This paper describes the cooling design and experimental evaluations of the 1700C class turbine blades in hydrogen fueled combustion turbine system. The hybrid cooling method combining recovery steam cooling with partial film cooling was chosen based on a careful study on several cooling systems from the viewpoint of plant efficiency and durability of turbine blades. In the development process, high temperature cooled turbine blades, the advanced cooling technologies, single crystal super alloy and thermal barrier coating (TBC) are important issues to be paid attention and following experiments were performed. First, outer heat transfer test on stator blade and internal heat transfer test in ribbed channel for cooling rotor blade were carried out using liquid crystal thermography. The cooling effectiveness of rotor blade was further investigated in steam driven wind tunnel. The characteristics of single crystal super alloy and TBC were also evaluated in hot steam environment. As a next step, the scale model test blades of size nearly one half to that of the first stage stator and rotor blades in actual turbine were designed and manufactured. Finally, the turbine blade cascade tests were conducted using hydrogen-oxygen combustion driven wind tunnel under practical hot steam conditions of 1700C and 2.5MPa. In these experiments, cooling effectiveness, metal temperatures and cooling steam flow characteristics were investigated. After completing all the test runs, the robustness of blade substrate and TBC were inspected. The experimental results on the hybrid cooling method and blade design procedures are discussed.

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