Viscous damping effect on the aeroelastic stability of subsonic wings: Introduction of the U-K method

This study aims at introduction of a novel method for evaluating the effect of viscous damping on the aeroelastic stability boundaries. The K-method is well-known for being one of the fastest methods in determining the instability conditions (i.e. critical speed and its corresponding frequency). However, formulation of the K-method is developed for aeroelastic systems without viscous damping and solution is valid where the introduced artificial damping is zero. Taking into account the framework of the K-method in general, this study has tried to remove the major shortcoming of the K-method, i.e. investigation of the effect of viscous damping on the aeroelastic stability boundaries. The aeroelastic feasibility of the introduced method is studied via the analysis of typical sections and subsonic high-aspect ratio wings. Parameter studies provided in the present investigation, indicate that viscous damping may alter the stability conditions significantly.