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A generalised model for acoustic and entropic transfer function of nozzles with losses

dc.contributor.authorDe Domenico, F
dc.contributor.authorRolland, EO
dc.contributor.authorHochgreb, S
dc.contributor.orcidHochgreb, Simone [0000-0001-7192-4786]
dc.date.accessioned2018-12-06T00:30:33Z
dc.date.available2018-12-06T00:30:33Z
dc.date.issued2019
dc.description.abstractWe investigate the low frequency transfer functions for acoustic and entropic perturbations through nozzles and nozzle guide vanes. Previous theories rely on the isentropic assumption; in real systems, however, pressure losses associated with local friction and flow recirculation may occur, as evidenced by a drop in static pressure. In this work we relax the isentropic assumption and derive a parametric model to predict the acoustic and entropic transfer functions of a generic nozzle with subsonic-to-sonic throat conditions in the low frequency domain. For a given geometry and operating conditions, the model can retrieve the acoustic impedance of three limit cases known from the literature, as a function of a pressure loss parameter: the isentropic nozzle, the ori ce plate and the converging nozzle terminating a duct. The generalised model is also able to predict the conversion of entropy to sound through ori ce plates and nonisentropic nozzles given a measured or estimated static pressure loss parameter. The analytical predictions compare favourably with experimental measurements acquired in the Cambridge Entropy Generator for circular ori fices and nozzles with subsonic-to-sonic throat conditions. The results highlight the need to correctly account for pressure losses in the system in order to properly capture the transfer functions of nozzles, as isentropic predictions di er substantially from the acquired experimental data.
dc.description.sponsorshipEPSRC Qualcomm
dc.identifier.doi10.17863/CAM.33664
dc.identifier.eissn1095-8568
dc.identifier.issn0022-460X
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/286354
dc.language.isoeng
dc.publisherElsevier BV
dc.publisher.urlhttp://dx.doi.org/10.1016/j.jsv.2018.09.011
dc.subjectThermoacoustics
dc.subjectNozzle transfer functions
dc.subjectEntropy noise
dc.subjectPressure losses
dc.titleA generalised model for acoustic and entropic transfer function of nozzles with losses
dc.typeArticle
dcterms.dateAccepted2018-09-03
prism.endingPage230
prism.publicationDate2019
prism.publicationNameJournal of Sound and Vibration
prism.startingPage212
prism.volume440
pubs.funder-project-idEngineering and Physical Sciences Research Council (EP/K02924X/1)
rioxxterms.licenseref.startdate2019-02-03
rioxxterms.licenseref.urihttp://www.rioxx.net/licenses/all-rights-reserved
rioxxterms.typeJournal Article/Review
rioxxterms.versionAM
rioxxterms.versionofrecord10.1016/j.jsv.2018.09.011

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