AN EXPERIMENTAL STUDY OF THERMAL BARRIER COATINGS AND FILM COOLING ON AN INTERNALLY COOLED SIMULATED TURBINE VANE

This study investigated the interaction of thermal barrier coatings (TBC) and various film cooling configurations to provide a detailed assessment of the thermal protection on a first stage turbine vane. The internally cooled, scaled-up turbine vane used for this study was designed to properly model the conjugate heat transfer effects found in a real engine. The TBC material was selected to properly scale the thicknesses and thermal conductivities of the model to those of the engine. External surface temperatures, TBC-vane interface temperatures and internal temperatures were all measured over a range of internal coolant Reynolds numbers and mainstream turbulence intensities. The blowing ratio of the various film-cooling designs was also varied. The addition of TBC on the vane surface was found to increase the overall effectiveness of the vane surface just downstream of the coolant holes by up to 0.25 when no film cooling was present. The presence of the TBC significantly dampened the variations in overall effectiveness due to changes in blowing ratio which mitigated the detrimental effects of coolant jet separation. It was also discovered that with the presence of TBC standard round holes showed equivalent, if not better, performance when compared to round holes embedded in a shallow transverse trench.