Evaluations were made of the short-term (5 minute) durability at high temperatures of 85 mm outer diameter ceramic radial turbine rotors made of silicon nitride using an improved hot gas spin test rig.
Under no load conditions, the rotors withstood a maximum turbine tip speed (Ut) of 550 m/s without bursting at a turbine inlet gas temperature (TIT) of 1240°C.
Under partially loaded conditions, they withstood up to Ut of 500 m/s at TIT of 1280°C without bursting.
The test results indicated that the knee point temperature in terms of TIT at which the failure tip speed decreased sharply was about 40°C higher under partially loaded condition than under no load condition.
The temperature and stress distribution in the turbine in the hot gas spin test were calculated by the finite element analysis, which supported the dependence of the knee point temperature in terms of TIT at spin test on load condition.