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URI permanente para esta coleçãohttps://rihomolog.furg.br/handle/1/515

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2009 - 200922010 - 20131

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Autor: search.filters.author.Rocha, Luiz Alberto de OliveiraAssunto: search.filters.subject.Numerical simulation

Resultados da Pesquisa

Agora exibindo 1 - 3 de 3
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    Computational modeling of the resin transfer molding process
    (2009) Oliveira, Cristiano Peres; Souza, Jeferson Avila; Isoldi, Liércio André; Rocha, Luiz Alberto de Oliveira; Amico, Sandro Campos
    The Resin Transfer Molding, or RTM, process has recently become one of the most important processes of fiber reinforced composites manufacturing. The process consists essentially of three stages: “an arrangement of fiber mats in a mold cavity, a mold filling by a polymeric resin and a curing phase”. Most of the difficulties of incorporating RTM occur during the filling stage. To create an acceptable composite part the preform must be completely impregnated with resin. The conditions which most strongly influence the flow are mold geometry, resin rheology, preform permeability, and location of the injection ports and vents. There are different types of RTM process, e.g. RTM Light or VARTM, employed in accordance with the final desired characteristics and properties of composite components. Besides, RTM may also be carried out using multilayers, with distinct characteristics. The numerical simulation of the mold filling stage becomes an important tool which helps the mold designer to understand the process parameters. Considering the fibrous preform as a porous media, the phenomenon can be modeled by Darcy’s law to describe resin flow. This study used two commercial softwares, FLUENT® and PAM-RTM®. FLUENT® is a general Computational Fluid Dynamics (CFD) code, based on Finite Volume Method (FVM). It applies the Volume of Fluid (VOF) method to solve the filling problem because it does not have a specific RTM module. PAM-RTM® is a specific package for RTM problems, based on the Finite Element Method (FEM). These tools were applied to simulate numerically several RTM examples of the resin flow into the mold and the results for both softwares were compared with previous works.
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    Constructal 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 Campos
    The 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.
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    Computational modeling of the air-flow in an oscillating water column system
    (2009) Gomes, Mateus das Neves; Olinto, Cláudio Rodrigues; Isoldi, Liércio André; Souza, Jeferson Avila; Rocha, Luiz Alberto de Oliveira
    Several alternatives for electric power production have been studied in the last decades. Because of the huge energetic resources stored in the oceans in the form of wave - about 2TW - value that is compared to the annual rate of electric power used in the earth, the conversion of the wave’s energy of the oceans in electric power comes up important as one of these alternatives. One of the ways to make that conversion is through the oscillating water column (OWC) system: the wave enters into the hydro-pneumatic chamber (resembling a cave with entry below the waterline) and the up-and-down movement of water column inside the chamber makes air flow to and from the atmosphere, driving an air turbine. The turbine is symmetric and is driven indifferently in which direction the air flows. This paper presents the computational modeling of the air flow in a oscillating water column chamber using two different methodologies: in one of them it is considered just the chamber, varying the velocity in its entrance according to the wave’s equation, considering just the air, and a new one considering the chamber put into a wave’s tank, so it takes in account the complete interaction between water and air into the chamber. In this method, to consider the water and air it is used the multiphase model volume of fluid (VOF). It was simulated the same geometric compound of an oscillating water column system with a vertically placed tower, in order to compare these two different numerical models. It is noted that the dimensions of the tested chamber are in laboratory scale and the proposed model was used to simulate a 2D case. It was used GAMBIT® software for geometry creation and mesh generation, while FLUENT® package was employed for solving the conservation equations and analysis of the results.