EE - Escola de Engenharia
URI permanente desta comunidadehttps://rihomolog.furg.br/handle/1/512
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11 resultados
Resultados da Pesquisa
- ItemAnálise do comportamento mecânico de brackets da fundação de fairleads de uma plataforma fpso através de simulação numérica(2019) Martins, Kauê Louro; Santos, Elizaldo Domingues dos; Isoldi, Liércio AndréOs sistemas de ancoragem em plataformas de produção de petróleo pois são responsáveis por manter o posicionamento da embarcação mediante ação de cargas ambientais. Usualmente tais sistemas fazem uso de diversas linhas de ancoragem, formadas por amarras e cabos de aço, aliados a diversos equipamentos situados na própria plataforma. Um destes equipamentos é o fairlead, uma roldana que guia a linha de ancoragem em direção ao deck da plataforma e não permite que cargas torcionais e horizontais se façam presentes nos demais equipamentos do sistema. As geometrias mais usuais de fairlead são fixadas a plataforma através de fundações soldadas, conhecidas como brackets. Os brackets são estruturas robustas compostas por chapas de aço espessas e de alta importância para o correto funcionamento não apenas do fairlead, mas de todo o sistema de ancoragem. Diante do exposto, o presente estudo analisou a geometria de brackets de sustentação de fairleads com chapas menos espessas que as comumente usadas, submetidos a um carregamento equivalente à solicitação ambiental máxima. A pesquisa fez uso do método Design Construtal para analisar o comportamento mecânico de 6 geometrias diferentes de brackets em relação ao limite de escoamento através de modelagem computacional desenvolvida na ferramenta Mechanical APDL do software ANSYS, que faz uso do Método dos Elementos Finitos. As geometrias estudadas foram baseadas nos brackets em operação na plataforma P-66 da Petrobras. Primeiramente, foram determinadas as cargas ambientais atuando na plataforma e as características das linhas de ancoragem para dois casos, o de carregamento máximo ambiental e o de carregamento máximo acidental, onde 4 linhas do caso anterior foram removidas. Os dados referentes a Bacia de Campos foram empregados nesses cálculos. A plataforma foi considerada estática assim como as cargas atuantes sobre ela. Os brackets são constituídos de chapas de aço AH36, com limite de escoamento de 355 MPa, e o carregamento foi aplicado a eles como pressão na região interna de uma furação que envolve um eixo acoplado ao fairlead. Para atestar o comportamento seguro dos brackets, a tensão máxima de von Mises neles deve ser inferior ao limite de escoamento do aço. As geometrias de brackets testadas são consideradas soldadas ao costado e variam entre si pela forma da chapa de aço horizontal. O modelo computacional do bracket foi desenvolvido utilizando o elemento finito do tipo sólido e as simulações foram efetuadas com malhas até cerca de 500 mil elementos finitos. Como conclusão, 3 das 6 geometrias extrapolaram a tensão de escoamento do aço, enquanto as outras 3 apresentaram valores em um dos brackets com baixo fator de segurança, mas dentro do comportamento linear. Ainda foi possível observar que o uso de chapas mais finas pode propiciar o surgimento de zonas de concentração de tensão, principalmente na região de união entre as chapas e o sólido ao redor da furação onde o carregamento é aplicado.
- ItemApplication of the computational modeling in the resin transfer molding (RTM) process: a case study of a marine propeller(2012) Porto, Joseane da Silva; Letzow, Max; Santos, Elizaldo Domingues dos; Souza, Jeferson Avila; Isoldi, Liércio André; Amico, Sandro CamposThis work presents one example of how the computational modeling can help in the Resin Transfer Molding (RTM) process when it is applied to the production of parts with complex geometry, such as the marine propellers. This manufacture process of composite material parts consists in the injection of a polymeric resin into a closed mold where a fibrous reinforcement is previously placed. The numerical simulation of the RTM process can be considered as the resin flow through a porous media. This computational model was developed in the FLUENT package, which is based on the Finite Volume Method (FVM), and was applied to study a propeller for naval propulsion. As the propeller has a complex format, the use of computational approach as a preliminar step in the manufacturing process is very important for the correct definition of the inlet and outlet nozzles. So, it is possible to design an efficient mold, avoinding extras costs related with the mold redesign, the resin waste and the increase of injection time. The results showed that an inadequate positioning of the mold outlet nozzles causes an increase about 10% and 2% in the production time and in the resin amount, respectively, for obtaining the marine propeller by RTM process.
- ItemConstructal design applied to the light resin transfer molding (LRTM) manufacturing process(2013) Isoldi, Liércio André; Souza, Jeferson Avila; Santos, Elizaldo Domingues dos; Marchesini, Renato; Porto, Joseane da Silva; Letzow, Max; Rocha, Luiz Alberto de Oliveira; Amico, Sandro CamposThe Light Resin Transfer Molding (LRTM) is a manufacturing process where a closed mold pre-loaded with a porous fibrous preform is filled by a liquid resin injected through an empty channel (without porous medium) which runs all around the perimeter of the mold, producing polymeric composite parts. Using the capability of FLUENT® package to simulate a multiphase flow (resin and air) in a geometry composed by porous media regions and empty regions, a computational model based on the Finite Volume Method (FVM) was applied to reproduce the resin flow behavior during the LRTM process. The aim of this work was to define the optimal geometry for the empty channel (border) by means the Constructal Design method. To do so, considering a border with a rectangular cross sectional area, the degree of freedom wb/tb (ratio between the width and thickness of the border) can vary while the border volume is kept constant. The results showed that employing the Constructal Design it is possible to decrease the filling time of the LRTM process in almost 20 %, being this an unpublished use for the Constructal Theory.
- ItemComputational modeling of RTM and LRTM processes applied to complex geometries(2012) Porto, Joseane da Silva; Letzow, Max; Santos, Elizaldo Domingues dos; Amico, Sandro Campos; Souza, Jeferson Avila; Isoldi, Liércio AndréLight Resin Transfer Molding (LRTM) is a variation of the conventional manufacturing process known as Resin Transfer Molding (RTM). In general terms, these manufacturing processes consist of a closed mould with a preplaced fibrous preform through which a polymeric resin is injected, filling the mold completely, producing parts with complex geometries (in general) and good finish. Those processes differ, among other aspects, in the way that injection occurs. In the RTM process the resin is injected through discrete points whereas in LRTM it is injected into an empty channel (with no porous medium) which surrounds the entire mold perimeter. There are several numerical studies involving the RTM process but LRTM has not been explored enough by the scientific community. Based on that, this work proposes a numerical model developed in the FLUENT package to study the resin flow behavior in the LRTM process. Darcy’s law and Volume of Fluid method (VOF) are used to treat the interaction between air and resin during the flow in the porous medium, i.e. the mold filling problem. Moreover, two three-dimensional geometries were numerically simulated considering the RTM and LRTM processes. It was possible to note the huge differences about resin flow behavior and filling time between these processes to manufacture the same parts.
- ItemTwo-dimensional computational modeling of the soil thermal behavior due to the incidence of solar radiation(2013) Brum, Ruth da Silva; Isoldi, Liércio André; Santos, Elizaldo Domingues dos; Vaz, Joaquim; Rocha, Luiz Alberto OliveiraNowadays, there is a focus on finding sustainable energy sources, as well as, alternatives to rationalize the use of electrical energy. In this sense, the employment of Earth-Air Heat Exchangers (EAHE) is one technique which allows the reduction of energy consumption for climatization of buildings environments. The present study shows the evaluation of a numerical method to estimate the ground thermal potential, allowing its applicability for future thermal design of EAHE. The soil domain is considered two-dimensional and a transient solution for the thermal behavior of the soil is obtained. Moreover, a soil surface temperature distribution equation based on experimental data is employed to define the domain boundary conditions. The simulations are performed with a numerical method based on the finite volume method, more precisely using the software FLUENT®. The results presented an excellent agreement with analytical solutions showing the validity and effectiveness of the computational model for prediction of the soil behavior. The numerical results were also confronted with experimental ones predicted into literature and show a good agreement, with a deviation lower than 14%. The main difference is attributed to the duct presence which is taken into account only for the experimental study.
- ItemA new computational modeling to predict the behavior of Earth-Air Heat Exchangers(2013) Brum, Ruth da Silva; Vaz, Joaquim; Rocha, Luiz Alberto Oliveira; Santos, Elizaldo Domingues dos; Isoldi, Liércio AndréThe use of renewable energy sources to improve the thermal conditions of built environments and hencedecreasing the consumption of conventional energy is an important aspect to design a sustainable build-ing. Within this context, it is possible to harness the solar energy that reaches the Earth’s surface andis stored by the soil as thermal energy. To do so, the Earth-Air Heat Exchanger (EAHE) device can beemployed, consisting of a buried duct through which the external ambient air is insufflated. The flowingair exchanges heat with surround soil, and leaves the device with a milder temperature compared to itsinput temperature. The main goal of this work was to present a new computational modeling to predictthe thermal behavior of EAHE. This new numerical model has the advantage of needing a lower com-putational effort, allowing the study about the influence of operational and constructive parameters, aswell as, the application of geometric optimization methods in EAHE. A case study was developed whereinfluence of the installation depth in the thermal potential of an EAHE was investigated. The results arein agreement with those found in literature; however they were obtained with a reduction in processingtime of almost 45%.
- ItemThree-dimensional numerical modeling of RTM and LRTM processes(2012) Isoldi, Liércio André; Oliveira, Cristiano Peres; Rocha, Luiz Alberto Oliveira; Souza, Jeferson Avila; Amico, Sandro CamposResin Transfer Molding (RTM) is a manufacturing process in which a liquid resin is injected into a closed mold pre-loaded with a porous fibrous preform, producing complex composite parts with good surface finishing. Resin flow is a critical step in the process. In this work, the numerical study of the resin flow in RTM applications was performed employing a general Computational Fluid Dynamics software which does not have a specific RTM module, making it necessary to use the Volume of Fluid method for the filling problem solution. Examples were presented and compared with analytical, experimental and numerical results showing the validity and effectiveness of the present study, with maximum difference among these solutions of around 8%. Besides, based on the computational model for the RTM process, a new computational methodology was developed to simulate Light Resin Transfer Molding (LRTM). In this process, resin is injected into the mold through an empty injection channel (without porous medium) which runs all around the perimeter of the mold. The ability of FLUENT® package to simulate geometries which combine porous media regions with open (empty) regions was used. Two specific cases were simulated, showing the differences in time and behavior between RTM and LRTM processes.
- ItemComputational modeling applied to the study of wave energy converters (WEC)(2014) Seibt, Flávio Medeiros; Letzow, Max; Gomes, Mateus das Neves; Souza, Jeferson Avila; Rocha, Luiz Alberto Oliveira; Santos, Elizaldo Domingues dos; Isoldi, Liércio AndréThe employment of numerical methods to solve engineering problems is a reality, as well as, the worldwide concern about the need of renewable and alternative energy sources. Thus, this work presents a computational model capable of simulating the operating principle of some Wave Energy Converters (WEC). To do so, the device is coupled in a wave tank, where the sea waves are reproduced. The Finite Volume Method (FVM) and the Volume of Fluid (VOF) model are adopted. The results showed that the converter's operating principle can be numerically reproduced, demonstrating the potential of computational modeling to study this subject.
- ItemModelagem computacional de um dispositivo do tipo coluna de água oscilante para a costa de Rio Grande(2009) Gomes, Mateus das Neves; Isoldi, Liércio André; Olinto, Cláudio Rodrigues; Rocha, Luiz Alberto Oliveira; Santos, Elizaldo Domingues dos; Souza, Jeferson AvilaEste trabalho apresenta a modelagem computacional de um conversor de energia das ondas do mar em energia elétrica do tipo Coluna de Água Oscilante (CAO) submetido ao clima de ondas da costa da cidade de Rio Grande. A simulação numérica foi realizada utilizando-se o pacote FLUENT® e empregando-se o modelo multifásico Volume of Fluid (VOF) na geração da onda e na interação da mesma com o conversor. O domínio computacional foi representado por um tanque de ondas acoplado ao dispositivo CAO, possibilitando analisar o seu comportamento quando sujeito a incidência de ondas regulares com características semelhantes ao clima de ondas na costa de Rio Grande. Os resultados obtidos demonstram a potencialidade da região em gerar energia elétrica a partir da energia das ondas do mar, através do conversor tipo CAO.
- ItemModelagem computacional de um dispositivo do tipo coluna de água oscilante para a costa de Rio Grande(2009) Gomes, Mateus das Neves; Isoldi, Liércio André; Olinto, Cláudio Rodrigues; Rocha, Luiz Alberto Oliveira; Santos, Elizaldo Domingues dos; Souza, Jeferson AvilaEste trabalho apresenta a modelagem computacional de um conversor de energia das ondas do mar em energia elétrica do tipo Coluna de Água Oscilante (CAO) submetido ao clima de ondas da costa da cidade de Rio Grande. A simulação numérica foi realizada utilizando-se o pacote FLUENT® e empregando-se o modelo multifásico Volume of Fluid (VOF) na geração da onda e na interação da mesma com o conversor. O domínio computacional foi representado por um tanque de ondas acoplado ao dispositivo CAO, possibilitando analisar o seu comportamento quando sujeito a incidência de ondas regulares com características semelhantes ao clima de ondas na costa de Rio Grande. Os resultados obtidos demonstram a potencialidade da região em gerar energia elétrica a partir da energia das ondas do mar, através do conversor tipo CAO.