AERODYNAMICS AND HEAT TRANSFER FOR A COOLED ONE AND ONE-HALF STAGE HIGH-PRESSURE TURBINE-PART III: IMPACT OF HOT STREAK CHARACTERISTICS ON BLADE ROW HEAT FLUX

The influence of hot streak magnitude and alignment relative to the vane leading edge on blade row heat flux are investigated for a one and one-half stage high-pressure turbine with a film-cooled vane, purge cooling, and un-cooled blades. The full-stage turbine is operated at design-corrected conditions. In addition to investigating the impact of different hot-streak characteristics, this study also looks at the interaction of cooling flow with the hot streaks. This paper builds on the investigation of profile migration utilizing temperature measurements presented in Part I and the heat transfer measurements presented in Part II. Hot streaks aligned with the vane mid-pitch have a greater impact on blade temperatures and heat-flux values than hot streaks aligned with the vane leading edge. The leading edge hot streaks tend to be mixed out over the surface of the vane. The magnitude of the hot streak is observed to have the largest influence on the temperature and heat flux for the downstream blade. Time-accurate measurements confirm these conclusions and indicate that further analysis of the time-accurate data is warranted. Film cooling is found to impact a hot streak profile in a way similar to that observed for a radial profile. Differences in core to coolant temperature ratio cause the uniform profile to show different coolant effects, but the overall spread of the cooling appears similar.