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《基于非定常微射流控制的圓湍射流數(shù)值模擬-研究》由會員上傳分享，免費在線閱讀，更多相關(guān)內(nèi)容在教育資源-天天文庫。
1、哈爾濱工業(yè)大學(xué)工學(xué)碩士學(xué)位論文AbstractTurbulentroundjetiswidelyusedinenvironmentandindustry,andreceivesalotofattentioninthelastdecade.Togetabettercombustionmixingratiooffossilfuels,decreasingcarbondioxide,toxicgasesandPM2.5emissions,rapiddiffusionforcooling,anddenoi
2、sing,etc,mixingenhancementofturbulentjetispopularinthoseresearch,andfluidicinjectionisaneffectivechoiceamongthemeanstogetthis.Thispaperbuiltasimulationplatformofturbulentroundjetwithunsteadymicro-jetcontrolbasedontheopensourceC++librarywhichisOpenFOAM
3、,andcomparedwithCFDcommercialsoftwareAnsysFluent.Wenumericallysimulatedthemixingcharacteristicsoftheturbulentroundjet(R?8000)underunsteadyemicro-jetcontrolbasedonandOpenFOAM.Firstly,differentgeometries(withnozzleandwithoutnozzle),fourmeshgenerationsol
4、utionsandLESturbulentmodelswerediscussedwithoutmicro-jetcontrol.Thenwecomparedthenumericalresultswiththeexperimentalresultsinordertovalidatethemathematicalmodel.Tofurtheranalyzingthemechanismofmixingenhancement,theeffectofactuationfrequencyandmassflow
5、ratioofthemicro-jetonthemixingcharacteristicswereinvestigated.Ithasbeennumericallyfoundoutthat:thedecayrateofthemeanvelocityfirstincreasethendecreasesastheactuationfrequencyincreasingwhentwomicro-jetcontrolwasused.Whentheactuationfrequencyequalstothev
6、ortexsheddingfrequencyoftheturbulentjet,thedecayratereachesthemaximum,whichindicatesthemixingisgreatlyenhanced.Alsowefoundthatwhenthemassflowratiois0.66%,thedecayratehasmaximumvalue.ByanalyzingthevorticalstructurerecognizedbasedonQriterion,ithasbeenfo
7、undthatwhenC<0.25%themicro-jetswereassimilatedintotheshearmlayerofthemainjet;AsCincreasesto0.33%,theshearlayerwaspenetratedbymthemicro-jets,andthemicro-jetsinteractwiththeringvorticesattheoutletofmainjet,resultinginenhancedmixing;WhenCincreasesto4.1%,
8、twomicro-jetscollidemandevolveintooppositelystructures,whichinteractwithringvorticesatthedownstream.Thisworkgainedanimprovedunderstandingoftheenhancedmixingmechanismwithunsteadymicro-jetcontrol,whichprovidesabasisforpromotingtheapplicationandd
