简介：AnexperimentalapparatustoinvestigateACMHDpumpwasestablished,whichmainlyconsistsofarotarypermanentmagnetwith4polesanannularchannel,amotor,ashaftandaplatform.Themagnetgeneratesafieldsimilartosinusoidwiththemaximumof0.9TinthechannelwhenitisrotatedupbythemotortosimulateanACmagneticfield.Thismovingmagneticfieldactsontheconductivefluidinthechannel,andproducesanelectromagneticforcetomovethefluidinthesamedirectionasthatofthemagnetrotating.Experimentswerecarriedouttoinvestigatetheperformanceofthepump.Flowvelocityintheannularchannelwasmeasuredfordifferentconductivitiesandrotatingspeedsofthemagnet.Theresultsshowthattheflowrateandpressureincreaseasthemagneticfieldstrength,fluidconductivityandfrequencyofthemagneticfieldincrease.

简介：Theaccuratemodelingandpredictionoftherotatingstallinacentrifugalpumpisasignificantchallenge.Oneofthemodelingtechniquesthatcanimprovetheaccuracyoftheflowpredictionsisthelargeeddysimulation(LES).ThequalityoftheLESpredictionsdependsonthesub-grid-scale(SGS)modelimplementedintheLES.ThispaperassessestheinfluenceofvariousSGSmodelsthataresuitableforpredictingrotatingstallinalow-specificspeedcentrifugalpumpimpeller.TheSGSmodelsconsideredinthepresentworkincludetheSmagorinskymodel(SM),thedynamicSmagorinskymodel(DSM),thedynamicnon-linearmodel(DNM),thedynamicmixedmodel(DMM)andthedynamicmixednon-linearmodel(DMNM).TheresultsobtainedfromthesemodelsarecomparedwiththePIVandLDVexperimentaldata.TheanalysisoftheresultsshowsthattheSGSmodelshavesignificantinfluencesontheflowfield.Amongthemodels,theDSM,theDMMandtheDMNMcansuccessfullypredictthe'two-channel'stallphenomenon,butnottheSMandtheDNM.Accordingtothesimulations,theDMNMgivesthebestpredictiononthemeanvelocityflowfieldandalsoindicatesimprovementsforthesimulationoftheturbulentflow.Moreover,thehighturbulentkineticenergypredictedbytheDMNMisinthebestagreementwiththeexperimentdata.

简介：Basedonestablishednumericalmethodsandhydrodynamicperformancetestingfacilities,CFDtechniqueareappliedtoimprovethedesignoftheimplantableaxialflowbloodpumpandtheflowanalysis.(1)Applyingbrushlessmachinemagnetsteel,reducingitsthicknesswhileincreasingthelength,theflowchannel'scross-sectionisincreased,withnospaceconnectionbetweenthelargeandthesmallrotators,andwithaconetransitionsegmentfromthebearingtotheprincipalaxis,theflowismadesmoother.Therotatingspeedisloweredby1000rpm-1200rpmunderthesameflowrateandpressurehead,andthusthehemolysiscanbeavoided.(2)Differentoutletstatorguidingvanesareselectedforthesamebloodpumpforanalysesofhydrodynamicperformancesandflowfields.Anexcellentdesignnotonlycanregulatetherotatingflowfieldintoanaxialone,reducethecirculationlossandimprovethepumpefficiency,butalsocanavoidbackflow,vortexandsecondaryflowatthepumpoutlet,andthusthethrombuscanbeprevented.(3)Thecalflivetestsshowthatsomeresidualclotsexistattheinnerwalloftheoutletconnectionbends,whichareanalyzedandexplainedbyCFDtechniquesandthecorrespondingimprovementsareproposed.AllresultsareverifiedbyhydrodynamicperformancetestsandPIVflowfieldtests,andconsistentconclusionsareobtained.

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