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Experimental characterization of acoustic liners with extended reaction
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. Hellwan University, Egypt .
KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.ORCID-id: 0000-0001-7898-8643
2008 (engelsk)Inngår i: 14th AIAA/CEAS Aeroacoustics Conference (29th AIAA Aeroacoustics Conference), 2008Konferansepaper, Publicerat paper (Fagfellevurdert)
Abstract [en]

Suppressing of jet engine noise by inlet and exhaust duct liners and internal combustion engine (ICE) noise by intake and exhaust systems is an important part of developing environmentally acceptable vehicles. The acoustic liner is designed to provide an impedance boundary condition in the engine duct that reduces the propagation of engine noise through the duct. An accurate impedance boundary condition is necessary to optimally suppress the noise at different conditions. The goal of the research presented in this paper is to present a new technique to Educe and characterize the acoustic liner impedance for cases with extended reaction. This technique is depending on comparing both the measured and predicted 2-port transfer matrices. The measurement of the transfer matrix is performed using the two microphone technique, while the prediction of the transfer matrix is obtained assuming plane waves in the inner pipe and outer chamber coupled by a perforated wall impedance. By using a regression process the unknown wall impedance is then educed. The method is applied to investigate the effect of flow on the impedance of so called Micro-perforated panels (MPP). A MPP consists of a panel (here a plate made of Al or steel) with small perforations distributed over its surface. When these perforations are of sub-millimeter size they provide by themselves enough acoustic resistance and low acoustic mass reactance necessary for a wideband absorber.

sted, utgiver, år, opplag, sider
2008.
Emneord [en]
Acoustic liners, Acoustic mass, Acoustic resistance, Engine noise, Exhaust ducts, Experimental characterization, Impedance boundary conditions, Intake and exhaust, Jet engine noise, Perforated walls, Plane wave, Submillimeters, Transfer matrixes, Two-microphone technique, Wall impedance, Wide-band, Acoustic impedance, Boundary conditions, Ducts, Exhaust systems (engine), Fiber optics, High energy physics, Internal combustion engines, Jet engines, Transfer matrix method, Aeroacoustics
HSV kategori
Identifikatorer
URN: urn:nbn:se:kth:diva-153973Scopus ID: 2-s2.0-78249265376ISBN: 9781563479397 (tryckt)OAI: oai:DiVA.org:kth-153973DiVA, id: diva2:761341
Konferanse
14th AIAA/CEAS Aeroacoustics Conference (29th AIAA Aeroacoustics Conference), 5 May 2008 through 7 May 2008, Vancouver, BC, Canada
Merknad

QC 20141106

Tilgjengelig fra: 2014-11-06 Laget: 2014-10-10 Sist oppdatert: 2014-11-06bibliografisk kontrollert

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