Abstract: A turbine blade has a body enclosing a labyrinth of internal channels for circulation of coolant received through an inlet integrally formed in terminal portion of blade root. The labyrinth includes; inlet arranged on an axially upstream face of terminal portion leading to an upstream duct portion having first section adjacent the inlet and a second section axially downstream of first, second section having reduced cross section compared to first section. Leading edge passage intersects first section and extends through blade body towards the tip. Main blade passage intersects second section. Trailing edge passage intersects downstream duct portion which is in axial alignment with but separate from second section and channel connects second section with the downstream duct portion. Channel has reduced cross section compared to second section and downstream duct portion. The inlet has an inverted keyhole shape with cross section extends through upstream duct portion first section.

Abstract: A turbine blade has a body enclosing a labyrinth of internal channels for circulation of coolant received through an inlet integrally formed in terminal portion of blade root. The labyrinth includes; inlet arranged on an axially upstream face of terminal portion leading to an upstream duct portion having first section adjacent the inlet and a second section axially downstream of first, second section having reduced cross section compared to first section. Leading edge passage intersects first section and extends through blade body towards the tip. Main blade passage intersects second section. Trailing edge passage intersects downstream duct portion which is in axial alignment with but separate from second section and channel connects second section with the downstream duct portion. Channel has reduced cross section compared to second section and downstream duct portion. The inlet has an inverted keyhole shape with cross section extends through upstream duct portion first section.