spray – 05 - ichmt喷雾–05国际传热传质中心

《spray – 05 - ichmt喷雾–05国际传热传质中心》由会员上传分享，免费在线阅读，更多相关内容在应用文档-天天文库。

1、ExperimentalAnalysisofaLiquidAtomizationProcessatLowWeberNumberDr.ChristopheDumouchelCNRSUMR6614–CORIAUniversitéetINSAdeRouen76801SaintEtienneduRouvray–FranceChristophe.Dumouchel@coria.fr0033232953623Liquidspraysproducedbytheejectionofliquidintoagaseousenvironme

2、ntatrestareconstitutedofdropswithdifferentsizes.Inallapplications,thespraydropsizedistributionisamajorparameterthatneedstobecontrolled.However,predictionsofdropsizedistributioninanysituationsarenotpossiblesofaranddependlargelyonempiricalknowledge.Themainreasonfo

3、rthisisthatverylittleisknownaboutthewayligamentsanddropsaretornofffromaperturbedliquidflowduetoadeficitofexperimentalinvestigationsonthistopic.Mostexperimentalapproachesprovidecorrelationsbetweensomeworkingconditions(injectionpressure,nozzledimensions)andmacrosc

4、opiccharacteristicfeaturesoftheissuingflow(angle,break-uplength)orcharacteristicsofthespray(meandiameter,dispersionparameter)butthebehavioroftheliquidflowandthebreak-upmechanismareveryseldomstudieddespitetheirimportanceintheprocess.Exceptinspecificsituations,liq

5、uidatomizationisaprocessofliquid-gasinterfaceareaproduction.Assoonastheliquidissuesfromthenozzle,itisperturbedbyinstabilitieswhosegrowthinducesanincreaseoftheliquid-gasinterface.Thisphenomenoncontinuesuntilliquidbreak-upoccurs,stoppingtheliquid-gasinterfaceincre

6、ase.Thedropsizedistributionoftheresultingspraydependsontheamountandontheshapeofliquid-gasinterfaceattheinstantofbreak-up:themoreinterfaceisproduced,thesmallerthediameterofthedrops.Theliquidgasinterfaceanditsrelationshipwiththespraydropsizedistributionappeartobei

7、mportantpointstobeaddressed.Fornon-airassistedatomizationprocesses,whicharethoseconsideredhere,theinitialenergygiventotheliquidviatheinjectionpressureDPiisdividedinthreeparts.Themainpartistransmittedtothefluidasflowingkineticenergy.Thesecondpartisdissipatedinfri

8、ctions.Thethirdpartincludesenergiesconveyedbytheliquidflowotherthantheflowingkineticenergy(non-axialliquidflow,turbulenceorcavitation…).Thepartdissipatedinfrictionsis