ANALYSIS OF MIXING IN CO-ROTATING TWIN SCREW EXTRUDERS THROUGH NUMERICAL SIMULATION

摘要

Nowadays, many materials, pigments, additives, gas or reactants, are mixed to create new products combining the characteristics of different raw materials to obtain a specific product properties. The quality of the mixing, i.e. the uniformity of the mixture, is a key issue that will determine the morphology and the properties of the resulting compound. An insight into those features can now be obtained through the numerical simulation of flow in extruder components. 3-D transient numerical simulations of two twin screw extruder (TSE) sections are presented and their behavior compared. A new technique, the mesh superposition method (MST), accurately determines the part of the computational domain which is occupied by the fluid with respect to the current screws position; the Navier-Stokes equations are then solved without involving any remeshing. Through the calculation of trajectories of material points, statistical information (of the RTD, deformations, dispersion, etc.) can be obtained to compare both configurations in a synthetic and quantitative way.