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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Simula??o computacional da intera??o fluido-estrutura em bombas de cavidades progressivas

Almeida, Rairam Francelino Cunha de 26 March 2010 (has links)
Made available in DSpace on 2014-12-17T14:58:00Z (GMT). No. of bitstreams: 1 RairamFCA_DISSERT2.pdf: 4758176 bytes, checksum: bfb1653549a50848b4721bda9a78bd6e (MD5) Previous issue date: 2010-03-26 / The pumping through progressing cavities system has been more and more employed in the petroleum industry. This occurs because of its capacity of elevation of highly viscous oils or fluids with great concentration of sand or other solid particles. A Progressing Cavity Pump (PCP) consists, basically, of a rotor - a metallic device similar to an eccentric screw, and a stator - a steel tube internally covered by a double helix, which may be rigid or deformable/elastomeric. In general, it is submitted to a combination of well pressure with the pressure generated by the pumping process itself. In elastomeric PCPs, this combined effort compresses the stator and generates, or enlarges, the clearance existing between the rotor and the stator, thus reducing the closing effect between their cavities. Such opening of the sealing region produces what is known as fluid slip or slippage, reducing the efficiency of the PCP pumping system. Therefore, this research aims to develop a transient three-dimensional computational model that, based on single-lobe PCP kinematics, is able to simulate the fluid-structure interaction that occurs in the interior of metallic and elastomeric PCPs. The main goal is to evaluate the dynamic characteristics of PCP s efficiency based on detailed and instantaneous information of velocity, pressure and deformation fields in their interior. To reach these goals (development and use of the model), it was also necessary the development of a methodology for generation of dynamic, mobile and deformable, computational meshes representing fluid and structural regions of a PCP. This additional intermediary step has been characterized as the biggest challenge for the elaboration and running of the computational model due to the complex kinematic and critical geometry of this type of pump (different helix angles between rotor and stator as well as large length scale aspect ratios). The processes of dynamic generation of meshes and of simultaneous evaluation of the deformations suffered by the elastomer are fulfilled through subroutines written in Fortan 90 language that dynamically interact with the CFX/ANSYS fluid dynamic software. Since a structural elastic linear model is employed to evaluate elastomer deformations, it is not necessary to use any CAE package for structural analysis. However, an initial proposal for dynamic simulation using hyperelastic models through ANSYS software is also presented in this research. Validation of the results produced with the present methodology (mesh generation, flow simulation in metallic PCPs and simulation of fluid-structure interaction in elastomeric PCPs) is obtained through comparison with experimental results reported by the literature. It is expected that the development and application of such a computational model may provide better details of the dynamics of the flow within metallic and elastomeric PCPs, so that better control systems may be implemented in the artificial elevation area by PCP / O sistema de bombeamento por cavidades progressivas est? sendo cada vez mais empregado na ind?stria do petr?leo, devido ? sua capacidade de eleva??o de ?leos altamente viscosos ou de fluidos com grandes concentra??es de areia ou outras part?culas s?lidas. Uma Bomba de Cavidades Progressivas (BCP) ? composta, basicamente, por um rotor - uma pe?a met?lica de forma semelhante a um parafuso exc?ntrico, e um estator - um tubo de a?o revestido internamente por uma h?lice dupla, a qual pode ser r?gida ou deform?vel/elastom?rica. Em geral, uma BCP ? submetida a uma combina??o de press?o do po?o com press?o gerada pelo pr?prio processo de bombeio. Em BCPs elastom?ricas, essa combina??o de esfor?os comprime o estator, gerando ou aumentando a folga existente entre o rotor e o estator, reduzindo, portanto, o efeito de veda??o entre suas cavidades. Tal abertura da regi?o de selagem produz o que ? conhecido como escorregamento do fluido, diminuindo, com isso, a efici?ncia de sistema de bombeio por BCP. Dessa maneira, este trabalho se prop?e a desenvolver um modelo computacional tridimensional transiente do processo din?mico da intera??o fluido-estrutural (FSI) que ocorre no interior de BCPs met?licas e elastom?ricas. O objetivo principal ? avaliar, a partir do uso do modelo desenvolvido, as caracter?sticas din?micas de efici?ncia de bombeio por BCPs, em fun??o de informa??es locais e instant?neas detalhadas dos campos de velocidade, press?o e deforma??o no seu interior. Para o alcance de tais metas (desenvolvimento e uso do modelo), fez-se necess?rio o desenvolvimento de uma metodologia pr?pria para gera??o de malhas computacionais din?micas, m?veis e deform?veis, representando as regi?es fluida e estrutural de uma BCP. Tal procedimento caracterizou-se como o maior desafio para a elabora??o do modelo computacional, devido ? cinem?tica complexa e ? geometria cr?tica desse tipo de bomba (?ngulos de h?lice diferentes entre rotor e estator e grandes diferen?as de escala de comprimento). Os processos de gera??o din?mica das malhas e de avalia??o simult?nea das deforma??es sofridas pelo elast?mero s?o realizados atrav?s de sub-rotinas em linguagem Fortran 90, as quais interagem dinamicamente com o software de din?mica dos fluidos computacional CFX/ANSYS. Desde que o modelo linear el?stico ? empregado para avaliar as deforma??es elastom?ricas, n?o ? necess?rio usar nenhum software para an?lise estrutural. Entretanto, uma proposta inicial para simula??o din?mica no ANSYS empregando-se modelos constitutivos hiper-el?sticos para o elast?mero ? tamb?m apresentada no presente trabalho. A valida??o dos resultados produzidos com a presente metodologia (gera??o de malha, simula??o do escoamento em BCPs met?licas e simula??o da intera??o fluido-estrutural em BCPs elastom?ricas) ? obtida atrav?s da compara??o com resultados experimentais reportados pela literatura. Vislumbra-se que o desenvolvimento e aplica??o de tal ferramenta computacional poder?o fornecer maiores detalhes da din?mica do escoamento no interior de BCPs met?licas e elastom?ricas, de maneira que melhores sistemas de controle possam ser implementados na ?rea de eleva??o artificial por BCPs

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