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experiments.Thestudy’sfindingsdemonstratethatalargeincidenceanglecausesastrongflowseparationphenom
enonneartherunnerinlet,whichcreatesamassivevortexstructureintherunnerbladepassage.Withtheincrease
oftherotatingspeed ,thevolumeofthevortexstructureincreasesgradually,andthevortexstructuredisturbsthe
mainflowstrongly.Thelow - frequencyandhigh - amplitudepressurefluctuationswithbroadbandcharacteristicsare
capturedbynumericalcalculation ,anditsfrequencyrangeisbelow0.5timesthebladepassingfrequency.Be
sides,thecorrespondingpressureamplitudeoftherunnerregionisthehighest.Theenergydissipationcharacteris
ticsoftheturbinearefurtheranalyzedonthebasisofenergybalanceequation,anditisfoundthattheenergydissi
pationofeachflowpassagecomponentmainlyoccursintheinitialstageoftheriseofthespeed,andthesumofthe
energydissipationintherunnerandthedrafttubeexceeds90% ofthetotalenergydissipation.Additionally ,turbu
lencedominatesenergytransportanddissipationintheunstablerunawayprocess,asshownbythefactthatthetur
bulentkineticenergygenerationtermandtheReynoldsstressworktermaremuchlargerthantheviscousdissipation
termandtheviscousforceworkterm.Besides ,thelocationofthemainenergydissipationinthewheelcoincides
withthelocationofthevortexduringrotation ,suggestingthattheintricatevortexstructureinthewheelisthe
sourceofenergydissipation.Itpointsoutthedirectionforfurtherstudyontheenergydissipationmechanismofthe
turbinetransientrunawayprocess.
Keywords:Francisturbine;runawayprocess;transientflow;vortex;energydissipation
(责任编辑:王 婧)
(上接第 793页)
Turnovercharacteristicsanddissolvedoxygenresponsesinalargestratifiedreservoir
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DUYanliang ,LIUXiaowei ,LIUXiaobo,LIUChang,WANGShiyan,ZHAOShilin 1
(1.DepartmentofWaterEcologyandEnvironment,ChinaInstituteofWaterResourcesandHydropowerResearch,Beijing 100038,China;
2.ShanghaiEngineeringResearchCenterofWaterEnvironmentSimulationandEcologicalRestoration,Shanghai 200233,China;
3.ChangchunInstituteofTechnology,Changchun 130000,China)
Abstract:Turnoverhasimportanteco -significancetothestratified reservoirs.Byin -situ monitoringin
PanjiakouReservoir,alargeanddeepreservoirinnorthernChina,associatedwithavertical2 - dimensionalhy
drodynamic - waterquality - waterecologicalmodel,thereservoirturningcharacteristicsanddissolvedoxygen
(DO)responsewerestudied.Theenvironmentalevolutionprocessesin2018and2020aremodelledrespectively,
andtheresultsshowthatwatertemperaturestratificationleadstoverticalstratificationofdissolvedoxygen(DO).
ThesurfaceDOhasacorrelationwiththeairtemperature,andthebottomDOcontinuestodropto0afterstratifi
cation.Theautumnturnoveristheprincipalwayofthebottomaerationannually.Theaverageoperatingwaterlev
elin2018was14.2mhigherthanthatin2020,andthemaximumthicknessoftheepilimnionin2018isnearly
10mgreaterthanthatin2020.Thereservoirturnoversstartedfromthetailofthereservoirtotheregioninfrontof
thedam.Thedurationofturnoverin2018was40daysshorterthanthatin2020intheanalyzeddomainwhichis
about30kmfromthetailtothedam.TheverticalmixingtimeofDOlagsbehindthewatertemperatureby7to10
days.SurfaceDOwasstronglyinfluencedbytheturnoveranddropped3 - 4mg?Lintheperiodwiththerelatively
lowwaterlevelin2020.Theannualavailablepotentialenergyindex (APE)ofeachsectionwasutilizetoanalyze
thestabilityofstratification.Whenthewaterlevelofthereservoirislow ,theDOofthesurfacewaterbodypro
ducedbythereservoirturnoverwilldropmore ,withadropof3 - 4mg?L.Theannualvariationprocessofthea
vailablepotentialenergyindex (APE)ofdifferentsectionsofthereservoirisanalyzedrespectively.Thedatesof
turnoverofdifferentlocationsinthetwoyearshaveagoodcorrelationwiththeaverageAPEindexinthesummer
mixingcycles.Thestudyexploredtheregularpatternofwaterenvironmentalevolutioninthedeepandstratified
reservoirs ,adminandsometheoreticalresultsforoptimaloperation.
Keywords:stratifiedreservoir;turnoverofwatertemperatureanddissolvedoxygen;turnoverdate;available
potentialenergyindex (APE);CE - QUAL - W2
(责任编辑:耿庆斋)
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