Modelagem do fenômeno de flutter pela CFD de perfis retangulares com diferentes razões de aspecto

Abstract

Some flexible structures tend to exhibit vibrations caused by interaction with the wind. These events are called aeroelastic phenomena and may cause discomfort and structural collapse. Flutter is the main aeroelastic phenomena observed in structures, which is characterized by the coupling of vertical bending and torsion modes and, in many cases, the vibrations diverge and can lead to the structure collapse. Among the tools available for the study of these phenomena, there is computational fluid dynamics (CFD), which uses concepts inherent to discrete methods for the solution of differential equations associated with the motion of the body and the fluid. This research aims to explore in this computational tool applied to real cases. A coupled methodology between the structural dynamic systems and the fluid medium is proposed, through simplifications of the real physical model. In this way, a methodology based on the research of Scanlan e Tomko (1971) is used, which attributes the linearity between the laws of motion and the force functions, in such a way that there is an overlap in the spaces of frequency and degrees of freedom. In this context, the first analysis for a static case resides in obtaining the aerodynamic coefficients of drag, lift and pitch, for rectangles with different aspect ratios. In the second analysis, the amplitudes of vertical and torsional displacements were evaluated to calculate and obtain the critical velocity. Through aerodynamic and aeroelastic analyzes of the studied rectangular sections, different turbulence models were adopted, such as: 𝑘 − 𝜀, k-𝜔 𝑆𝑆𝑇 and k-𝜔 𝑆𝑆𝑇 𝐿𝑀. The incompressible Navier-Stokes equations were solved using a proposed numerical model and performed using the open source OpenFOAM®. For the validation of the research, the results were compared with the numerical and experimental data present in the literature.