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On the Noise Generated by Shear-Layer Instabilities in Turbulent Jets

Bertolotti, Fabio P. and Colonius, Tim (2003) On the Noise Generated by Shear-Layer Instabilities in Turbulent Jets. In: 41st Aerospace Sciences Meeting and Exhibit, 6-9 January 2003, Reno, NV.

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Solutions to the linearized equations of motion are used to study sound radiation by convected disturbances in the jet core. The spectrum of eigenmodes reveals the presence of modes that represent convected vortical and entropic motions in the potential core of the jet. We investigate the near-field acoustics produced by these core modes using the Parabolozied Stability Equations. At the conditions of commercial jet engines during take-off, the core modes radiate sound effectively along Mach lines due to the jet centerline velocity being supersonic relative to the fee-stream speed of sound. Summing three of these modes to create two distinct disturbances - one that is velocity dominated, and another that is entropy dominated - one observes that entropy variations radiate sound more effectively than vortical variations. The results yield a first insight into the impact of large-scale mixing inhomogeneities on the acoustic field. Such disturbances are created by devices in the jet engine itself, such as flow mixers, turbine exit vanes, and combustion-chamber (i.e. pattern factors).

Item Type:Conference or Workshop Item (Paper)
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URLURL TypeDescription Paper Paper
Colonius, Tim0000-0003-0326-3909
Alternate Title:On the Noise Generated by Convected Structures in a Mach 0.9, Hot, Turbulent Jet
Additional Information:© 2003 by United Technologies Corporation. Published by the American Institute of Aeronautics and Astronautics, Inc. with permission. Published Online: 11 Nov 2012.
Subject Keywords:Aerospace Systems, Operations and Life Cycle
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Other Numbering System NameOther Numbering System ID
AIAA Paper2003-1062
Record Number:CaltechAUTHORS:20190718-165125289
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:97248
Deposited By: Melissa Ray
Deposited On:22 Jul 2019 21:02
Last Modified:16 Nov 2021 17:30

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