ACTIVE CONTROL OF SOUND TRANSMISSION THROUGH A CURVED PANEL INTO A CYLINDRICAL ENCLOSURE

Current research has focused on the reduction of sound transmission through the aircraft fuselage into the interior of aircraft due to turbulent boundary layer excitation. The present work utilizes an analytical model, previously developed by the authors, as a design tool in the development of feedback control systems to attenuate sound transmission. The model is of a typical aircraft panel in service conditions with attached piezoelectric actuators, coupled to the interior acoustics of a rigid-wall cylinder. The control design process, which includes transducer optimization andH2 synthesis, is documented. Control designs are presented utilizing both acoustic pressure measurements and structural velocity measurements. Results indicate that an active structural acoustic control design using structural velocity measurements and insight gained from analysis of the structural acoustic coupling can achieve performance similar to a control design utilizing acoustic pressure measurements. Further analysis shows that the active structural acoustic control design can be implemented regardless of panel position on the enclosure, and can withstand perturbations in panel dynamics resulting from variations in static pressure loading with flight altitude. Significant reduction of sound transmission into the enclosure is achieved.