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DESIGN

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DESIGN

    DESIGN

?72?

    ;CHINESEJOURNALOFMECHANICALENGINEERING

    ;Vo1.2l,No.1,2008

    ;LlUWei

    ;YANGCanjun

    ;WUShijun

    ;XIEYingjun

    ;CHENYing

    ;StateKeyLaboratoryofFluidPower ;TransmissionandContro1.

    ;ZhejiangUniversity.

    ;Hangzhou310027,China

    ;0INTRoDUCTIoN

    ;DESIGNOFNOVELHIGHPRESSURE. ;RESISTANTHYDROTHERMALFLUID ;SAMPLEVALVE

    ;Abstract:Samplingstudyisanericctiveexplorationmethod.butthemostextr

    emeenvironmentsof

    ;hydrothermalventsposeconsiderableengineeringchallengesforsamplingh

ydrothermalfluids.

    ;Moreover,traditiona1samplersystemswithsamplevalveshavedifficultyinmaintainingsamplesin

    ;situpressure.However,decompressionchangeshaveeffectonmicroorganismssensitivetosuch

    ;stressesT0addressthetechnica1difficultyofcollectingsamplesfromhydrothermalvents.aNew

    ;bidirectiona1highpressure-resistantsamplevalvewithbalancedP0Dpetwasdesigned.Thesample

    ;valveutilizesasofthi.ghperformanceplastic”PEEK”aspoppet.Thepoppetwithinapposite

    ;dimensionispronetooccurtoplasticdeformationorruptureforhighworkingpressurein

    ;experiments.T0addressthisissue.basedonthefiniteelementmode1.simulatedresultsonstress

    ;distributionofthepoppetwitl1di

    erentstructureparametersandpreloadspringforcewereobtained. ;Thesmticaxia1deformationsontopofthepoppetwereexperimented.Thesimulatedresultsagree

    ;withtheexperimentalresults.Thenewsamplevalvesealswel1anditcanwithstandhighworking

    ;pressure.

    ;Keywords:HydrothermalventsHighpressure-resistantSamplevalveFiniteelementanalysis

    ;BalancedpoppetBidirectionalseal

    ;Sincehydrothermalventswerefirstlyfoundatmid.ocean ;ridgeintheEastPacificRisein1979.hydrothermalsystems ;attractscientistsfromdifferentfields,suchasmarinegeology, ;geophysics,geochemistryandmarinebiology,fortheirunique ;biologicalcommunitiesandhydrothermalactivities.Sampling ;studyisoneeffectiveexplorationmethodtoknowcharactersof ;hydrothermalfluidsIJ_However,theextremeenvironmentsof

    ;hydrothermalvents,suchashightemperaau’e,highpressureand

    ;corrosion,poseconsiderableengineeringchallengesforfluids ;sampling.Mostpresentdevicesaredifficulttomaintaininsitu ;pressure,whiledecompressionchangesofthesampleshavean ;effectonmicroorganism[.

    ;Variousdeviceswithsamplevalvesweredevelopedtocollect ;hydrothcrmalfluids.Thetitanium”major”samplershydraulically

    ;activatedhavebeenusedforhydrothermalfluidsamplingsince ;1981.Theyhavebeenveryeffectiveatcollectinghigh ;temperaturefluidsamplesbutarcnotgas.tight,sotheyarcnot ;suitabletodeterminetheabundanceofdissolvedgasesljJ.Forpoor ;qualityofsamplesforgasanalysescollectedbythemajor

;samplers,thegas—fight”Lupton”samplerisdeveloped,whichuses

    ;ahydraulicallyactivatedvalvetoopenanevacuatedsample ;chamber.However,thecomplicatedsampletransfersystem ;requiredduringtheextractionprocessreducesanalysisefficiency. ;Anewgas.tightisobaricsamplerlJisdevelopedtoprovide

    ;quantitativeinformationregardingtheabundanceofaqueous ;volatileandsemivolatileorganicspeciesinhydrothermalvent ;fluids.However,itssamplevalveisdriyenbyDCmotor.soit ;mustassemblywithanelectronicspressurecaseforcarrying ;batterypacks.Moreover,ahigh.pressureserialsamplertzJhas ;beendevelopedformeasuringmicrobialactivity.However,its ;inletvalveopeningsystemiscomplicated.

    ;Toacquireabetteranalyzingresult,hydrothermalfluid ;samplesmustbemaintainedinsitupressureandcannotbe ;polluted.Toaddressthesedifficulties.abidirectionalhigh ;pressure.resistantsamplevalvewasdesignedandconstructed. ;Thevalveisconvenientlytriggeredbyaramwhichisinstalledon ;ThisprojectissuppoaedbyNationalHitechResearchandDevelopment

    ;ProgramofChina(863Program,No.2002AA40100205).ReceivedJanua

    ry

    ;4,2007;receivedinrevisedformJune26,2007;acceptedSeptember25, ;2007

    ;themanipulator,soiteliminatcstheneedforextrapowersupply ;andcomplicatedcontro1.Themaximalworkingpressureof ;samplevalvedesignedis70MPaanditdemandssealingwel1. ;However,thepoppetwithinappositedimensionispronetooccur ;toplasticdeformationortop.reforexcessiveaxialforcethatis ;inducedbyhighworkingpressureinexperiments;itisdicultto

    ;maintainthesamplesinsitupressure.T0addressthisissue. ;accordingtofiniteelementanalysis,thestressdistributionat ;direntsectionsandtheaxialdeformationontopofthepoppet ;wereobtained.Thestaticaxialdeformationsinexperiments ;validatethemathematicalmode1.Thenewsamplevalvesealswell ;anditcanworkathighpressure.

    ;1WoRKINGPRINCIPLE

    ;Samplevalveisoneofthemostimportantcomponentsinthe ;samplersystem,whichmustmeetsomedemandsasfollows. ;Firstly.thesamplevalvemusthavebidirectionalsealing ;capabilityunderhighpressure,becauseanyleakagebeforeor ;aftersamplingisnotpermittedforthesakeofsamplepurityand ;gas.tight.Secondly,thevalveshouldbeextremelyresistantto ;corrosionsincetheflowmediaishotchloride.richacidicfluids. ;Atlast.thematerialsofthesamplevalvecannotcontaminatethe ;samples.

    ;Thesamplevalveispresentlytriggeredbytheramonthe ;submersible’smanipulator.Consideringthevalvestrokeismuch

    ;shorterthantheramstrokef1.5”ontheAlvinsubmersible’s

    ;manipulator)atriggermechanismisespeciallydesignedforthe ;samplevalve(Fig.1a).Thetriggermechanismutilizesanincline ;ontheslideblocktomovethepoppet,whichmagnifiesthevalve ;strokemorethan15timesandalsoreducestheramforcetoopen ;thevalve.

    ;Forcollectinghydrothermalfluids.thesnorkelisinsertedinto ;vent.Theramonthesubmersible’smanipulator,activatedfrom

    ;insidethesubmersible,actsontheactuatingbolttoopenthe ;samplevalve.Thenhydrothermalfluidsentersamplechamber ;throughthesamplevalve.Aftersampling,theramisretractedto ;closethesamplevalve.

    ;AsshowninFig.1b.thevalveutilizesadesignof”balanced

    ;poppet”J.whichisbeneficialindirectactingoccasions(the

    ;directionofthearrowsstandsfortheflowingdirection).Thetwo ;slidingsealdthevalveseat,whichthepOppetsealsagainst. ;havethesamediameter(DD2=D).Whicheverportthenuids ;nowinthevalve,a1lf.orcesonthepoppetarenullifiedbvequal ;andoppositef.orces.Solessf.0I_ceisneededtomovethepoppet. ;thentheramhastocOunteractOnlVtheret1mspringforceanda

;

    ;CHINESEJOURNALOFMECHANICALENGINEERrNG?73?

    ;littlefrictionforceproducedbyO-tingsthatcontactwiththevalve ;seat.

    ;(a)Schematicsofsamplevalve

    ;go)Schematicsofpressurebalancedpopp~

    ;Fig.1Structureanditsprincipleofsamplevalve

    ;Thematerialofsamplevalveiscriticalforthemostextreme ;environmentofhydrothermalvent,suchashighsalinity,lowpH, ;hitemperatureandhighpressure.Sothesamplevalveismainly ;madeof6..aluminum..4..vanadiumalloyoftitanium(commonly ;referredtoasTi.6A1.4V)becauseofitshighstrength.1owdensity ;andspecialresistancetocorrosion.exceptthestainlesssteel ;springandpoppet.Thepoppetismadeofahighperformance ;thermoplastic”PEEK”whichhashighmechanicalstrength.

    ;chemicalresistanceandbiocompatibilityPropertiesofPEEK ;areshowninTable.AlltheO.ringsofsamplevalvealemadeof ;fluoroelastomer.Thetriggermechanismismadeof431stainless ;stee1.

    ;TablePropertiesofPEEK

    ;WhatthehighlightofsamplevalvedesignisthesoftPEEK ;poppetmatchesthehardtitaniumseat.Withenoughreturnspring

    ;force,thevalvecomponent ;——

    ;Cularcomponent

    zdirectionalcomponent ;dz——

    ;——

    ;Tangemstressintheplane ;Thegeometricequationis ;(2)

    ;a

    ;ar

    ;r

    ;oco.

    ;oz

    ;丝垒

    ;8z8r

    ;wheres.——Radialstraincomponent ;.——Circularstraincomponent ;s:zdirectionalstraincomponent ;——

    ;Tngentstraininther-zplane ;u.

    ;——

;Radialdisplacementcomponent

    ;zdirectionaldisplacementcomponent

    ;Thephysicalequationis

    ;r,]f一一0lI

    ;1l-10IJ=il一一

    ;10

    ;1jl0002(1+)

    ;whereE——Modulusofelasticity

    ;f——Poissonratio

    ;3NUMEIUCALSIMULATIoN

    ;(3)

    ;(4)

    ;Thepoppet(contactedwiththepushpin,experimentedwim ;inappositedimensionispronetoOCCurtoplasticdeformationor ;ruptureforexcessiveaxialforceinducedbyllighworking ;pressure,soitisimportanttodetermineitsstructuralparameters. ;Becausethepoppetreturnspringforcecounteractsapartofaxial ;foreeinducedbyhiworkingpressure,thispartofpoppetis

    ;saferthantheotherpartofpoppetcontactedwiththepushPin. ;SimulationanalysisisconductedonthepoppeteasytoOCCurto ;plasticdeformationorrupture.

    ;Accordingtolinearelasticitytheory,stressanddeformation

    ;aresymmetricalforanaxisymmetricproblem.Becausethepoppet ;isanaxisymmetricstructure.a2Daxisymmetricgeometrymodel ;(Fig.2,isestablishedforsavingcalculatingtime.Stress ;concentrationlsapttooccuratO-ringgroovelbrabrupt ;dimension,whichcausesstressdistributionnon.uniform.how

    ;ever,withouttakingaccountofthestressconcentration.ifthepart ;madeofplasticmateria1onlyenduresstaticload ;C

    ;D

    ;RI

    ;.I

    ;:tionJJI

    ;1l

    ;:tion._.J}

    ;:tion

    ;2

    ;

    ;\

    ;Fig.22Daxisymmetricgeometrymodel

    ;InFig.2,t,bandrrepresentthedimensionofO.ringgroove; ;R1andR,representthedifferentradiusofpoppet. ;Toestimatestructuralparametersofthepoppet.simulation

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