Blade Vortex Interaction 2D Modelling for Rotor Noise Control Synthesis

"The aim of the present work is the presentation and application of a methodology for the iden-. tification of multi-cyclic higher harmonic actuation of blade pitch motion suited for alleviation. of BVI loads, and hence of corresponding noise annoyance generated by helicopter main ro-. tors in low-speed descent flight. The blade pitch actuation is defined by a feedback control. law obtained through an optimal control approach. First, strong BVI phenomena occurring in. the specific flight condition are simulated as equivalent two-dimensional, multi-vortex, parallel. BVI problems, and then a local controller methodology is applied for the efficient identification. of the closed-loop control algorithm. This control methodology is validated by application to. a realistic helicopter main rotor in descent flight; results concerning its capability to alleviate. blade loads and emitted noise are presented and discussed.. "