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Physics of Acoustic Radiation from Jet Engine InletsNumerical 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.
Document ID
20130000433
Acquisition Source
Glenn Research Center
Document Type
Conference Paper
Authors
Tam, Christopher K. W.
(Florida State Univ. Tallahassee, FL, United States)
Parrish, Sarah A.
(Florida State Univ. Tallahassee, FL, United States)
Envia, Edmane
(NASA Glenn Research Center Cleveland, OH, United States)
Chien, Eugene W.
(Goodrich Aerostructures Group Chula Vista, CA, United States)
Date Acquired
August 27, 2013
Publication Date
June 4, 2012
Subject Category
Acoustics
Report/Patent Number
E-18505
Meeting Information
Meeting: 18th AIAA/CEAS Aeroacostics Conference
Location: Colorado Springs, CO
Country: United States
Start Date: June 4, 2012
End Date: June 6, 2012
Sponsors: American Inst. of Aeronautics and Astronautics, National Oceanic and Atmospheric Administration
Funding Number(s)
WBS: WBS 561581.02.08.03.45.02.04
Distribution Limits
Public
Copyright
Public Use Permitted.
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