Robust Flutter Prediction of an Airfoil Including Uncertainties

This work presents the robust stability analysis of 2DoF airfoil by including various uncertainties. These uncertainties arise due to several factors such as modeling and manufacturing errors as well as disturbances in the flight conditions. The approach adopted to study the uncertain aeroelastic system is based on the structured singular value (µ-method). In this approach, the aeroelastic system is formulated in a robust stability framework by parameterizing around dynamic pressure and introducing uncertainties in the system parameters to account for errors and disturbances. This results in the perturbed aeroelastic system which is then represented using Linear Fractional Transformation (LFT). Then, the nominal and robust stability analysis of the perturbed aeroelastic system is carried out using µ method. In this work, first the validation of µ method is done for 2DoF airfoil with quasi-steady aerodynamics having uncertainties in the structural and aerodynamic properties. Further, the robust flutter boundary of 2DoF airfoil with Theodorsen’s unsteady aerodynamics is studied using µ method in the presence of stiffness, damping, and aerodynamic uncertainties