CYCLONE

A high speed rotating (air) flow is established within a cylindrical or conical container called a cyclone. Air flows in a spiral pattern, beginning at the top (wide end) of the cyclone and ending at the bottom (narrow) end before exiting the cyclone in a straight stream through the center of the cyclone and out of the top. Larger (denser) particles in the rotating stream have too much inertia to follow the tight curve of the stream and strike the outside wall, falling then the bottom of the cyclone where it can be removed. In a conical system, as the rotating flow moves towards the narrow end of  the cyclone  the  rotational radius of  the stream is reduced, separating smaller particles.