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1、NOISE-CON2003Paper105R.H.ThomasInvitedPaper,JetNoiseSession,NOISE-CON2003,PaperNo.105Cleveland,Ohio,June23-25,2003AeroacousticsofPropulsionAirframeIntegration:OverviewofNASA’sResearchRussellH.ThomasAeroacousticsBranch,MS166NASALangleyResearchCenterHampton,VA23681-2199R.H.Thom
2、as@larc.nasa.govABSTRACTTheintegrationofpropulsionandairframeisfundamentaltothedesignofanaircraftsystem.Manyconsiderationsinfluencetheintegration,suchasstructural,aerodynamic,andmaintenancefactors.Inregardtotheacousticsofanaircraft,theintegrationcanhavesignificanteffectsonthe
3、netradiatednoise.Whetheranengineismountedaboveawingorbelowcanhaveasignificanteffectonnoisethatreachescommunitiesbelowbecauseofshieldingorreflectionofenginenoise.Thisisanobviousexampleoftheacousticeffectsofpropulsionairframeinstallation.Anotherexamplecouldbetheeffectofthepylon
4、onthedevelopmentoftheexhaustplumeandontheresultingjetnoise.Inaddition,foreffectivesystemnoisereductiontheimpactthatinstallationhasonnoisereductiondevicesdevelopedonisolatedcomponentsmustbeunderstood.Inthefuture,afocusontheaerodynamicandacousticinteractioneffectsofinstallation
5、,propulsionairframeaeroacoustics,willbecomemoreimportantasnoisereductiontargetsbecomemoredifficulttoachieve.Inadditiontocontinuedfundamentalcomponentreductionefforts,asystemlevelapproachthatincludespropulsionairframeaeroacousticswillberequiredinordertoachievethe20dBofperceive
6、dnoisereductionenvisionedbythelong-rangeNASAgoals.ThisemphasisontheaeroacousticsofpropulsionairframeintegrationisanewpartofNASA’snoiseresearch.Thefollowingpaperwillreviewcurrenteffortsandhighlighttechnicalchallengesandapproaches.1.INTRODUCTIONNASAhasalonghistoryofaircraftnois
7、eresearchdatingbacktoatleastthe1960’s.Thisresearchhasbeendonewithsignificantcontributionsfromawidevarietyofindustrialpartnersanduniversities.Oneofthebestsummariesofaircraftnoiseresearchcoveringdevelopmentsupto1991was1editedbyHubbard.Inrecentyears,NASAconductedthenoisereductio
8、nelementoftheAdvancedSubsonicTransport(AST)programfrom1994toitsconcl
