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dc.contributor.authorSundström, Een
dc.contributor.authorSemlitsch, Bernharden
dc.contributor.authorMihăescu, Men
dc.date.accessioned2018-11-07T00:30:54Z
dc.date.available2018-11-07T00:30:54Z
dc.date.issued2018-11-10en
dc.identifier.issn0022-460X
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/284697
dc.description.abstractRotating stall and surge are flow instabilities contributing to the acoustic noise generated in centrifugal compressors at low mass flow rates. Their acoustic generation mechanisms are exposed employing compressible Large Eddy Sim- ulations (LES). The LES data are used for calculating the dominant acoustic sources emerging at low mass flow rates. They give the inhomogeneous char- acter of the Ffowcs Williams and Hawkings (FW-H) wave equation. The blade loading term associated with the unsteady pressure loads developed on solid surfaces (dipole in character) is found to be the major contributor to the aerodynamically generated noise at low mass flow rates. The acoustic source due to the velocity variations and compressibility effects (quadrupole in character) as well as the acoustic source caused by the displacement of the fluid due to the accelerations of the solid surfaces (monopole in character) were found to be not as dominant. We show that the acoustic source associated with surge is generated by the pressure oscillation, which is governed by the tip leakage flow. The vortical structures of rotating stall are interacting with the impeller. These manipulate the flow incidence angles and cause thereby unsteady blade loading towards the discharge. A low-pressure sink between 4 and 6 o’clock causes a halving of the perturbation frequencies at low mass flow rates operat- ing conditions. From two point space-time cross correlation analysis based on circumferential velocity in the diffuser it was found that the rotating stall cell propagation speed increases locally in the low pressure zone under the volute tongue. It was also found that rotating stall can coexist with surge operat- ing condition, but the feature is then seen to operate over a broader frequency interval.
dc.publisherElsevier
dc.titleAcoustic signature of flow instabilities in radial compressorsen
dc.typeArticle
prism.endingPage236
prism.publicationDate2018en
prism.publicationNameJournal of Sound and Vibrationen
prism.startingPage221
prism.volume434en
dc.identifier.doi10.17863/CAM.32070
dcterms.dateAccepted2018-07-24en
rioxxterms.versionofrecord10.1016/j.jsv.2018.07.040en
rioxxterms.licenseref.urihttp://www.rioxx.net/licenses/all-rights-reserveden
rioxxterms.licenseref.startdate2018-11-10en
dc.contributor.orcidSemlitsch, Bernhard [0000-0001-7715-863X]
dc.identifier.eissn1095-8568
rioxxterms.typeJournal Article/Reviewen
rioxxterms.freetoread.startdate2019-11-10


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