Numerical Simulation of Polymer Flow Dynamics in Cable Extrusion Processes

The quality of the insulation in a HV cable is largely determined in the extrusion process and more needs to be understood about the behavior of polymer melt within the extrusion die. This master thesis aims to increase the knowledge of how to properly simulate the polymer flow pattern and thermal build up within the extrusion die. The main part of the work is to recreate a simulation model made in 1998 by ABB, and improve the model based on literature recommendations. The model is implemented in Ansys Fluent Material Processing with the same boundary conditions as presented in the legacy report, with very similar results. Realistic wall slip conditions, material properties and thermal boundary condition for the conductor are then added separately. The largest improvements come from including wall slip, since undesired local effects highlighted as important in the legacy report are drastically lowered in the more realistic case. Changing the material properties and thermal condition appears to mostly affect the viscosity and for the latter case of course also the thermal buildup close to the conductor. Further, there were several aspects that could not be simulated in the study, but due to their potential importance they are still analyzed.