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The Steady Flow Resistance of Perforated Sheet Materials in High Speed Grazing FlowsA study was conducted to determine the effects of high speed grazing air flow on the acoustic resistance of perforated sheet materials used in the construction of acoustically absorptive liners placed in commercial aircraft engine nacelles. Since DC flow resistance of porous sheet materials is known to be a major component of the acoustic resistance of sound suppression liners, the DC flow resistance of a set of perforated face-sheets and linear 'wiremesh' face-sheets was measured in a flow duct apparatus (up to Mach 0.8). Samples were fabricated to cover typical variations in perforated face-sheet parameters, such as hole diameter, porosity and sheet thickness, as well as those due to different manufacturing processes. The DC flow resistance data from perforated sheets were found to correlate strongly with the grazing flow Mach number and the face-sheet porosity. The data also show correlation against the boundary layer displacement thickness to hole-diameter ratio. The increase in resistance with grazing flow for punched aluminum sheets is in good agreement with published results up to Mach 0.4, but is significantly larger than expected above Mach 0.4. Finally, the tests demonstrated that there is a significant increase in the resistance of linear 'wiremesh' type face-sheet materials.
Document ID
20020065231
Acquisition Source
Langley Research Center
Document Type
Contractor Report (CR)
Authors
Syed, Asif A.
(General Electric Aircraft Engines Cincinnati, OH United States)
Yu, Jia
(General Electric Aircraft Engines Cincinnati, OH United States)
Kwan, H. W.
(General Electric Aircraft Engines Cincinnati, OH United States)
Chien, E.
(General Electric Aircraft Engines Cincinnati, OH United States)
Jones, Michael G.
Date Acquired
September 7, 2013
Publication Date
July 1, 2002
Subject Category
Acoustics
Report/Patent Number
NAS 1.26:211749
NASA/CR-2002-211749
Funding Number(s)
PROJECT: RTOP 781-30-14-01
CONTRACT_GRANT: NAS3-98004
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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