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Accession Number
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N20120010351
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Title
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Development and Validation of an Interactive Liner Design and Impedance Modeling Tool.
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Publication Date
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Jun 2012
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Media Count
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19p
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Personal Author
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B. M. Howerton J. L. Buckley M. G. Jones
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Abstract
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The Interactive Liner Impedance Analysis and Design (ILIAD) tool is a LabVIEW-based software package used to design the composite surface impedance of a series of small-diameter quarter-wavelength resonators incorporating variable depth and sharp bends. Such structures are useful for packaging broadband acoustic liners into constrained spaces for turbofan engine noise control applications. ILIAD s graphical user interface allows the acoustic channel geometry to be drawn in the liner volume while the surface impedance and absorption coefficient calculations are updated in real-time. A one-dimensional transmission line model serves as the basis for the impedance calculation and can be applied to many liner configurations. Experimentally, tonal and broadband acoustic data were acquired in the NASA Langley Normal Incidence Tube over the frequency range of 500 to 3000 Hz at 120 and 140 dB SPL. Normalized impedance spectra were measured using the Two-Microphone Method for the various combinations of channel configurations. Comparisons between the computed and measured impedances show excellent agreement for broadband liners comprised of multiple, variable-depth channels. The software can be used to design arrays of resonators that can be packaged into complex geometries heretofore unsuitable for effective acoustic treatment.
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Keywords
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Acoustic impedance
Acoustic properties
Broadband
Frequency ranges
Graphical user interface
Linings
Mathematical models
Noise reduction
Resonators
Sound transmission
Surface properties
Transmission lines
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Source Agency
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National Aeronautics and Space Administration
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NTIS Subject Category
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46A - Acoustics
49 - Electrotechnology
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Corporate Author
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National Aeronautics and Space Administration, Hampton, VA. Langley Research Center.
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Document Type
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Conference proceedings
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Title Note
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N/A
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NTIS Issue Number
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1226
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Contract Number
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N/A
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