According to one embodiment of the invention, the disc is monobloc and has radial ducts for the flow of cooling air.
According to another embodiment of the invention, the disc consists of two half-discs having radial grooves which, after assembly of the half-discs, constitute radial ducts for the flow of cooling air.
According to another characteristic of the invention, introduction of the air into the discs is achieved through ports made in the platforms of the blades attached to the discs.