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简介：Themotionofaspark-inducedcavitationbubbleandanairbubbleneararigidboundaryisexperimentallystudiedbyusinghigh-speedphotography.Severaldimensionlessparametersareusedtodescribethegeometricalconfigurationofthebubble-bubble-boundaryinteraction.Thebubble-bubbleinteractioncanbeconsideredintwodifferentconditions.Thecavitationbubblewillcollapsetowardstheairbubbleiftheairbubbleisrelativelysmall,andawayfromtheairbubbleiftheairbubbleisrelativelylarge.Thetwozonesareidentifiedinthebubble-boundaryinteraction,andtheyarethedangerzoneandthesafetyzone.Therelativeposition,thebubble-boundarydistanceandthebubble-bubbledistanceplayimportantrolesinthebubble-bubble-boundaryinteraction,whichcanbeconsideredinseveralconditionsaccordingtotheresponsesofthebubbles.Airjetsarefoundtopenetrateintothecavitationbubbles.Thecavitationbubbleandtheairbubble(airjet)moveintheirownwaywithoutmixing.Themotionofacavitationbubblemaybeinfluencedbyanairbubbleand/orarigidboundary.Theinfluenceoftheairbubbleandtheinfluenceoftheboundarymaybecombined,likesomethingofavector.

简介：Thisstudypresentsthenumericalresultsforthethree-dimensionalnaturalgas-airmixinginarectangularsubsonicchannelunderthestandarddatumstate.ThelowerandupperdecompositionmethodwasemployedtoobtainthesolutionsofthefullNavier-Stokesequationscapableofdescribingcompressiblefluidmixing.Gridwasgeneratedbytheareaorthogonaltechnique.Theresultsindicatethatthree-dimensionalmixingbetweenNaturalGas(NG)andairhasmorecomplicatedcompressiblewavesaroundtheinjectionnozzle.Thepresenceofinjectionwithlargespeedcansuppresstheboundaryseparationhappenedoccurringatthetopwallduetothechannelexpansion,butmakesthenear-wakeflowmorecomplicated.Themixingregioncanbewidenedbyincreasingtheinjectionspeed.TherecurrenceofthevortexstructureandthecoherentstructurecanbefoundfromthefullNavier-Stokessimulation.ItcanbeconcludedthattheincreaseintheinjectionvelocitycanimprovetheeffectivenessofmixingofNGandairinthenearwakeoftheinjectors.

简介：Inthiswork,weperformanumericalstudyofawaterflowoverasteppedspillway.ThisflowisdescribedbytheReynoldsaveragedNavier-Stokesequation(RANS)associatedwiththeturbulencek-εmodel.Theseequationsaresolvedusingacommercialsoftwarebasedonthefinitevolumeschemeandanunstructuredmesh.Theair-waterflowwasmodeledusingvolumeoffluid(VOF)andmultiphasicmethods.Thecharacteristicsoftheflowwereinvestigatedincludingthetotalpressure,thevelocityprofile,etc..Weanalyzetheeffectsontheflowstructureofthestepsandcountermarchinclination,theairinjectionthroughthecountermarchintothewaterflowandthedynamicswaterdischarges.Resultsshowthattheinclinationofthecountermarchrelativetotheverticalandtheairinjectionintothewaterflowincreasethetotalpressureintheneighbourhoodofthesteps.

简介：Theaimofthisexperimentalstudyistoinvestigatetheeffectsofhydraulicparametersontheformationofair-entrainingvorticesathorizontalintakestructureswithoutapproachflowinducedcirculation.Sixintakepipesofdifferentdiametersweretestedinthestudy.Theintakepipetobetestedwashorizontallymountedtothefrontsideofalargereservoirandthenforawiderangeofdischargesexperimentswereconductedandcriticalsubmergencesweredetectedwithadjustableapproachchannelsidewalls.Empiricalequationswerederivedforthedimensionlesscriticalsubmergenceasafunctionoftherelevantdimensionlessparameters.Availabledataisalsocheckedforthepossiblescaleeffect.Then,theseobtainedequationswerecomparedwiththesimilaronesintheliteraturewhichshowedaquitegoodagreement.

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