The three-dimensional nature of boundary-layer instability英文文献资料

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1、1Thethree-dimensionalnatureofboundary-layerinstabilityByP.S.KLEBANOFF,K.D.TIDSTROMANDL.M.SARGENTNationalBureauofStandards,Washington,D.C.(Received5June1961)Anexperimentalinvestigationisdescribedinwhichprincipalemphasisisgiventorevealingthenatureofthemotionsinth

2、enon-linearrangeofboundary-layerinstabilityandtheonsetofturbulence.Ithasasitscentralpurposetheevaluationofexistingtheoreticalconsiderationsandtheprovisionofasoundphysicalmodelwhichcanbetakenasabasisforatheoreticalapproach.Theexperimentalmethodconsistedofintrodu

3、cing,inatwo-dimensionalboundarylayeronaflatplateat‘incompressible’speeds,three-dimensionaldisturbancesundercontrolledconditionsusingthevibrating-ribbontechnique,andstudyingtheirgrowthandevolutionusinghot-wiremethods.Ithasbeendefinitelyestab-lishedthatlongitudin

4、alvorticesareassociatedwiththenon-linearthree-dimen-sionalwavemotions.Suacientdatawereobtainedforanevaluationofexistingtheoreticalapproaches.Thosewhichhavebeenconsideredarethegenerationofhigherharmonics,theinteractionofthemeanflowandtheReynoldstress,theconcaves

5、treamlinecurvatureassociatedwiththewavemotion,thevortexloopandthenon-lineareffectofathree-dimensionalperturbation.Itappearsthatexceptforthelattertheydonotadequatelydescribetheobservedphenomena.Itisnotthattheyareincorrectormaynotplayaroleinsomeaspectofthelocalbe

6、haviour,butfromtheover-allpointofviewtheresultssuggestthatitisthenon-lineareffectofathree-dimensionalperturbationwhichdominatesthebe-haviour.Aprincipalconclusiontobedrawnisthatanewperspective,onethattakesthree-dimensionalityintoaccount,isrequiredinconnexionwith

7、boundary-layerinstability.Itisdemonstratedthattheactualbreakdownofthewavemotionintoturbulenceisaconsequenceofanewinstabilitywhicharisesintheaforementionedthree-dimensionalwavemotion.Thisinstabilityinvolvesthegenerationof‘hairpin’eddiesandisremarkablysimilarinbe

8、haviourto‘in-flexional’instability.Itisalsoshownthattheresultsobtainedfromthestudyofcontrolleddisturbancesareequallyapplicableto‘natural’transition.1.IntroductionOneofthemos