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Advances in Acoustics and Vibration
Volume 2011 (2011), Article ID 473282, 14 pages
http://dx.doi.org/10.1155/2011/473282
Research Article

Development of Adaptive Acoustic Impedance Control Technologies of Acoustic Duct Liner

1Japan Aerospace Exploration Agency, 1-12-14 Benten, Chiba, Urayasu 279-0026, Japan
2Graduate School of Waseda University, 3-4-1 Oukubo, Shinjuku-Ku, Tokyo 169-8555, Japan

Received 13 December 2010; Revised 15 April 2011; Accepted 26 May 2011

Academic Editor: Marek Pawelczyk

Copyright © 2011 Hiroshi Kobayashi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This paper describes the development of adaptive acoustic impedance control (AAC) technologies to achieve a larger fan noise reduction, by adaptively adjusting reactance and resistance of the acoustic liner impedance. For the actual proof of the AAC technology III performance, the advanced fan noise absorption control duct liner II was made on trial basis, with the simple control system and the plain device. And, then, the duct liner II was examined for the AAC technology I, II, and III models, using the high speed fan test facility. The test results made clear that the duct liner II of the AAC technology III model could achieve the fan noise reduction higher than O.A. SPL 10 dB (A) at the maximum fan speed 6000 rpm, containing the reduction of fundamental BPF tone of 18 dB and 2nd BPF tone of 10 dB in response to the fan peed change from 3000 to 6000 rpm.