Synthesis of rotor BVI noise active controller through efficient aerodynamics/aeroacoustics solver

This paper presents an efficient computational process for the synthesis of a low-frequency controller aimed at reducing helicopter rotor BVI noise by application of the active twist rotor (ATR) concept. It is based on an optimal, multi-cyclic, control approach where distributed torque loads actuated by smart materials are used to twist rotor blades at the 2/rev frequency. Rotor simulations are obtained by combining aerodynamic, aeroelastic and aeroacoustic tools able to capture wake-blade miss distance, which plays a crucial role in BVI noise emission. Its modification is the main objective of the controller action proposed. The control law is identified through a numerically efficient aeroacoustic solver based on analytical-numerical sectional aerodynamics modelling. Numerical investigations present validation of the proposed low-frequency BVI controller by examining its performance in applications concerning with descent flight of helicopter rotors.