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A gas turbine engine comprises a pre-swirl structure coupled to a shaft cover structure and located radially between a supply of cooling fluid and a flow path. The pre-swirl structure defines a flow passage and includes a plurality of swirl members in the flow passage. A flow direction of cooling fl

A gas turbine engine comprises a pre-swirl structure coupled to a shaft cover structure and located radially between a supply of cooling fluid and a flow path. The pre-swirl structure defines a flow passage and includes a plurality of swirl members in the flow passage. A flow direction of cooling fluid passing through the flow passage is altered by the swirl members such that the cooling fluid has a velocity component in a direction tangential to the circumferential direction. The bypass passages provide cooling fluid into a turbine rim cavity associated with a first row vane assembly to prevent hot gas ingestion into the turbine rim cavity from a hot gas flow path associated with a turbine section of the engine.

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1. A gas turbine engine having a central axis defining an axial direction comprising: a supply of cooling fluid;a rotatable shaft extending in the axial direction of the engine;shaft cover structure disposed about said shaft such that a flow path extends in the axial direction between said shaft and

1. A gas turbine engine having a central axis defining an axial direction comprising: a supply of cooling fluid;a rotatable shaft extending in the axial direction of the engine;shaft cover structure disposed about said shaft such that a flow path extends in the axial direction between said shaft and said shaft cover structure;pre-swirl structure coupled to said shaft cover structure and located radially between said supply of cooling fluid and said flow path, said pre-swirl structure extending in a circumferential direction about said shaft, said pre-swirl structure comprising: forward wall structure;aft wall structure spaced in the axial direction from said forward wall structure, said forward and aft wall structures defining a flow passage therebetween, said flow passage including an inlet in communication with said supply of cooling fluid and an outlet in communication with said flow path, said flow passage supplying a first portion of cooling fluid from said supply of cooling fluid to said flow path; anda plurality of swirl members in said flow passage extending between said forward and aft wall structures, said swirl members each including a leading edge and a trailing edge spaced from said leading edge in a radial direction, wherein said trailing edge is offset from said leading edge in the circumferential direction;wherein a flow direction of the first portion of cooling fluid passing through said flow passage is altered by said swirl members such that the first portion of cooling fluid has a velocity component in a direction tangential to the circumferential direction when the first portion of cooling fluid enters said flow passage;at least one bypass passage defined through said shaft cover structure, said at least one bypass passage receiving a second portion of cooling fluid from said supply of cooling fluid, said at least one bypass passage including an exit opening at an end of said shaft cover structure supplying the second portion of cooling fluid to a turbine rim cavity associated with a first row vane assembly to prevent hot gas ingestion into the turbine rim cavity from a hot gas flow path associated with a turbine section of the engine; anda metering structure associated with an outlet of said at least one bypass passage, said metering structure comprising a corresponding flow passageway formed therein in communication with the outlet of each respective bypass passage for permitting the second portion of cooling fluid in said at least one bypass passage to pass into the turbine rim cavity, wherein at least one of said flow passageways is formed in said metering structure at an angle such that the second portion of cooling fluid flowing out of said at least one flow passageway has a velocity component in the direction tangential to the circumferential direction;wherein: said shaft cover structure comprises a plurality of struts spaced apart from each other in the circumferential direction;inlet openings to said pre-swirl structure are defined between adjacent struts; andat least an upstream portion of said at least one bypass passage extends through a corresponding one of said struts. 2. The gas turbine engine according to claim 1, further comprising an air separator structure between said shaft and said shaft cover structure and having a portion extending axially from said pre-swirl structure to a location adjacent to a blade disc structure coupled to said shaft, said air separator structure and said shaft cooperating to define said flow path therebetween. 3. The gas turbine engine according to claim 2, wherein said air separator structure comprises a plurality of openings therein adjacent to said outlet of said pre-swirl structure, said openings permitting the first portion of cooling fluid to pass from said pre-swirl structure into said flow path. 4. The gas turbine engine according to claim 2, further comprising sealing structure downstream from said pre-swirl structure and located between said air separator structure and said shaft cover structure, said sealing structure limiting leakage between said outlet of said flow passage and the turbine rim cavity. 5. The gas turbine engine according to claim 4, wherein said pre-swirl structure and said shaft cover structure do not rotate with said shaft and said air separator structure rotates with said shaft during operation of the gas turbine engine. 6. The gas turbine engine according to claim 1, further comprising blade disc structure coupled to said shaft at a location axially downstream from said pre-swirl structure, said blade disc structure having at least one bore formed therein, said at least one bore receiving cooling fluid from said flow path and delivering the cooling fluid from said flow path to structure to be cooled within a turbine section of the engine. 7. The gas turbine engine according to claim 1, wherein said swirl members are configured such that the cooling fluid exiting said flow passage flows at an angle of from about 75° to about 85° relative to a radial axis of the gas turbine engine transverse to the central axis. 8. The gas turbine engine according to claim 1, wherein said swirl members are arranged such that a spacing between a first sidewall at said trailing edge of each said swirl member and a second sidewall of an adjacent swirl member causes a Venturi effect as the cooling fluid flows through said flow passage, the Venturi effect resulting in a pressure drop and a velocity increase of the cooling fluid flowing through said flow passage. 9. The gas turbine engine according to claim 1, wherein: said shaft cover structure comprises inner and outer shaft covers, said outer shaft cover structurally supported by an engine casing and providing structural support for said inner shaft cover;said supply of cooling fluid comprises a chamber located between said inner and outer shaft covers; andsaid pre-swirl structure is coupled to said inner shaft cover. 10. The gas turbine engine according to claim 1, wherein each said flow passageway is formed in said metering structure at an angle such that the second portion of cooling fluid flowing out of each said flow passageway has a velocity component in the direction tangential to the circumferential direction. 11. A gas turbine engine having a central axis defining an axial direction comprising: a supply of cooling fluid;a rotatable shaft extending in the axial direction of the engine;shaft cover structure disposed about said shaft such that a flow path extends in the axial direction between said shaft and said shaft cover structure;pre-swirl structure coupled to said shaft cover structure and located radially between said supply of cooling fluid and said flow path, said pre-swirl structure extending in a circumferential direction about said shaft, said pre-swirl structure comprising: a flow passage including an inlet in communication with said supply of cooling fluid and an outlet in communication with said flow path, said flow passage supplying a first portion of cooling fluid from said supply of cooling fluid to said flow path; anda plurality of swirl members in said flow passage, said swirl members each including a leading edge and a trailing edge spaced from said leading edge in a radial direction, wherein said trailing edge is offset from said leading edge in the circumferential direction;wherein a flow direction of the first portion of cooling fluid passing through said flow passage is altered by said swirl members such that the first portion of cooling fluid has a velocity component in a direction tangential to the circumferential direction when the first portion of cooling fluid enters said flow passage;a plurality of bypass passages associated with said shaft cover structure, said bypass passages receiving a second portion of cooling fluid from said supply of cooling fluid and supplying the second portion of cooling fluid to a turbine rim cavity associated with a first row vane assembly to prevent hot gas ingestion into the turbine rim cavity from a hot gas flow path associated with a turbine section of the engine; anda metering structure associated with an outlet of each said bypass passage, said metering structure comprising a plurality of flow passageways formed therein at outlets of said bypass passages for permitting the second portion of cooling fluid in said bypass passages to pass into the turbine rim cavity, wherein at least one of said flow passageways is formed in said metering structure at an angle such that the second portion of cooling fluid flowing out of said flow passageways has a velocity component in the direction tangential to the circumferential direction;wherein said shaft cover structure comprises a plurality of struts spaced apart from each other in the circumferential direction, said struts defining inlet openings to said pre-swirl structure therebetween, wherein at least an upstream portion of each said bypass passage extends through a corresponding one of said struts. 12. The gas turbine engine according to claim 11, wherein said pre-swirl structure further comprises: forward wall structure; andaft wall structure spaced in the axial direction from said forward wall structure, said forward and aft wall structures defining said flow passage therebetween and said swirl members extending from said forward wall structure to said aft wall structure. 13. The gas turbine engine according to claim 11, wherein: said shaft cover structure comprises inner and outer shaft covers, said outer shaft cover structurally supported by an engine casing and providing structural support for said inner shaft cover;said supply of cooling fluid comprises a chamber located between said inner and outer shaft covers;said pre-swirl structure is coupled to said inner shaft cover; andsaid bypass passages are associated with said inner shaft cover. 14. The gas turbine engine according to claim 11, further comprising: an air separator structure between said shaft and said shaft cover structure, said air separator structure and said shaft cooperating to define said flow path therebetween;first sealing structure located radially between a first axially extending portion of said air separator structure and said shaft cover structure and located axially between said bypass passages and said pre-swirl structure, said first sealing structure limiting leakage between said bypass passages and said outlet of said flow passage; andsecond sealing structure located radially between a second axially extending portion of said air separator structure and said shaft cover structure and located axially between said pre-swirl structure and said turbine rim cavity, said second sealing structure limiting leakage between said outlet of said flow passage and said turbine rim cavity. 15. The gas turbine engine according to claim 11, further comprising blade disc structure coupled to said shaft at a location axially downstream from said pre-swirl structure, said blade disc structure having at least one bore formed therein, said at least one bore receiving the first portion of cooling fluid from said flow path and delivering the first portion of cooling fluid to structure to be cooled within the turbine section of the engine. 16. The gas turbine engine according to claim 11, wherein said shaft cover structure comprises at least one cooling fluid port formed therein for permitting cooling fluid to flow into a chamber in communication with a compressor section of the engine for cooling structure to be cooled in the compressor section. 17. A gas turbine engine having a central axis defining an axial direction comprising: a supply of cooling fluid;a rotatable shaft extending in the axial direction of the engine;shaft cover structure disposed about said shaft such that a flow path extends in the axial direction between said shaft and said shaft cover structure;pre-swirl structure coupled to said shaft cover structure and located radially between said supply of cooling fluid and said flow path, said pre-swirl structure: extending in a circumferential direction about said shaft;defining a flow passage including an inlet in communication with said supply of cooling fluid and an outlet in communication with said flow path, said flow passage supplying a first portion of cooling fluid from said supply of cooling fluid to said flow path; andcomprising a plurality of swirl members in said flow passage, said swirl members each including a leading edge and a trailing edge spaced from said leading edge in a radial direction, wherein said trailing edge is offset from said leading edge in the circumferential direction, wherein a flow direction of the first portion of cooling fluid passing through said flow passage is altered by said swirl members such that the first portion of cooling fluid has a velocity component in a direction tangential to the circumferential direction when the first portion of cooling fluid enters said flow passage;a plurality of circumferentially spaced apart and axially extending bypass passages receiving a second portion of cooling fluid from said supply of cooling fluid, said bypass passages each including an exit opening proximate to an end of said shaft cover structure and supplying the second portion of cooling fluid to a turbine rim cavity associated with a first row vane assembly, wherein inlet openings to said pre-swirl structure are defined between structure that defines at least upstream portions of said bypass passages; anda metering structure associated with outlets of said bypass passages, said metering structure comprising corresponding flow passageways formed therein in communication with said outlet of each respective bypass passage for permitting the second portion of cooling fluid in said bypass passages to pass into the turbine rim cavity, wherein at least one of said flow passageways is formed in said metering structure at an angle such that the second portion of cooling fluid flowing out of said at least one flow passageway has a velocity component in the direction tangential to the circumferential direction. 18. The gas turbine engine according to claim 17, wherein said shaft cover structure comprises bores that define each of said bypass passages. 19. The gas turbine engine according to claim 17, wherein: said shaft cover structure comprises inner and outer shaft covers, said outer shaft cover providing structural support for said inner shaft cover;said supply of cooling fluid comprises a chamber located between said inner and outer shaft covers;said pre-swirl structure is coupled to said inner shaft cover; andsaid bypass passages are formed in said inner shaft cover. 20. The gas turbine engine according to claim 17, wherein each said flow passageway is formed in said metering structure at an angle such that the second portion of cooling fluid flowing out of each said flow passageway has a velocity component in the direction tangential to the circumferential direction.