Key points are not available for this paper at this time.
Abstract As turbine inlet temperatures steadily increased over several decades, turbine blade designs have transformed to accommodate higher gas path temperatures through addition of internal convective cooling, external film cooling, and protective thermal barrier coatings. First order cooling effectiveness benefits of different features can be predicted through correlations presented throughout the literature and validated experimentally. Experiments are typically conducted at scaled conditions which necessitates the use of non-dimensional parameters to relate experimental results to engine conditions. Experiments and corresponding correlations are often developed using scaling approaches with nondimensional parameters. This study compiles a first-order analysis using experimentally-based correlations to predict cooling effectiveness for true-scale engine blades operated at scaled conditions. Turbine blade temperatures were measured using infrared imaging under rotating blade conditions for increasing levels of blade cooling flow and multiple cooling designs: internal convective only; blades with different thermal barrier coating thicknesses; and blades with internal convection and film-cooling. For this study, a subset of shaped, compound-angle film holes was evaluated for overall cooling effectiveness and compared to results achieved from a one-dimensional analysis. This analysis showed the ability of available correlations to predict cooling effectiveness changes within 3% of experimentally measured values. Additionally, the validated heat transfer correlations were used to infer the cooling benefit by further changing the designs and operating conditions, then, investigate additional heat transfer effects of film cooling. TBC and film cooling were observed to reduce heat flux but improved overall cooling effectiveness when evaluating heat load parameter.
Bonn et al. (Mon,) studied this question.