Active control of sound transmission through an aircraft fuselage test section

Abstract

The present study addresses the reduction of the sound transmission through an aircraft fuselage by means of a combined active noise and vibration control system, so as to reduce the noise level inside the passengers' cabin. A finite element model is used to describe the vibro-acoustic behaviour of the double-panel fuselage test section. This model is combined with a simplified model of the active control system, allowing the use of control actuators with limited control signals. The problem of optimising the locations of the error sensors and the control actuators is simplified by taking into account these limits on the control signals. Experiments prove that the control loudspeakers and error microphones in the trim cavity yield higher reductions in the radiated sound power, than control shakers and error accelerometers on the trim panel. The optimised control system performs much better than a control system with sensors and actuators in arbitrarily chosen positions. The robustness of the control system can be significantly enhanced by limiting the control signals, without losing too much of the performance.