NDLI: A time dependent difference theory for sound propagation in ducts with flow. [characteristic of inlet and exhaust ducts of turbofan engines

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A time dependent difference theory for sound propagation in ducts with flow. [characteristic of inlet and exhaust ducts of turbofan engines

Content Provider	NASA Technical Reports Server (NTRS)
Author	Baumeister, K. J.
Copyright Year	1979
Description	A time dependent numerical solution of the linearized continuity and momentum equation was developed for sound propagation in a two dimensional straight hard or soft wall duct with a sheared mean flow. The time dependent governing acoustic difference equations and boundary conditions were developed along with a numerical determination of the maximum stable time increments. A harmonic noise source radiating into a quiescent duct was analyzed. This explicit iteration method then calculated stepwise in real time to obtain the transient as well as the steady state solution of the acoustic field. Example calculations were presented for sound propagation in hard and soft wall ducts, with no flow and plug flow. Although the problem with sheared flow was formulated and programmed, sample calculations were not examined. The time dependent finite difference analysis was found to be superior to the steady state finite difference and finite element techniques because of shorter solution times and the elimination of large matrix storage requirements.
File Size	782898
Page Count	39
File Format	PDF
Alternate Webpage(s)	http://archive.org/details/NASA_NTRS_Archive_19800004569
Archival Resource Key	ark:/13960/t9n34nq8v
Language	English
Publisher Date	1979-01-01
Access Restriction	Open
Subject Keyword	Acoustics Shear Flow Acoustic Velocity Iteration Finite Element Method Time Dependence Sound Propagation Wave Propagation Nozzle Flow Finite Difference Theory Turbofan Engines Mathematical Models Aeroacoustics Mach Number Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science
Content Type	Text
Resource Type	Article

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