Numerical simulation of flow characteristics in new co-rotating triangle arrayed triple screw extruders

Abstract

Triangle arrayed triple screw extruder (TATSE) is a new equipment of polymer processing, which is different from traditional single and twin-screw extruder in flow and mixing characteristics. The studies about TATSE are very limited and all have been in the conditions of qualitative analysis due to its complicated geometry. In order to understand the flow rule of polymer melt and optimise the design of TATSE, in this paper, 3D flow of polymer melt in TATSE was simulated by using finite element method (FEM). A special study of flow in particular central region of TATSE was carried out by the analysis of the velocity distribution, pressure distribution and partial residence time distribution (RTD). The extrusion characteristics of TATSE, namely the abilities of pumping capability, distributive mixing, dispersive mixing, power consumption and productivity ratio, were compared with those of twin-screw and four-screw extruder. The results showed that there was circumfluence in central region but no stagnation in it. Although the velocity and pressure gradients were small relatively, the ability of pressure generation for TATSE was not evidently lower. TATSE had better operative abilities and high productivity ratio than intermeshing twin-screw extruder in the capacities of pumping capability and mixing.