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ID:49166180
大小:2.81 MB
页数:34页
时间:2020-01-31
《多相流基础 chapter 2-two-phase flow patterns and flow pattern maps.ppt》由会员上传分享,免费在线阅读,更多相关内容在行业资料-天天文库。
1、Chaptertwo—Two-phaseflowpatternsandflowpatternmaps(第二章-两相流型和流型图)——gas-liquidtwo-phaseflowhasobviousinterface(气液两相流动具有明显的流动界面)——hasvariousgeometricconfigurations(流动具有各种不同的几何构型)1、Flowpatternorflowregime(流型)Introduction(简介)2、Importantphysicalparametersindeterminingtheflowpa
2、ttern:(流型)——surfacetension(表面张力)KeepchannelswallsalwayswetMakesmallliquiddropsandsmallgasbubblesspherical——gravity(重力)Tendstopulltheliquidtothebottomofthechannelespeciallyinnon-verticalchannel……3、Flowpatternsinverticalupwardtubes——gasandliquidphasebothflowingupwards,adia
3、baticflow(垂直上升管内的流型——气液两相均向上流,绝热流)——Whenthequalityisgraduallyincreasedfrom0to1,theflowpatternscanbeclassified:(1)Bubblyflow(泡状流)LiquidphaseisthecontinuousphaseGasorvaporphaseisthedispersedphaseGasorvaporbubblesareofapproximatelyuniformsize.(2)PlugfloworSlugflow(弹状流)Gasfl
4、owsaslargebullet-shapedbubbles(sometimescalledTaylorbubble)GasbubbleandliquidslugflowacrosstubealternativelySomesmallgasbubblesdistributedthroughouttheliquidphase.(3)Churnflow(搅拌流,块状流)Highlyunstableflow,oscillatoryflowtheshapeofgasbubblesisnotregularLiquidnearthetubewall
5、continuallypulsesupanddown(4)Annularflow(环状流)GasflowsinthecenterofthetubeLiquidpartiallyflowsasanannularfilmonthewallsofthetubeLiquidpartiallyflowsassmalldropletsdistributedinthegasflowinginthecenterofthetube4、Flowpatternsinhorizontaltubes,adiabaticflow(水平管内两相流型,绝热流)——Wh
6、enthequalityisgraduallyincreasedfrom0to1,theflowpatternscanbeclassified:(1)Bubblyflow(泡状流)LowqualityandlowvelocityLiquidisthecontinuousphaseGasorvaporphaseisthedispersedphasenearthetopofthetube(2)Plugflow(塞状流、间歇流)BiggerqualityandlowvelocityIndividualsmallgasbubblescoales
7、cetoproducelongplugsGasbubblesstilltendtoflowalongthetopofthetube(3)Stratifiedflow(光滑分层流)GasandliquidphasehaveobviousinterfaceThegas-liquidinterfaceissmoothThisflowpatterndoesnotusuallyoccurGasandliquidphasearebothcontinuousphaseGasphaseflowsaboveandliquidphaseflowsbelow
8、(4)Wavyflow(波状分层流)GasandliquidphasehaveobviousinterfaceThegas-liquidinterfaceiswavyGasvelocityisbiggert
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