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1、AnalysisofThree-DimensionalDynamicStallAntonellaFerrecchiaThesissubmittedtotheFacultyofEngineering,UniversityofGlasgow,fortheDe-greeofDoctorofPhilosophy.Allaspectsoftheworkpresentedhereinareoriginalinconceptwhereindicated.TheresearchwasconductedbetweenOctober1997andOctober2000attheDe-partmentofAeros
2、paceEngineering,UniversityofGlasgow.AntonellaFerrecchia,December2000c2000AntonellaFerrecchiaAbstractThepurposeofthisworkistoenhancetheunderstandingofthedynamicstallpro-cessinboththetwodimensionalandthree-dimensionalcasesandto ndoutwhata ectsthedevelopmentandgrowthoftheleadingedgevortexassociatedwith
3、thephenomenonofstall.Inherentinthis,thestudyinvolvedtheanalysisofunsteadypressuredatarecordedalongthechordoftestmodelsundergoingaconstantrateramp-upmotion.Thisinvestigation,supportedby
owvisualizationtestspointedoutthemainfeaturesofthedynamicstallvortexbehaviouralongthewingspanonbotharectangularanda
4、swepttipwing.Acomparisonoftheaerodynamicfeaturesoftheunsteady
owatlocalcross-sectionsofbothwingswiththoseovertheNACA0015aerofoilshowedqualitativesimilarityofthestallprocessinboththetwodimensionalandthreedimensionalcasesandsingledoutthee ectsofthewingspangeometry.Further,thedynamicstallvorticalstruct
5、ureattheleadingedgecouldbeattributedtoalocalvorticityaccumulation.Thevorticity
uxwasexaminedtoidentifythemechanismsthatplaykeyrolesintheinitiationanddevelopmentofthevortex.Itwasfoundthatthe
uxofvorticityfromthesurfaceoriginatedprimarilyfromtwoconcentratedregionsorsources.Thebehaviourofvorticity
uxfr
6、omthesesourceswasrelatedtotheinteractingmechanismresponsibleforthedevelopmentofthe
ow eld.Moreover,theinvestigationsuggestedthatthevorticity
uxisapracticaliiengineeringtooltopredicttheonsetofthestall.Inaddition,thechangesofthepressureandsurfacevorticity
uxvariationsduetochangesinthereducedpitchratew
7、erealsocharacterized.Thelastpartoftheresearchfocussedonaninvestigationofdynamicstallvortexconvectionoverbothtwo-dimensionalandthreedimensionalaerodynamicsurfaces.Fromtheanalysisofthedynamicstallvortex
