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Acoustic Mach number, jet Mach number or jet speed – what is the optimal control property for jet noise experiments at AWB

Jente, Christian (2021) Acoustic Mach number, jet Mach number or jet speed – what is the optimal control property for jet noise experiments at AWB. EU H2020 1st DJINN Conference: Industrially oriented jet noise reduction technologies, 01.-03. Dez 2021, Brüssel, Belgien.

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Abstract

Some experimental facilities are planned energy-lean, but this comes typically with slightly imperfect test conditions. Especially temperature control systems are often slow, demand energy and increase operational cost. Contrary to this, low-cost experimental pressurized air test rigs, such as the one at AWB (Acoustic Wind tunnel Braunschweig), respond to control commands much faster, but do not meet norm conditions. Therefore, the question needs to be answered which flow parameter should be used for operation control, the acoustic Mach number Mac, jet Mach number Mj or jet velocity Uj. This study starts with the definition of ideal ISA norm conditions and a re-writing of the FfowcsWilliams jet noise analogy without any temperature terms. Using a rough assumption for the mixed (shear layer) density, the jet noise scales according to I ~ Mj2 Uj Mac5. The derivation will be used in order to judge the three control options at a test rig with a constant total temperature for the jet. As a result, this study will recommend the testing of jet velocities for jet noise experiments at AWB.

Item URL in elib:https://elib.dlr.de/146770/
Document Type:Conference or Workshop Item (Speech)
Title:Acoustic Mach number, jet Mach number or jet speed – what is the optimal control property for jet noise experiments at AWB
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Jente, ChristianChristian.Jente (at) dlr.dehttps://orcid.org/0000-0001-6115-3084
Date:3 December 2021
Refereed publication:No
Open Access:Yes
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:wind tunnel operations jet noise scaling law
Event Title:EU H2020 1st DJINN Conference: Industrially oriented jet noise reduction technologies
Event Location:Brüssel, Belgien
Event Type:international Conference
Event Dates:01.-03. Dez 2021
Organizer:CFD Berlin and the von Karman Institute for Fluid Dynamics (VKI)
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:Clean Propulsion
DLR - Research area:Aeronautics
DLR - Program:L CP - Clean Propulsion
DLR - Research theme (Project):L - Future Engines and Engine Integration
Location: Braunschweig
Institutes and Institutions:Institute for Aerodynamics and Flow Technology
Institute for Aerodynamics and Flow Technology > Technical Acoustics
Deposited By: Jente, Christian
Deposited On:06 Dec 2021 08:49
Last Modified:06 Dec 2021 08:49

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