Superposition predictions of the reduction of hot streaks by coolant from a film cooled guide vane

The turbine section of a gas turbine engine is subjected to hot gases flowing from the combustor that typically have high temperature regions known as "hot streaks." These hot streaks pass through the nozzle guide vanes, either impacting the vanes or passing through the passages between vanes. Generally the vanes are highly film cooled, and the coolant from the vanes interacts with the hot streak resulting in a reduction of the hot streak temperature. In this study, predictions of the reduction of hot streaks were made using superposition of measured temperature distributions due to coolant injection and measured temperature distributions of hot streaks. These predictions were compared to the measured hot streak reduction to determine the accuracy of the superposition technique. Results showed that the superposition predictions generally underpredicted the reduction of the peak hot streak temperature, but were within at least 20% of the peak temperature value. The superposition technique was also found to be useful for determining the hot streak reduction for different hot streak locations, and different coolant and hot streak operating conditions. Keywords: film cooling, hot streak, superposition.