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1、飞动专业英语阅读大作业班级：0906102学号：090610223姓名：马康康日期：2012年4月5日ENERGYTRANSFERFROMGASFLOWTOTURBINE6.Fromthedescriptioncontainedinpara.1,itwillbeseenthattheturbinedependsforitsoperationonthetransferofenergybetweenthecombustiongasesandtheturbine・Thistransferisnever100percentbecaus
2、eofthermodynamicandmechanicallosses,(para.11).7.Whenthegasisexpandedbythecombustionprocess(Part4),itforces让swayintothedischargenozzlesoftheturbinewhere,becauseoftheirconvergentshape,itisacceleratedtoaboutthespeedofsoundwhich,atthegastemperature,isabout2,500feetperse
3、cond.Atthesametimethegasflowisgivena'spin'or1whirl1inthedirectionofrotationoftheturbinebladesbythenozzleguidevanes・Onimpactwiththebladesandduringthesubsequentreactionthroughtheblades,energyisabsorbed,causingtheturbinetorotateathighspeedandsoprovidethepowerfordriving
4、theturbineshaftandcompressor.8.Thetorqueorturningpowerappliedtotheturbineisgovernedbytherateofgasflowandtheenergychangeofthegasbetweentheinletandtheoutletoftheturbineblades,Thedesignoftheturbineissuchthatthewhirlwillberemovedfromthegasstreamsothattheflowatexitfromth
5、eturbinewillbesubstantiallyStraightenedout1togiveanaxialflowintotheexhaustsystem(Part6).Excessiveresidualwhirlreducestheefficiencyoftheexhaustsystemandalsotendstoproducejetpipevibrationwhichhasadetrimentaleffectontheexhaustconesupportsandstruts・9.Itwillbeseenthatthe
6、nozzleguidevanesandbladesoftheturbinearetwisted；thebladeshavingastaggeranglethatisgreateratthetipthanattheroot(fig.5-6).Thereasonforthetwististomakethegasflowfromthecombustionsystemdoequalworkatallpositionsalongthelengthofthebladeandtoensurethattheflowenterstheexhau
7、stsystemwithauniformaxialvelocity.Thisresultsincertainchangesinvelocity,pressureandtemperatureoccurringthroughtheturbine,asshowndiagram-maticallyinfig.5・7・Fig.5-6Atypicalturbinebladeshowingtwistedcontour.STAGGERANGLEDIRECTIONOFFLOWDIRECTIONOFROTATIONSTAGGERANGLEVelo
8、city————Staticpressure"VELOCITYDECREASESFig.5-7Gasflowpatternthroughnozzleandblade・10.Thedegreeofreaction*variesfromroottotip,beingleastat
