NDLI: Nonlinear effects on sound propagation through high subsonic mach number flows in variable area ducts

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Nonlinear effects on sound propagation through high subsonic mach number flows in variable area ducts

Content Provider	NASA Technical Reports Server (NTRS)
Author	Callegari, A. J.
Copyright Year	1979
Description	A nonlinear theory for sound propagation in variable area ducts carrying a nearly sonic flow is presented. Linear acoustic theory is shown to be singular and the detailed nature of the singularity is used to develop the correct nonlinear theory. The theory is based on a quasi-one dimensional model. It is derived by the method of matched asymptotic expansions. In a nearly chocked flow, the theory indicates the following processes to be acting: a transonic trapping of upstream propagating sound causing an intensification of this sound in the throat region of the duct; generation of superharmonics and an acoustic streaming effect; development of shocks in the acoustic quantities near the throat. Several specific problems are solved analytically and numerical parameter studies are carried out. Results indicate that appreciable acoustic power is shifted to higher harmonics as shocked conditions are approached. The effect of the throat Mach number on the attenuation of upstream propagating sound excited by a fixed source is also determined.
File Size	3784039
Page Count	86
File Format	PDF
Alternate Webpage(s)	http://archive.org/details/NASA_NTRS_Archive_19790014679
Archival Resource Key	ark:/13960/t3c010d18
Language	English
Publisher Date	1979-05-01
Access Restriction	Open
Subject Keyword	Acoustics Harmonics Boundary Value Problems Throats Sound Propagation Subsonic Flow Acoustic Velocity Series Expansion Nonlinearity Acoustic Ducts Fourier Series Acoustic Attenuation 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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