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On the Contribution of Higher Azimuthal Modes to the Near- and Far-Field of Jet Mixing Noise

Neifeld, A. and Ewert, R. (2012) On the Contribution of Higher Azimuthal Modes to the Near- and Far-Field of Jet Mixing Noise. 18th AIAA/CEAS Aeroacoustics Conference (33rd AIAA Aeroacoustics Conference), 2012-06-04 - 2012-06-06, Colorado Springs, CO, USA.


Official URL: http://www.aiaa.org


The prediction of jet mixing noise is studied using a stochastic realization of the Tam & Auriault source model. The acoustical sources are generated by means of the Random Particle-Mesh Method (RPM), which utilizes turbulence statistics as provided by solu- tions to the Reynolds Averaged Navier-Stokes (RANS) equations. The generated stochas- tic sound sources closely realize the two-point cross-correlation function used in the jet noise model to prescribe the fine-scale sound source. The RPM code is coupled with the DLR CAA solver PIANO. The azimuthal-modal decomposed linearized Euler equations are applied as governing equations. With this approach, it is possible to evaluate jet noise spectra at any position in the near-field. Based on an azimuthal decomposition, 3-D sound radiation from the jet can be reproduced at the computational price of a few axisymmetric 2-D computations. Furthermore, it will be shown, that we are able to verify the imple- mented methodology with the results published for the genuine model. The spectra are correctly predicted in terms of sound pressure levels, Mach scaling exponent and spectral shape. A Strouhal number range of up to St = 10 can be covered using the first six az- imuthal mode components of the broadband source. To reach higher Strouhal numbers more azimuthal modes have to be adopted. The presented results reveal the importance of individual azimuthal contributions to the total spectra. To evaluate the spectra in the far-field, the generated near-field noise is extrapolated with a modal Ffowcs-Williams & Hawkings (FWH) method. For the static single stream jet (Ma = 0.9) two different kinds of extrapolation were used - a simplified extrapolation and the modal FWH method. With this computational case, it was possible to predict a jet noise spectrum in the range of St = 0.01 . . . 20. To investigate the effect of different nozzle configurations on sound gener- ation, different nozzle configurations, i.e. dual-stream nozzles with and without nozzle lip treatments are simulated. Good agreement with experimental data for the noise reduction potential of nozzle lip treatments is found.

Item URL in elib:https://elib.dlr.de/76046/
Document Type:Conference or Workshop Item (Speech, Paper)
Title:On the Contribution of Higher Azimuthal Modes to the Near- and Far-Field of Jet Mixing Noise
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Date:4 June 2012
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:No
Series Name:Conference Proceedings online
Keywords:jet noise, sound source modeling, azimuthal modes, far-field extrapolation
Event Title:18th AIAA/CEAS Aeroacoustics Conference (33rd AIAA Aeroacoustics Conference)
Event Location:Colorado Springs, CO, USA
Event Type:international Conference
Event Start Date:4 June 2012
Event End Date:6 June 2012
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:Aircraft Research (old)
DLR - Research area:Aeronautics
DLR - Program:L AR - Aircraft Research
DLR - Research theme (Project):L - Simulation & Validation (old)
Location: Braunschweig
Institutes and Institutions:Institute of Aerodynamics and Flow Technology > Technical Acoustics
Deposited By: Neifeld, Dr.-Ing. Andrej
Deposited On:09 Aug 2012 09:58
Last Modified:24 Apr 2024 19:42

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