Abstract: In the rotor of a centrifugal separator a stack of conical separation discs (4) is arranged concentric with the rotor axis. The rotor has an inlet for a dispersion and an outlet for liquid having been freed from a substance dispersed therein. In each space between adjacent separation discs (4) the disc surface from which the dispersed substance moves away as a consequence of centrifugal force during rotor operation has flow influencing members, whereas the surface of the other separation disc, situated opposite to said members, is substantially smooth. The relation (L/H) where L is the distance between adjacent flow influencing members and H is the distance between the separation discs, and the relation (1/H) where 1 is the extension of each flow influencing member along the disc surface and H is the distance between the separation discs, are larger than zero but less than 2.