Active Vibration Reduction of Coaxial Rotor System using Multicyclic Controller with Fluid-Structure Coupling Approach

This study investigates the active vibration reduction of a coaxial rotor system in high-speed forward flight using an individual blade control (IBC) scheme with multicyclic control strategy. A high-fidelity simulation framework is developed based on a loosely coupled analysis between a compressible three-dimensional computational fluid dynamics (CFD) solver and a comprehensive aeromechanics (CA) analysis program. The rotorcraft analysis model adopts an isolated rotor model and is validated against flight test data, resulting in reasonable agreements in predicting the rotor hub vibratory loads. Through the open-loop analysis, dominant control frequencies are identified which are used to design a closed-loop multicyclic controller. The closed-loop controller implemented using the identified system is shown to significantly reduce the rotor hub vibration. A maximum reduction up to 84.7% in vibratory hub loads is achieved in reference to the uncontrolled case. The results reveal that the multicyclic IBC actuation, integrated through using CFD/CA-based analysis, provides an accurate and robust solution for the suppression of the rotor hub vibration for a lift-offset (L.O.) coaxial rotor system operating in high-speed flights.