简介：Aeratorisanimportantdeviceforreleaseworksofhydraulicstructureswithhigh-speedflowinordertoprotectthemfromcavitationdamage.Thiskindofprotectingeffectisrelatedcloselytocavitylengthbelowtheaerator,whilethecavitylengthisdominatedbytheemergenceangleovertheaerator.Thereforeitiscrucialtodeterminethisangleaccurately.Inthepresentpapertheaffectingintensitiesofflowdepthandthefluctuatingvelocityonthisanglewereanalyzedthroughtwointroducedparameters.Furthermore,theimprovedexpressionsofemergenceangleestimation,forbothramp-typeandstep-typeaerators,werepresentedbymeansof68setsofexperimentaldatafrom6projectsbasedonerrortheory.Theresultsshowedthatthepresentmethodhashigheraccuracythanthepreviouslyreportedmethods.

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

简介：Basedonthenon-Darcyflowcharacteristicsofsurfactantfloodinginthelowpermeabilityoilfield,consideringthechangesofthresholdpressureandinfluenceofsurfactantonconvection,diffusion,adsorptionandretention,amathematicalmodelisestablishedforathree-dimensional,two-phase,three-componentsurfactantflooding.Anewtreatmentforthechangesofthresholdpressureandanovelcorrectionmethodfortherelativepermeabilitycurveintheprocessofsurfactantfloodingarederived,whichenhancesthematchingdegreebetweenthemathematicalmodelandfieldpractice.ThemathematicalmodelwasusedtoperformthenumericalsimulationstudyforapilottestofsurfactantfloodinginChao45BlockofDaqingOilfield,aproperinjectionplanwasoptimized.Aftertheoptimizedplanwascarriedoutinoilfield,thedesirableeffects,likepressure-reducing,injectionrateincrease,andtheincreaseofoilrecovery,wereachieved.Theaverageoilincreaseforsinglewellreaches37%,theratioofcosttorevenueisabove1:4,sotheeconomiceffectofscaleispromising.

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简介：Inthisarticle,the2-Dunsteadyviscousflowaroundtwocircularcylindersinatandemarrangementisnumericallysimulatedinordertostudythecharacteristicsoftheflowinbothlaminarandturbulentregimes.ThemethodappliedalternativelyisbasedonthefinitevolumemethodonaCartesian-staggeredgrid.Thegreatsourcetermtechniqueisemployedtoidentifythecylindersplacedintheflowfield.Toapplytheboundaryconditions,theghost-celltechniqueisused.Theimplementedcomputationalmethodisfirstlyvalidatedthroughsimulationoflaminarandturbulentflowsaroundafixedcircularcylinder.Finally,theflowaroundtwocircularcylindersinatandemarrangementissimulatedandanalyzed.Theflowvisualizationparameters,theStrouhalnumbers,anddragandliftcoefficientsarecomprehensivelypresentedandcomparedfordifferentcasesinordertorevealtheeffectoftheReynoldsnumberandgapspacingonthebehavioroftheflow.Theobtainedresultshaveshowntwocompletelydistinctflowcharacteristicsinlaminarandturbulentregimes.

简介：ThenumericalsolutionofincompressibleviscousflowoveranaerofoilisobtainedbyH-typegridsandaspecialdifferencescheme.Themethodofmassfluxcorectionisintroducedwithsuccessinordertoaccelerateconvergenceiniterationofvelocityandpressurecalculation.

简介：Thesheet/cloudcavitationisofagreatpracticalinterestsincethehighlyunsteadyfeatureinvolvessignificantfluctuationsaroundthebodywherethecavitationoccurs.Moreover,thecavitatingflowsarecomplicatedduetothethermaleffects.ThepresentpapernumericallystudiestheunsteadycavitatingflowsaroundaNACA0015hydrofoilinthefluoreketoneandtheliquidnitrogenwithparticularemphasisonthethermaleffectsandthedynamicevolution.Thenumericalresultsandtheexperimentalmeasurementsaregenerallyinagreement.Itisshownthatthetemperaturedistributionsarecloselyrelatedtothecavityevolution.Meanwhile,thetemperaturedropismoreevidentintheliquidnitrogenforthesamecavitationnumber,andthethermaleffectsuppressestheoccurrenceandthedevelopmentofthecavitatingflow,especiallyatalowtemperatureinthefluoroketone.Furthermore,thecavitatingflowsarecloselyrelatedtothecomplicatedvortexstructures.Thedistributionsofthepressurearoundthehydrofoilisamajorfactoroftriggeringtheunsteadysheet/cloudcavitation.Atlast,itisinterestingtofindthatoneseesasignificantthermaleffectonthecavitationtransition,asmallvalueofσ/2ɑisrequiredinthethermo-sensitivefluidstoachievethesimilarcavitationtransitionthatoccursinthewater.

简介：Thisarticleexperimentallyinvestigatedthepressureandcavitationcharacteristicsofhighvelocityflowoverasurfaceirregularitywithandwithoutaerationinanon-circulatingwatertunnelsystem.Thesurfaceirregularityisacylindricalprotrusionmadeofstainlesssteelof6mmdiameterand2mmheight.PressureswithandwithoutaerationweremeasuredwithMPX400Dpressuretransducersandreal-timelyacquiredbyaSINOCERAYE6263dataacquisitionsystem.Variationsinflowregimeswithandwithoutaerationwereobserved.Pressureprofilesandtheirvariationswithairconcentrationupperandlowercylindricalprotrusionontheinvertandobvertwallsweredetermined.Variationsofcavitationnumberwithairconcentrationlowercylindricalprotrusionwereanalyzed.Also,cavitationnumbersinthepresenceandabsenceofaerationwerecompared.

简介：Spatio-temporalcharacteristicsofthewall-boundedturbulentmixinglayerflowoveranopenstepandasquare-edgedribwereextensivelystudiedinalow-speedwindtunnel.Simultaneousmeasurementsofwall-pressurefluctuationsandvelocitymeasurementswereperformedbyusingmicrophonearrayandX-wire/splitfim,respectively.