Avoiding thermal mismatch between turbine rotor parts with a thermal medium

摘要

In a turbine rotor (10), an aft shaft wheel (42) and the final-stage wheel (18) of the rotor (10) are coupled together by a rabbeted joint (40). During shutdown and startup of the turbine, a thermal mismatch between the aft shaft wheel (16) and final-stage wheel (18) is avoided by respectively heating and cooling the aft shaft wheel (42) to maintain the thermal mismatch within acceptable limits, thereby avoiding opening of the rabbeted joint (40) and the potential for unbalancing the rotor (10) and rotor vibration. The thermal medium may be supplied by piping (70) in the aft bearing cavity (66) into the cavity (60) between the forward closure plate (62) and the aft shaft wheel (42). <IMAGE>