简介：TheintrinsicphysicalrelationshipofvorticitybetweenmodesAandBinthethree-dimensionalwaketransitionisinvestigated.Directnumericalsimulationsfortheflowpastasquare-sectioncylinderarecarriedoutatReynoldsnumbersof180and250,associatedwithmodesAandB,respectively.Basedontheanalysisofspacialdistributionsofvorticityinthenearwake,characteristicsoftheverticalvorticityinmodesAandBareidentified.Moreover,therelationshipofthreevorticitycomponentswithspecificsignsissummarizedintotwosignlaws,asintrinsicphysicalrelationshipsbetweentwoinstabilitymodes.Bythetheoryofvortex-inducedvortex,suchtwosignlawsconfirmthattherearetwoandonlytwokindsofvortex-sheddingpatternsinthenearwake,justcorrespondingtomodesAandB.Inbrief,alongthefreestreamdirection,modeAcanbedescribedbytheparallelsheddingverticalvorticeswiththesamesign,whilemodeBisdescribedbytheparallelsheddingstreamwisevorticeswiththesamesign.Finally,itisfoundoutthatthe-typevortexisabasickindofvortexstructureinbothmodesAandB.

简介：这份报纸集中于调查相互作用效果为打漩并且在稳定的火焰过程直率身体。粒子图象velocimetry被用来在三个炉子测量速度领域。首先，在直率身体的稳定的炉子有或没有的火焰的比较打漩被介绍。实验的结果介绍直率身体的稳定的火焰的变化什么时候打漩，被增加进炉子：最大的反向的流动速度和最大的平均数平均光线的速度减少；最大的光线的根平均数摆平波动(rms)速度增加；嘴轴的方面上的轴的速度山峰的价值更低，并且在山峰和中心线之间的距离更大；最大的光线的rms速度的地点从中央再通行地区(CRZ)搬到环形的气流的插头。然后，火焰在的比较打漩炉子有或没有直率身体被提供。实验的结果显示出打漩的变化火焰什么时候直率身体被增加进打漩炉子：在CRZ的空气旋涡搬到炉子；轴的平均数和rms速度减少的山峰价值；在中心线和轴的平均数和rms速度山峰增加之间的距离；吝啬的光线的速度减少的山峰，和rmsraidial速度增加的山峰。从这个实验的数据能也为燃烧的发展和确认作为基准被建立数字模拟。

简介：Open-loopflowcontrolmethodwasusedtoaffectthedevelopmentofaturbulentwakebehindaD-shapedbluffbody.Loudspeakerswereembeddedinsidethebluffbodytoproducetwozero-net-massfluxjetsthrough2mm-widespan-wiseslotslocatedalongtheupperandloweredgesontherearwall.Thedragforcesfordifferentactuationamplitudes(C_μtheratiobetweenthemomentumoftheactuatingjetsandthemomentdeficitcausedbythebluffbody)andfrequencies(Sr_A)wereexamined.Theeffectsofthephasedifferenceinthetwojets(0andπ)werealsostudied.ItwasfoundthatwhenC_μwas0.1%,adragreductionupto5%wasachievedwhenthevelocitiesofthetwojetsvariedinphaseatafrequencyofSt_A=0.16.Whenthevelocitiesofthetwojetsvariedrroutofphase,significantdragincreasewasobserved.