Ceramic-to-metal turbine shaft attachment

摘要

A metallic-ceramic joint for a turbo-compressor spool is disclosed. A temperature-limited joint is moved from outside the bearings to between the bearings and near the center of the shaft joining the turbine and compressor. This placement can lower the temperature at and around the joint and reduces the sharp gradient (and associated thermal stress) naturally occurring between the turbine rotor and the cooler joint. The bearing closest to the compressor can be an oil bearing and the bearing closest to the turbine an air bearing. The bearing closest to the compressor and the bearing closest to the turbine can both be an oil bearing. The bearing closest to the compressor and the bearing closest to the turbine can both be an air bearing. Moving the metallic-ceramic joint between the bearings can provide sufficient isolation to enable the all-air bearing solution.

主权项

1. An engine, comprising:
a plurality of turbo-compressor spool assemblies, each turbo-compressor spool assembly comprising a compressor and a turbine attached by a common shaft and a first of the turbo-compressor spool assemblies is in fluid communication with a second of the turbo-compressor spool assemblies, at least one of the common shafts of a selected turbo-compressor spool assembly comprising a metallic compressor rotor and a ceramic turbine rotor connected by a metallic-to-ceramic attachment joint and a first bearing being positioned adjacent to the metallic compressor rotor and a second bearing adjacent to the ceramic turbine rotor; a free power turbine driven by a gas flow output by at least one of the turbo-compressor assemblies; and a combustor operable to combust a fuel and a gas output by one of the plurality of turbo-compressor spool assemblies, wherein: when the engine is in operation, the ceramic turbine rotor of the selected turbo-compressor spool assembly operates in a no-failure regime of the ceramic material; the ceramic-to-metallic attachment joint is located on the common shaft of the selected turbo-compressor spool assembly to be in a no-failure regime of the ceramic material, the location of the metallic-to-ceramic attachment joint being positioned between the first and second bearings on the common shaft, and when the engine is in operation, the metallic-to-ceramic attachment joint operates at a temperature of no more than about 800° K.