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Master's Dissertation
Full name
Rafael Salles
Knowledge Area
Date of Defense
São Paulo, 2016
Pesce, Celso Pupo (President)
Mazzilli, Carlos Eduardo Nigro
Savi, Marcelo Amorim
Title in English
Experimental analysis of fluid-structure interaction phenomena on a vertical flexible cylinder: modal coeficients and parametric resonance.
Keywords in English
Flexible pipes
Fluid-structure interaction
Mathieu instability
Offshore structure
Abstract in English
Oil and gas exploitation in deep waters has become more than just a profit business to be a daily necessity, since the world energy matrix is based on fossil components. Risers are offshore structures that are intimately linked with oil and gas exploitation and those are subjected to a great variety of effects in field, e.g., marine currents, Vortex Induced Vibration (VIV), heave motion caused by gravitational waves, non-linear contact with the sea floor, and many others. Riser dynamics is essentially non-linear and experimental tests in real scale are almost impossible due to a great variety of control parameters acting concomitantly. Small-scale models are a better experimental approach. Nevertheless, there are many structural and hydrodynamical parameters to be evaluated. Considering only vertical risers in the present work, Galerkin's modal decomposition is used in order to reduce the dynamics of a vertical flexible cylinder to a few linear modes in which the majority of energy and information are contained. From the modal analysis, added mass and structural parameters damping of a vertical flexible cylinder using data obtained from free-decay tests performed both in water and in air are evaluated. Finally, a modal Mathieu-Hill oscillator with non-linear damping is constructed and, based on aStrutt diagram, modal stability under parametric resonance is discussed.
Title in Portuguese
Análise experimental de fenômeno de interação fluido-estrutura em um cilindro vertical flexível: coeficientes modais e ressonância paramétrica.
Keywords in Portuguese
Estrutura offshore
Instabilidade de Mathieu
Interação fluido-estrutura
Tubos flexíveis
Abstract in Portuguese
Exploração de óleo e gás em bacias de águas profundas tem-se tornado mais do que apenas uma economia lucrativa, para ser uma necessidade diária, já que a matriz energética mundial está baseada em componentes fósseis. Risers são estruturas offshore ligadas intimamente com a exploração de óleo e gás e essas estão sujeitas a uma grande variedade de efeitos na operação, e.g., correntes marítimas, Vibrações Induzidas por Vórtices (VIV), movimento de heave causado por ondas gravitacionais, contato não-linear com o solo marinho, entre outros. Dinâmica de risers é essencialmente não-linear e testes experimentais em escala real são praticamente impossíveis devido a uma enorme variedade de parâmetros de controle agindo concomitantemente. Modelos em escala reduzida são uma abordagem experimental mais conveniente. Não obstante, há muitos parâmetros estruturais e hidrodinâmicos a serem determinados. Considerando apenas risers verticais no trabalho presente, a decomposição modal de Galerkin é usada a fim de reduzir a dinâmica de um cilindro fléxivel vertical a alguns modos lineares em que a maior parte da energia e informação estão contidos. A partir da análise modal, parâmetros de massa adicional e amortecimento estrutural de um cilindro flexível vertical são obtidos usando testes de decaimento livre conduzidos na água e no ar. Finalmente, um oscilador modal de Mathieu-Hill com amortecimento não-linear é proposto e, baseado em um diagrama de Strutt, a estabilidade modal sob excitação de ressonânica paramétrica é discutida.
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Publishing Date
WARNING: The material described below relates to works resulting from this thesis or dissertation. The contents of these works are the author's responsibility.
  • Franzini, Guilherme R., et al. An Experimental Assessment of Rigidity Parameter of a Small-Scaled Riser Model. In PACAM2012, Port of Spain, 2012. Twelfth Pan American Congress of Applied Mechanics., 2012. Abstract.
  • Franzini, Guilherme R., et al. Experimental Analysis of a Vertical and Flexible Cylinder in Water: Response to Top Motion Excitation and Parametric Resonance. In OMAE2014, San Francisco, 2014. Proceedings of the ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering.NY : ASME, 2014.
  • Pereira, Felipe R., et al. Risers Model Tests: Scaling Methodology and Dynamic Similarity. In ISOPE2012, Rhodes, Greece, 2012. Proceedings of the Twenty-second (2012) International Offshore and Polar Engineering Conference., 2012.
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