Abstract: The invention refers to a general solution to the problem of establishing, maintaining and re-establishing an even distribution of two or more components in a composite material flow that is conveyed through a pipe. According to the invention teh problem is solved by installing a rotating assembly (b 3) of limited axial length in the pipe, the assembly having wings supported on a common shaft to extend transversely over the flow and generating a radial motion component in the axial flow as they rotate. In a further development of the invention the wings are formed for progressively accelerating the flow from the upstream end (I) of the assembly towards the downstream end (U) thereof.