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Development and testing of cabin sidewall acoustic resonators for the reduction of cabin tone levels in propfan-powered aircraftThe use of Helmholtz resonators to increase the sidewall transmission loss (TL) in aircraft cabin sidewalls is evaluated. Development, construction, and test of an aircraft cabin acoustic enclosure, built in support of the Propfan Test Assessment (PTA) program, is described. Laboratory and flight test results are discussed. Resonators (448) were located between the enclosure trim panels and the fuselage shell. In addition, 152 resonators were placed between the enclosure and aircraft floors. The 600 resonators were each tuned to a propfan fundamental blade passage frequency (235 Hz). After flight testing on the PTA aircraft, noise reduction (NR) tests were performed with the enclosure in the Kelly Johnson Research and Development Center Acoustics Laboratory. Broadband and tonal excitations were used in the laboratory. Tonal excitation simulated the propfan flight test excitation. The resonators increase the NR of the cabin walls around the resonance frequency of the resonator array. Increases in NR of up to 11 dB were measured. The effects of flanking, sidewall absorption, cabin absorption, resonator loading of trim panels, and panel vibrations are presented. Resonator and sidewall panel design and test are discussed.
Document ID
19920004539
Document Type
Contractor Report (CR)
Authors
Kuntz, H. L. (Lockheed Aeronautical Systems Co. Burbank, CA, United States)
Gatineau, R. J. (Lockheed Aeronautical Systems Co. Burbank, CA, United States)
Prydz, R. A. (Lockheed Aeronautical Systems Co. Burbank, CA, United States)
Balena, F. J. (Lockheed Aeronautical Systems Co. Burbank, CA, United States)
Date Acquired
September 6, 2013
Publication Date
October 1, 1991
Subject Category
ACOUSTICS
Report/Patent Number
NASA-CR-4388
LG90ER0119
NAS 1.26:4388
Funding Number(s)
CONTRACT_GRANT: NAS1-18036
PROJECT: RTOP 535-03-11-04
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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