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How Chevrons Decrease Broadband Jet Noise in Cruise.

Gutmark, Ephraim J. and Rask, Olaf R. and Michel, Ulf (2007) How Chevrons Decrease Broadband Jet Noise in Cruise. In: 13th AIAA/CEAS Aeroacoustics Conference (28th AIAA Aeroacoustics Conference) (AIAA-2007-3611). 13th AIAA/CEAS Aeroacoustics Conference (28th AIAA Aeroacoustics Conference), AIAA Papers (AIAA-2007-3611), 2007-05-21 - 2007-05-23, Rome, Italy.

Full text not available from this repository.

Abstract

Broadband shock noise is reduced because chevrons increase the shear-layer thickness between the flight stream and the jet. It is shown experimentally and with results of a theory of Michalke that this is directly related to a reduction of the axial variation of the pressure amplitudes in the mean flow field of the jet. Since broadband shock noise is the result of an interaction between the turbulence in a jet and the axial variation of the mean flow field the chevrons yield a reduced noise emission. The effects of chevrons on the sound emission from nozzles operating at underexpanded conditions are demonstrated with experimental results. In a cruise condition with a flight Mach number 0.85, the chevron nozzle yields a lower broadband shock noise. It is shown experimentally as well as with the theory of Michalke that chevrons reduce the shock cell spacing, which explains the higher frequencies for broadband shock noise.

Document Type:Conference or Workshop Item (Paper)
Title:How Chevrons Decrease Broadband Jet Noise in Cruise.
Authors:
AuthorsInstitution or Email of Authors
Gutmark, Ephraim J.University of Cincinnati, Ohio
Rask, Olaf R.University of Cincinatti, Ohio
Michel, UlfUNSPECIFIED
Date:21 May 2007
Journal or Publication Title:13th AIAA/CEAS Aeroacoustics Conference (28th AIAA Aeroacoustics Conference)
Refereed publication:No
In SCOPUS:No
In ISI Web of Science:No
Series Name:AIAA Papers
Status:Published
Keywords:Broadband shock noise, chevrons, nozzle serrations, supersonic jets, cabin noise reduction, shear layer thickness
Event Title:13th AIAA/CEAS Aeroacoustics Conference (28th AIAA Aeroacoustics Conference), AIAA Papers (AIAA-2007-3611)
Event Location:Rome, Italy
Event Type:international Conference
Event Dates:2007-05-21 - 2007-05-23
Organizer:ASSOCIAZIONE ITALIANA DI AERONAUTICA E ASTRONAUTICA
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Aeronautics
HGF - Program Themes:L VU - Air Traffic and Environment (old)
DLR - Research area:Aeronautics
DLR - Program:L VU - Air Traffic and Environment
DLR - Research theme (Project):L - Quiet Air Traffic (old)
Location: other
Institutes and Institutions:Institute of Propulsion Technology > Engine Acoustic
Deposited By: Prof. Dr.-Ing. Ulf Michel
Deposited On:21 Jun 2007
Last Modified:27 Apr 2009 13:50

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