NEW VORTEX/SURFACE INTERACTION METHODS FOR THE PREDICTION OF WAKE-INDUCED AIRFRAME LOADS

The status of work on a unified, consistent model of wake/airframe interaction is described. The model incorporates a variety of recently-developed tools for the analysis of vortex dynamics and vortex/ surface interaction, including a full-span free wake model of the rotor coupled to a panelled body, as well as new methods for the prediction of surface pressures due to close vortex interactions based on Analytical Numerical Matching (ANM). Correlation studies with measured rotor flow fields are presented that establish the success of the free wake model in capturing flow fields near rotor/body combinations. Also, model problems are solved to demonstrate the ability of the methods under development to predict inviscid vortex/surface interactions accurately and with greater efficiency than traditional methods. Finally, fundamental studies of curved filament dynamics near a flat surface are described, studies which are intended to guide the modelling of vortex behavior near the body in the free wake calculation as well as to provide a framework for the study of viscous effects. The fundamental conclusion is that the analytical and computational tools developed here represent several of the key components for a unified model of rotorcraft interactional aerodynamics.