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Recent interest has been shown in using synthetic gaseous (syngas) fuels to power gas turbine engines. An important issue concerning these fuels is the potential for increased contaminant deposition that can inhibit cooling designs and expedite the material degra-dation of vital turbine components. The purpose of this study was to provide a detailed understanding of how contaminants deposit on the surface of a turbine vane with a ther-mal barrier coating (TBC). The vane model used in this study was designed to match the thermal behavior of real engine components by properly scaling the convective heat transfer coefficients as well as the thermal conductivity of the vane wall. Four different film cooling configurations were studied: round holes, craters, a trench, and a modified trench. The contaminants used in this study were small particles of paraffin wax that were sprayed into the mainstream flow of the wind tunnel. The wax particles modeled both the molten nature of contaminants in an engine as well as the particle trajectory by properly matching the expected range of Stokes number. This study found that the pres-ence of film cooling significantly increased the accumulation of deposits. It was also found that the deposition behavior was strongly affected by the film cooling configuration that was used on the pressure side of the vane. The craters and trench performed the best in mitigating the accumulation of deposits immediately downstream of the film cooling configuration. In general, the presence of deposits reduced the film cooling performance on the surface of the TBC. However, the additional thermal insulation provided by the deposits improved the cooling performance at the interface of the TBC and vane wall. [ABSTRACT FROM AUTHOR]

Little work has been done to understand the interconnected nature of film cooling and thermal barrier coatings (TBCs) on protecting high temperature turbine components. With increasing demands for improved engine performance it is vital that a greater understanding of the thermal behavior of turbine components is achieved. The purpose of this study was to investigate how various film cooling geometries affect the cooling per-formance of a thermally conducting turbine vane with a TBC. The vane model used in this study was designed to match the thermal behavior of real engine components by properly scaling the convective heat transfer coefficients along with the thermal conduc-tivity of the vane wall. This allowed for the measurement of temperatures at the inteiface of the TBC and vane wall which, when nondimensionalized, are representative of the tem-peratures present for actual engine vanes. This study found that the addition of a TBC on the surface of an internally cooled vane produced a near constant cooling performance despite significant changes in the blowing ratio. The craters, trench, and modified trench of this study were found to provide much better film cooling coverage than round holes; however, the improved film cooling coverage led to only slight improvements in tempera-ture at the interface of the TBC and vane wall. These results suggest that there is minimal advantage in using more complicated cooling configurations, particularly since they may be more susceptible to TBC spallation. However, the improved film coverage from the trench and crater designs may increase the life of the TBC, which would be greatly bene-ficial to the long-term thermal protection of the vane. [ABSTRACT FROM AUTHOR]