粒径表示方法

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1、粒徑大小的測定(原文)HowmethodsandinstrumentshavekeptpacewithchangingtechnologyTherearemanymethodsandinstrumentsavailablefordropsizedatacollection.Sincerepeatabletestresultsareessentialincomparingnozzleperformancedata,itisessentialtousetestingproceduresthattakeintoaccount

2、allofthepotentialvariablesinthesamplingtechniqueforbothmethodsandinstrumentation.Bysprayingwaterintoapanofoilandshutteringthespray,itispossibletocountandsizeindividualdropsusingamicroscope.Thistechniqueisstillusedbysomeresearchers.Problemswiththismethodinvolvedr

3、opcoalescence,inadequatesamplesizeandthefactthatverysmalldropswillbedeflectedawayfromtheoilbyaircurrentsatthesurfaceduetothesprayvelocity.Also,largerdropscananddobreak-upfromimpactingthesurface.Thesametypeofmethodisusedwhensprayingadyeontoastationarycard,orwater

4、ontoliquidsensitivepaper.Again,thesmalldropsmightbedeflectedawayfromthetargetandthelargedropscanbreak-upfromtheimpact.Datacollectedbythese"intrusive"methodsdependsonanumberofuncontrolledvariablesmakingsuchtestresultsgenerallynon-repeatable.Whiledropsizedatawasbe

5、ingcollectedintheearly1950'susingmethodssuchasflashphotography,probablythefirstrealbreakthroughindropsizingtechnologywasthedevelopmentin1961ofanautomatedimaginganalyzer(Figure5).11TheElectronicImagingAnalyzerwasdevelopedatSprayingSystemsCo.byDr.VerneDietrichandb

6、uiltbytheDageDivisionofTRW,MichiganCity,Indiana.ThedesignwasawardedU.S.Patent3275733inSeptemberof1966,andiscurrentlyinitssecondgeneration.Basically,theElectronicImagingAnalyzerincorporatesthespatialmeasurementtechniqueusingastrobelighttoilluminatethesprayandreco

7、rdtheimagewithavidicontube.Theimageisscanned,andthedropsaresizedandseparatedintodifferentclasses.Resultingdatacanbemathematicallycorrectedusingvelocitydatatogiveafluxdistribution.Sourcesoferrorearlyinthedevelopmentofthisdeviceincludedblurring,depthoffieldvariati

8、onsandvidicontubesaturation.Thesesourceswererecognizedandcorrected.Theimagingtypeanalyzerisstillactivelypromotedbysomenozzlemanufacturers.Thelimitedavailabilityofthis