DEVELOPMENT OF AIR-COOLED CERAMIC NOZZLES FOR A POWER-GENERATING GAS-TURBINE

The development of air-cooled ceramic nozzle vanes for a power-generat ing gas turbine has been reported. To make up the limited temperature resistance of present ceramic materials, the utilization of a small am ount of cooling air has been studied for the first-stage nozzle vanes of a 1500 degrees C class gas turbine. A series of cascade tests were carried out for the designed air-cooled Si3N4 nozzle vanes under 6 atm and 1500 degrees C conditions. It was confirmed that the maximum cera mic temperature cart be maintained below 1300 degrees C by a small amo unt of cooling air In spite of the increased thermal stresses from loc al cooling, all Si3N4 nozzle vanes survived the cascade tests, includi ng both steady-state and transients of emergency shutdown. The potenti al for an air-cooled ceramic nozzle was demonstrated for a 1500 degree s C class gas turbine application.