Interior active noise control in turbofan aircraft: Numerical simulation and optimal actuators positioning using dedicated genetic algorithms

This paper presents the activities developed by the authors within the first year of the research project named M.E.S.E.M.A. (Magnetoelastic Energy Systems for Even More Electric Aircraft) funded by the European Commission within the 6th Framework Program and coordinated by the "Dipartimento di Progettazione Aeronautica" of the University of Naples "Federico II" (DPA). One of the main targets for the MESEMA Consortium consists in reducing the level of disturbance noise in turbofan aircraft. A noise & vibration control system using magnetostrictive actuators will be designed, developed and tested, with the goal of controlling noise & vibrations in a frequency range between 150-500 Hz. The environmental noise & vibration excitations will be representative of a small/medium turbofan aircraft case. During the first two years of the project a numerical (Finite Element) model of the test article has been developed in MSC/NASTRAN environment coupling the structural part with the interior acoustic volume. Furthermore a complete experimental characterisation of the test-article has been carried on. Numerical model has been correlated with experimental results, updating it in order to achieve the best fitting in terms of natural frequencies and modes shapes at low frequencies [1], Then the updated model has been employed to derive the required control actuators performances in order to achieve the best theoretical interior noise control predicted using a well consolidated "feed- forward" approach [2] and Genetic Algorithms have been employed in order to optimise the positioning of the actuators.