elib
DLR-Header
DLR-Logo -> http://www.dlr.de
DLR Portal Home | Imprint | Privacy Policy | Contact | Deutsch
Fontsize: [-] Text [+]

Aeroacoustic Research in Europe: The CEAS-ASC Report on 2000 Highlights. CAA Simulation of Sound Generation By Linear Interaction of Vorticity with a Wedge

Ianniello, Sandro and Delfs, Jan and Lauke, Thomas (2002) Aeroacoustic Research in Europe: The CEAS-ASC Report on 2000 Highlights. CAA Simulation of Sound Generation By Linear Interaction of Vorticity with a Wedge. Journal of Sound and Vibration, 249 (2), pp. 351-353. Elsevier.

[img]
Preview
Postscript
357kB

Abstract

THE STUDY OF AIRFRAME NOISE IS INTIMATELY CONNECTED WITH THE INTERACTION OF FLOW WITH EDGES. IN THIS CONTEXT THE QUESTION ARISES, WHETHER LINEARIZED CONSERVATION EQUATIONS DESCRIBE SUCH SOURCES. LILLEY'S AEROACOUSTIC WAVE EQUATION STATES THAT IN A SUBSONIC PARALLEL STEADY MEAN SHEAR FLOW SOUND IS GENERATED BY NONLINEAR PROCESSES ONLY, BECAUSE THE RESPECTIVE AEROACOUSTIC SOURCE TERM VANISHES UPON LINEARIZATION ABOUT THE BASIC STATE. THE LINEAR DYNAMICS OF WHATSOEVER SMALL PERTURBATIONS, E.G. DUE TO SMALL FLUCTUATIONS OF THE VORTICITY, WILL THEREFORE NOT CONTRIBUTE TO THE GENERATION OF NOISE. IN ORDER TO VERIFY THE ABOVE STATEMENT A NUMERICAL SIMULATION OF THE LINEAR DYNAMICS OF A PURELY VORTICAL PERTURBATION EVOLVING IN A FREE PARALLEL SHEARLAYER WAS CARRIED OUT USING THE PIANO CODE. AS A RESULT A DOWNSTREAM CONVECTING UNSTABLE WAVE PACKET EVOLVES REPRESENTING THE CLASSICAL KELVIN-HELMHOLTZ INSTABILITY, WHICH CONSISTS OF PURELY HYDRODYNAMIC (I.E. NON-PROPAGATING) COMPONENTS INDICATING COMPLETE SILENCE AND THUS CONFIRMING THE STATEMENT OF LILLEY'S EQUATION. IF A SHARP VERTICAL WEDGE IS ORIGINALLY PLACED BELOW THE SHEARLAYER THE SOUND IS GENERATED BY SCATTERING OF THE WAVE PACKET'S LINEAR HYDRODYNAMIC PRESSURE FIELD AT THE WEDGE ALTHOUGH THE MEAN FLOW DOES NOT EVEN TOUCH THE WEDGE. THE EXAMPLE SHOWS THAT IN THE PRESENCE OF EDGES THE SOUND GENERATION BY VORTICITY BECOMES A LINEAR PROBLEM EVEN IN THE PRESENCE OF A PARALLEL SHEAR FLOW.

Item URL in elib:https://elib.dlr.de/19694/
Document Type:Article
Title:Aeroacoustic Research in Europe: The CEAS-ASC Report on 2000 Highlights. CAA Simulation of Sound Generation By Linear Interaction of Vorticity with a Wedge
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Ianniello, SandroUNSPECIFIEDUNSPECIFIED
Delfs, JanUNSPECIFIEDUNSPECIFIED
Lauke, ThomasUNSPECIFIEDUNSPECIFIED
Date:2002
Journal or Publication Title:Journal of Sound and Vibration
Open Access:Yes
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Volume:249
Page Range:pp. 351-353
Publisher:Elsevier
Status:Published
Keywords:CAA, perturbation equations, Piano, airframe noise, Lilley, Kelvin-Helmholtz instability
HGF - Research field:Aeronautics, Space and Transport
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: Braunschweig
Institutes and Institutions:Institute of Aerodynamics and Flow Technology > Technical Acoustics
Deposited By: Lauke, Thomas
Deposited On:12 Aug 2008
Last Modified:31 Jul 2019 19:15

Repository Staff Only: item control page

Browse
Search
Help & Contact
Information
electronic library is running on EPrints 3.3.12
Copyright © 2008-2017 German Aerospace Center (DLR). All rights reserved.