Feedforward Piezoelectric Structural Control: An Application to Aircraft Cabin Noise Reduction

The use of adaptive feedforward control within the active structural acoustic control framework was applied to the problem of propeller-induced noise and vibration reduction in the passenger cabin of the Bombardier (de Havilland) Dash-8 aircraft. Piezoceramic elements were used for structural actuation, and either vibration or acoustic sensing was employed. Actuators comprised of segmented piezoelectric elements were designed with the objective of reducing the noise and vibration levels at the propeller blade passage frequency (BPF) and the e rst harmonic.Theactuatordesignobjectivewassuppressionoftheoperating dee ectionshapes (ODS)ofthefuselageat the various frequencies by the judicious placement of piezoelectric elements. Using an actuator and sensor design optimized for the BPF together with vibration error sensing, the controller was successful in reducing interior noise in addition to vibration. Further improvement in noise reduction was obtained when acoustic error sensing was employed. Similar optimized designs for actuator and sensors were also found to exist at other frequencies, providing good noise and vibration attenuation. Furthermore, this strategy was successfully applied to noise reduction at two operating frequencies, where suppression of the ODSs at both the BPF and 2 £ BPF was the objective.