Smart Double Panel for the Sound Radiation Control: Blended Velocity Feedback

In this paper an active damping method using blended velocity feedback for the reduction of sound transmission through a simplified aircraft double panel is considered. The double panel consists of a source and a radiating panel, which are coupled acoustically by the air in the cavity between them and structurally by four elastic mounts. The double panel is equipped with an array of nine voice-coil actuators that can react against the two panels. A velocity sensor is mounted at both panel junctions of each actuator. The outputs from the sensors on the source and radiating panels are weighted by factors α and 1 α α, respectively. The two weighted signals are then subtracted and combined into the error signal fed back to the actuator via a constant amplification gain. The stability and performance of such a decentralized velocity feedback system are analyzed experimentally as a function of the weighting factor α. Reductions betweenα10 andα18 dB in the radiated sound power have been measured at low-frequency resonances of the double panel, depending on the weighting factor implemented.