FLOW PATTERNS OF A NEWTONIAN FLUID FLOWING IN A SINGLE-SCREW EXTRUDER WITH THE SCREW ROTATING.

Flow patterns in a single-screw extruder, with the screw rotating, are described. A flat plate model and an isothermal Newtonian fluid are employed. The use of the rotating screw model helps in clarifying some misconceptions, which have appeared in the literature, regarding the flow patterns. Closely following the derivations for the case of the rotating barrel, the different velocity components for the rotating screw are given and the two cases are compared. While the method of calculating the flow rate using the velocity component in the screw-axial direction is straightforward for both the cases, it is not so if the downchannel or circumferential velocity component is used for the rotating screw; the equations necessary for this purpose are also derived.