This diploma deals with the calculation of the cross channel flow, strain and residence time of a polymer melt in the metering zone of a single screw extruder. The screw channel is unwound to a rectangular one and the computer simulation is done under steady state and isothermal conditions. For the solution of this flow problem it is necessary to solve the Navier-Stokes equations with the Finite Differences Method. An iterative pressure-correcting algorithm considers the equation of continuity. With the obtained velocity distribution function strain and residence time are computed in the metering zone.
Plots of streamlines in the screw channel show the circular flow. The cross channel velocity decreases while approaching to the fligthts, the zero point moves closer to the barrel surface. Only near the flights the vertical velocity component is different from zero. The dragging of the melt causes a pressure rise from the passive to the active flight. Pressure differences between the barrel surface and the screw root near the flights explain the vertical flow. The residence time distribution function reaches ist minimum value at two thirds of the channel depth, near the screw root and the barrel surface it goes to infinity. Narrow channels show a longer residence time near the screw root than wide ones. Deeper channels reduce the strain generally. Comparisons between numerical and analytical calculation show great faults in the analytical results already for shallow screw channels.