简介：Thechemicaloxygen–iodinelaser(COIL)istheshortest-wavelengthhigh-powerchemicallaserthathasbeendemonstrated.Thecharacteristics,suchasgoodatmosphericpropagation,shortwavelengthandexcellenttransmissionthroughopticalfibers,maketheCOILagoodcandidateforhigh-powerlaserapplication.TomodelthecompleteCOILlasinginteraction,athree-dimensionalformulationofthefluiddynamics,speciescontinuityandradiationtransportequationsisnecessary.Thecomputationalefforttocalculatetheflowfieldovertheentirenozzlebankwithagridfineenoughtoresolvetheinjectionholesissolargeastoprecludedoingthecalculation.Theapproachtomodelingchemicallasersthenhasbeentoreducethecomplexityofthemodeltocorrespondtotheavailablecomputationalcapability,addingdetailsascomputingpowerincreased.ThemodelingoflasingintheCOILmediumisproposed,whichiscouplingwiththeeffectsinducedbytransverseinjectionofsecondarygases,non-equilibriumchemicalreactions,nozzletailflowandboundarylayer.ThecoupledsteadysolutionsofthefluiddynamicsandopticsinaCOILcomplexthree-dimensionalcavityflowfieldareobtainedfollowingtheproposal.Themodelingresultsshowthattheseeffectshavesomeinfluenceonthelasingproperties.Afeasiblemethodologyandatheoreticaltoolareofferedtopredictthebeamqualityforlarge-scaleCOILdevices.
简介：Powdermetallurgy(PM)superalloysareanimportantclassofhightemperaturestructuralmaterials,keytotherotatingcomponentsofaeroengines.InthepurviewofthepresentchallengesassociatedwithPMsuperalloys,twonovelapproachesnamely,powderpreparationandtheinnovativespray-formingtechnique(formakingturbinedisk)areproposedandstudied.Subsequently,advancedtechnologieslikeelectrode-induction-meltinggasatomization(EIGA),andspark-plasmadischargespheroidization(SPDS)areintroduced,forceramic-freesuperalloypowders.Presently,newprocessingroutesaresoughtafterforpreparingfinerandcleanerrawpowdersfordisksuperalloys.Theprogressofresearchinspray-formedPMsuperalloysisfirstsummarizedindetail.Thespray-formedsuperalloydisksspecificallyexhibitexcellentmechanicalproperties.ThispaperreviewstherecentprogressininnovativetechnologiesforPMsuperalloys,withanemphasisonnewideasandapproaches,centraltotheinnovationdrivingtechniqueslikepowderprocessingandsprayforming.
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