Tiltrotor cabin noise control through smart actuators

This paper deals with the abatement of the tonal noise inside the fuselage of a mid-range tiltrotor aircraft, as generated by the propulsive system. The problem is basically multidisciplinary, involving interactions among the exterior noise field, elastic fuselage dynamics, interior acoustics and control system. A stiffened fuselage, with piezoelectric patches embedded into the structure, is supposed to be impinged on by the aeroacoustic field generated by propellers and excited by the wing/pylon/proprotor vibratory loads at the wing-fuselage attachment. An optimal linear quadratic regulator cyclic control formulation, coupled with a genetic optimization algorithm, is applied to synthesize the control law driving the smart actuators so as to alleviate cabin noise. The aeroacoustoelastic model considered in the control problem is obtained by combining cabin interior acoustics, fuselage smart shell dynamics and wing/pylon/proprotor aeroelasticity described through modal approaches with the exterior pressure field provided by boundary element method solvers. Numerical results examine the effectiveness and robustness of the proposed active control strategy.