简介：Thispaperinvestigatestheswimmingperformanceoffishundulatorymotionwhichisthebasicforminlocomotionofaquaticalanimalfromahydrodynamicspointofview.Inparticular,thepropulsivecharacteristicsisdiscussed.Thethree-dimensionalpotentialflowoveramodelrectangularflexibleplateperformingthemotionwhichconsistsofaprogressivewaveofagivenwavelengthandphasevelocityalongthechordistreated.Vortexringmethodisusedtocalculatethethrust,thepowerrequiredandthehydrodynamicpropulsiveefficiency,etc.Thedependenceoftheseenergeticsoncertainphysicalparameters,suchastheaspectratio,thereducedfrequencyandthewavenumber,isdiscussed.Itisfoundthatasthewavetengthgetsclosetothebodylength,propulsiveperformanceisnolongersensitivetotheaspectratio.Somequalitativeexplanationofthefishswimmingphenomenaisalsogiven.

简介：Theacousticperformanceofthestructureformeasuringcavitationnoiseistheoreticallyanalysed,andtwojudgingcriteriaoftheacousticperformanceofSTW（soundtransmissionwindow）arepresentedinthispaper.OneisofimpedancematchingbetweenworkingliquidandSTW:ρ1C1=ρ2C2.Theotherisofmaximumfrequency（orminimumwavelength）ofcavitationnoisespectrum:fmax≤c/60D(orλmin/D≥60).Ifeitherofthecriteriaismetreliablemeasuredresultsofcavitationnoisewillbeobtained.Thetheoreticalresultsareverifiedthroughexperi-ments.Accordingtothecriteria,thepaperanalysestheacousticperformanceofroutinelyusedplexiglassSTW.Theresultsshowthatintheresearchofclearwatercavitationtheimpedanceratio,2.18,doesnotsatisfyρ1C1=ρ2C2,andfmax≤C/60Dhardlyholdsforactualcavitationnoisespectrum.Therefore,plexiglassSTWisnotgoodenoughforsoundtransmission.Fromthispointofview,polyethyleneisbettersoundtransmissionmaterialthanplexi-glass.

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

简介：InspiredbyDryobalanopsaromaticaseed,anewbiomimicrymarinecurrentturbineisproposed.Hydrodynamicperformanceandwakepropertiesaretwokeyfactorsdeterminingwhetheranewmarinecurrentturbinedesignispracticalornot.Thus,astudyofhydrodynamicperformanceandwakeoftheproposedbiomimicryturbineisconducted.Thecomputationalfluiddynamics(CFD)software,OpenFOAMisusedtogeneratetherequiredresultsforthementionedstudy.ThehydrodynamicperformanceandwakepropertiesoftheproposedbiomimicryturbineiscomparedtotwoconventionalturbinesofBahajetal.andPinonetal.respectively.Thesimulationresultsshowedthattheproposedbiomimicrymarinecurrentturbinegivesoptimumpoweroutputwithitspowercoefficient,0.376PC≈atthetipspeedratio(TSR)of1.5.Underthesameboundaryconditions,themaximumtorqueproducedbytheproposedbiomimicryturbineatzerorotationalspeedis38.71Nmwhichis1110%greaterthanthetorquegeneratedbytheturbineofBahajetal..Therecoverydistanceforthewakeofthebiomimicryturbineispredictedtobe10.6%shorterthanthatofIFREMER-LOMCturbine.Theabove-mentionedresultsconfirmthepotentialapplicationoftheproposedbiomimicrymarinecurrentturbineintherenewableenergyindustry.

简介：Inthisarticle,thelowpressureaxialflowfanwithcircumferentialskewedrotorblade,includingtheradialblade,theforward-skewedbladeandthebackward-skewedblade,wasstudiedwithexperimentalmethods.Theaerodynamicperformanceoftherotorswasmeasured.Atthedesignconditionatoutletoftherotors,detailedflowmeasurementswereperformedwithafive-holeprobeandaHot-WireAnemometer(HWA).Theresultsshowthatcomparedtotheradialrotor,theforward-skewedrotordemonstratesawiderStableOperatingRange(SOR),isabletoreducethetotalpressurelossinthehubregionandmakemainloadingofbladeaccumulatinginthemid-spanregion.Thereisawiderwakeintheuppermid-spanregionoftheforward-skewedrotor.Comparedtotheradialrotor,inthebackward-skewedrotorthereishighertotalpressurelossnearthehubandshroudregionsandlowerlossinthemid-spanregion.Inaddition,thevelocitydeficitinthewakeisloweratmid-spanofthebackward-skewedrotorthantheforward-skewedrotor.