PIV

PARTICLEIMAGEVELOCIMETRY(PIV)INSTRUCTIONTYUSTYUXIANHUParticleImageVelocimetry(PIV)PIVisawhole-flow-fieldtechniqueprovidinginstantaneousvelocityvectormeasurementsinacross-sectionofaflow.Non-intrusivelaseropticalmeasurementtechniqueforresearchanddiagnosticsintoflow,turbulence,microfluidics,sprayatomizationandcombustionprocesses.MacroscalePIVPIV2Contents1.Whymeasure?2.CharacteristicsandapplicationsofPIV*MacroscalePIV*MicroscalePIVμPIVnPIV31.Whymeasure?Industrial:Engineering:Theoreticalfluidmechanics:Conceptualideas:searchfornewideas•investigatetechnicalproblems•checktechnicalspecifications•verifyperformance•improveperformance•determineparametersinturbulencemodels•develop,extend,refinemodels•investigatemodellimits•verifymodelpredictions•verifytheoreticalpredictions•verifynewconcepts4*MacroscalePIV*MicroscalePIV1.Whymeasure?2.CharacteristicsandapplicationsofPIVMeasurescale:1cm~?cmMeasurescale:0.1mm~1cmμPIVnPIVMeasurescale:10cm~?MMeasurementareasfrom1mm2=to=1m25DantecDynamicsStereoscopicPIVSystemComponentsSeedingPIV-Laser(Double-cavityNd:YAG)Lightguidingarm&Lightsheetoptics2camerasonScheimpflugmountsCalibrationtargetDynamicStudioPIVsoftwareDynamicStudiostereoscopicPIVAdd-onMacroscalePIVMacroscalePIV6Nonintrusive,planarorvolumetrictechniqueVelocityrange0tosupersonicTwoorthreevelocitycomponentssimultaneouslyMeasurementareasfrom1mm2=to=1m2SnapshotsofflowfieldsInstantaneousvelocityvectormapsinacross-sectionorvolumeoftheflowStatistics,spatialcorrelationsandotherrelevantdataareavailableResultsaresimilartocomputationalfluiddynamics,i.e.largeeddysimulations.FeaturesMacroscalePIV7MacroscalePIV8MacroscalePIV9StereoscopicEvaluation&StatisticsMacroscalePIV1011MeasurementofwaterflowinsideapumpmodelPhotocourtesyofGrundfosA/S,DKMacroscalePIVMeasurementofflowinavalvemodelPhotocourtesyofWestsächsischeHochschuleZwickau,Germany12MeasurementofvelocityprofilesinawaterpipeMacroscalePIVMeasurementofflowaroundashippropellerinacavitationtank13MacroscalePIV14CFDANALYSISOFMIXINGINLARGEAERATEDLAGOONS,EngineeringapplicationofcomputationalfluidmechanicsVol4,no1.pp127-138(2010)MacroscalePIV15Velocityprofile,fullydevelopedturbulentpipeflowMacroscalePIVPhaseresolvedandphaseaverageddataWakeflowfieldbehindhangarComparisonofPIVandCFDresults16vortexpairfromapumpexit.MacroscalePIV17a.原结构的液相PIV矢量图b.反应器改造后的液相PIV矢量图c廊道结构改变后的涡漩示意图图6-17某瞬态廊道转弯尾流区的速度矢量图MacroscalePIV18(a)气相(b)液相图6-6气液两相PIV实验经IPL处理后图片(a)气相的3D速度矢量图(b)液相的3D速度矢量图图6-7气液两相曝气条上方3D速度矢量图(a)液相速度矢量图(b气相速度矢量图图6-8x=100mm处两相速度矢量图MacroscalePIV19XYZ•Theliquidphase’straceplusedvelocityvectoratx=100mm(NO.1)00.050.10.150.20.250.30.270.320.370.420.470.520.57Witdthinydirection(m)V（m/s）SimulationExperiment00.0020.0040.0060.0080.010.0120.01400.10.20.30.40.50.60.70.8Widthinthexdirection（m）v（m/s）SimulationExperiment•Thephasevelocitycomparisonchartbetweensimulationandexperimentaty=520mm,z=120mminconditon120•Thespeedoftheliquidphaseatx=100mmincondition1Micro-PIVdiffersfrommacroscalePIVinthatitusessmaller(about100–500nmdiameter)fluorescentparticlesandvolumeilluminations.Flowvelocitiesfromnanometerspersecondtometerspersecondcanbemeasuredbyadaptingthetimingofthemeasurementdevicestotheflowproblemandhaveiametersof200nmto2mm.µPIViscommerciallyavailable,butnanoPTVisnotmatureμPIVMicroscalePIV(μPIV&nPIV)21μPIV22Ref:μPIV24SchematicviewofaμPIVapparatususingpulsedlaser-lightilluminationintoanepi-fluorescentinvertedmicroscope.Theilluminationlightisreflectedbyadichroicmirrorintoaflowingmicrochannelbeingchargedbyasyringepump.Fluorescentlylabeledseedparticles(commonlypolystyrene)areexcitedbytheilluminationlightandemitfluorescentlightthatpassesthroughabarrierfilteranddichroicmirror,recordedbyaCCDorCMOScamera,andthendigitallyprocessed.μPIVRef:Meinhart,S.T.W.A.(2010).RecentAdvancesinMicro-ParticleImageVelocimetry.Annu.Rev.FluidMech.42:557-576.25μPIVMicroscopeobjectivelensesthatareusedcommonlyinμPIVrangefromoil-immersionlenses(M=60,NA=1.4)toair-immersionlenses(M=10,NA=0.1).Ref:Meinhart,S.T.W.A.(2010).RecentAdvancesinMicro-ParticleImageVelocimetry.Annu.Rev.FluidMech.42:557-576.26μPIVRef:Meinhart,S.T.W.A.(2010).RecentAdvancesinMicro-ParticleImageVelocimetry.Annu.Rev.FluidMech.42:557-576.27Ref:Winer,M.H.andA.Ahmadi,etal.(2014).Applicationofathree-dimensional(3D)particletrackingmethodtomicrofluidicparticlefocusing.LabChip14(8):1443-51.μPIVRef:Meinhart,S.T.W.A.(2010).RecentAdvancesinMicro-ParticleImageVelocimetry.Annu.Rev.FluidMech.42:557-576.28Ref:Li,H.andR.Sadr,etal.(2006).Multilayernano-particleimagevelocimetry.41:185-194.μPIV29Ref:Lindken,R.andM.Rossi,etal.(2009).Micro-ParticleImageVelocimetry(µPIV):Recentdevelopments,applications,andguidelines.9:2551.μPIV30Ref:Lindken,R.andM.Rossi,etal.(2009).Micro-ParticleImageVelocimetry(µPIV):Recentdevelopments,applications,andguidelines.9:2551.Ref:Li,H.F.&.Y.(2008).Multilayernano-particleimagevelocimetry(MnPIV)inmicroscalePoiseu