Mild Combustion in Homogeneous Charge Diffusion Ignition (HCDI) regime .pdf

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1、ProceedingsoftheCombustionInstituteProceedingsoftheCombustionInstitute31(2007)3409–3416www.elsevier.com/locate/prociMildCombustioninHomogeneousChargeDiffusionIgnition(HCDI)regimeabbb,*M.deJoannon,A.Matarazzo,P.Sabia,A.CavaliereaIstitutodiRicerchesullaCombustione–

2、C.N.R.,Naples,ItalybDipartimentodiIngegneriaChimica–Universita`FedericoII,Naples,ItalyAbstractThepaperdealswithasubcategoryofMildCombustion,whichhasbeennamedHomogeneousChargeDiffusionIgnition(HCDI).Itisanalyzedthroughcharacterizationofprocessesthattakeplaceincoun

3、ter-diffusionconfigurationobtainedbytwoopposedjetsofthefreshair–fuelmixtureandinertflow.Thereac-tivefieldismodeledthroughanumericalcodeexploitingadetailedchemicalkineticsschemeofO2/CH4/N2system.Distributionsoftemperatureandenthalpyasafunctionofthespatialcoordinatean

4、dthemixturefractionareobtainedfordifferentvaluesoftheexternalparameters,i.e.themaximumtemperatureincrease,thefreshmixturetemperature,theinertgasmixture,thereferencestrainrate.Theycanbeclas-sifiedinfourmaincategoriesonthegroundoflocationandbroadnessoftheheatrelease

5、andoccurincon-tiguousexclusiveregionsofexternalparametersplots.Continuoustransitionsbetweenregionsarecharacterizedbysinglesolutions,whereasextinction/ignitiondiscontinuousmechanismsareobtainedintransitionregionswheredoublesolutionsareallowed.Uniquecharacteristic

6、s,differentfromthoseofdef-lagration,emergedforwell-identifiedrangesofexternalparameters.Theyarerelatedtoadistributionoftheheatreleaseinabroadspatialandmixturefractionrange.Theoperativeconditions,forwhichsuchpeculiarbehavioroccurs,arecoincidentwiththosewhereMildCom

7、bustionisexpectedtotakeplaceonthegroundofits‘‘apriori’’definition.Ó2006PublishedbyElsevierInc.onbehalfofTheCombustionInstitute.Keywords:Dilutedcombustion;Combustionregimes1.Introductionturedifference[2,3]).Intheseconditionsthesystemisexpectedtoautoignite,butnottob

8、eMildCombustionregimes,accordingtothecapabletostabilizedeflagrativeor‘‘traditional’’definitionreportedinliterature[1–3],occurindiffusiveflames.Eveniftheliteratureonthesep