Thermal management of a gas turbine engine shaft

A method of operating a gas turbine engine comprising the steps of:

• driving a fan drive turbine in a turbine section, and driving a shaft connecting said fan drive turbine to drive a fan rotor, an outer passage within said shaft, and an inner passage within said shaft;
• supplying cooling air into an inlet duct and then to a cooling compressor driven by said shaft downstream of said fan drive turbine, and passing compressed air from the cooling compressor in an upstream direction through one of said inner and outer passages in said shaft, and providing communication between said inner and outer passages such that the compressed air, having passed in said upstream direction is returned in the other of said inner and outer passages in a downstream direction to provide cooling to said shaft;
• and
• said one of said inner and outer passages being said outer passage, with the other of said inner and outer passages being said inner passage.

A gas turbine engine comprising:

• a fan rotor, a compressor section, a combustor section, and a turbine section, said turbine section being positioned downstream of said combustor section;
• a fan drive turbine in said turbine section, and a shaft connecting said fan drive turbine to said fan rotor, said shaft also driving a cooling compressor;
• an inlet duct connected to a cooling air source and connected to provide air to said cooling compressor downstream of said fan drive turbine, and said cooling compressor is connected to a turning duct for passing compressed air from said cooling compressor in an upstream direction through said shaft;
• connection passages in said shaft to provide communication between inner and outer passages in said shaft such that the compressed air, having passed in said upstream direction through said shaft in one of said inner and outer passages is returned in the other of said inner and outer passages in a downstream direction to provide cooling to said shaft;
• said turning duct extending to initially pass the compressed air downstream of said cooling compressor in said downstream direction, and then turn the compressed air into the upstream direction;
• and
• wherein a tube is positioned within said shaft to define said inner and outer passages, and said connection passages extend through said tube to communicate between said inner and outer passages, with compressed air downstream of said turning duct intially passing through said outer passage in said upstream direction, and then turning into said inner passage to return in said downstream direction.