Parametric model reduction for aeroelastic systems: Invariant aeroelastic modes

A novel model reduction methodology for coupled aeroelastic systems undergoing parameter variations is presented based on a frequency-domain formulation and use of the Proper Orthogonal Decomposition. Typically, an aeroelastic system is a function of multiple parameters such as air density, speed, as well as structural parameters, hence its aeroelastic characteristics vary from one condition to another. It is shown that using the Modally Equivalent Perturbed System it is possible to interpret and analyze the parameter variations in the context of ordinary differential equation with forcing terms. The new procedure is applied to Goland wing modeled by a finite element and unsteady vortex to produce a new class of aeroelastic modes that are invariant under the parameter variations. When used for model reduction these aeroelastic modes are shown to produce accurate parametric reduced-order models for a wide range of the parameters.