Numerical Simulation of Extrusion Characteristics of Intermeshing Co-rotating Tri-Screw Extruder

Three-dimension isothermal and non-Newtonian flow of polyethylene melt in new-style intermeshing co-rotating tri-screw extruder was simulated using Computational Fluid Dynamics(CFD) method.The mixing and flow of polymer melt in special center region of tri-screw extruder were also studied.Based on velocity and pressure fields calculated,the extrusion characteristics of tri-screw extruder,such as flow rate,back flow rate,mean shear rate,power consumption and productivity ratio,were calculated and compared with those of twin screw extruder.The simulation results show that circumfluence appears in center region and increases mixing times.Tri-screw extruder has better operative abilities than traditional twin screw extruder in pumping capacity,distributive and dispersive mixing.Whereas the productivity ratio of tri-screw extruder is 1.3 times of twin screw extruder.This study proves that tri-screw extruders have a good prospect of application and extension in polymer processing.