’attaque, encoreimpossible à modéliser ou mesurer avec précision. Après une étape de validation, la sensibilitédu BDL au niveau de turbulence extérieure est étudiée et comparée favorablement à celleétablie récemment dans la littérature. La phase d’établissement du décollement massif depuisle BDL est reproduite en réalisant de petites variations d’incidence à travers l’angle critiqued’apparition du décrochage. Ce raisonnement ”aux petites perturbations” permet de reproduirel’éclatement du BDL communément rattaché au décrochage statique. La déstabilisation de larégion de BDL est alors étudiée à l’aide d’une base de données instationnaires et moyennes quipermet pour la première fois de rendre compte des déformations 3D du BDL. Conservant ceprotocole, et faisant varier la vitesse du profil, on est en mesure d’évaluer l’influence de cettedernière sur le régime transitoire. Des mouvements de rotation de plus forte amplitude angulaireont permis de mettre en évidence un mécanisme de décrochage sensiblement différent duprécédent. La couche de mélange surplombant le BDL s’enroule alors pour donner naissance àun tourbillon énergétique (Leading Edge Vortex), communément associé au décrochage dynamique.Enfin, l’analyse du champ de vitesse moyen a permis de valider un critère empiriqued’apparition de l’éclatement du BDL, qui s’est révélé pertinent aussi bien pour les mouvementsde faible amplitude que ceux plus amples. / High fidelity numerical simulation is used to study the transitory flow involved during the staIl ofan airfoil at high angle of attack. The nearly DNS resolution in the Laminar Separation Bubbleprovides the required accuracy to reproduce this complex flow that still represents a challenge forboth experimentation and modeling. The numerical procedure is comprehensively validated withparticular attention to the LSB region. The sensitivity of the LSB to an external disturbance ismonitored on the airfoil and is favorably compared with a recent study on flat plate in the literature.The destabilization of the LSB during staIl is reproduced with a small variation of the angle ofattack through the critical angle. The LSB bursting, typical of a static leading edge staIl, is thusreproduced. A comprehensive study of the unsteady events during the transitory flow is performedby means of a high frequency sampling of spanwise and short time averaged data base. Ofparticular interest is the 3D deformation of the flow captured by using a large spanwisecomputational domain (one chord length). The influence of the motion dynamic is then explored.The transitory is significantly affected by a high angular amplitude motion. The shear-Iayer in theLSB undergoes a roll-up which is found to be responsible for the formation of the Leading EdgeVortex, typical of a dynamic staIl configuration. An empirical criterion for the prediction of burstingis then assessed using the statistical data base. Results are found to surprisingly match the incipientof staIl in both static and dynamicaJ conditions.

Small weight percentages of certain high-molecular weight polymers added to liquids in turbulent flow through conduits can result in dramatic friction reduction. Although many current and potential uses of the drag reduction phenomenon exist, there is a fundamental problem: drag reduction efficacy decreases rapidly with flow time due to the mechanical degradation in flow of the added polymer. In this thesis study, dilute aqueous solutions of polyacrylamide were tested under turbulent flow conditions in an attempt to determine where mechanical degradation in flow occurs.

No description available.

With the current development of the computer industry, CFD simulations have become the widespread standard in the industry, forming a baseline tool for numerous designs and safety procedures. This extensive dependence on the CFD codes rather than experiments raises the issue of the reliability of the results obtained from these codes. This thesis is intended to study the dependence of the CFD results on the grid types, numerical schemes and turbulence models. Additionally, comparisons between a general purpose commercial code STAR-CCM+ and a specialized code FDS are presented towards the end of this thesis. To study the numerical errors introduced by the grids and schemes, a laminar flow induced by natural convection inside a square cavity was considered first. Using Richardson’s extrapolation, a grid independent solution was calculated and compared with the results obtained from different grid types and schemes for Rayleigh (Ra) numbers , and . Comparison plots showed a higher dependence of the accuracy of the results on the cell shapes along with the order of the scheme and the cell size. Additionally, with the same cavity a grid dependence study for the and model has been done at .To test the reliability of the Quasi-DNS performed by an Unstructured Finite Volume (FV) CFD code, Turbulent Kinetic Energy (TKE) budgets should be calculated. User subroutines were developed to calculate the budgets of the TKE and to verify the user subroutines, prior to coaxial cylinder test case, a Q-DNS of the channel flow at has been performed using different grid configurations and numerical schemes. Results obtained from the Q-DNS of the channel flow on the polyhedral cells with the bounded central differencing scheme were found to be in good agreement with the reference DNS data. After the validation test case, a Q-DNS of the buoyancy driven turbulent flow inside a horizontal annular cavity at a high Rayleigh number, Ra = 1.18x109 with outer to inner cylinder ratio of 4.85 was carried out using a commercial code. Comparisons of Q-DNS results with low-Re URANS models, and model, showed that the latter models are able to capture the general flow features but fail to predict the large unsteadiness and high turbulence levels in the plume. However, local heat transfer rates along the inner and outer cylinder walls are on average of acceptable accuracy for engineering purposes. Finally, a full scale industrial test case of a fire in a compartment has been simulated. Both URANS ( model) and LES (Smagorinsky model) approaches are applied to model the turbulence with and without incorporating the combustion modelling. A comparison of the CFD results with the experimental data showed that for building fire simulations, accuracy of the results is more sensitive to the correlations used in the combustion modelling rather than the type of the turbulence model.

Orientador: Erick de Moraes Franklin / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-26T21:46:41Z (GMT). No. of bitstreams: 1 Penteado_MarcosRobertoMendes_M.pdf: 9443939 bytes, checksum: ee4e74d0df7e1ec320410dcc330c86e3 (MD5) Previous issue date: 2015 / Resumo: O transporte de sedimentos por um fluido é frequentemente encontrado em rios, oceanos, escoamentos periglaciais e outros processos naturais. É também encontrado na indústria, tal como em linhas de petróleo que arrastam sedimentos, em sistemas de esgotos e em processos de dragagem, por exemplo. Nessa dissertação, o transporte de grãos em um leito granular cisalhado pelo escoamento de um líquido será investigado experimentalmente. Nos experimentos, um escoamento de água turbulento totalmente desenvolvido foi imposto sobre o leito granular de geometria conhecida. Sob as condições testadas, os grãos foram transportados como leito móvel (\textit{bed load}, em inglês), i.e., sedimentos são transportados rolando ou deslizando sobre o leito. Para diferentes vazões de água, os deslocamentos dos grãos são filmados por uma câmera rápida. Os deslocamentos e campos de velocidade dos grãos foram determinados através do tratamento das imagens. A taxa de transporte dos grãos foi então estimada e correlacionada com o escoamento do fluido / Abstract: Sediment transport by a fluid flow is frequently found in rivers, oceans, periglacial flows and other natural processes. It is also commonly found in industry, such as in petroleum pipelines conveying grains, in sewer systems and in dredging lines, for example. In this thesis, the transport of grains of a granular bed sheared by a liquid flow was experimentally investigated. In the experiments, fully-developed turbulent water flows were imposed over a granular bed of known granulometry. Under the tested conditions, the grains were transported as bed load, i.e., sediment was carried by rolling and sliding over the bed. For different water flow rates, the displacements of grains were filmed by a high-speed camera. The grains displacement and velocity fields were determined by post-processing the images. The bed-load transport rate was estimated and correlated to the water flow conditions / Mestrado / Termica e Fluidos / Mestre em Engenharia Mecânica