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1、WindNoisecausedbytheA-pillarandtheSideMirrorflowofaGenericVehicleModel12M.Hartmann,J.Ocker,2344455T.Lemke,A.Mutzke,V.Schwarz,H.Tokuno,R.Toppinga,P.Unterlechner,G.WickernAconsortiumofGermanautomotivemanufacturersAudi,Daimler,PorscheandVolkswagenhasinvestigatedthenoisegeneratedbytheairflowaroun
2、dtheA-pillarandthesidemirrorofagenericvehiclemodel.Thismodelisbuiltinsuchawaythatonlythenoisetransmissionthroughthefrontsidewindowisrelevant–exceptforverylowfrequencies.Infact,thefrontsidewindowatthedriver’ssideistheonlywindowofthemodel,whiletherestofthestructureisnearlyrigidandhighlydamped.T
3、hepressureloadingofthewindowwasmeasuredwith96flushmountedautomotivesurfacemicrophones.ThetestswereperformedintheAudiaero-acousticwind-tunnelatdifferentflowvelocities(80km/hto200km/h),incidenceanglesandmodelsetups.Theinteriorsoundpressurelevelwasdeterminedatdifferentlocationsinsidethecabinanda
4、lsothewindowaccelerationwasrecorded.Inaddition,differentCFDsolverswereusedtosimulatethetransientpressureloading.Bothtocomparetheresultswiththeexperimentaldataandtoevaluatewavenumber-frequencyspectra(WFS)toseparatetheacousticfromthehydrodynamicpressurefluctuations.TheWFSwereusedasafilterbasist
5、oextracttheacousticfractionfromtherawpressuretimesignals.Bymeansofselectedtestvehicleconfigurationsitwasfoundthattheinteriorsoundpressurelevels(SPL)aredominatedbytheacousticwindowexcitationsandthatthehydrodynamicexcitationisofminorimportance.Nomenclature=pressure=density=freestreamvelocity
6、=convectionvelocity=glassbendingwavevelocity=velocityvector,
,=coordinatevector:xflowdirection,yverticaldirection,zspan-wisedirection=correlationfunction=wavenumber-frequencyspectrumorpowerspectraldensity,=2D-wavenumbervector,=2D-distancevector=time=timedelay=freq
7、uency2=circularfrequency.∗=conjugate1Correspondingauthor,VolkswagenAG,Letterbox1777,D-38436Wolfsburg,Germany2Dr.-Ing.h.c.F.PorscheAG,D-71287Weissach,Germany3VolkswagenAG,D-38436Wolfsburg,Germany4DaimlerAG,D-71059Sindelfingen,Germany5AudiAG,