学科分类
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1 个结果
  • 简介:Thecontrolofturbulencebydimples/pimpleshasdrawnmoreandmoreattention.Theobjectiveofthispaperistoinvestigatetheeffectivenessoftheactivedimples/pimplesforthedragreductionintheincompressibleturbulentflow.Firstly,thedragreductionbytheoppositioncontrolbasedonactivedimples/pimplesatthelowerwallisstudiedviathedirectnumericalsimulationoftheturbulentchannelflow.Itisfoundthatlargeactivedimples/pimplescannotsuppressthestreamwisevorticessignificantlyandthusalmostnodragreductionisachieved.Smallactivedimplesandpimpleswiththediameterofonefourthofthestreakwidthcanbothreducethefrictiondrag,butpimpleswillinducealargerpressuredragthandimples.Thenthesuboptimalcontrolschemeisexaminedbasedonsmallactivedimplesusingthespanwisewallshearinformationonly.Itisshownthatthefrictiondragdecreasesbyabout4.5%butthetotaldragisonlyreducedbyabout2.7%abatedbythepressuredrag.Comparedwiththeactuationoftheall-pointblowing/suctionortheall-pointwallmovement,theeffectivenessoftheturbulentdragreductionbasedonactiveshallowdimplesismuchsmaller.

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