Abstract: A gaseous or liquid fluid to be centrifuged, for the purpose of purification or of separation of different phases, is conducted at high speed in a curved channel past a vortex chamber formed in one of the channel walls at the concave side thereof, this chamber being partly separated from the main fluid path by an overhanging sharp upstream edge and by a possibly rounded downstream edge which extend over the full width of the channel. A body of fluid whirling in this chamber develops a cylindrical core free from entrained solids, or from an accompanying heavier phase, which can be axially extracted from the chamber while the remaining fluid continues its flow through a reduced channel portion which may also be curved and provided with another vortex chamber to repeat the process. Entrained particles may be removed from the solid-enriched residual flow by way of end apertures along the periphery of the vortex chamber and/or at the convex side of the curved channel.