Conjugate Calculations for a Film-Cooled Blade Under Different Operating Conditions

Abstract

Conjugate heat transfer and flow calculation techniques (CCT: Conjugate Calculation Technique) developed by several numerical groups have been applied to more and more complex three-dimensional cooling configurations. With respect to gas turbine blade cooling, conjugate calculation codes are turning out as useful tools for the support of the thermal design process. Thus, the main focus of the present study is to investigate the applicability of the CCT on a realistic film-cooling configuration of a modern gas turbine blade under hot gas operating conditions. Thermal index paint measurements for the investigated configuration have been performed at KHI Gas Turbine R&D Center in order to provide thermal load data for comparison to results of conjugate blade analysis. The comparison shows that with respect to regions with high thermal load a qualitatively good agreement of the conjugate results and the measurements can be found although the calculation models contain several simplifications for the internal cooling configuration particularly. The tip region of the blade trailing edge is exposed to a high thermal load. This result can be found in the measurement data as well as in the numerical analysis. The influence of off-design flow conditions on the film cooling flow at the blade leading edge is also investigated. Despite the model simplification, the Conjugate Calculation Technique turns out to be applicable for the numerical testing of the cooling configuration investigated. With the numerical results, useful information for further improvement of the investigated cooling configuration can be provided.