INFLUENCES OF MAINSTREAM TURBULENCE AND END-WALL EFFECT ON CONVECTIVE HEAT TRANSFER OF TURBINE BLADE

The influences of mainstream turbulence,end-wall effect and mainstream Reynolds number on the beginning location of transition,transition length and heat transfer both in the middle region and root region of a turbine blade were comparatively studied.A five-blade linear cascade in a large-scale low-speed opening wind tunnel was used in the experiment.A thin-foil thermocouple technique was applied to determining the heat transfer coefficients on the blade surface.Three row of thermocouple located 5 mm,30 mm and 150 mm in the span-wise direction of blade from end-wall.The mainstream Reynolds number changed from 60000 to 240000.The mainstream turbulence varied from 0 75% to 13 5%.The results showed that the mainstream turbulence enhanced heat transfer coefficients on the suction surface to a great extent,and also increased the heat transfer coefficients on the pressure surface.Both onset and end of transition on the suction surface boundary layer move forward with increase of mainstream turbulence intensity.The end-wall effect region emerged at the root region of x/C >0 24 of suction surface for the present turbine blade.The end-wall effect raised on the heat transfer coefficients for a low mainstream turbulence,but diminished for a high mainstream turbulence at the end-wall effect region.The influence of mainstream turbulence on the heat transfer coefficients vanished at the end-wall effect region.