Vortex methods for the computational analysis of rotor/body interaction

Abstract

This paper describes the development and implementation of a unified model of rotorcraft interactional aerodynamics using advanced methods in vortex dynamics. The model incorporates several recently-developed tools for the analysis of vortex wake dynamics and vortex/surface interaction including: a Constant Vorticity Contour (CVC) full-span free wake model; a method for the prediction of surface pressures due to close vortex interactions based on Analytical Numerical Matching (ANM); and a new analytical asymptotic analysis of curved vortex interaction with curved surfaces. The development of each of these features of the analysis are described as is their coupling with a panel method analysis of the fuselage. Correlation studies with measured rotor velocity fields are presented, and model problems are also solved to demonstrate the ability of the ANM model to predict inviscid vortex/surface interactions accurately and with greater efficiency than traditional methods. In addition, fundamental studies of curved filament dynamics near curved surfaces are described, along with correlations of measured and predicted surface pressures. While considerable additional work is required to formulate a fully general analysis of rotorcraft interactional aerodynamics, the computational tools developed here provide a significant predictive capability for realistic wake/airframe interactions.

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