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Noise reduction potential of flow permeable materials for jet-flap interaction noise

Jente, Christian and Schmidt, Johannes and Delfs, Jan Werner and Rossignol, Karl-Stephane and Pott-Pollenske, Michael and Siller, Henri (2022) Noise reduction potential of flow permeable materials for jet-flap interaction noise. In: 28th AIAA/CEAS Aeroacoustics Conference, 2022, pp. 1-18. 28th AIAA/CEAS Aeroacoustics Conference, 14.-17. Jun. 2022, Southampton, UK. doi: 10.2514/6.2022-3040. ISBN 978-162410664-4.

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Official URL: https://doi.org/10.2514/6.2022-3040


Jet-flap interaction (JFI) noise plays a particularly important role during take-offs and landings, i.e. when the aircraft is in the immediate vicinity of inhabited areas. The interaction of the jet with the deployed flaps causes a substantial increase of low-frequent aircraft noise. Noise reduction technologies (NRTs) were studied for their potential to diminish the JFI effect: The wing was equipped with various permeable or porous (flap) trailing edges which cover the last 10% of the clean chord length. The first test was conducted at the Aeroacoustic Wind tunnel in Braunschweig (AWB) on a cruise wing model, i.e. the engine was not installed. Beneath the testing of various materials and concepts, a design parameter study was conducted about the minimally needed treated chord length. The four most promising materials were down-selected for an installed engine test at the jet noise test facility JExTRA in Berlin: Two NRTs are designed as hollow flaps: perforated or slotted metal sheets are fixed onto a rib structure. The other two NRTs are porous materials (fine/coarse size). The tests were conducted for static operations between Mj=0.45 and 0.75. The engine integration was mainly defined by a height of H=0.6Dj (close integration) and a length of L=2Dj. Remarkable noise reduction was measured especially for low jet Mach numbers and up to Mj=0.7. At high Mach number, some NRTs produce tones which follow a Helmholtz analogy. The only tested NRT which is immune to this, uses a cover mesh which introduces another trailing edge. The tests with flow permable flap trailing edges show the great potential of reducing jet-flap interaction noise. Open questions regard (1) the deepening of the physical understanding of noise reduction mechanisms, (2) a proof of performance under flight conditions and (3) a design optimization which balances a small aerodynamic lift penalty vs. the acoustic benefit.

Item URL in elib:https://elib.dlr.de/186938/
Document Type:Conference or Workshop Item (Speech)
Title:Noise reduction potential of flow permeable materials for jet-flap interaction noise
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Jente, ChristianUNSPECIFIEDhttps://orcid.org/0000-0001-6115-3084UNSPECIFIED
Delfs, Jan WernerUNSPECIFIEDhttps://orcid.org/0000-0001-8893-1747UNSPECIFIED
Pott-Pollenske, MichaelUNSPECIFIEDhttps://orcid.org/0000-0002-9996-5624UNSPECIFIED
Siller, HenriUNSPECIFIEDhttps://orcid.org/0009-0000-7155-6899UNSPECIFIED
Date:13 June 2022
Journal or Publication Title:28th AIAA/CEAS Aeroacoustics Conference, 2022
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:No
Page Range:pp. 1-18
Keywords:noise reduction porous materials hollow flap jet-flap interaction
Event Title:28th AIAA/CEAS Aeroacoustics Conference
Event Location:Southampton, UK
Event Type:international Conference
Event Dates:14.-17. Jun. 2022
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: Berlin-Charlottenburg , Braunschweig
Institutes and Institutions:Institute for Aerodynamics and Flow Technology > Technical Acoustics
Institute of Propulsion Technology > Engine Acoustic
Deposited By: Jente, Christian
Deposited On:13 Oct 2022 12:10
Last Modified:29 Mar 2023 00:51

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