A turbine rotor wheel is part of a turbine that can be part of a gas turbine engine. In a gas turbine engine, a compressor provides pressurized air to a combustor where air is mixed with fuel and the mixture ignited to produce hot combustion gases. These hot combustion gases flow downstream to one or more turbine rotors that extract energy from the hot combustion gases for powering the compressor and for providing useful work, such as powering an electric generator or powering an aircraft in flight.
A turbine rotor can include multiple turbine rotor blades mounted to the perimeter of a turbine rotor wheel, which can rotate about the centerline axis of the engine. As hot combustion gases exit the combustor and flow across the turbine rotor blades, the turbine rotor wheel begins to rotate. In doing so, energy from the hot combustion gases is converted. At the same time, the hot combustion gases subject the turbine rotor wheel to high temperatures, particularly at the turbine rotor wheel's rim. The materials used to construct the turbine rotor wheel, however, can differ from other turbine components such that the turbine rotor wheel is not as resistant to heat. As a result, the high temperatures of the hot combustion gases can exceed the metallurgical limitations of the turbine rotor wheel, causing thermal stresses, oxidation, and structural cracking.
To prevent the turbine rotor wheel from overheating, cooling air can be extracted from the compressor to cool the spaces surrounding and within the turbine rotor assembly, including those in thermal contact with the turbine rotor wheel. Extracting air in this way though, diverts air from the combustor and hampers the efficiency of the engine cycle. Given this loss of efficiency, minimizing the amount of air diverted from the combustor for cooling, without exposing the turbine rotor wheel to additional stresses, is desirable. In addition, the demand for larger and more efficient gas turbine engines requires turbine rotor wheels that can endure higher combustion temperatures without increasing individual component costs.
Thus, there is a need for systems, methods, and an apparatus for thermally isolating a turbine rotor wheel.