DNS of a plane mixing layer for the investigation of sound generation mechanisms

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1、Availableonlineatwww.sciencedirect.comComputers&Fluids37(2008)360–368www.elsevier.com/locate/compfluidDNSofaplanemixinglayerfortheinvestigationofsoundgenerationmechanismsAndreasBabucke*,MarkusKloker,UlrichRistInstitutfu¨rAerodynamikundGasdynamik,Universita¨tS

2、tuttgart,Pfaffenwaldring21,D-70550Stuttgart,GermanyAvailableonline20February2007AbstractDirectnumericalsimulationsintwoandthreedimensionshavebeenperformedtoinvestigatethesoundgenerationbyvortexpairinginacompressibleplanemixinglayerwithMa1=0.5beingtheupperandM

3、a2=0.25beingthelowerstreamMachnumber.TheReynoldsnumberbasedonthevorticitythicknessattheinflowandthevelocityoftheupperstreamisRe¼500.Theflowisforcedattheinflowwitheigenfunctionsobtainedfromviscouslinearstabilitytheoryincludingthree-dimensionaldisturbances.Theres

4、ultsareverifiedwithlinearstabilitytheoryandthetwo-dimensionalsimulationsperformedbyColoniusetal.[ColoniusT,LeleSK,MoinP.Soundgenerationinamixinglayer.JFluidMech1997;330:375–409].Theexcitationofasteadylongitudinalvortexmodeleadstoanearlythree-dimensionaldeform

5、ationofthetravellingspanwisevorticesandreducedsoundemissiontotheslowerfluidstreamside.Ó2007ElsevierLtd.Allrightsreserved.1.Introductionhyperbolic-tangentvelocityprofile.DirectNumericalSim-ulationsofatwo-dimensionalmixinglayerhavebeenper-Noisereductionisanimpor

6、tantissueforawiderangeofformedbyColoniusetal.[6].Bogeyetal.aswellasapplicationslikeaircraftsandturbomachineryforexample.Coloniusetal.comparedtheacousticfarfieldwithLight-BeingpartoftheFrench–GermanDFG-CNRSResearchhill’sacousticanalogy[12]showinggoodagreementG

7、roup‘‘NoiseGenerationinTurbulentFlows’’,ourmoti-betweensimulationsandtheacousticanalogy.vationistosimulateboththecompressiblemixinglayerAeroacousticcomputationsfacetheproblemsof(i)theitselfaswellaspartsofthesurroundingacousticfield.largeextentoftheacousticfiel

8、dcomparedtotheflowThetermmixinglayerdescribesaflowfieldcomposedoffieldand(ii)thelowamplitudesoftheemittedsoundrel-twostreamswithunequalvelocitiesandservesasamodelativetopressurefluctuationsoftheinsta