NDLI: Optimal one-section and two-section circular sound-absorbing duct liners for plane-wave and monopole sources without flow

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Optimal one-section and two-section circular sound-absorbing duct liners for plane-wave and monopole sources without flow

Content Provider	NASA Technical Reports Server (NTRS)
Author	Lester, H. C. Posey, J. W.
Copyright Year	1976
Description	A discrete frequency study is made of the influence of source characteristics on the optimal properties of acoustically lined uniform and two section ducts. Two simplified sources, a plane wave and a monopole, are considered in some detail and over a greater frequency range than has been previously studied. Source and termination impedance effects are given limited examination. An example of a turbomachinery source and three associated source variants is also presented. Optimal liner designs based on modal theory approach the Cremer criterion at low frequencies and the geometric acoustics limit at high frequencies. Over an intermediate frequency range, optimal two section liners produced higher transmission losses than did the uniform configurations. Source distribution effects were found to have a significant effect on optimal liner design, but source and termination impedance effects appear to be relatively unimportant.
File Size	1870022
Page Count	54
File Format	PDF
Alternate Webpage(s)	http://archive.org/details/NASA_NTRS_Archive_19770008847
Archival Resource Key	ark:/13960/t0101zb7x
Language	English
Publisher Date	1976-12-01
Access Restriction	Open
Subject Keyword	Acoustics Sound Waves Sound Propagation Noise Reduction Linings Plane Waves Acoustic Ducts Aircraft Engines Transmission Loss Optimization Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science
Content Type	Text
Resource Type	Technical Report

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