Investigation of Particle Trajectories in 2-Phase Flow Systems

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1、J.FluidMe&.(1972),vol.55,paTt2,pp.193-208193Printedin@eatBritainAninvestigationofparticletrajectoriesintwo-phaseflowsystemsByS.A.MORS1DepartmentofMechanicalEngineering,UniversityofSurreyANDA.J.ALEXANDERLoughboroughUniversityofTechnology(Received12November1971)Thispaperdescribesatheo

2、reticalinvestigationinto(i)theresponseofasphericalparticletoaone-dimensionalfluidflow,(ii)themotionofasphericalparticleinauniformtwo-dimensionalfluidflowaboutacircularcylinderand(iii)themotionofaparticleaboutaliftingaerofoilsection.Inallthreecasesthedragoftheparticleisallowedtovaryw

3、ith(instantaneous)Reynoldsnumberbyusingananalyticalapproximationtothestandardexperimentaldrag-Reynolds-numberrelationshipforsphericalparticles.1.IntroductionThepredictionofparticlevelocitiesandtrajectoriesinfluidflowisofacon-siderableimportanceinmanyfields.Instudyingtheerosiondamage

4、sustainedbynozzlesorbladesinsteamorgasturbines,wherethesepartsaresubjectedtotheflowofamixtureofgasandsolidsorgasandwaterdrops,Martlew(1960)andNeilson&Gilchrist(1968)havefoundthattheerosiondependsonthewallmaterial,theparticlevelocityandtheangleofattack.Similarly,inthedesignofinertiaa

5、ndimpingementfilters,thepredictionofparticletrajectorieswillbeofgreathelpinassessingtheefficiencyofthesefiltersincapturingsolidparticlesfromthecarrierfluid.Inthecaseofflowthroughaturbineitisdesirableforparticlesnottocontactthebladeswhereasinflowthroughafiltertheoppositeeffectisneede

6、d.Ineithercaseitisnecessarytoknowwhatpathaparticlewilltakeandalthoughcalcula-tionshavebeenmadebyLangmiur&Blodgett(1946)andMichael&Norey(1969),itisusualtoassumethattheparticleReynoldsnumberissmallandthattheStokeslinearapproximationtothedragcoeficient(C,=24/RN)willbevalid.Thisisnotalw

7、aysthecaseandatsufficientlyhighReynoldsnumbersverylargeerrorswillresultfromtheuseofthisformula.Inthispaperanexpressionforthedragcoefficientwhichcloselyapproximatestothestandardexperimentaldrag-Reynolds-numberrelationshipisusedtogiveananalyticalsolutioninthecaseofone-dimensionalflowa

8、ndtosavecomputation