High-Accuracy Viscous Analysis of Unsteady Flexible Airfoil Response to Impinging Gust

Abstract

The current work extends the previously developed high-accuracy inviscid analysis of unsteady, nonlinear, aeroelastic gust-airfoil interaction, to include viscous effects. In the implemented iterative procedure, a set of governing Navier-Stokes equations is solved simultaneously with equations of motion of the structure, so that the fluid and structure are treated as a coupled dynamic system. The numerical procedure employs a high-order low-pass filter operator which selectively damps the poorly resolved high-frequency content to retain numerical accuracy and stability over a wide range of flow regimes. An efficient analytical model is developed to introduce an unsteady incompressible 2D vortical flow perturbation inside the computational domain through a source term in the momentum equations. Strongly coupled unsteady aerodynamic, aeroelastic and aeroacoustic responses of rigid and flexible Joukowski airfoil subject to a viscous upstream flow with imposed harmonic, high-amplitude, vortical gust are examined in test studies.