Turbine assembly of an axial-flow turbine and axial-flow turbine

A turbine assembly of an axial-flow turbine, comprising a stator having a stator wheel and a rotor having a rotor wheel arranged in the direction of a working medium flow downstream, or turbine stage,

• wherein the stator wheel includes airfoils of blades arranged side by side around the circumference of the stator wheel to form a stator blade cascade, and at least one stator fixing part fixing the blades of the stator wheel to the stator and sealing the stator blade cascade at the outer circumference, wherein the stator blade cascade is sealed against the rotor at the inner circumference by at least one stator shroud or a stator disc with a non-contact seal of the stator wheel, the non-contact seal of the stator wheel having a last fin and axial gaps in front of and behind the non-contact seal of the stator wheel for connection to a primary flow path, and
• the rotor wheel includes airfoils of blades placed side by side around the circumference of the rotor wheel to form a rotor blade cascade, at least one rotor fixing part fixing the blades of the rotor wheel to the rotor or a rotor disc and which seals the rotor blade cascade on the inner circumference, wherein on the outer circumference the rotor blade cascade is sealed against the stator by at least one rotor shroud with a non-contact seal of the rotor wheel, the non-contact seal of the rotor wheel having a last fin and axial gaps in front of and behind the non-contact seal of the rotor wheel for connection to the primary flow path, wherein passages are formed in the at least one rotor fixing part of the rotor wheel at least between some adjacent blades of the rotor wheel for draining the working medium that has leaked through the non-contact seal of the stator wheel, from the axial gap behind the non-contact seal of the stator wheel into the primary flow path, wherein
• the inlet of the passages is located on the side of the fixing part facing the radial gap at the last fin of the non-contact seal of the stator wheel radially between a virtual circle with the centre on the axis of the turbine assembly and with a radius of
• R
• ⁢
• 8
• ⁢
• s
• in
• -
• 0.6
• *
• Ar
• and a virtual circle with the centre on the axis of the turbine assembly and a radius of
• R
• ⁢
• 8
• ⁢
• s
• o
• ⁢
• u
• ⁢
• t
• +
• 0.6
• *
• Ar
• where
• R8sin is the inner radius of the radial gap at the last fin of the non-contact seal of the stator wheel, R8sout is the outer radius of the radial gap at the last fin of the non-contact seal of the stator wheel, and
• Ar is the axial distance between the last fin of the non-contact seal of the stator wheel and the side of the fixing part of the rotor wheel facing the radial gap at the last fin of the non-contact seal of the stator wheel in operation,
• the outlet of the passages exits into a primary flow path between the blades of the rotor wheel at an axial distance of at least ⅕*Br from the leading edge of the blades of the rotor wheel, where Br is the total axial width of the rotor blade cascade at the point of its connection to the fixing part of the rotor wheel.