Determination of liner impedance under high temperature and grazing flow conditions
2014 (English)In: 20th AIAA/CEAS Aeroacoustics Conference, 2014Conference paper (Refereed)
Acoustic liners have traditionally been used to reduce fan noise from the aircraft engine intake. To increase noise reduction there are now plans to also put liners in hot stream parts of the engine. In order to test liners under as realistic conditions as possible there has been a large development in inverse techniques for determination of liner impedance under grazing flow conditions, so called impedance eduction techniques. Testing under hot stream conditions has received smaller attention. This paper discusses techniques for measuring liner impedance under hot stream conditions and present some results obtained for single degree of freedom Helmholtz resonator liners with different configurations. It could be argued that the main effect of high temperatures is a change of medium properties such as: density, viscosity and speed of sound. If this is true the high temperature impedance could be predicted by scaling from the result at cold conditions. This is investigated in the paper by comparing measured results from liner impedance models available in the literature.
Place, publisher, year, edition, pages
Acoustic impedance, Aeroacoustics, Aircraft engines, Noise abatement, Helmholtz resonators, High temperature, Impedance eduction, Inverse techniques, Measured results, Realistic conditions, Single degree of freedoms, Stream condition, Acoustic noise
IdentifiersURN: urn:nbn:se:kth:diva-167578ScopusID: 2-s2.0-84903888324ISBN: 9781624102851OAI: oai:DiVA.org:kth-167578DiVA: diva2:815883
20th AIAA/CEAS Aeroacoustics Conference 2014, 16 June 2014 through 20 June 2014, Atlanta, GA
QC 201506022015-06-022015-05-222015-06-02Bibliographically approved