简介：Thefeaturesofunsteadyflowsuchaspressurevariationandfluctuationinalargehydraulicturbineusuallyleadtotheinstabilityofoperation.Thisarticlereportstherecentinsiteinvestigationconcerningthecharacteristicfrequenciesinpressurefluctuation,shafttorsionaloscillationandstructuralvibrationofaprototype700MWFrancisturbineunit.Theinvestigationwascarriedoutforawideloadrangeof200MW-700MWintheconditionofwaterhead57m-90m.Anextensiveanalysisofbothtime-historyandfrequencydataoftheseunsteadyhydraulicbehaviourswasconducted.Itwasobservedthatthepressurefluctuationinadrafttubeisstrongerthanthatinupstreamflowpassage.Thelowfrequencywithaboutonethirdofrotationfrequencyisdominativeforthepressurefluctuationinpartloadrange.Alsotheunsteadyfeaturesofvibrationofheadcoverandtorsionaloscillationofshaftexhibitedthesimilarfeatures.Numericalanalysisshowedthatthevibrationandoscillationarecausedbyvortexropeinthedrafttube.Inaddition,astrongvibrationwithspecialcharacteristicfrequencywasobservedfortheheadcoverinmiddleloadrange.Thepressurefluctuationinthedrafttubewiththesamefrequencywasalsorecorded.Becausethisspecialvibrationhasappearedinthedesignednormalrunningcondition,itshouldbeavoidedbycarefullyallocatingpowerloadinthefutureoperation.

简介：Thispapermainlysummarizestherecentprogressesforthecavitationstudyinthehydraulicmachineryincludingturbopumps,hydroturbines,etc..Especially,thenewlydevelopednumericalmethodsforsimulatingcavitatingturbulentflowsandtheachievementswithregardtothecomplicatedflowfeaturesrevealedbyusingadvancedopticaltechniquesaswellascavitationsimulationareintroducedsoastomakeabetterunderstandingofthecavitatingflowmechanismforhydraulicmachinery.Sincecavitationinstabilitiesarealsovitalissueandratherharmfulfortheoperationsafetyofhydromachines,wepresentthe1-Danalysismethod,whichisidentifiedtobeveryusefulforengineeringapplicationsregardingthecavitatingflowsininducers,turbinedrafttubes,etc.Thoughbothcavitationandhydraulicmachineryareextensivelydiscussedinliteratures,oneshouldbeawarethatafewproblemsstillremainsandareopenforsolution,suchasthecomprehensiveunderstandingofcavitatingturbulentflowsespeciallyinsidehydroturbines,theunneglectablediscrepanciesbetweenthenumericalandexperimentaldata,etc..Tofurtherpromotethestudyofcavitationinhydraulicmachinery,someadvancedtopicssuchasaDensity-Basedsolversuitableforhighlycompressiblecavitatingturbulentflows,avirtualcavitationtunnel,etc.areaddressedforthefutureworks.

简介：Theformulaeusedtocalculatethefrictioninthenon-uniformflowchutewereexaminedwiththeexperimentaldata,andtheresultsshowthattheaccuracyoftheformulaisenoughforengineeringapplications.Acomparisonbetweentheresultsoffrictionrespectivelyfromtheuniformflowassumptionandthenon-uniformflowapproximationindicatesthattheformerisanorderofmagnitudelargerthanthelatterinthecaseofsteepchute.Thehydraulicdragonasteepchutewithaeratorswasmeasuredonthehydraulicmodeldirectlyandthecoefficientoftheaeratoreffectonthedragwasobtained.Thevariationpatternsofthewallshearjustdownstreamoftheaeratorswereinvestigatedandthemechanismoftheincreaseinthedragbyaeratorwereanalyzedqualitativelywiththemeasuredwater-depthsjustdownstreamtheaerators.

简介：Submergedvegetationhasasignificantimpactonwaterflowvelocity.Currentinvestigationsincludetheimpactthroughaddingdragresistanceandincreasingbottomroughnesscoefficient,whichcannotelucidatethecharactersofrealsubmergedvegetation.Toevaluatetheeffectsofsubmergedvegetationonwatercurrentsatdifferentvelocities,alaboratoryexperimentwasconductedusingthreekindsofvegetations.Theeffectiveheightsofthesevegetationsonvaryingflowvelocitieswereevaluated.AnequationdescribingtherelationshipbetweenthenormalizedresistanceofthesubmergedplantsandtheReynoldsnumberbasedontheplanteffectiveheightwasthenestablishedandusedtocalculatethehydraulicresistanceparametersofsubmergedplantsindifferentstagesofgrowth.

简介：Thehydrauliccharacteristicsattheconfluencereachofriverandlakeareinfluencedbymultiplefactorssuchasinflow,topographyandvegetationresistance,andareverycomplicated.Inthisarticle,theconfluencereachofYangtzeRiverandDong-tingLakeisselectedasaspecialexampleandahybridmodelisbuilttostudytheflowatthisconfluence,withtheconsiderationoftheinteractionsbetweenaquaticvegetationandflow.Validationtestsandcalculationsshowthatthemodeliseffectiveandhighlyaccurate.Thesimulationsshowthattheseparationleveeattheconfluencereachmaychangethedischargecapacityinthefloodplain,whichwouldbeenhancedintheupperreachofthelevee,hardlychangedinthemiddlereachandreducedatthelowerplace.Moreover,theseparationleveealsolimitsthewaterexchangebetweentheYangtzeRiverandDong-tingLake.

简介：Throughaseriesofmodeltestsoffivescalesfor2-Dfreehydraulicjump,theda-taoffluctuatingpressureactingonthefloorlevelwithinthehydraulicjumpwereobtained.Dur-ingtheexperiments,Froudenumbervariedfrom2.94to8.61,andReynoldsnumberrangedfrom2×10~4to6×10~5.Experimentresultsindicatethattheamplitudescaleoffluctuatingpres-sureisthelengthscaleofmodel,i.e.P’=L,whichagreeswithgravitysimilaritylaw:Thefrequencyscaleofthefluctuatingpressureisaunityi.e.,f=1,whichdoesnotsatisfythegravitysimilaritylaw.

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简介：Theartificialecologicalfloatingbediswidelyusedinriversandlakestorepairandpurifypollutedwater.However,thewaterflowpatternandthewaterleveldistributionaresignificantlychangedbythefloatingbeds,andtheinfluenceonthewaterflowisdifferentfromthatofaquaticplants.Inthispaper,basedonthecontinuousporousmediamodel,amoveabletwo-layercombinationmodelisbuilttodescribethefloatingbed.Theinfluencesofthefloatingbedsonthewaterflowcharacteristicsarestudiedbynumericalsimulationsandexperimentsusinganexperimentalwaterchannel.Thevariationsofthewaterleveldistributionarediscussedunderconditionsofdifferentflowvelocities(v=0.1m/s,0.2m/s,0.30m/s,0.4m/s),floatingbedcoveragerates(20%,40%,60%)andarrangementpositionsawayfromthechannelwall(D=0m,0.1m,0.2m).Theresultsindicatethattheflowvelocityincreasesunderthefloatingbeds,andthewaterlevelrisessignificantlyunderhighflowvelocityconditionsintheupstreamregionandthefloatingbedregion.Inaddition,theaveragerisingwaterlevelvalue(ARWLV)increasessignificantlywiththeincreaseofthefloatingbedcoveragerate,andthearrangementpositionoffloatingbedsintherivercanalsogreatlyinfluencethewaterleveldistributionunderahigh-flowvelocitycondition(v?0.2m/s).

简介：Thebesthydraulicchannelsectionmakesthemaximumflowcapacityforthesameflowcross-area,andtheminimumcross-areaandwettedperimeterforthesamedischarge.Theconstructioncostcanbereducednearlytotheminimumatthesametime.Thehorizontalbottomparabolicsection(HBPsection)isacompositesection.Itisimportantfordesigntofindthebestcombinationformofthehorizontalbottomandtheparabolicsides.Thispaperstudiesthebesthydraulicsectionanditshydrauliccharacteristics.Theexplicitformulaeareproposedtodeterminethedimensionsandthebestcombinationformofthehorizontalbottomandtheparabolicsides.Theseexplicitformulaeandtheparametersmakeiteasytodesignthechannel.Itisshownthattheratiosofthesurfacewidthtothedepthandthebottomwidthtothedepthareconstantforthebesthydraulicsection.Thecomparisonswiththeclassicparabolic,rectangular,trapezoid,triangular,semi-cubicandhorizontal-bottomedsemi-cubicsectionsshowthattheHBPsectionhasthelargestflowcapacityandtheshortestwettedperimeterforthesameflowarea,andhasthesmallestflowareaforthesamedischarge.ItisindicatedthattheparabolicsidepartsofthebesthydraulicHBPsectionaredifferentfromthoseoftheclassicsection.TheresultsofthebesthydraulicsectionoftheclassicparabolicchannelcannotbeapplieddirectlytotheHBCsection.

简介：Thispaperpresentsastudyofthemovementandthehydrodynamicperformanceofanewtide-poweredhydraulicturbinethroughnumericalsimulations.Bymeansofthemovingmeshmethod,theopen-closedsequencesofthebladesandthemovementoftherotorsareobtainedandtheangularvelocityandtheaverageenergyutilizationcoefficientunderdifferenttipspeedratiosarealsoobtained.Moreover,theoptimumtipspeedratioisidentifiedbyintegratingtheoutputpowerandtheenergyutilizationcoefficientofthehydraulicturbinewithdifferenttipspeedratios,providingdatasupportfortheprototypedesignofthehydraulicturbine.

简介：Thepier,placedattheoutletofthepressureflowsection,isaneffectivedesigntodealwiththeproblemsofthemanufactureandoperationofthegatesforadischargetunnelwithhighwaterhead.Itiscrucialtocontrolthewater-wing,inducedbythistypeofthepier.Throughobservingthephenomenaofthewater-wing,thereasonofthewater-winginception,i.e.,theconcaveoftheflowsurface,waspresented,andatypeofthenewpierwithbottomunderlaywasdesigned.Thehydrauliccharacteristicsofthepier,includingthevariationsofthewater-wingfeatures,bothlengthandheight,withthewaterhead,aswellaswiththeconcavedepth,andwiththeheightofthebottomunderlay,andthevariationsoftheconcavedepthwiththeheightofthebottomunderlay,wereinvestigatedbyphysicalmodelexperiments.Theresultsshowthattheapproachofthemodificationoftheconcavethroughthestructureswiththebottomunderlay-typepierisremarkablyeffectiveinthewater-wingcontrol.

简介：Throughmechanicalanalysis,animprovedhydraulicmodelforannularcuttingstransportwithfoamwasestablishedforhorizontaldrilling.Basedonthetwocriticalinclinationangles,theentirewellwasdividedintothreesegments.TheBagnoldstress,generalizedpowerlawrheologicalmodelandmodifiedhinderedparticlesettlingvelocityinfoamfluidwereadoptedinthemodeltoimprovethesimulationaccuracy.Theproposedmodelallowsmoreprecisepredictionofcuttingstransportpropertyinthewholerangeofwellinclinationangle.Modelperformancewasexaminedviacasestudyandexperimentaldata.Simulationresultsgivenbythepropulsioniterationandtrial-and-errormethodagreewellwithin-situhorizontalwelldrillingpracticeforthecasestudy,andthecomparisonbetweenthemodelpredictionandCapo’sexperimentaldatashowssatisfactoryagreement.

简介：Apre-filtercombinedwiththresholdself-learningwaveletalgorithmisproposedforhydraulicpressuresignalsdenoising.Thedenoisingthresholdisself-learntinthesteadyflowstate,andthenmodifiedunderagivenlimittomakethemeansquareerrorsbetweenreconstructionsignalsanddesirableoutputsminimum,sothecorrespondingoptimaldenoisingthresholdinasingleoperatingcasecanbeobtained.Theseoptimalthresholdsareusedforthewholesignaldenoisingandaredifferentinvariouscases.Simulationresultsandcomparativestudiesshowthatthepresentapproachhasanobviouseffectofnoisesuppressionandissuperiortothoseoftraditionalwaveletalgorithmsandback-propagationneuralnetworks.Italsoprovidestheprecisedataforthenextstepofpipelineleakdetectionusingtransienttechnique.

简介：TheturbulenceflowFreeSurfacehasimportantapplicationsinhydraulicspillwaysstructure,suchasthehydraulicjump,energydissipationflowetc.Thisisbeingconsideredasverycomplicatedflow,andhasnotyetbeensolvedquitewellbynumericalmethod.Inthispaper,aLarge-scalecomputationalsoftwarepackagearedevelopedfornumericallaboratoryofhydraulicspillwaystructure.Somemethods,suchasturbulencemodel,freesurfaceandirregularboundarytreatingtechniques,scientificcomputervisualizationareputforwardandperformed.

简介：Takingaccountofturbulenceintensity,non-uniformityofvelocitydistributionattheinitialandsequentsec-tionofhydraulicjumpandfrictionaldragonthefloorwithinjumprange,thispaperderivesnewformulasforcal-culatingtheratioofconjugatedepthsandtheefficiencyofenergydissipationinthetwo-dimensionalfreehydraulicjump.Ithasbeenverifiedbytestdatathatthenewformulasarenotonlyexactintheorybutalsostillbetterinconformitywithpractice.

简介：Thewaterintakeheadinstalledwithinclinedboardingsiscalledlaminatesedimentprecipitation,whichseparatesliquidandsolidparticlesintwo-phaseflowbygravity.ThepaperpresentstheequationsforcalculatingthedistanceHbetweentwoincllinedboardings,indicatingthatHhasakeyeffectontheparticleprecipitationvelocityV2.Thepaperfocusesalsoonthecal-culationofhydraulicsimilarityofmodelwiththetheoreticmodel.