学科分类
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6 个结果
  • 简介:ThispaperdescribesanewphenomenonofacousticstreamingwhichtakesplacewhenaHelmholtzresonatorisexcitedbyaninsidesoundsourcewithresonantfrequency,andtakestheformofastrongturbulentjet.Theflowvisualizations,hotwireandLDVmeasurementsarecombinedtoinvestigatetheprocessofacousticstreaming.ItisfoundthatthiskindofacousticstreamingresultsfromthecontributionofReynoldsstress.

  • 标签: ACOUSTIC STREAMING RESONANT FREQUENCY REYNOLDS STRESS
  • 简介:Theacousticemission(AE)featuresinrockfracturearesimulatednumericallywithdiscreteelementmodel(DEM).Thespecimenisconstructedbyusingsphericalparticlesbondedviatheparallelbondmodel.Asaresultoftheheterogeneityinrockspecimen,thefailurecriterionofbondedparticleiscoupledbytheshearandtensilestrengths,whichfollowanormalprobabilitydistribution.TheKaisereffectissimulatedinthefractureprocess,foracubicrockspecimenunderuniaxialcompressionwithaconstantrate.TheAEnumberisestimatedwithbreakagesofbondedparticlesusingapairofparameters,inthetemporalandspatialscale,respectively.ItisfoundthattheAEnumbersandtheelasticenergyreleasecurvescoincide.TherangefortheKaisereffectfromtheAEnumberandtheelasticenergyreleasearethesame.Furthermore,thefrequency-magnituderelationoftheAEnumbershowsthatthevalueofBdeterminedwithDEMisconsistentwiththeexperimentaldata.

  • 标签: 声发射 元模型 岩石断裂 KAISER效应 离散 岩石试样
  • 简介:Acousticfatiguelifeevaluationisessentialforthermalprotectionstructuresduetotheseverethermo-acousticloadinservice.AstudyontemperaturedependenceofacousticfatiguelifeforaC/SiCpanelispresentedinthispaper.EffectsoftemperatureonboththestructuralresponsesandtheS–Ncurvesareinvestigated.TheDirlikmethodisadoptedtopredictthefatiguelifeofaC/SiCpanelatthreedifferenttemperaturesrespectively.Significantdifferencesareobservedfromtheresultsofnumericalsimulationsbetweenthefatiguelivesofthepanelinthethreecases.Thetemperature-dependenceofacousticfatiguelifeofaC/SiCpanelisverified,andfatiguetestofthematerialneedstobemoreattentivelyperformed.

  • 标签: 温度依赖性 疲劳寿命 保护结构 SIC纤维 热防护结构 寿命评价
  • 简介:四种SiO2(510nm)+Fe3O4(44.8m)粒子在一块唯一的声学的地,一个唯一的磁场和一块联合的声学磁性的地里被使流体化。一块单个场地,声学的100dB/4060Hz或10mT的介绍磁性,能压制插并且channeling和还原剂表面的最小的使液化气体速度,Umf。联合声学并且磁场表明了甚至更有希望的结果,特别Umf的更重要的减小。

  • 标签: 流态化 组合声-磁场 声场 超细颗粒