The role of pressure field dynamics on the onset of transonic aeroelastic instabilities of high aspect ratio swept wings

Abstract

The dynamic aeroelastic responses in the transonic regime for a conventional swept wing and a curved-planform wing, both having a high aspect ratio, are analysed in detail. Using 2-way fluid structure interaction (FSI) analysis, the power spectral density of both wing-tip displacements and wing aerodynamic coefficients are analysed to highlight instabilities. Furthermore, a study of the interaction between the structural dynamics and the dynamics of the pressure field is performed. To do this, transient computational fluid dynamics (CFD) analyses, performed on rigid wings with updated geometry, provided the frequency spectra of the pressure fields. For the conventional swept wing, a clear interaction between a structural bending mode and pressure field oscillations generates a flutter-buffet instability. Conversely, for the curved-planform wing, this work demonstrated that the transonic pressure field oscillations, although not negligible, are not a direct cause of the onset of the bending-torsion flutter of the wing.