带肋横流对凹槽孔气膜冷却特性影响的机理研究.docx

带肋横流对凹槽孔气膜冷却特性影响的机理研究
摘要
本文研究了带肋横流对凹槽孔气膜冷却特性的影响机理。通过实验和数值模拟，研究发现，带肋横流可以促进冷却气膜的混合和换热，从而提高冷却效果。同时，肋片几何尺寸和流体入口速度也会对气膜冷却特性产生影响。本文研究结果可以为制定更有效的航空发动机冷却方案提供参考。
关键词：带肋横流；凹槽孔；气膜冷却特性；数值模拟；实验
Introduction
Withthedevelopmentofaviationtechnology,jetengineshavebecomemoreandmorepowerful.However,thehigherpoweroutputhasalsoincreasedtheheatloadoftheengine.Therefore,coolingtechnologyisacriticalpartoftheaircraftenginedesign.Filmcoolingisacommonlyusedtechniquetoprotectenginecomponentsfromhightemperaturedamage.Infilmcooling,acoolantfilmisinjectedontothesurfaceofahotcomponenttoformaprotectivelayer.Thecoolantfilmcanbeformedbyeitherpressure-sensitiveholesorslots.
Theuseofribbedinsertsinjetengineshasbeeninvestigatedforseveralyears.Ribbedinsertscanenhanceturbulenceandheattransferinthecoolantflow,leadingtobettercooling.
Inthispaper,theeffectofribbedinsertsonthecoolingcharacteristicsofslotfilmcoolingisstudiedthroughnumericalsimulationandexperimentaltests.Themechanismoftheeffectisanalyzedindetail.
Experimentandsimulation
TheexperimentalapparatususedtotestthecoolingeffectsofribbedflowinslotfilmcoolingisshowninFigure1.Thetestsectionconsistsoftwoflatplatesseparatedbyaninsulatinglayer.Theupperplateisheatedbyanelectricalheatertosimulatethehotsurfaceofanenginecomponent.Thelowerplateisthecoolantoutlet.Thefluidisinjectedthroughaslotalongthecenterlineoftheupperplate.
Theribbedflowinsertsareplacedonthesurfaceoftheupperplate.Theribsarecylindricalpillarsthatstandperpendiculartothesurface.ThegeometricdimensionsoftheribsareshowninTable1.
Theribbedinsertsarearrangedinastaggeredconfiguration,asshowninFigure2.
[Figure1]
[Table1]
[Figure2]
ThecoolantflowandheattransferprocessaresimulatedusingthecommercialCFDsoftwareANSYSFluent.Atwo-dimensionalmodelisbuiltbasedonthetestsection.ThecoolantflowismodeledwiththeReynolds-averagedNavier-Stokesequations.Theturbulenceismodeledusingthek-ωSSTmodel.
Resultsanddiscussion
Theheattransfercoefficientandcoolantfilmcoverageareusedasindicatorsofthecoolingperformance.Theheattransferc