Synthesis of a Rotor Noise Controller by Parallel Blade-Vortex Interaction Aeroelastic Modelling

The aim of this paper is the presentation and application of a methodology for the identification of a multi-cyclic, higher harmonic blade pitch actuation controller suited for alleviating impulsive noise induced by Blade-Vortex Interactions (BVI). The blade pitch actuation is driven by a feedback control law derived by an optimal linear-quadratic regulator control formulation based on simulations provided by an equivalent two-dimensional, multi-vortex, parallel BVI problem that describes the aerodynamic response of elastic rotor blade cross sections in BVI conditions. This control law identification process is particularly efficient in that exploits two-dimensional simulations, instead of using three-dimensional, time-consuming predictions. In order to examine the effectiveness of the proposed controller in alleviating BVI noise, it is applied to the analysis of a realistic helicopter main rotor in descent flight.