Patent ID: 8469669

Claim:
A cover disk for a closed rotor of a flow machine, comprising: an outer surface ( 1 . 1 ), a wall thickness and an inner surface ( 1 . 2 ) defining a flow channel, a meridional cross section having a profile mean line; said wall thickness having a local maximum along said profile mean line of said meridional cross section of said cover disk between a first front side ( 2 ) and a second front side ( 3 ); said outer surface ( 1 . 2 ) of said cover disk remote of the flow channel having in an area of said local maximum a convex curvature having a radius (R 2 . 2 .), the ratio (R 2 . 2 /D 2 ) of said radius of said convex curvature to an outer diameter (D 2 ) of said rotor being within the range of from 0.05 to 0.5 (0.05≦R 2 . 2 /D 2 ≦0.5).