4.3 turbine blade aerodynamics外语英文电子书

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1、4.34.3-1IntroductionTurbineBladeAerodynamicsTheaerodynamicsoftheflowinaturbinestage(stator/rotor)israthercomplexandisstillthesubjectofmanyongoingresearchactivitiesinthegasturbinecommunity.Theflowisinherentlythreedimensionalduetothevane/bladepassagegeometrywithfeaturessuchastwistingofthevane/b

2、ladealongthespan,clearancebetweenthebladetipandtheshroud,filmcoolingholes,andendwallcontouring1.Thepassageflowischaracterizedbyboundarylayereffects,secondaryflowsgeneratedbythepassagepressuregradients,andvorticalflowstructuressuchastheleadingedgehorse-shoevortices,tip-leakageflowvortices,andcorn

3、ervortices2.Theeffectsofcentrifugal-buoyancy,shock-boundarylayerinteraction,andflowinteractionsbetweenthestatorandrotorrowscomplicatethepassageflowfieldevenfurther.Alongtheendwalls,theflowstructureisstronglythree-dimensionalwiththepassagevortexandcoolantinjectiononthehubsideandthetip-leakagevor

4、texonthetipside.Inthemid-spanregionslocatedawayfromthepassagewallsandoutsidetheviscousshearlayer,theradialflowisalmostnegligibleandSumantaAcharyatheflowiseffectivelytwodimensional.Thefluiddynamicsinthisregioncanthenbebasedontwodimensionalplanarcascadeflowstudieswithoutanysignificantlossofinforma

5、tion.Thethreedimensionalcomplexflowstructuresnearthehubendwallregionandinthebladetip-shroudclearancehavebeensimulatedinannularvane/bladepassageswithandwithoutrotatingbladerow3.Studiesofthecomplexend-wallflowshavealsobeenperformedinstationarycascadeswiththreedimensionalairfoilshapes4.Thequalit

6、ativefeaturesofthepassageflows,whichcomprisemainlyofthepassagecrossflow(flowfromthepressuresideofvane/bladetosuctionsideofadjacentvane/blade)andvorticalflowsinducedbytheleadingedge,thecorners,andtheinjectedcoolantflowshavebeenstudiedindetailinstationarycascadesandareconsideredtobesimilarinbothst

7、ationaryandrotatingbladerows.TheprimarydifferenceinthesecondaryflowstructurebetweenthebladepassageandvanepassageisthattheGaziMahmoodvorticalflowsandcrossflowsinthebladepassagearestrongerbecauseofhigherturningoftheflowsalongthebladepassage.Secondaryflowsarethe