HEAT TRANSFER CHARACTERISTICS OF AN INTEGRATED COOLING CONFIGURATION FOR ULTRA-HIGH TEMPERATURE TURBINE BLADES: EXPERIMENTAL AND NUMERICAL INVESTIGATIONS

This paper deals with fundamental research on heat transfer char-acteristics inside a cooling configuration designed for an ultra-high temperature turbine nozzle. The cooling configuration adopted in this study integrates impingement cooling and pin cooling devices into one body, aiming at the enhancement of the effective area for the im-pingement cooling. A large-scaled test model of this cooling system is constructed to measure its internal heat transfer distribution, where a number of pins are sandwiched between an impingement plate and a target plate. The target plate are provided with several air discharging holes. A focus of this study is on how the heat transfer characteristics depend on the effect of stand-off distance: a distance between these two plates. Ratios of the stand-off distance to the impingement hole diameter varies from 0.75 to 2.00. A transient measurement technique using narrow-banded thermochromatic liquid crystal (TLC) is em-ployed to determine the heat transfer characteristics of the model. Numerical investigations using a commercial CFD code are also ex-ecuted and those results are compared with the experimental data. It is accordingly found that the numerical results almost match the mea-surements. It is also shown that the addition of pins to the conven-tional impingement cooling system can produce about 50 % increase in the effective cooling area