简介:步水池系统和卵石簇是由大石头组成的结构,山streambeds上的卵石由洪水流动重排到达高抵抗和高床稳定性。床结构和床负担运动能保护河床免受切口的伤害。在每个步水池,流动精力被转变成骚乱,并且最后进热。床负担运动也消费流动精力并且起一个作用保护床免受侵蚀的伤害。有床的床负担粒子的碰撞导致力量,作为散力量知道,它平衡电梯力量并且控制床的侵蚀沉积。域调查和域实验在中国的云南贵州高原上在Xiaojiang河盆被进行,在与床负担运动或与步水池系统有切入的流和稳定的流的地方。这研究表明为给定的溪流力量,强壮的床结构与被联系低或零床负担交通;并且弱或没有床结构与集中的床被联系负担运动。如果有床负担运动或有床结构,实验证明为切入的溪流,最后的床侧面是一样。当钥匙投掷完成了床结构那时,例如在步的大大石头,被移开,流动立即搜索了沉积床。严厉地到100次和床负担的中部的直径增加的床负担交通到2-20时间增加了。床结构和床负担运动为他们流动精力消费和streambed切口控制上的效果是互相可替代的。这是床负担运动和床结构的相等的原则。在一个很强壮的步水池系统发展了的地方,,尽管是由于原则在Yalutsangpo宏大峡谷没有床负担运动床坡度并且砍流动的应力极其高。为三个峡水坝的下游的活动范围的切口控制的这个原则的一个可能的应用程序也在这份报纸被讨论。
简介:Theparticlesizedistributionofbedmaterialsinthesandyriverbedofalluvialriversisimportantinthestudyoftopicssuchasfriction,riverbedevolution,erosion,andsiltation.Italsocanreflectthedependencyrelationbetweenriverbedsedimentandflowintensity.Inthispaper,thecriticalpatternofsedimentmovementinthenear-wallregionofasandyriverbedwasanalyzed.Accordingtotheprincipleofmomentumbalance,thecriticalsettling-risingconditionofbedmaterialinasandyriverbedwasfoundtobeinstantaneousturbulentvelocityequalto2.7timesthesedimentsettlingvelocityinquiescentwater.BasedonaverticalinstantaneousturbulentvelocitywithaGaussiandistribution,atheoreticalrelationforcalculatingtheparticlesizedistributionofbedmaterialsinasandyriverbedwithoutpre-knowncharacteristicgrainsizeswasdevelopedbysolvingastochasticequation.Theformulaisverifiedusingmeasureddata,andtheresultsshowthattheproposedformulawasinaccordancewiththemeasureddata.Thisstudyhastheoreticalsignificanceandpracticalvaluefordeterminingthebedmaterialparticlesizedistributionofthesandybedofalluvialrivers.
简介:Inthepaperthewaveattenuationinatwolayerfluidsystemisstudied.ThefluidinthetoplayerisidealandthatinthelowerlayeristheVoigtmodeloftheviscoelasticmedium.Adispersionrelationisderivedandtherateofthewavedecayiscomputed.Theapproximateexplicitexpressionsofthedecayratefordifferentwaterdeptharegiven,wheretheviscoelasticityiseitherverylargeorverysmall.Comparedwiththenumericalresults,ourresultsareveryaccurate,whichcanbeusedbyanengineer.
简介:Inthepresentwork,theheattransferstudyfocusesonassessmentoftheimpactofbedtemperatureonthelocalheattransfercharacteristicbetweenafluidizedbedandverticalrifledtubes(38mm-O.D.)inacommercialcirculatingfluidizedbed(CFB)boiler.Heattransferbehaviorina1296t/hsupercriticalCFBfurnacehasbeenanalyzedforGeldartBparticlewithSautermeandiameterof0.219and0.246mm.TheheattransferexperimentswereconductedfortheactiveheattransfersurfaceintheformofmembranetubewithalongitudinalfinatthetubecrestunderthenormaloperatingconditionsofCFBboiler.AheattransferanalysisofCFBboilerwithdetailedconsiderationofthebed-to-wallheattransfercoefficientandthecontributionofheattransfermechanismsinsidefurnacechamberwereinvestigatedusingmechanisticheattransfermodelbasedonclusterrenewalapproach.ThepredictedvaluesofheattransfercoefficientarecomparedwithempiricalcorrelationforCFBunitsinlarge-scale.
简介:FieldexperimentswereconductedontotalloadtransportintheChelichayRiverBasin,amountainouscatchment(1,400km~2)locatedinnortheasternofIran,toevaluatetotalloadformulasincludingfourgravelbedriversandasandbedriver(QaresooRiver).GravelbedriversinChelichayRiverBasincanbegroupedintotwotypes;steepsloperiverswithhighshearvalues(ChehelchayRiverandKhormalooRiver)andmildsloperiverswithlowshearvalues(NarmabRiverandSoosaraRiver).Twodepthintegratingsuspendedloadsamplers(DH-48andD-49),andtwobedloadsamplers(Helley-SmithandBLSH)wereusedtomeasuretotalload.Theperformanceistestedof8totalloadtransportformulaeincluding4macroscopicand4microscopicmethods.Asystematicandthoroughanalysisof59setsofdatacollectedfromsandbedriverindicatethatYangandEngelundandHansenreachtothebetterresults,andfromfourgravelbedriversconfirmedthatthemethodsofKarimandKennedyandEngelundandHansenyieldsthebestresultsforsteepsloperivers,andthemethodsofEinsteinandBijkerarerankedhighestingradualsloperivers.
简介:Fromthegroupmovementofthebedloadwithinthebottomlayer,detailsofthenonlineardynamiccharacteristicsofbedloadmovementarediscussedinthispaper.Whetherthesedimentisinitiatedintomotioncorrespondstowhethertheconstanttermintheequationisequaltozero.Ifconstanttermiszeroandnodispersiveforceisconsidered,theequationrepresentsthetraditionalShieldsinitiationcurve,andifconstanttermiszerowithoutthedispersiveforcebeingconsidered,thenanewShieldscurvewhichismuchlowerthanthetraditionaloneisgot.Thefixedpointoftheequationcorrespondstotheequilibriumsedimenttransportofbedload.Inthemutationanalysis,wehavefoundthattheinflectionpointisthedemarcationpointofbreaking.Intheory,thebreakingpointcorrespondstothedividingboundaryline,acrosswhichthebedformchangesfromflatbedtosandrippleorsanddune.ComparedwiththeexperimentaldataofChatouHydraulicLabinFrance,theconclusionsareverified.
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