简介：Toexploretheeffectofthegassourceflowrateontheactualdieselexhaustparticulatematter(PM),atestbenchfordieselengineexhaustpurificationwasconstructed,usingindirectnonthermalplasmatechnology.Theeffectsofdifferentgassourceflowratesonthequantityconcentration,composition,andapparentactivationenergyofPMwereinvestigated,usinganengineexhaustparticlesizerandathermo-gravimetricanalyzer.Theresultsshowthatwhenthegassourceflowratewaslarge,notonlythemaximumpeakquantityconcentrationsofparticleshadalargedrop,butalsothepeakquantityconcentrationsshiftedtosmallerparticlesizesfrom100nmto80nm.Whenthegassourceflowratewas10Lmin~(-1),thetotalquantityconcentrationgreatlydecreasedwheretheremovalrateofparticleswas79.2%,andthevariationofthedifferentmodeparticleproportionwasobvious.Non-thermalplasma(NTP)improvedtheoxidationabilityofvolatilematteraswellasthatofsolidcarbon.However,theNTPgassourceratehadlittleeffectsonoxidationactivityofvolatilematter,whileitstronglyinfluencedtheoxidationactivityofsolidcarbon.Consideringthequantityconcentrationandoxidationactivityofparticles,agassourceflowrateof10Lmin~(-1)wasmoreappropriateforthepurificationofparticles.

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简介：Dielectric-barrierdischarges(DBDs)inatmosphericpressureairhavebeenstudiedbyusingapower-frequencyvoltagesource.InthispapertheelectricalcharacteristicsofDBDsus-ingglassandaluminadielectricshavebeeninvestigatedexperimentally.AccordingtotheLissajousfiguresofvoltage-charges,itisdiscoveredthatthedischargepowerforanaluminadielectricismuchhigherthanthatforaglassdielectricatthesameappliedvoltage.Also,thevoltage-currentcurvesoftheglassandaluminadielectricsconfirmthefactthatthedielectricbarriersbehavelikesemiconductingmaterialsatcertainappliedvoltages.

简介：Amodellingstudyisperformedtocomparetheplasmaflowandheattransfercharacteristicsoflow-powerarc-heatedthrusters(arcjets)forthreedifferentpropellants:hydrogen,nitrogenandargon.Theall-speedSIMPLEalgorithmisemployedtosolvethegoverningequations,whichtakeintoaccounttheeffectsofcompressibility,LorentzforceandJouleheating,aswellasthetemperature-andpressure-dependenceofthegasproperties.Thetemperature,velocityandMachnumberdistributionscalculatedwithinthethrusternozzleobtainedwithdifferentpropellantgasesarecomparedforthesamethrusterstructure,dimensions,inlet-gasstagnantpressureandarccurrents.Thetemperaturedistributionsinthesolidregionoftheanode-nozzlewallarealsogiven.Itisfoundthattheflowandenergyconversionprocessesinthethrusternozzleshowmanysimilarfeaturesforallthreepropellants.Forexample,thepropellantisheatedmainlyinthenear-cathodeandconstrictorregion,withthehighestplasmatemperatureappearingnearthecathodetip;theflowtransitionfromthesubsonictosupersonicregimeoccurswithintheconstrictorregion;thehighestaxialvelocityappearsinsidethenozzle;andmostoftheinputpropellantflowstowardsthethrusterexitthroughthecoolergasregionneartheanode-nozzlewall.However,sincethepropertiesofhydrogen,nitrogenandargon,especiallytheirmolecularweights,specificenthalpiesandthermalconductivities,aredifferent,thereareappreciabledifferencesinarcjetperformance.Forexample,comparedtotheothertwopropellants,thehydrogenarcjetthrustershowsahigherplasmatemperatureinthearcregion,andhigheraxialvelocitybutlowertemperatureatthethrusterexit.Correspondingly,thehydrogenarcjetthrusterhasthehighestspecificimpulseandarcvoltageforthesameinletstagnantpressureandarccurrent.Thepredictionsofthemodellingarecomparedfavourablywithavailableexperimentalresults.

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