NDLI: Physics of acoustic radiation from jet engine inlets

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Physics of acoustic radiation from jet engine inlets

Content Provider	NASA Technical Reports Server (NTRS)
Author	Parrish, Sarah A. Envia, Edmane Tam, Christopher K. W. Chien, Eugene W.
Copyright Year	2012
Description	Numerical simulations of acoustic radiation from a jet engine inlet are performed using advanced computational aeroacoustics (CAA) algorithms and high-quality numerical boundary treatments. As a model of modern commercial jet engine inlets, the inlet geometry of the NASA Source Diagnostic Test (SDT) is used. Fan noise consists of tones and broadband sound. This investigation considers the radiation of tones associated with upstream propagating duct modes. The primary objective is to identify the dominant physical processes that determine the directivity of the radiated sound. Two such processes have been identified. They are acoustic diffraction and refraction. Diffraction is the natural tendency for an acoustic wave to follow a curved solid surface as it propagates. Refraction is the turning of the direction of propagation of sound waves by mean flow gradients. Parametric studies on the changes in the directivity of radiated sound due to variations in forward flight Mach number and duct mode frequency, azimuthal mode number, and radial mode number are carried out. It is found there is a significant difference in directivity for the radiation of the same duct mode from an engine inlet when operating in static condition and in forward flight. It will be shown that the large change in directivity is the result of the combined effects of diffraction and refraction.
File Size	3721702
Page Count	40
File Format	PDF
Alternate Webpage(s)	http://archive.org/details/NASA_NTRS_Archive_20130000433
Archival Resource Key	ark:/13960/t46q6z82d
Language	English
Publisher Date	2012-06-04
Access Restriction	Open
Subject Keyword	Acoustics Sound Waves Wave Propagation Broadband Ducts Refraction Engine Inlets Aerodynamic Noise Refracted Waves Frequencies Acoustic Attenuation Jet Engines 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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