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1、MechanicalSystemsandSignalProcessing(2003)17(6),1335–1347doi:10.1006/mssp.2002.1514DETECTIONOFCAVITATIONPHENOMENONINACENTRIFUGALPUMPUSINGAUDIBLESOUNDM.C$udinaFacultyofMechanicalEngineering,UniversityofLjubljana,Assker$cce$va6,1000Ljubljana,SloveniaE-mail:mirko.cudi
2、na@fs.uni-lj.si(Received26February2002,acceptedafterrevisions25July2002)Oneofthesourcesofinstabilityinacentrifugalpumpiscavitationphenomenon.Cavitationwithinacentrifugalpumpcancausemoreundesirableeffects,suchasdeteriorationofthehydraulicperformance(dropinhead-capaci
3、tyandefficiencycurves),damageofthepumpbypittinganderosionandstructurevibrationandresultingnoise.Cavitationcanappearwithintheentirerangeofoperatingconditions;thereforeitmust,byallmeans,beprevented.Topreventtheonsetofthecavitation,wehavetoknowthebeginningofcavitationph
4、enomenoninthepump.Todetectthebeginningofthecavitationprocess,theemittednoisecanalsobeused,amongotherpossibilities.Experimentshaveshownthatthereisadiscretefrequencytonewithintheaudiblenoisespectra,at147HzorBPF=2;whichisstronglydependentonthecavitationprocessanditsde
5、velopment.Therefore,thediscretefrequencytoneat147Hzwasseparatedfromthenoisespectraofcavitatingpumpsandthenusedtodetecttheincipientofcavitationanditsdevelopment.Itwasalsousedtodeterminethenetpositivesuctionheadrequiredorthecriticalvalue,aswellastopreventcavitationin
6、thepumpbymeansofinitiatinganalarm,shutdownorcontrolsignalviaanelectricalcontrolsystem.#2003ElsevierScienceLtd.Allrightsreserved.1.INTRODUCTIONThenoisegeneratedbyacentrifugalpumpdependsonitsgeometry(sizeandform)andontheoperatingconditions(speedandload).Anotherfactor
7、thatincreasesnoiseispumpinstability.Pumpinstabilitymaybecausedbystall,surgeandcavitationinthepump.StallandsurgecanoccurwhenthepumpoperatesbelowthedesignflowrateorBEPðQ5QdesÞ;whereascavitationcanoccurwithintheentireoperatingregime.Cavitationcanoccurwithoutstallandsur
8、ge,andviceversa[1,2].CavitationoccursmoreeasilyathigherflowratesðQ>QdesÞduetotheincreasedvelocityofflowandthepressuredrop;thereforethistypeofinstab
