System Identification and Active Control of Interior Noise in a Business Aircraft 951178

This work primarily consists of two main parts. First a series of acoustic system identification experiments of the interior space of a business aircraft were performed. The system was subjected to both a structural based excitation (at the left forward engine mount), and an acoustic based excitation (speaker mounted in cockpit). Sound pressure was measured at over 3000 points in the cabin over a frequency range of 0-400 Hz. Data was reduced to produce 3-D acoustic plots at single frequency bins and 2-D dispersion diagrams (wavenumber vs. frequency). Secondly, preliminary experiments on controlling interior noise using small patch type piezoceramic actuators bonded to the fuselage were investigated. The results demonstrate that the piezoceramic patch actuators have enough control authority for this application. In addition, for the dominant noise case of a cabin resonance, reasonable sound reductions with only four control inputs were measured throughout the cabin space except at one location. Results at the off-resonance case show reduced control performance. Important non-linear behavior, most likely due to curving the flat piezoceramic actuators on attachment was identified.