Modeling the flutter phenomenon by CFD of rectangular profiles

• Published in: Journal of the Brazilian Society of Mechanical Sciences and Engineering 2023-11, Vol.45 (11), Article 578
• Main Authors: Fronczak, Juliema, Silva Araújo, Alexandre Miguel, Mendes das Flores, Gabriel Antonio, de Sá, Lucas Lucinda, Cury, Alexandre Abrahão, Habib Hallak, Patricia
• Format: Article
• Language: English
• Subjects: Aerodynamic coefficients; Aeroelasticity; Aspect ratio; Collapse; Engineering; Finite element method; Flexible structures; Flutter; Forced vibration; Linearity; Mathematical models; Mechanical Engineering; Methodology; Resonant frequencies; Technical Paper; Vertical forces
• ISSN: 1678-5878; 1806-3691
• DOI: 10.1007/s40430-023-04499-x

Some flexible structures are subjected to a range of vibrations caused by their interaction with the wind. Such events, referred as aeroelastic phenomena, may cause discomfort to the users and even structural collapse. Among these, flutter is one of the most observed, being characterized by the coupling of vertical bending and torsional modes. In many cases, divergent vibrations can lead to the collapse of the structure. In this paper, a coupled methodology between structural dynamic systems and the fluid medium has been applied, through simplifications of the real physical model. A methodology based on the research of Le Maître, Scanlan and Knio has also been 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 with the degrees of freedom. In this context, the first analysis for a static case consists in obtaining the aerodynamic coefficients of drag, lift, and Strouhal numbers for rectangles with different aspect ratios. In the second analysis, the signal of forces for vertical and torsional forced vibrations is evaluated and used to calculate the flutter derivatives. These coefficients are, then, associated with the natural frequency of the structures, in order to obtain the critical flutter velocity. To validate this research, the values obtained were compared with numerical and experimental data available in the literature, evidencing satisfactory results. This research stands out for introducing an assertive methodology, ideal for the initial design stage that integrates a two-dimensional linear aeroelastic computational model with structural data derived from a three-dimensional finite element method (FEM) model.