| Grant number: | 17/06016-7 |
| Support Opportunities: | Scholarships in Brazil - Master |
| Start date: | July 01, 2017 |
| End date: | December 31, 2018 |
| Field of knowledge: | Engineering - Naval and Oceanic Engineering - Hydrodynamics of Ships and Ocean Systems |
| Agreement: | Coordination of Improvement of Higher Education Personnel (CAPES) |
| Principal Investigator: | Guilherme Rosa Franzini |
| Grantee: | Tatiana Ueno |
| Host Institution: | Escola Politécnica (EP). Universidade de São Paulo (USP). São Paulo , SP, Brazil |
Abstract Vortex-induced vibration phenomenon (VIV) is very common in several engineering applications, particularly in offshore engineering. Slender structures, such as risers, are subject to this fluid-structure interaction phenomenon, which can accelerate the structural lifespan due to fatigue.VIV is a self-excited and self-limited phenomenon observed when the vortex-shedding is close to a natural frequency of the structure. The maximum oscillation amplitudes are of the order of one diameter and occur in a well defined range of free-stream velocities.Due to its complexity, VIV is studied following different approaches, including Computational Fluid Dynamics techniques as well as laboratory experiments. Besides these forms, there is another form of study, based on non-linear equations to represent the fluid dynamics. These non-linear equations are coupled to a structural equation by means of some coefficients to be calibrated. This research project will focus on this last approach, also called phenomenological.There are several forms of passive suppression of VIV. Some of them, such as strakes, imply that the suppressor is in contact with the fluid. There are also suppressors, internally assembled to the cylinder which indirectly modify the flow field. This research project focuses on studying two passive suppressors of this last class. The suppressors herein are based on the concept of non-linear energy sink (NES). Two types of NES will be investigated, namely rotational NES and translational NES.The main objective of this research project is to investigate the efficacy of these mentioned passive suppressors in the mitigation of VIV phenomenon in rigid cylinders mounted on an elastic support with one or two degrees-of-freedom. Hydrodynamic loads will be considered through phenomenological models. Numerical simulators will be obtained. It will also be obtained curves and tables, showing modifications in the oscillation amplitude of the main structure as functions of the flow velocity and the parameters that define the suppressors. (AU) | |
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