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Experimental and Numerical Analysis of the Vibro-Acoustic Behavior of a Helmholtz Resonator with a Flexible Wall

Kohlenberg, Hans-Fleming and Radmann, Vincent and Genßler, Julia and Enghardt, Lars and Knobloch, Karsten (2023) Experimental and Numerical Analysis of the Vibro-Acoustic Behavior of a Helmholtz Resonator with a Flexible Wall. 2023 AIAA AVIATION Forum, 12.-16. Juni 2023, San Diego, USA. doi: 10.2514/6.2023-3348.

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Modern aircraft engines have large fans with a low-frequency noise signature, which conventional liners struggle to damp efficiently. New liner concepts are therefore needed to address low-frequency aircraft noise. In this paper, a Helmholtz resonator is combined with a flexible plate dividing the cavity into two. The flexible plate extends the conventional single-degree of freedom system to a multi-degree of freedom system, with resonances below the conventional Helmholtz resonance. The plate's motion is investigated experimentally at the aero-acoustic wind tunnel DUCT-R with a vibrometer and compared to numerical simulations based on FEM, where good agreement is found. We showed that the face sheet and plate size is a crucial parameter of the concept which alters the number of resonance frequencies, their absorption amplitudes and their resonance frequencies. The flexible wall vibrates strongly and adds multiple damping peaks when the plate resonances lie in the vicinity of the Helmholtz resonance. Furthermore, we resolved the deflection shapes and the absorption of the Helmholtz resonator with a flexible wall of variable size numerically. The results help to fortify confidence in the proposed liner concept for future optimization and application.

Item URL in elib:https://elib.dlr.de/195747/
Document Type:Conference or Workshop Item (Speech)
Title:Experimental and Numerical Analysis of the Vibro-Acoustic Behavior of a Helmholtz Resonator with a Flexible Wall
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Kohlenberg, Hans-FlemingUNSPECIFIEDhttps://orcid.org/0000-0002-6983-1545137949817
Knobloch, KarstenUNSPECIFIEDhttps://orcid.org/0000-0002-3424-0809UNSPECIFIED
Date:12 June 2023
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:No
Keywords:aircraft, noise reduction, damping, liner, helmholtz resonator, coupling, flexible walls, flexible plate, plate vibration, material damping, aeroacoustic, FEM, impedance tube, vibrometer
Event Title:2023 AIAA AVIATION Forum
Event Location:San Diego, USA
Event Type:international Conference
Event Dates:12.-16. Juni 2023
Organizer:American Institute of Aeronautics and Astronautics
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 - Components and Emissions, L - Future Engines and Engine Integration
Location: Berlin-Charlottenburg
Institutes and Institutions:Institute of Propulsion Technology > Engine Acoustic
Deposited By: Kohlenberg, Hans-Fleming
Deposited On:03 Jul 2023 09:25
Last Modified:03 Jul 2023 09:25

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