<p> This study investigates the flow patterns and wall shear rate distributions downstream from a series of three glass model symmetric bifurcations, typical of the blood vessels in man. The models have a single included angle of 75° and total output to input flow area ratios of 0.75, 1.02 and 1.29, covering the physiological range. The Reynolds numbers studied (based on parent tube) were 400, 800 and 1200 in steady flow.</p> <p> Local fluid velocities were obtained at a number of axial positions along the bifurcation daughter tube via a neutrally buoyant tracer particle technique utilizing cine photography. This provided sufficient information to determine the three velocity components for each particle. The tangential and radial components were in general less than 6% of the mean axial velocity. In the case of the axial components, an analytical representation of the velocity in polar coordinates was obtained. This analytical function permits evaluation of wall shear rate distribution.</p> <p> The velocity pro£iles were found to be symmetric with respect to the plane of the bifurcation. At two diameters downstream from the carina the velocity profiles in the plane of the bifurcation showed a high peak near the inside wall of the branch. With distance downstream the peak was convected tangentially evening out the profile towards an axially symmetric mountain plateau with a dished top.</p> <p> Wall shear rate as a function of θ at constant axial position was represented by displaced cosine function. The highest shear rates always occurred on the inside wall of the daughter tube and the lowest on the outside wall. In general, the largest deviation from developed shear rates occurred close to the carina.</p> <p> The largest positive deviation in wall shear rate from developed values was found in the small area ratio bifurcation and the lowest wall shear rate value was found in the large area ratio bifurcation (a = 1.29) indicating possible flow separation near the carina. The biological implications of the shear rate information generated are discussed.</p> / Thesis / Master of Engineering (MEngr)

No description available.

O presente trabalho tem como objetivo fundamental a construção de um sistema de identificação capaz de diagnosticar em tempo real as diferentes configurações de escoamentos bifásicos horizontais. É importante ressaltar que o desenvolvimento deste know-how é capital para a operação eficaz de instalações de manipulação e ou transporte de fluidos multifásicos, e representa, hoje, um dos grandes desafios nas indústrias do petróleo e termonuclear. O princípio de funcionamento do sistema proposto baseia-se nos sinais captados por um sensor de pressão flutuante de resposta rápida, e no seu pósprocessamento com auxílio da transformada de Gabor e de uma rede neural convenientemente treinada. A implementação é tal que a operação de diagnóstico pode ser feita on-line, desde a aquisição dos sinais até o pósprocessamento. Resultados experimentais foram obtidos no circuito experimental do NETeF - Núcleo de Engenharia Térmica e Fluidos da USP - Universidade de São Paulo, para uma secção de testes horizo ntal com 12 m de comprimento e diâmetro interno de 30 mm. Em específico foram ensaiados os seguintes padrões de escoamento ar-água: estratificado liso, ondulado, intermitente, anular e a bolhas. Os resultados mostram que, dependendo dos limites de detecção pré-estabelecidos, todos o principais padrões de escoamento bifásico horizontal são identificados corretamente. / The fundamental objective of this work is the construction of an identification system capable of diagnosing in real time different configurations of horizontal two-phase flow patterns. It is important to emphasize that the development of this know-how is capital to the efficient operation of facilities for manipulation and transportation of multiphase fluids, and represents, today, one of the most important challenges in the oil and thermonuclear industries. The working principle of the proposed system is based on the signals acquired by a rapid response fluctuating pressure sensor, and on its post processing through Gabor Transform and on a conveniently trained artificial neural network. The implementation is accomplished in way that the diagnosis operation is performed on-line, from signal acquisition to post-processing. Experimental results were obtained on the experimental circuit at NETeF - Núcleo de Engenharia Térmica e Fluidos of USP - Universidade de São Paulo, at São Carlos, using a horizontal test section, with 12 m length and 30 mm internal diameter. Experiments were done with the following air-water flow patterns: stratified smooth, wavy, intermittent, annular, and bubbly. Results show that, depending on the preset detection limits, all the main horizontal two phase flow patterns were correctly identified.

Surgical Site Infections (SSI) are a significant and potentially preventable source of illness and death for surgical patients. An unknown, but potentially significant fraction of SSI may be caused by airborne infectious particles. Improved or optimized room air distribution may reduce these infections by minimizing the transport of infectious particles into the surgical site. A sophisticated CFD analysis, previously conducted by researchers at the National Institutes of Health (NIH), found that a buoyant thermal plume produced by heat from the surgical site itself could play a significant role in protecting the site from infectious particles. This study experimentally determines the airflow patterns around a simulated patient in a mock operating room using particle image velocimetry (PIV) to find the influence of the buoyant thermal plume on the flow. In addition, independent CFD analysis was performed using a standard commercial CFD program both to help guide and interpret the experimental results and to test the performance of a more readily available tool in predicting the experimental findings. The results of the experimental results and CFD analysis were quantitatively compared to find their agreement.

Orientador: Antonio Carlos Bannwart / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica e Instituto de Geociencias / Made available in DSpace on 2018-08-11T18:13:05Z (GMT). No. of bitstreams: 1 Vieira_FernandoFabris_M.pdf: 2246872 bytes, checksum: 214594df4e03b6e7638cc0a23a757366 (MD5) Previous issue date: 2004 / Resumo: As empresas de petróleo, através de seu segmento de exploração e produção - E&P - têm buscado o'aproveitamento das reservas de óleos. pesados, delimitando-as e produzindo-as de forma economicamente viável. Nessa busca, a atividade de Elevação e Escoamento tem o papel de viabilizar a movimentação desses óleos através de linhas e dutos. Um óleo é geralmente denominado pesado quando sua densidade é maior que 934 kg/m3, ou seja, seu grau API é inferior a 20, e sua viscosidade maior que 100 cP em condições de reservatório, características que dificultam sua movimentação e processamento primário. Este trabalho investiga o escoamento trifásico de misturas de óleo pesado cru com ar e água em um tubo vertical de vidro, em proporções variadas das três fases, no qual a água é injetada de forma a impedir o contato do óleo com a parede e reduzir o atrito (sistema core-flow). Para cada trio de vazões lidas nos correspondentes rotâmetros, determinou-se o padrão de escoamento com o auxílio de uma câmera de filmagem rápida (1000 quadros/segundo), e mediu-se o gradiente de pressão por meio de um transdutor diferencial de pressão. Os resultados são apresentados na forma de mapas de fluxo baseados nas velocidades superficiais e gráficos de gradiente de pressão total, possibilitando algumas comparações e interpretações. A principal conclusão aponta para a grande viabilidade da técnica de escoamento proposta. / Abstract: The oil companies, by their Exploration and Production departments (E&P), have worldwide sought viable means of recovery and prQduction of heavy oil fields, so as to aggregate and delimit those reserves in order to provide the highest revenues. In this search, the role of elevation and flow is to supply an adequate transport for these oils through lines and ducts. An oil is generally considered to be 'heavy' whenever its density is higher than 934 kg/m3 (i.e. API degree lower thari 20) and its viscosity is higher than 100 cP at reservo ir conditions; these features make it difficult their transportation and primary processing. In this work the threephase flow of a heavy crude oil, air and water in a vertical glass pipe, at several combinations of flow rates, is investigated, in which water is injected so as to avoid oil-wall contact and reduce friction (core-flow system). For each trio offlow rates read at the correspondent rotameters, the flow pattem was determined using a high speed camera (1000 ftames/second), and the pressure gradient was provided by a differential pressure transducer. The results are presented in flow maps based on superficial velocities and total pressure gradient 'plots, allowing some comparisons and interpretations. The main conclusion indicates the great viability of the proposed flow technique. / Mestrado / Explotação / Mestre em Ciências e Engenharia de Petróleo

O presente trabalho tem como objetivo fundamental a construção de um sistema de identificação capaz de diagnosticar em tempo real as diferentes configurações de escoamentos bifásicos horizontais. É importante ressaltar que o desenvolvimento deste know-how é capital para a operação eficaz de instalações de manipulação e ou transporte de fluidos multifásicos, e representa, hoje, um dos grandes desafios nas indústrias do petróleo e termonuclear. O princípio de funcionamento do sistema proposto baseia-se nos sinais captados por um sensor de pressão flutuante de resposta rápida, e no seu pósprocessamento com auxílio da transformada de Gabor e de uma rede neural convenientemente treinada. A implementação é tal que a operação de diagnóstico pode ser feita on-line, desde a aquisição dos sinais até o pósprocessamento. Resultados experimentais foram obtidos no circuito experimental do NETeF - Núcleo de Engenharia Térmica e Fluidos da USP - Universidade de São Paulo, para uma secção de testes horizo ntal com 12 m de comprimento e diâmetro interno de 30 mm. Em específico foram ensaiados os seguintes padrões de escoamento ar-água: estratificado liso, ondulado, intermitente, anular e a bolhas. Os resultados mostram que, dependendo dos limites de detecção pré-estabelecidos, todos o principais padrões de escoamento bifásico horizontal são identificados corretamente. / The fundamental objective of this work is the construction of an identification system capable of diagnosing in real time different configurations of horizontal two-phase flow patterns. It is important to emphasize that the development of this know-how is capital to the efficient operation of facilities for manipulation and transportation of multiphase fluids, and represents, today, one of the most important challenges in the oil and thermonuclear industries. The working principle of the proposed system is based on the signals acquired by a rapid response fluctuating pressure sensor, and on its post processing through Gabor Transform and on a conveniently trained artificial neural network. The implementation is accomplished in way that the diagnosis operation is performed on-line, from signal acquisition to post-processing. Experimental results were obtained on the experimental circuit at NETeF - Núcleo de Engenharia Térmica e Fluidos of USP - Universidade de São Paulo, at São Carlos, using a horizontal test section, with 12 m length and 30 mm internal diameter. Experiments were done with the following air-water flow patterns: stratified smooth, wavy, intermittent, annular, and bubbly. Results show that, depending on the preset detection limits, all the main horizontal two phase flow patterns were correctly identified.

The centrifugal casting process is a common method for manufacturing the tubes, etc. Due to its high temperature and invisible mold, it is really difficult to know the mechanism of molten steel inside the mold. It is important to know the mechanism of the molten steel inside mold, since it will help the manufacturer to know more accuracy of the flow of the molten steel so that it can work for improving the productivity and quality of the products. Casting funnel design is the designed by Åkers for their funnel which will result in different flow behavior. In thesis work, casting funnel design will be investigated so that it can make sure that the casting funnel design can affect the flow behavior of molten steel or not. Another method of changing the diameter of nozzle was also carried out and investigated with both simulation and experiment to changing flow behavior of molten steel. It will give Åkers alternative method for changing the flow behavior to liquid steel. The mechanism of solidification in centrifugal casting is also really important since it can give manufacturer the general view of solidification process. So solidification of centrifugal casting is also investigated in the thesis work.

No description available.

In this thesis report, interactive algorithms aid in the analysis of fluid flows are presented. Special functions and algorithms to average, smooth, and calculate the similarity between digitized curves were developed. The developed routines process the images in the spatial domain, thereby eliminating the need to calculate discrete Fourier and inverse Fourier transforms. The algorithms are effective, efficient, and fast. As an integral part of the algorithms, special data buffer routines for the effective data manipulation of curves, as well as cursor routines, were developed. An arbitrary set of frames consisting of curves, or an arbitrary set of curves, can be averaged or smoothed. Curves can be smoothed with a modified, variable, convolution filter. A special function makes it possible to express the similarity of two curves in a numerical value. This technique can be used to study time effects in fluid flows. Noise reduction can be obtained by averaging and smoothing a set of curves. / Thesis / Master of Science in Manufacturing Engineering (MSMANFE)

A presente dissertação trata de um estudo teórico-experimental sobre escoamento monofásico e bifásico no interior de tubos com fitas retorcidas. Esta técnica tem sido utilizada há várias décadas para a intensificação de troca de calor para escoamento monofásico e evaporação convectiva no interior de tubos. No entanto, com sua utilização, o aumento do coeficiente de troca de calor é acompanhado pelo incremento da perda de pressão. Portanto a compreensão dos fenômenos relacionados aos incrementos da perda de pressão e troca de calor são fundamentais para engenheiros projetistas. Neste estudo, inicialmente, é apresentada uma extensa revisão bibliográfica sobre padrões de escoamento, modelos para estimativa de fração de vazio e metodologias para previsão da perda de pressão em tubos com e sem fitas retorcidas para escoamentos bifásicos e monofásicos. Foram realizados experimentos em bancada experimental utilizando seção de testes com diâmetro interno de 15,9 mm e dois metros de comprimento com fitas apresentando razões de retorcimento de 3, 4, 9, 14 e , a última correspondente ao tubo sem inserto. Os experimentos foram executados para o refrigerante R134a, velocidades mássicas entre 75 e 250 kg/m²s, e títulos de vapor entre 5 e 95% no caso de escoamentos bifásicos. Resultados foram levantados para velocidades mássicas entre 100 e 450 kg/m²s para escoamentos monofásicos. Durante os ensaios foram levantados resultados de perda de pressão e identificados subjetivamente os respectivos padrões de escoamento. Como resultado final deste estudo é proposta uma correlação para previsão da perda de pressão durante o escoamento no interior de tubos com fitas retorcidas. / A theoretical and experimental study on single and two-phase flow inside tubes with twisted tapes inserts is presented. Twisted tape inserts have been used for decades as a technique of heat transfer enhancement. However, their heat transfer enhancement is accompanied by an increase of the pressure drop. Therefore, understanding the pressure drop and heat transfer mechanisms is fundamental for heat exchanger designers in order to optimize these devices when using twisted-tape inserts. Based on these aspects the present study concerns single and two-phase flows inside tubes with twisted tapes. Experiments were performed in an experimental apparatus for a 15.9 mm ID and twisted tape with twist ratios of 3, 4, 9, 14 and , the last one corresponding to a plain tube without tape. For two-phase flow, experiments were conducted for R134a, mass velocities from 75 to 250 kg/m²s and vapor qualities from 5 to 95%. In case of single-phase flow, experiments were performed for mass velocities from 100 to 450 kg/m²s. The experimental campaign was focused on pressure drop and flow pattern subjective identification. Additionally an extensive literature review on flow patterns, superficial void fraction, and methodologies for prediction of the pressure drop in plain tubes with and without twisted-tape inserts during single and two-phase flow is presented. As final result, a correlation for prediction of pressure drop during flow inside tubes with twisted tape inserts is proposed.