The internally generated noise which can be attenuated by liners when propagating in piping-system can be modelled by acoustic waves travelling in an infinite two-dimensional lined duct with an inhomogeneous medium. Since the duct is lined, all acoustic parameters and disturbances are
complex, and this complicates the resolution of the mathematical formulation of the problem. In this paper and using the finite difference method, we analyse the behaviours of acoustic energy flux in a rectangular lined duct containing temperature and mean flow gradients for upstream and downstream
propagation. Some results are presented for the separated and combined effects of these inhomogeneous factors on the attenuation rate. These results show that cooling the duct wall further strengthens the attenuation in downstream propagation and improves it in upstream propagation.
Document Type: Research Article
Publication date: January 1, 1997
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Acta Acustica united with Acustica, published together with the European Acoustics Association (EAA), is an international, peer-reviewed journal on acoustics. It publishes original articles on all subjects in the field of acoustics, such as general linear acoustics, nonlinear acoustics, macrosonics, flow acoustics, atmospheric sound, underwater sound, ultrasonics, physical acoustics, structural acoustics, noise control, active control, environmental noise, building acoustics, room acoustics, acoustic materials, acoustic signal processing, computational and numerical acoustics, hearing, audiology and psychoacoustics, speech, musical acoustics, electroacoustics, auditory quality of systems. It reports on original scientific research in acoustics and on engineering applications. The journal considers scientific papers, technical and applied papers, book reviews, short communications, doctoral thesis abstracts, etc. In irregular intervals also special issues and review articles are published.