Simulations of Airfoil Limit-cycle Oscillations at Transitional Reynolds Numbers

Structural response models addressing one-degree-of-freedom (1DOF) and twodegree-of-freedom (2DOF) aeroelastic oscillations were coupled with an in-house incompressible CFD code to perform large-eddy-based simulations (LES) for flows past rigid airfoils in free-to-rotate and free-to-rotate-and-heave conditions at low Reynolds numbers. As observed in experiments, the numerical simulations confirmed the presence of the self-sustained low-amplitude limit-cycle oscillations (LCOs) of the airfoils. It is understood that this behavior in the transitional Reynolds number regime results from the unsteadiness of the laminar boundary layer separation and its delayed recovery when compared to the corresponding static conditions.