简介：Dropshaftsareverticalstructureswidelyusedinurbandrainagesystemsandbuildingsforwatertransportation.Inthispaper,aphysicalmodelstudywasconductedtoinvestigatetheairentrainmentinthedropshaftundervariousflowregimeswithandwithoutairventilation.Observedfromtheexperiments,theairentrainmentmechanismsvariedwiththewaterflowregimesinthedropshaft.Whentherewasnowaterplugformedinthedropshaft,aircouldbesupplieddirectlyfromdownstream.Oncethewaterplugwasformed,whilewithoutventing,theairwasreplenishedonlyfromdownstreamintermittentlyandthenintheformoflargeairbubbletravelingupwardstotheairspaceatthetop;whilewithventing,airwasmainlyreplenishedfromthedropshafttopandnolargeairbubblewasobserved.Theexperimentalresultsalsoshowedthattheamountofentrainedairinthedropshaftwithventingwasgreaterthanthatwithoutventing.

简介：Thevibrationmethodrepresentsapracticalmethodforthemeasurementofadhesionforcesandadhesionforcedistributions.Thismethodcausessinusoidallyalternatingstressesandyieldsdetachmentandcontactforcesbetweenparticlesandsubstrateofthesameorderofmagnitude.Alternatingcontactforcesofthevibrationmethodcancauseanadhesionforceintensificationthroughflatteningofasperities.Themeasuringprincipleofthevibrationmethodandtheanalysisofexperimentalresultsaredescribedinthearticle.Normaladhesionforces(pull-offforces)aremeasuredusingthevibrationmethodandthecolloidalprobetechnique.Theresultsofbothmethodsshowgoodagreementforsmallparticlesizes.Theinfluenceofthedetachmentforcedirectionisshownbycomparingtangentialandnormaladhesionforcesmeasuredusingparticlereentrainmentinaturbulentairflowandthevibrationmethod,respectively.Thesurfaceroughnessofthesubstrateandtherelativehumidityareshowntosignificantlyinfluencethemeasuredadhesionforces.Forthecalculationoftheadhesionforces,anapproachbyRabinovichwascombinedwithapproximationsofplasticmicroasperityflattening.TheRabinovichapproachaccountsforroughnesseffectsonthevanderWaalsforcebyincorporatingthermsroughnessoftheinteractingsurfaces,rms-valuesoftheparticlesandsubstratesweremeasuredwithatomicforcemicroscopyatdifferentscanningareas.

简介：Airdistributionincommercialairlinercabinsisveryimportantforthecomfortandhealthofpassengersandcrew.Experimentalmeasurements,computationalfluiddynamics(CFD)simulations,andinversemodelingarestate-of-the-artmethodsavailableforstudyingtheairdistribution.Thispapergaveanoverviewofthediferentexperimentalmodels,suchasscalemodels,simplifiedmodels,full-scalemockups,andactualaircabins.Althoughexperimentalmeasurementswereexpensiveandtimeconsuming,thedatawereessentialforvalidatingCFDsimulations.DiferentmodelingstrategiesforCFDsimulationswerealsodiscussedinthispaper,includinglargeeddysimulationsandReynoldsaveragedNavier–Stokesequationmodeling.CFDsimulationsweremainstreamapproachesforstudyingtheairdistributionbuttheycouldnoteasilyleadtooptimaldesign.Inversemodelingofairdistributionhasrecentlyemergedintoaverypowerfulandattractivetoolfordesigningtheairdistributioninairlinercabins,althoughmostofthestudieswerepreliminary.

简介：Theunifiedgas-kineticscheme(UGKS)ispresentedandusedinthislettertostudythesliderairbearingproblem.TheUGKSsolutionsarefirstvalidatedbycomparisonwithdirectsimulationMonteCarloresults.Aftervalidation,theUGKSisusedtostudytheair-bearingproblemunderdifferentnonequilibriumconditions.Onthesurfaceoftheslider,thedependencyofthegaspressureandnormalforceontheMachandKnudsennumbersarefullyevaluated.Thenon-equilibriumeffectontheforceloadinginthewholetransitionregimeuptothefreemolecularlimitisalsostudied.

简介：为水里的大球形的水泡，几何光学近似为散布模式的精明的光被认为一个更好的方法。在这份报纸，几何光学近似的基本理论被澄清。当全部的思考发生时，为水泡的阶段的变化被计算，它与有比1大的相对折射索引的粒子不同。方法的确认被假定一个球形的粒子并且把现在的结果比作Mie散布和Debye计算完成。当无尺寸的尺寸参数比50大时，对Mie理论的同意在所有方向是优秀的。几何光学近似的限制也被讨论。

简介：Experimentswereconductedtostudythegenerationofaircoreanditseffectontheoutflowshapeanddischargeinacylindricalwatertankwithabottomwell-designedoutlet.Dependingonthestagesoftheaircoreinthetank,theoutflowshapecanvaryfromasmoothwaterjettoasmoothspindleshapewithair-core,andtowatersprays.Thediameterofthenozzlesizealsohasinfluenceontheoutflowpattern.Theexistenceofthepenetratedaircorecandramaticallyreducetheoutflowdischarge,withthedischargecoefficientdecreasingwiththenozzlediameter.

简介：Wingfappingandmorphingcanbeverybenefcialtomanagingtheweightofmicroairvehiclesthroughcouplingtheaerodynamicforceswithstabilityandcontrol.Inthisletter,harvestingenergyfromthewingmorphingisstudiedtopowercameras,sensors,orcommunicationdevicesofmicroairvehiclesandtoaidinthemanagementoftheirpower.Theaerodynamicloadsonfappingwingsaresimulatedusingathree-dimensionalunsteadyvortexlatticemethod.Activewingshapemorphingisconsideredtoenhancetheperformanceofthefappingmotion.Agradient-basedoptimizationalgorithmisusedtopinpointtheoptimalkinematicsmaximizingthepropellentefciency.Tobeneftfromthewingdeformation,weplacepiezoelectriclayersnearthewingroots.Gausslawisusedtoestimatetheelectricalharvestedpower.Wedemonstratethatenoughpowercanbegeneratedtooperateacamera.Numericalanalysisshowsthefeasibilityofexploitingwingmorphingtoharvestenergyandimprovingthedesignandperformanceofmicroairvehicles.

简介：Asawidelyusedfloodenergydissipator,thesteppedspillwaycansignificantlydissipatethekineticorhydraulicenergyduetotheair-entrainmentinskimmingflowoverthesteps.Thefree-surfaceaerationinvolvesthesharpdeformationofthefreesurfaceandthecomplexturbulentshearflows.Inthisstudy,thevolumeoffluid(VOF),mixture,andEulerianmethodsareutilizedtosimulatetheair-entrainmentbycouplingwiththeReynolds-averagedNavier–Stokes/largeeddysimulation(RANS/LES)turbulencemodels.Thefreesurfacedeformation,airvolumefraction,pressure,andvelocityarecomparedforthethreedifferentnumericalmethods.OnlytheEulerian+RANSmethodfailstocapturethefree-surfaceaeration.TheairvolumefractionpredictedbytheVOF+LESmethodbestmatchestheexperimentalmeasurement,whilethemixture+LESmethodpredictstheinceptionpointoftheairentrainmentmoreaccurately.

简介：InChinamorethantwo-thirdsofavailablecoalreservesareinaridareas,where,tobeneficiatetherun-of-minecoal,thereisnotenoughwaterresourcerequiredbyconventionalprocessing.DevelopingefficientdrybeneficiationtechnologyisofgreatsignificanceforefficientcoalutilizationinChina,notablythecleancoaltechnology(CCT).Thedrycoalbeneficiationtechnologywithair-densemediumfluidizedbedutilizesair-solidsuspensionasbeneficiatingmediumwhosedensityisconsistentforbeneflciation,similarinprincipletothewetdensemediumbeneficiationusingliquid-solidsuspensionasseparatingmedium.Theheavyportioninfeedstockwhosedensityishigherthanthedensityofthefluidizedbedwillsink,whereasthelighterportionwillfloat,thusstratifyingthefeedmaterialsaccordingtotheirdensity.Inordertoobtainefficientdryseparationinair-densemediumfluidizedbed,stablefluidizationwithwelldispersedmicro-bubblesmustbeachievedtoensurelowviscosityandhighfluidity.Thepurebuoyancyofbeneficiationmaterialsplaysamainroleinfluidizedbed,andthedisplaceddistributioneffectshouldberestrained.Thedisplaceddistributioneffectsincludeviscositydisplaceddistributioneffectandmovementdisplaceddistributioneffect.Theformeriscausedbyviscosityofthefluidizedbed.Itdecreaseswithincreasingairflowvelocity.Movementdisplaceddistributioneffectwillbelargewhenairflowrateistoolowortoohigh.Ifmediumparticlesizedistributionandairflowarewellcontrolled,bothdisplaceddistributioneffectscouldbecontrolledeffectively.Abeneficiationdisplaceddistributionmodelmaybeusedtooptimizebeneficiationoffeedstockwithawideparticlesizedistributionandmultiplecomponentsinthefluidizedbed.Therheologicalcharacteristicsoffluidizedbedswerestudiedusingthefallingspheremethod.ExperimentalresultsindicatedthatthefluidizedbedbehavesasaBinghamfluid.Theplasticviscosityandyieldstresscanbe

简介：Theturbulencestructuresnearashearedair-waterinterfacewereexperimentallyinvestigatedwiththehydrogenbubblevisualizationtechnique.Sur-faceshearwasimposedbyanairflowoverthewaterflowwhichwaskeptfreefromsurfacewaves.Resultsshowthatthewindshearhasthemaininfluenceoncoher-entstructuresunderair-waterinterfaces.Low-andhigh-speedstreaksformintheregionclosetotheinterfaceasaresultoftheimposedshearstress.Whenacertainairflowvelocityisreached,'turbulentspots'appearrandomlyatlow-speedstreakswithsomecharacteristicsofhairpinvortices.Atevenhighershearrates,theflowneartheinterfaceisdominatedprimarilybyintermittentburstingevents.Thecoher-entstructuresobservednearshearedair-waterinterfacesshowqualitativesimilaritieswiththoseoccurringinnear-wallturbulence.However,afewdistinctivephenomenawerealsoobserved,includingthefluctuatingthicknessoftheinstantaneousboundarylayerandverticalvorticesinburstingprocesses,whichappeartobeassociatedwiththecharacteristicsofair-waterinterfaces.

简介：

简介：TheRichtmyer–Meshkovinstabilityofa‘V'shapedair/heliumgaseousinterfacesubjectedtoaweakshockwaveisexperimentallystudied.Asoapfilmtechniqueisadoptedtocreatea‘V'shapedinterfacewithaccurateinitialconditions.Fivekindsof‘V'shapedinterfaceswithdifferentvertexanglesareformedtohighlighttheeffectsofinitialconditionsontheflowcharacteristics.Theresultsshowthataspikeisgeneratedaftertheshockimpact,andgrowsconstantlywithtime.Asthevertexangleincreases,vorticesgeneratedontheinterfacebecomelessnoticeable,andthespikedevelopslesspronouncedly.Thelineargrowthrateofinterfacewidthaftercompressionphaseisestimatedbyalinearmodelandarevisedlinearmodel,andthelatterisproventobemoreeffectivefortheinterfacewithhighinitialamplitudes.Thelineargrowthrateofinterfacewidthis,forthefirsttimeinaheavy/lightinterfaceconfiguration,foundtobeanon-monotonousfunctionoftheinitialperturbationamplitude–wavelengthratio.

简介：AvisualizedinvestigationwascarriedoutontheeffectofthedivergingangleonthebubblemotionandinterfacialbehaviorinaVenturi-typebubblegenerator.Itwasfoundtwoorthreelargevortexesformedinthedivergingsection,resultinginstrongreentrantjetflowinthefrontofthebubblesorslugsrushingoutofthethroat.Thejetflowinreturnbumpsintotheongoingbubblesorslugs,leadingtostronginteractionbetweenthegasandliquidphases.Thediverginganglehassignificantinfluenceonthereentrantflowprocessandtheperformanceofthebubblegeneratoraswell.Increasingthedivergingangleresultsinthereentrantflowmovingfurtherforwardtotheupstreamandintensifiestheinteractionbetweenthetwophases.Asaconsequence,thebreakuporcollapseofbubblesbecomesmoreviolent,wherebyfinerbubblesaregenerated.Assuch,thereentrantflowstronglylinkstotheperformanceoftheVenturichanneltakenasabubblegenerator,andthatamoderateincreaseinthediverginganglecanimproveitsperformancewithoutadditionalincreaseinflowresistancelikethatbyincreasingliquidflowrate.

简介：

简介：Theauthorsinvestigateadisturbance-compensatingandenergy-savingcontrolmethodforairturbinespindlesequippedwitharotationcontrolsystemdesignedforuseinultra-precisionmilling.Thecontrollabilityandenergy-conservingcharacteristicsoftheproposedmethodusingtheproposedpneumaticregulatingdevice,calledahigh-precisionquick-responsepneumaticpressureregulator,weredemonstratedexperimentallypreviously.Herein,theproposedrotation-controlledairturbinespindleisfirstsummarised.Subsequently,theproposedrotation-controlledairturbinespindleissettoamillingmachineandappliedtothemillingofanalloytoolsteel,togaindataandvalidatetheeffectivenessofthein-processtoolwearestimationmethodthathavebeenrecentlydevelopedandproposedbytheauthors.Particularly,toevaluatethepossibilityofapplyingtheproposedestimationmethodtothree-dimensionalmilling,millingexperimentswheretheairturbinespindleissetata45°inclinewereconductedandtheresultsindicateahighpossibilityoftheproposedmethod.

简介：Theauthorsinvestigateadisturbance-compensatingandenergy-savingcontrolmethodforairturbinespindlesequippedwitharotationcontrolsystemdesignedforuseinultra-precisionmilling.Thecontrollabilityandenergy-conservingcharacteristicsoftheproposedmethodusingtheproposedpneumaticregulatingdevice,calledahigh-precisionquick-responsepneumaticpressureregulator,weredemonstratedexperimentallypreviously.Herein,theproposedrotation-controlledairturbinespindleisfirstsummarised.Subsequently,theproposedrotation-controlledairturbinespindleissettoamillingmachineandappliedtothemillingofanalloytoolsteel,togaindataandvalidatetheeffectivenessofthein-processtoolwearestimationmethodthathavebeenrecentlydevelopedandproposedbytheauthors.Particularly,toevaluatethepossibilityofapplyingtheproposedestimationmethodtothree-dimensionalmilling,millingexperimentswheretheairturbinespindleissetata45°inclinewereconductedandtheresultsindicateahighpossibilityoftheproposedmethod.