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Transport of microscopic particles in microchannels and microbubblesLaker, Travis S. 05 1900 (has links)
No description available.
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A modal analysis method for a lumped parameter model of a dynamic fluid systemWicks, Matthew L. 29 July 2009 (has links)
A lumped parameter model is developed for the analysis of dynamic fluid systems and the techniques of modal analysis are applied. An introduction to the lumped parameter modeling approach is accomplished by a thorough review of the dynamic mechanical system. This review of mechanical system analysis introduces terms such as the natural frequency, damping ratio and the frequency response function. For the analysis of more complex mechanical systems the topic of modal analysis is introduced. Proceeding in a manner analogous to that of the review of the mechanical system, the lumped parameter fluid model is introduced. This introduction includes the definition of the dynamic fluid properties and two relatively simple examples of how these properties may be used in the modeling of fluid systems. As an example of this method an analytical model is developed for a compressor system and the techniques of modal analysis are applied in a fluid sense. / Master of Science
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Studies on Aboveground Storgae Tanks Subjeected to Wind Loading: Static, Dynamic, and Computational Fluid Dynamics AnalysesYen-Chen Chiang (6620447) 14 May 2019 (has links)
<p>Due
to the slender geometries of aboveground storage tanks, maintaining the
stability under wind gusts of these tanks has always been a challenge.
Therefore, this thesis aims to provide a through insight on the behavior of
tanks under wind gusts using finite element analysis and computational fluid
dynamic (CFD) analysis. The present thesis is composed of three independent
studies, and different types of
analysis were conducted. In Chapter 2, the main purpose is to model the wind
loading dynamically and to investigate whether a resonance can be triggered.
Research on tanks subjected to static wind load have thrived for decades, while
only few studies consider the wind loading dynamically. Five tanks with
different height (<i>H</i>) to diameter (<i>D</i>) ratios, ranging from 0.2 to 4, were
investigated in this chapter. To ensure the quality of the obtained solution, a
study on the time step increment of an explicit dynamic analysis, and a on the
mesh convergence were conducted before the analyses were performed. The natural
vibration frequencies and the effective masses of the selected tanks were first
solved. Then, the tanks were loaded with wind gusts with the magnitude of the
pressure fluctuating at the frequency associating with the most effective mass
and other frequencies. Moreover, tanks with eigen-affine imperfections were
also considered. It was concluded that resonance was not observed in any of
these analyses. However, since the static buckling capacity and the dynamic
buckling capacity has a relatively large difference for tall tanks (<i>H</i>/<i>D
</i>≥ 2.0), a
proper safety factor shall be included during the design if a static analysis
is adopted. </p>
<p> </p>
<p>Chapter
3 focus on the effect of an internal pressure generated by wind gusts on
open-top tanks. Based on boundary layer wind tunnel tests (BLWT), a significant
pressure would be generated on the internal side of the tank shell when a gust
of wind blow through an open-top tank. This factor so far has not been sufficiently
accounted for by either ASCE-7 or API 650, despite the fact that this internal
pressure may almost double the design pressure. Therefore, to investigate the
effect of the wind profile along with the internal pressure, multiple wind
profiles specified in different design documents were considered. The buckling
capacities of six tanks with aspect ratios (<i>H</i>/<i>D</i>) ranging from 0.1 to 4 were analyzed
adopting geometrically nonlinear analysis with imperfection using an arc-length
algorithm (Riks analysis). Material nonlinearity was also included in some
analyses. It was observed that the buckling capacity of a tank obtained using
ASCE-7/API 650 wind profile is higher than buckling capacities obtained through
any other profiles. It was then concluded that the wind profile dictated by the
current North American design documents may not be conservative enough and may
need a revision. </p>
<p> </p>
<p>Chapter
4 investigates how CFD can be applied to obtain the wind pressure distribution
on tanks. Though CFD has been widely employed in different research areas, to
the author’s best knowledge, only one research has been dedicated to
investigate the interaction between wind gusts and tanks using CFD. Thus, a
literature review on the guideline of selecting input parameter for CFD and a
parametric study as how to choose proper input parameters was presented in
Chapter 4. A tank with an aspect ratio of 0.5 and a flat roof was employed for
the parametric study. To ensure the validity of the input parameters, the
obtained results were compared with published BLWT results. After confirming
that the selected input parameters produces acceptable results, tanks with
aspect ratio ranging from 0.4 to 2 were adopted and wind pressure distribution
on such tanks were reported. It was concluded that the established criteria for
deciding the input parameters were able to guarantee converged results, and the
obtained pressure coefficients agree well with the BLWT results available in
the literature. </p>
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Análise do comportamento sísmico das partes internas de um equipamento de proteção ambiental. / Analysis of seismic behavior of the internal parts of an environmental control equipment.Orbolato, Leandro Marino Takazono 15 October 2012 (has links)
Neste trabalho o comportamento sísmico das partes internas de um equipamento de proteção ambiental é estudado. O equipamento, um precipitador eletrostático, é composto basicamente de uma grande caixa de metal elevada, que contem eletrodos positivos e negativos responsáveis pela coleta de material particulado no fluxo de gases industriais. Esses componentes se comportam como pêndulos. No modelo foram considerados os deslocamentos sísmicos horizontais em duas direções ortogonais. De especial interesse está o fato de os eletrodos terem a liberdade de oscilar no plano de uma direção, mas não no seu plano perpendicular. Serão analisados quatro modelos com um, dois, três graus de liberdade, e um com três graus de liberdade linearizado. O modelo mais completo considera como graus de liberdade e coordenadas generalizadas os dois deslocamentos horizontais, e o deslocamento angular do pendulo. Foi adotada a formulação Lagrangeana para derivar as equações de movimento do modelo. As equações diferenciais do movimento de segunda ordem obtidas apresentam um comportamento não linear. Os movimentos sísmicos, que são estocásticos por natureza, serão simulados por meio de um registro sísmico existente, arbitrariamente escolhido. A obtenção dos parâmetros do modelo a ser estudado é de especial interesse para a melhor previsão do comportamento do equipamento quando solicitado a esforços sísmicos. A integração numérica do modelo matemático é efetuada, sendo posteriormente realizados comparativos entre as respostas dos modelos, quando submetidos tanto a vibração livre, como a um sismo real já registrado, arbitrário. / In this work, the seismic behavior of the internal parts of an environmental control equipment is studied. The equipment, an electrostatic precipitator, is basic composed of an elevated large steel box, containing positive and negative electrodes that capture powdered material of industrial effluent gases. These internal components behave essentially as pendula. In the mathematical model seismic motions in two orthogonal directions are considered. It is interesting to realize that the pendular electrodes are free to swing in one plane but not in the other plane. Four increasingly complex nonlinear models are analyzed, with one, two and three degrees of freedom, as well as one 3-degree-of-freedom linearized model. The generalized coordinates of the most complete model are the two horizontal displacements of the top mass and the angular motion of the pendulum. Lagranges formulation is used to derive the equations of motion of the models. These are second order nonlinear ordinary differential equations. The base seismic motions, that are stochastic in nature, are replaced by a arbitrarily chosen existing seismic record. The models parameters are carefully chosen to a good prediction of the equipment under seismic support excitation. Numerical integration of the mathematical model is performed, and comparisons are made of the several models response submitted to free vibrations and to an existing seismic record.
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Análise sísmica de estruturas para máquinas de papel. / Seismic analysis of structures for paper machines.Morcelli, Rodrigo Silva 02 December 2010 (has links)
Em geral, os desenvolvimentos na literatura e em códigos de construção voltados para projeto sísmico tem grande ênfase em edifícios civis e seu respectivo comportamento dinâmico. Entretanto, em diversas ocasiões, faz-se necessário o projeto e dimensionamento de equipamentos ou estruturas de geometria e comportamento distintos dos de um edifício usual. Contudo, são encontradas em diferentes normas afirmações e advertências de que as informações lá contidas aplicam-se inteiramente a essas estruturas ou construções similares. Nesses documentos, emitidos por vários países para aplicação em seus respectivos territórios, são estabelecidos procedimentos e métodos. Ademais, opções para análise são propostas, com base em diversos fatores como o tipo de estrutura resistente, a função da edificação, os custos relacionados, a importância da obra e as características geológicas do local de construção. Nesse trabalho, foi realizado o estudo de estruturas para máquinas de fabricação de papel, de modo analítico e por meio do método dos elementos finitos, com respeito a projeto sísmico. Esses equipamentos consistem de pórticos metálicos suportados por estruturas civis, e que suportam rotores por cuja superfície passa o papel durante operação. Os métodos usualmente presentes em normas, força horizontal equivalente, análise espectral e análise transiente com históricos de acelerações no tempo foram aplicados, e suas respostas comparadas e comentadas. Buscou-se como resultado uma melhor compreensão das considerações e dos métodos mais adequados para essas estruturas, assim como das eventuais variações ocasionadas pela sua aplicação. / Usually, the progresses in codes and technical literature regarding seismic analyses are aimed at civil buildings and their dynamic behavior. Nevertheless, frequently, the dimensioning and construction of equipments or structures with distinct geometry and behavior are required. In numerous codes, though, statements that the comprised information should be fully applied solely to buildings and similar constructions are found. In these codes, issued by many countries for the application in their respective territories, there are procedures and criteria established for seismic design. Moreover, applicable analysis methods are presented, and the selection of which one to employ is based on details as type of resistant systems, intended occupation, rebuilding costs, significance and the geological features of the erection site. In this work, the study of structures for paper production machines is presented, regarding seismic analysis and employing analytical and the finite element methods. These machines consist of metallic frames supported by civil structures and supporting rotors, whose surfaces are in contact with the paper web. The methods usually found in codes, equivalent lateral force, spectrum analysis and transient with acceleration time history were considered, and their results compared and commented afterwards. A better understanding of the more appropriate methods and input parameters for these structures was intended, as well as of any eventual deviation caused by their use.
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Análise térmica e dinâmica do sistema de freio a disco de veículos comerciais pesados / Thermal and dynamic analysis of disc brake system of heavy vehiclesIombriller, Silvia Faria 13 June 2003 (has links)
Este trabalho apresenta um procedimento para a análise dinâmica da frenagem total de emergência de um veículo de dois eixos (4x2), considerando os efeitos do aumento da temperatura no sistema de freios. Um protótipo de ônibus urbano equipado com freios a disco foi utilizado nos ensaios em perímetro urbano e em pista de teste da TRW Automotive em Limeira- SP. O sistema de freios do veículo protótipo foi instrumentado com termopares em diversos de seus componentes, com sensores de velocidade e pressão, percorrendo um perímetro típico urbano com trânsito intenso na cidade de São Paulo. Os pontos críticos de aquecimento foram observados bem como sua tendência de aumento de temperatura no tempo. Paralelamente ao teste em perímetro urbano foi realizado um teste padrão de \"fade\" na pista da TRW Automotive, estendendo o ciclo de frenagens até se observar o aumento e estabilização da temperatura do sistema de freios. Simultaneamente aos testes de pista foi realizado um teste em dinamômetro inercial na Fras-Le, em Caxias do Sul- RS, para se obter a variação do fator de freio com a variação da temperatura do sistema de freios. Parte de um programa computacional em Matlab, que simula computacionalmente o veículo freando, foi desenvolvido, considerando os efeitos da temperatura do sistema de freios, durante frenagens totais de emergência, partindo de diferentes velocidades iniciais de frenagem. O sistema de freios em estudo mostrou-se capaz de simular a frenagem de um veículo em emergência mesmo estando em altas temperaturas, observadas no perímetro urbano. / One procedure for vehicle dynamics analysis during total emergency braking in a two axles vehicle (4x2) was showed. For this procedure the effect of increasing temperature in the brake system was considered. A bus (prototype) equipped with disc brake was used in two practical test when the bus go through: a urban rout (São Paulo city) an a TRW\'s test lane (Limeira-SP). Thermocouples were installed in several parts of the brake system as well as velocity and pressure sensors. Acquisitions of date were made during the intensive traffic of São Paulo city. Critical temperature points were observed as well as the raise temperature tendency with the time. Tests in an inertial dynamometer were also performed in Fras-Le company (Caxias do Sul- RS) to get the brake factor variation related to temperature variation of the brake system. Simulation using MatLab program to study the vehicle performance during braking was developed. In this simulation the effect of brake system temperature was considered. Two main conclusions could be obtained: MatLab model is a useful tool to study emergency braking considering the variation of brake system and the brake system studied was able to stop the vehicle in a emergency braking even under high temperature.
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Análise térmica e dinâmica do sistema de freio a disco de veículos comerciais pesados / Thermal and dynamic analysis of disc brake system of heavy vehiclesSilvia Faria Iombriller 13 June 2003 (has links)
Este trabalho apresenta um procedimento para a análise dinâmica da frenagem total de emergência de um veículo de dois eixos (4x2), considerando os efeitos do aumento da temperatura no sistema de freios. Um protótipo de ônibus urbano equipado com freios a disco foi utilizado nos ensaios em perímetro urbano e em pista de teste da TRW Automotive em Limeira- SP. O sistema de freios do veículo protótipo foi instrumentado com termopares em diversos de seus componentes, com sensores de velocidade e pressão, percorrendo um perímetro típico urbano com trânsito intenso na cidade de São Paulo. Os pontos críticos de aquecimento foram observados bem como sua tendência de aumento de temperatura no tempo. Paralelamente ao teste em perímetro urbano foi realizado um teste padrão de \"fade\" na pista da TRW Automotive, estendendo o ciclo de frenagens até se observar o aumento e estabilização da temperatura do sistema de freios. Simultaneamente aos testes de pista foi realizado um teste em dinamômetro inercial na Fras-Le, em Caxias do Sul- RS, para se obter a variação do fator de freio com a variação da temperatura do sistema de freios. Parte de um programa computacional em Matlab, que simula computacionalmente o veículo freando, foi desenvolvido, considerando os efeitos da temperatura do sistema de freios, durante frenagens totais de emergência, partindo de diferentes velocidades iniciais de frenagem. O sistema de freios em estudo mostrou-se capaz de simular a frenagem de um veículo em emergência mesmo estando em altas temperaturas, observadas no perímetro urbano. / One procedure for vehicle dynamics analysis during total emergency braking in a two axles vehicle (4x2) was showed. For this procedure the effect of increasing temperature in the brake system was considered. A bus (prototype) equipped with disc brake was used in two practical test when the bus go through: a urban rout (São Paulo city) an a TRW\'s test lane (Limeira-SP). Thermocouples were installed in several parts of the brake system as well as velocity and pressure sensors. Acquisitions of date were made during the intensive traffic of São Paulo city. Critical temperature points were observed as well as the raise temperature tendency with the time. Tests in an inertial dynamometer were also performed in Fras-Le company (Caxias do Sul- RS) to get the brake factor variation related to temperature variation of the brake system. Simulation using MatLab program to study the vehicle performance during braking was developed. In this simulation the effect of brake system temperature was considered. Two main conclusions could be obtained: MatLab model is a useful tool to study emergency braking considering the variation of brake system and the brake system studied was able to stop the vehicle in a emergency braking even under high temperature.
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Análise do comportamento sísmico das partes internas de um equipamento de proteção ambiental. / Analysis of seismic behavior of the internal parts of an environmental control equipment.Leandro Marino Takazono Orbolato 15 October 2012 (has links)
Neste trabalho o comportamento sísmico das partes internas de um equipamento de proteção ambiental é estudado. O equipamento, um precipitador eletrostático, é composto basicamente de uma grande caixa de metal elevada, que contem eletrodos positivos e negativos responsáveis pela coleta de material particulado no fluxo de gases industriais. Esses componentes se comportam como pêndulos. No modelo foram considerados os deslocamentos sísmicos horizontais em duas direções ortogonais. De especial interesse está o fato de os eletrodos terem a liberdade de oscilar no plano de uma direção, mas não no seu plano perpendicular. Serão analisados quatro modelos com um, dois, três graus de liberdade, e um com três graus de liberdade linearizado. O modelo mais completo considera como graus de liberdade e coordenadas generalizadas os dois deslocamentos horizontais, e o deslocamento angular do pendulo. Foi adotada a formulação Lagrangeana para derivar as equações de movimento do modelo. As equações diferenciais do movimento de segunda ordem obtidas apresentam um comportamento não linear. Os movimentos sísmicos, que são estocásticos por natureza, serão simulados por meio de um registro sísmico existente, arbitrariamente escolhido. A obtenção dos parâmetros do modelo a ser estudado é de especial interesse para a melhor previsão do comportamento do equipamento quando solicitado a esforços sísmicos. A integração numérica do modelo matemático é efetuada, sendo posteriormente realizados comparativos entre as respostas dos modelos, quando submetidos tanto a vibração livre, como a um sismo real já registrado, arbitrário. / In this work, the seismic behavior of the internal parts of an environmental control equipment is studied. The equipment, an electrostatic precipitator, is basic composed of an elevated large steel box, containing positive and negative electrodes that capture powdered material of industrial effluent gases. These internal components behave essentially as pendula. In the mathematical model seismic motions in two orthogonal directions are considered. It is interesting to realize that the pendular electrodes are free to swing in one plane but not in the other plane. Four increasingly complex nonlinear models are analyzed, with one, two and three degrees of freedom, as well as one 3-degree-of-freedom linearized model. The generalized coordinates of the most complete model are the two horizontal displacements of the top mass and the angular motion of the pendulum. Lagranges formulation is used to derive the equations of motion of the models. These are second order nonlinear ordinary differential equations. The base seismic motions, that are stochastic in nature, are replaced by a arbitrarily chosen existing seismic record. The models parameters are carefully chosen to a good prediction of the equipment under seismic support excitation. Numerical integration of the mathematical model is performed, and comparisons are made of the several models response submitted to free vibrations and to an existing seismic record.
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Análise sísmica de estruturas para máquinas de papel. / Seismic analysis of structures for paper machines.Rodrigo Silva Morcelli 02 December 2010 (has links)
Em geral, os desenvolvimentos na literatura e em códigos de construção voltados para projeto sísmico tem grande ênfase em edifícios civis e seu respectivo comportamento dinâmico. Entretanto, em diversas ocasiões, faz-se necessário o projeto e dimensionamento de equipamentos ou estruturas de geometria e comportamento distintos dos de um edifício usual. Contudo, são encontradas em diferentes normas afirmações e advertências de que as informações lá contidas aplicam-se inteiramente a essas estruturas ou construções similares. Nesses documentos, emitidos por vários países para aplicação em seus respectivos territórios, são estabelecidos procedimentos e métodos. Ademais, opções para análise são propostas, com base em diversos fatores como o tipo de estrutura resistente, a função da edificação, os custos relacionados, a importância da obra e as características geológicas do local de construção. Nesse trabalho, foi realizado o estudo de estruturas para máquinas de fabricação de papel, de modo analítico e por meio do método dos elementos finitos, com respeito a projeto sísmico. Esses equipamentos consistem de pórticos metálicos suportados por estruturas civis, e que suportam rotores por cuja superfície passa o papel durante operação. Os métodos usualmente presentes em normas, força horizontal equivalente, análise espectral e análise transiente com históricos de acelerações no tempo foram aplicados, e suas respostas comparadas e comentadas. Buscou-se como resultado uma melhor compreensão das considerações e dos métodos mais adequados para essas estruturas, assim como das eventuais variações ocasionadas pela sua aplicação. / Usually, the progresses in codes and technical literature regarding seismic analyses are aimed at civil buildings and their dynamic behavior. Nevertheless, frequently, the dimensioning and construction of equipments or structures with distinct geometry and behavior are required. In numerous codes, though, statements that the comprised information should be fully applied solely to buildings and similar constructions are found. In these codes, issued by many countries for the application in their respective territories, there are procedures and criteria established for seismic design. Moreover, applicable analysis methods are presented, and the selection of which one to employ is based on details as type of resistant systems, intended occupation, rebuilding costs, significance and the geological features of the erection site. In this work, the study of structures for paper production machines is presented, regarding seismic analysis and employing analytical and the finite element methods. These machines consist of metallic frames supported by civil structures and supporting rotors, whose surfaces are in contact with the paper web. The methods usually found in codes, equivalent lateral force, spectrum analysis and transient with acceleration time history were considered, and their results compared and commented afterwards. A better understanding of the more appropriate methods and input parameters for these structures was intended, as well as of any eventual deviation caused by their use.
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Numerical Study of Arc Exposure about Water-Panel Overheating in an Electric Arc FurnaceQingxuan Luo (11825660) 20 December 2021 (has links)
<p>Electric arc furnace (EAF) is a
furnace that utilizes electric energy and chemical energy to melt scraps and
produce liquid steel. During the industrial process of EAF, an electric arc
will be generated around the electrode located at the center of the furnace,
and this phenomenon will generate a lot of heat. If any part of the electric
arc is exposed to the freeboard region, a region above the slag layer inside
the furnace, the heat emitted by this exposed arc can significantly heat on
side wall temperatures, resulting in an overheating issue of side wall. Water-cooling
panels (WCP) have been used to cool down the side wall, but the concentrated
overheating area, may damage the water-cooling panel. In this study, a
combination of slag foaming phenomenon and electric arc has been considered. A
calculator is developed based on several arc models to calculate the parameters
about slag foaming and arc power. The parameters can be used as input in a
computational fluid dynamics (CFD) model. The commercial software, ANSYS FLUENT<sup>®</sup>, was utilized to give a prediction
of the side wall temperature distribution of an EAF. Data from the plant has
been used to validate the calculation results. Furthermore, a series of
parametric studies has been investigated to study the influence of operating
conditions. The developed model can help to predict the risk of overheating from
given electrode conditions and slag compositions.</p>
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