Mechanisms of active control in cylindrical fuselage structures

This paper summarizes ongoing efforts to understand and exploit active control techniques for low-frequency noise suppression in aerospace applications. Analytical models are used in an effort to understand the mechanisms of noise transmission into acoustic spaces enclosed by lightweight structures and to examine the results of experimental implementations of active control schemes. Emphasis is placed on attaining global noise reductions using a minimum number of actuators rather than localized control over many subregions. This program has demonstrated the effect of synchrophasing and interface modal filtering in limiting the modal density within the acoustic space and how strong reactive effects may occur in two-dimensional geometries.