Abstract: The rotor has a body with recesses formed therein in which airfoil-type blades are secured. The blades have platforms which abut one another to define an annular wall which circumscribes the rotor body. One edge of each of the platforms, which abuts an adjacent platform, has a rectilinear cut-out formed therein. The resulting void constitutes a slot which extracts fluid therethrough, and each void has an evacuating duct in communication therewith for venting the extracted fluid. The voids and ducts bleed off a minimal volume of the fluid handled by the rotor, principally the volume which comprises the secondary flows. These are the secondary flows which, otherwise, would result in the formation of eddies and vortices which are susceptible of eroding the roots of the blades.