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1、一．InternalFlowandSprayCharacteristicsofPintle-TypeOutwardsOpeningPiezoInjectorsforGasolineDirect-InjectionEnginesDatePublished:2007-04-16PaperNumber:2007-01-1406DOI:10.4271/2007-01-1406Citation:Marchi,A.,Nouri,J.,Yan,Y.,andArcoumanis,C.,"InternalFlowandSprayCharacteristicsofPintle-TypeOutw
2、ardsOpeningPiezoInjectorsforGasolineDirect-InjectionEngines,"SAETechnicalPaper2007-01-1406,2007,doi:10.4271/2007-01-1406.Author(s):A.Marchi-CityUniversity,LondonJ.M.Nouri-CityUniversity,LondonY.Yan-CityUniversity,LondonC.Arcoumanis-CityUniversity,LondonViewAllCollapseAbstract:Thenearnozzle
3、exitflowandspraystructuregeneratedbyanenlargedmodelofasecondgenerationpintletypeoutwardsopeninginjectorhavebeeninvestigatedundersteadyflowconditionsasafunctionofflow-rateandneedlelift.AhighresolutionCCDcameraandhigh-speedvideocamerahavebeenemployedinthisstudytoobtainhigh-magnificationimage
4、softheinternalnozzleexitflowinordertoidentifytheoriginofstringligaments/dropletsformationatthenozzleexit.Theimagesoftheflowaroundthenozzleseatareashowedclearlythatairwasentrainedfromoutsideintothenozzleseatareaundercertainflowoperatingconditions(lowcavitationnumber,CN);theformedairpocketsi
5、nsidetheannularnozzleprovedtobethemaincauseofthebreakingofthefuelliquidfilmintostringsasitemergedfromthenozzlewithastructureconsistingofalternatingthinandthickliquidfilaments.Astheflowrateincreased,theairpocketsweresuppressed,reducedinsizeandpushedtowardstheexitofthenozzleresultinginasmoot
6、herspray.Theresultsshowedthatthenumberofstringsincreasedlinearly,withinthemeasuredrange,withliquidexitvelocityandthatthesprayconeanglewassmallerorlargerthanthenominalvaluedependingontheattachmentofairpocketstothecartridgeorneedlesurfaces,respectively;thesetwodistinctsmallandlargeconeangles
7、werefoundtobedominantatlowandhighlifts.IncreasingtheflowratefurthersothatCNexceedsthecriticalvalue,gaverisetopocketsofvapourthatstartedtoemergeinthenozzleseatregionanddisintegratedrapidlyastheywereconvectedtowardsthenozzleexit.Theanalysisofthenearnozzleflowvis
