01054382

Component

This paper presents an experimental study on the active control of sound transmission in a large cylinder with a similar construction to that of a composite payload fairing. A feed forward control system utilized both structural and acoustic actuators with the objective of comparing their performance. The paper determined that the four loudspeakers system and the four DAVA systems produced similar reductions but that it was the acausality in the optimal controller filters that restricted performance. Because of this, the control system could only control the resonance peaks in the system (i.e. the most predictable parts of the spectrum). The optimal performance was calculated using measured transfer functions and showed that 13.6dB was achievable if causality was not a problem and this was re-enforce by experiments using added delay (9.1dB measured across the band). From this it can be concluded that 8 control channels provided sufficient control complexity in order to achieve high levels of broadband control but that the spatial distribution and coupling of the actuators limits performance. It was also shown that 134.7dB of external noise levels could be controlled using loudspeakers weighing 9kg. This is very similar to but slightly larger than the weight of the structural actuators (DAVAs) required for control of the same level of exterior noise.

01054353

English

pp 889-898

2004

Noise-Con 04. The 2004 National Conference on Noise Control Engineering

CD-ROM

Figures; Photos; References (16)

Broadband; Noise control; Noise sources; Sound level meters; Sound transmission; Vibration; Vibration isolation

Loudspeakers; Vibration absorbers

Energy; Environment; Highways; I15: Environment

TRIS, TRB

Jul 26 2007 2:01PM