Development of Air-Cooled Ceramic Nozzles for a Power Generating Gas Turbine

Abstract

The development of air-cooled ceramic nozzle vanes for a power generating gas turbine has been reported. To make up the limited temperature resistance of present ceramic materials, the utilization of a small amount of cooling air has been studied for the first stage nozzle vanes of a 1500°C class gas turbine. A series of cascade tests were carried out for the designed air-cooled Si3N4 nozzle vanes under 6 ata and 1500°C conditions. It was confirmed that the maximum ceramic temperature can be maintained below 1300°C by a small amount of cooling air. In spite of the increased thermal stresses by local cooling, all Si3N4 nozzle vanes survived in the cascade tests including both steady state and transients of emergency shutdown and the possibility of air cooled ceramic nozzle was demonstrated for a 1500°C class gas turbine application.