Aero-acoustic characterization of the sudden area expansion
2014 (English)In: 21st International Congress on Sound and Vibration 2014, ICSV 2014, 2014, 2174-2181 p.Conference paper (Refereed)
In combustion devices, thermo-acoustic instabilities are often encountered and are formed by the complex interaction between acoustics, hydrodynamics and combustion. A common geometrical feature found in these devices is the sudden area expansion. Downstream of the area expansion a recirculation zone is formed together with an unstable shear layer when flow is present. This shear layer creates a pathway for interactions between the acoustic and the hydrodynamic field and this interaction could be a precursor for thermo-acoustic instabilities. The work presented here takes a step to gain more insight into these interactions by experimentally investigating the aero-acoustic properties of a sudden area expansion with mean flow. The aero-acoustic properties are characterized by a linear two port model and the scattering matrix representation is used to relate the state variables up-and downstream of the area expansion. The scattering coefficients of the area expansion have been determined for frequencies up to the first cut on frequency of the duct system and for a range of subsonic flow speeds. The measurements have been performed by applying a stepped sine excitation as sound excitation and by using the multi-microphone method.
Place, publisher, year, edition, pages
2014. 2174-2181 p.
Acoustic properties, Aeroacoustics, Combustion, Fluid dynamics, Hydrodynamics, Scattering parameters, Shear flow, Combustion device, Geometrical features, Hydrodynamic field, Recirculation zones, Scattering co-efficient, Scattering matrices, Sound excitation, Thermoacoustic instability, Acoustic wave scattering
IdentifiersURN: urn:nbn:se:kth:diva-167521ScopusID: 2-s2.0-84922640053ISBN: 9781634392389OAI: oai:DiVA.org:kth-167521DiVA: diva2:819718
21st International Congress on Sound and Vibration 2014, ICSV 2014, 13 July 2014 through 17 July 2014
QC 201506112015-06-112015-05-222015-06-11Bibliographically approved