Airfoil flutter is the result of a net positive exchange of energy from the fluid to the structure. In the present study, a rigid symmetric airfoil is elastically maintained in an upstream flow and is totally free to pitch and heave independently. Over a wide range of stiffness and damping in both pitch and heave degrees of freedom, it is found that dynamic stall flutter occurs. It involves oscillations of various amplitudes and different phases between both motions with various levels of energy extraction from the flow. In addition to the structural characteristics of the airfoil support, the airfoil mass and moment of inertia as well as the pitching axis location provide enough adjustable parameters to control the airfoil’s dynamics and eventually optimize its application as a wind or hydro-kinetic turbine.
The present work focuses on a parametric study of an elastically mounted NACA0012 airfoil. It aims at providing physical insights onto the motion control available through key parameters of the setup. In this study, we use the open source CFD code OpenFOAM, which implements a finite-volume solver, to carry out unsteady Reynolds averaged Navier-Stokes (URANS) simulations. The proposed fluid-structure coupling strategy as well as some of the validation tests carried out with the present FSI solver will be presented together with the main results of this ongoing research.