Neste trabalho são analisados os aspectos relacionados à otimização estrutural de cilindros de alta pressão em compósitos, a partir do estudo detalhado dos procedimentos de cálculo analítico, utilizando o método análise de rede (netting analysis), juntamente com procedimentos baseados em análise numérica pelo método dos Elementos Finitos, considerando modelos de comportamento ortotrópico do material compósito. São considerados cilindros utilizados para armazenamento de oxigênio, fabricados pelo processo de enrolamento filamentar (filament winding), comparados a cilindros confeccionados em metal quanto à sua aplicabilidade. Após análise de diferentes estudos de caso, conclui-se que os materiais compósitos podem ser aplicados com sucesso em cilindros de alta pressão, desde que estabelecidos alguns parâmetros decisivos ao projeto estrutural do vaso, tais como: critério de falha mais adequado; determinação de dados experimentais dos materiais utilizados; normas e códigos utilizados no projeto e dados da geometria final do vaso, dependentes do processo de fabricação. Propõe-se também a utilização de um ambiente integrado das atividades de projeto e fabricação do compósito. / In this work the aspects related to the structural optimization of composite high-pressure cylinders are analyzed from the thorough study of analytical calculation, by the use of netting analysis, along with procedures based on numerical analysis by the Finite Element method, considering models of composite materials with orthotropic behaviour. Cylinders used for oxygen containment, manufactured by filament winding process, are considered and compared to the cylinders manufactured in metal in terms of their application. The analyses of different case studies allowed to conclude that composite materials can be applied successfully in high pressure cylinders provided that some critical parameters have been established to the vessel structural design, such as: an adequate failure criteria; determination of experimental data for the composite materials used; standards and codes used in the design and the final vessel geometry data, dependent variables of the manufacturing process. An integrated environment of the design and manufacturing activities is proposed as well in order to embrace all of these aspects.

In this study we investigates the thermal behavior of an assembly of consecutive cylinders in a counter-rotating configuration cooled by natural convection with the objective of maximizing the heat transfer density rate (heat transfer rate per unit volume). A numerical model was used to solve the governing equations that describe the temperature and flow fields and an optimization algorithm was used to find the optimal structure for flow configurations with two or more degrees of freedom. The geometric structure of the consecutive cylinders was optimized for each flow regime (Rayleigh number) and cylinder rotation speed for one and two degrees of freedom. Smaller cylinders were placed at the entrance to the assembly, in the wedge-shaped flow regions occupied by fluid that had not yet been used for heat transfer, to create additional length scales to the flow configuration. It was found that the optimized spacing decreases and the heat transfer density rate increases as the Rayleigh number increases, for the optimized structure. It was also found that the optimized spacing decreases and the maximum heat transfer density rate increases, as the cylinder rotation speed was increased for the single scale configuration at each Rayleigh number. Results further showed that there was an increase in the heat transfer density rate of the rotating cylinders over stationary cylinders for a single scale configuration. For a multi scale configuration it was found that there was almost no effect of cylinder rotation on the maximum heat transfer density rate, when compared to stationary cylinders, at each Rayleigh number; with the exception of high cylinder rotation speeds, which serve to suppress the heat transfer density rate. It was, however, found that the optimized spacing decreases as the cylinder rotation speed was increased at each Rayleigh number. Results further showed that the maximum heat transfer density rate for a multi scale configuration (with stationary cylinders) was higher than a single scale configuration (with rotating cylinders) with an exception at very low Rayleigh numbers. / Dissertation (MEng)--University of Pretoria, 2012. / Mechanical and Aeronautical Engineering / unrestricted

[pt] A dissertação de Mestrado tem por objetivo examinar a formação do mercado fonográfico no Brasil a partir da atuação da primeira gravadora de cilindros de cera com canções brasileiras, a Casa Edison, na capital federal no final do século XIX até o início da segunda década do século XX. Para empreender tal análise, a pesquisa focou-se nos documentos produzidos pela gravadora, como os seus catálogos e suplementos de divulgação, as correspondências com empresas fonográficas estrangeiras e as cessões de direitos autorais. A gravadora foi um espaço polifônico que dialogou e negociou com diversos gêneros musicais, compositores, poetas, cantores, empresários e empresas de sua época, indispensáveis para dar início ao seu processo de estruturação e expansão. A Casa Edison foi responsável pelo registro quase absoluto das músicas brasileiras durante as primeiras décadas do século XX e lançou as bases para estruturação do mercado fonográfico no Brasil. / [en] This Master s thesis aims to examine the formation of Brazil s phonographic market from the operation of the first record of wax cylinders with Brazilian songs, Casa Edison, in the federal capital at the end of the late nineteenth until the beginnings at second decade of the twentieth century. To undertake this analysis, the research focused on documents made by the record label, even as their catalogues and supplemental disclosure, their letters with foreign phonograph companies and their copyrights. The label was a polyphonic place that dialoged and dealt to several musical genres, songwriter, poets, singers, businessman and companies of their time, needful to start the process for its structuring and expansion. Casa Edison was responsible to almost all records of Brazilian music during the first decades on twentieth century and to spread the basis for phonograph market structuration in Brazil.

O escoamento ao redor de cilindros inclinados, ou escoamento oblíquo, é um problema bastante comum em diversas áreas da engenharia. Embora o escoamento ao redor de um cilindro não inclinado consista em um tópico clássico e bastante estudado no contexto da mecânica dos fluídos, os estudos investigativos do escoamento oblíquo existem em menor número. O procedimento mais adotado para o estudo do escoamento ao redor de um cilindro inclinado é o Princípio da Independência, que atesta que todas as características da esteira dependem unicamente da componente da correnteza incidente que é ortogonal ao eixo do cilindro. Visando um melhor entendimento do escoamento ao redor de cilindros rígidos e inclinados, três grupos de experimentos foram conduzidos com cilindros inclinados tanto à montante como à jusante. Cinco ângulos de inclinação, definidos entre o eixo do cilindro e a direção ortogonal à da correnteza foram ensaiados, a saber: teta = 0°, 10°, 20°, 30° e 45°. No primeiro grupo de experimentos, os resultados obtidos com os cilindros estacionários inclinados à montante mostraram que o coeficiente de arrasto médio concorda com os resultados da configuração de referência, desde que a componente da correnteza incidente ortogonal ao eixo do cilindro seja utilizada na normalização da força. No tocante aos experimentos dos cilindros sujeitos ao fenômeno de vibrações induzidas pela emissão de vórtices com um ou dois graus de liberdade, existe um decréscimo da amplitude de oscilação dos cilindros com o aumento do ângulo de inclinação. Em todas as campanhas experimentais, foram verificadas diferenças entre os resultados obtidos com os cilindros inclinados à montante ou à jusante. Essa diferença é tão maior quanto maior for o ângulo de inclinação, e está associada à assimetria nas condições de extremidade do cilindro. / The flow around yawed cylinders, or oblique flow, is a common subject in several engineering applications. Despite the flow around a non-yawed cylinder consists on a classical and extensively investigated problem, there is a considerable lower number of investigation concerning the oblique flow. The most employed approach aiming at investigating the oblique flow is the so called Independence Principle, which states that the flow characteristics depend only on the component of the free-stream that is normal to the cylinder axis. Three groups of experiments were carried out aiming at a better understanding of the flow around yawed cylinders. Five yaw angles defined between the cylinder axis and the direction orthogonal to the free-steam were tested, namely: theta = 0°, 10°, 20°, 30° e 45°. From the first group of experiments, the results obtained with stationary cylinders yawed in the upstream orientation shown that the mean drag coeficient matches the classical results from the non-yawed cylinder, if the component of the free-stream that is orthogonal to the cylinder axis is employed in the normalization of the hydrodynamic force. Concerning vortex-induced vibrations experiments with one and two degrees-of-freedom, a decrease was observed in the maximum oscillation amplitude. For all the experiments, it was observed that the results obtained from the upstream orientation tests can be different from those obtained for the downstream orientation ones. The larger the yaw angle, the larger are the differences, which are associated to the asymmetric end conditions.

O crescimento da exploração do petróleo e gás em águas ultraprofundas fez com que a demanda por unidades flutuantes crescesse e, com isso, aumentasse a ocorrência do fenômeno de Movimentos Induzidos por Vórtices (ou VIM, de Vortex-Induced Motions) que age em plataformas com casco cilíndrico, como é o caso das monocolunas e spars. Efeito natural desse aumento nas ocorrências foi um maior interesse pelo fenômeno de VIM, simplificadamente investigado em cilindros lisos e curtos como os utilizados nesta pesquisa. A fim de contribuir com o conhecimento dos fundamentos fluido-dinâmicos nesta área, foram investigados quatro diferentes cilindros flutuantes de baixa razão de aspecto, todos caracterizados pelo valor típico de L/D = 2 (comprimento imerso por diâmetro, onde L= 250 mm e D= 125 mm), mas com diferentes condições de arredondamento da extremidade imersa, estas caracterizadas por quatro razões distintas entre o raio de adoçamento e o raio do cilindro, especificamente r/R= 0,00; 0,25; 0,50 e 1,00. Com este objetivo de observar a resposta dos cilindros curtos sob efeito dos vórtices gerados em diferentes formatos de extremidade imersa, experimentos foram realizados no tanque de provas do Instituto de Pesquisas Tecnológicas do Estado de S~ao Paulo (IPT), compreendendo velocidades de reboque entre 0,024 a 0,154 m/s, ou seja, uma faixa de números de Reynolds entre 3.300 e 19.200. Os resultados de amplitude adimensional de resposta observados na direção transversal mostram influência moderada das modificações na extremidade imersa, ligeiramente mais acentuadas no modelo com razão de arredondamento de r/R=0,25, sendo que para este caso, as amplitudes máximas ficaram abaixo daquelas exibidas pelos demais modelos, com uma tendência geral de queda para as velocidades de reboque mais altas. A variação da geometria da extremidade imersa também influenciou moderadamente os resultados de amplitude adimensional de resposta na direção longitudinal, onde o modelo com r/R=1,00 apresentou menores amplitudes nas velocidades mais altas. Por outro lado, a razão entre as frequências de resposta e as frequências naturais de referência mostraram comportamentos típicos, semelhantes aos encontrados em análises de VIV de cilindros longos montados em suportes elásticos com dois graus de liberdade. Além disso, a observação dos movimentos dos modelos no plano da superfície livre não indicaram mudanças significativas nas trajetórias em função do arredondamento da extremidade livre. No tocante aos coeficientes de força (arrasto e sustentação), as comparações entre os modelos foram semelhantes, mas os coeficientes para o cilindro sem chanfro (r/R=0) mostraram-se maiores para grande parte das velocidades ensaiadas. Para o modelo com r/R=1,00, as força (arrasto e sustentação não se mostraram com a mesma intensidade do que aquelas nos demais modelos, o que, desta forma, se refletiu nos menores valores de coeficiente encontrados. Sob uma ótica geral, os resultados levam a crer que o modelo fluido responsável pelas oscilações nos cilindros com L/D = 2 não tem relação com a existência de vórtices de ponta e aresta, mas com a emissão de vórtices em forma de arco. / The oil and gas exploration in deep and ultra-deep water has increased in the past years, and at the same time, increasing the oating vessel demand, thereby the vortex-induced motion phenomenon (VIM) has been present for cylindrical hull structures, for example, spar and monocolumns oating units. The impact of this, enhance the VIM phenomenon interest with simplify investigations on smooth cylinders, as was used in the present research. In order to expand the knowledge, experiments were made in four floating cylinders with low aspect of ratio, L/D = 2 (Length / Diameter) were tested with different free end corner shape types, namely by the relation between chamfer rounding radius (r) divided by the radius of cylinder (R) (r/R = 0.0, 0.25, 0.5 and 1.0). For the initial case, r/R =0.0 represents at tip and r/R = 1.0 the semi-hemispherical tip. The aims were to understand the effect of different free-end types on VIV behaviour of cylinders. The oating circular cylinders, i.e. unit mass ratio m* = 1(structural mass/displaced uid mass), were elastically supported by a set of linear springs to provide low structural damping on the system and allow six degrees of freedom. The aim is to understand the effects of the free end vortex in the cylinder movements, varying the free end shape. The experiments were carried out in a towing tank of IPT - Institute for Technological Research of the state of São Paulo, Brazil. The range of velocities tested is 0.024 to 0.154 m/s , and Reynolds number covered 3;300 <= Re <= 19;200. The nondimensional amplitudes results for transversal direction, show a moderated effect when the free end shape has changed, more significant in the r/R=0.25 case, where the maximum amplitudes present lower values compare with the others cylinders. For in-line nondimensional amplitudes, model with r/R= 1.00 shown lower values for high velocities. On the other hand, the frequencies ratios between in-line/transverse and natural sistem frequency, presented typical VIV response for long cylinders with two degree of freedom. In addition, the trajectory observations in the XY plane have not illustrated differences for cylinders with rounded edges. Force coeffcients outcome (drag and lift), the no-rounded edge case (r/R=0.0), presented higher coeffcients for the large proportion velocities. Furthermore, the model with a semi-spherical shape in the free end (r/R=1.00), demonstrated the both force coeffcients have not acted with the same severity as was observed for the others cylinders, and thus, the r/R=1.00 models has presented lowest values. In general, the present results suggest the answer for oscillation on L/D=2 models is caused by arc-type vortex shedding, not by the free end vortex effects.

O fenômeno de vibração induzida por vórtices (VIV) é particularmente danoso para estruturas submarinas como risers de exploração de petróleo. A maneira mais usual de se atenuarem os efeitos de VIV é instalar um supressor, como por exemplo strakes ou fairings. Dentre esses, foi desenvolvido por All Brow Universal Components um supressor chamado Ventilated Trousers (VT), que consiste em uma malha permeável feita de uma rede flexível e dezenas de bobbins. Através de um estudo experimental, procurou-se investigar os mecanismos hidrodinâmicos pelos quais o supressor V T funciona. Foram construídos três modelos diferentes de supressores: um modelo idêntico ao V T e duas malhas dele derivadas, alterando-se a geometria dos bobbins e a distribuição destes ao redor da malha. Foram realizados ensaios com o modelo xo e ensaios de VIV em um grau de liberdade alterando-se o amortecimento estrutural. Foram medidos deslocamento e forças de sustentação e arrasto. Os resultados mostraram que o supressor do tipo V T reduz as amplitudes de vibração, força de sustentação e arrasto quando comparados com um cilindro oscilando. No entanto, aumenta a força de arrasto quando comparado com o cilindro xo. A geometria da malha mostrou-se de grande importância para a supressão de VIV. Modelos que possuem o disco externo no bobbin impedem o surgimento de folga entre o modelo e o cilindro, além de aumentar o amortecimento hidrodinâmico. Três hipóteses foram levantadas para explicar o funcionamento do supressor V T. A primeira diz que a supressão é provocada pelo aumento do amortecimento hidrodinâmico. Os ensaios mostraram que, de fato, o supressor V T aumenta o amortecimento e, consequentemente, diminui as VIV. No entanto, somente esse efeito não explica toda a supressão obtida. As outras hipóteses, relacionadas à alterações bi e tridimensionais da esteira, foram avaliadas, porém não se pode afirmar que alguma delas seja isoladamente responsável por produzir o mecanismo hidrodinâmico de supressão. / The phenomenon of vortex-induced vibration (VIV) is particularly harmful to submarine structures such as risers used for oil extraction. The most usual way to attenuate the effects of VIV is the installation of suppressors, like strakes or fairings. Among them, All Brow Universal Components developed a VIV suppressor called Ventilated Trousers (VT), which consist of a permeable mesh made of a flexible net and tens of bobbins. Three different models of suppressors based on permeable meshes have been assembled with the objective to understand the hydrodynamic mechanism behind the suppression: one model identical to the VT and two meshes with different bobbin geometries and distribution. Tests were carried out with xed models and models free to oscillate in one degree of freedom varying the structural damping. Displacements, drag and lift forces were measured. Results showed that the VT suppressor reduced vibration amplitudes, lift and drag forces when compared to an oscillating circular cylinder. However, it increased drag force when compared to a fixed circular cylinder. The mesh geometry proved to be important to VIV suppression. Models that had an external disc on the bobbins avoided the appearance of a gap between the model and the cylinder. Three hypotheses were formulated to explain how the VT suppressor works. The first one says that the increase on hydrodynamic damping is responsible for suppression. In fact, tests showed that the VT increased hydrodynamic damping and, consequently, reduced the VIV response. However, this effect alone does not explain the suppression as a whole. The other two hypotheses related to two-dimensional and three-dimensional wake changes were evaluated, but it cannot be stated that any of them, on its own, is responsible for the whole of the suppression mechanism.

No description available.

The aim of this study is to develop an explicit analytical formulation based on the anisotropic elasticity theory that determines the behavior of fiber reinforced composite vessel under hygrothermal loading. The loading is studied for three cases separately, which are plane strain case, free ends and pressure vessel cases. For free-end and pressure vessel cases, the vessel is free to expand, on the other hand for plane strain case, the vessel is prevented to expand. Throughout the study, constant, linear and parabolic temperature distributions are investigated and for each distribution, separate equations are developed. Then, a suitable failure theory is applied to investigate the behavior of fiber reinforced composite vessels under the thermal and moisture effects. Throughout the study, two computer programs are developed which makes possible to investigate the behavior of both symmetrically and antisymmetrically oriented layers. The first program is developed for plane strain case, where the second one is for pressure vessel and free-end cases. Finally, several thermal loading conditions have been carried out by changing the moisture concentration and temperature distributions and the results are tabulated for comparison purposes.

Mémoire (M.Sc. A.)-- Université du Québec à Chicoutimi, 1984. / "Mémoire présenté comme exigence partielle de la maîtrise en sciences appliquées en ressources et systèmes" CaQCU bibliographie: p. 56-58. Document électronique également accessible en format PDF. CaQCU

Vegetation is commonly modelled as emergent arrays of rigid, circular cylinders. However, the drag coefficient (CD) of real stems or trunks is closer to that of cylinders with a square cross-section. In this thesis, vegetation has been idealised as square cylinders in laboratory experiments with a turbulence intensity of the order of 10% which is similar to that of typical river flows. These cylinders may also represent other obstacles such as architectural structures. This research has determined CD of an isolated cylinder and cylinder pairs as a function of position as well as the average drag coefficient (CDv) of larger arrays. A strain gauge was used to measure CD whilst CDv was computed with a momentum balance which was validated by strain gauge measurements for a regularly spaced array. The velocity and turbulence intensity surrounding a pair of cylinders arranged one behind the other with respect to mean flow (in tandem) were also measured with an Acoustic Doppler Velocimeter. The isolated cylinder CD was found to be 2.11 in close agreement with other researchers. Under fixed flow conditions CD for a cylinder in a pair was found to be as low as -0.40 and as high as 3.46 depending on their relative positioning. For arrays, CDv was influenced more by the distribution of cylinders than the flow conditions over the range of conditions tested. Mean values of CDv for each array were found to be between 1.52 and 3.06. This new insight therefore suggests that CDv for vegetation in bulk may actually be much higher than the typical value of 1 which is often assumed to apply in practice. If little other information is available, a crude estimate of CDv = 2 would be reasonable for many practical applications. The validity of a 2D realizable k-epsilon turbulence model for predicting the flow around square cylinders was evaluated. The model was successful in predicting CD for an isolated cylinder. In this regard the model performed as well as Large Eddy Simulations by other authors with a significant increase in computational efficiency. However, the numerical model underestimates CD of downstream cylinders in tandem pairs and overestimates velocities in their wake. This suggests it may be necessary to expand the model to three-dimensions when attempting to simulate the flow around two or more bluff obstacles with sharp edges.