Simulation Of Flight Element Runner In Co-Rotating Twin Screw Extruder

This thesis is concerned with three-dimensional non-Newtonian isothermal flow simulation of melts in full filling region of the flight element runner belonging to intermeshing co-rotating twin screw extruder. The math models of the screw were established based on twin-screw geometry.In order to possess the models the same dimension with the co-rotating twin screw extruder, the math models of the screw curve based on actual geometry dimension of the twin screw extruder have been developed. And meanwhile, a condition of boundary with non-slip is supposed for the velocity boundary. The mass velocity is restricted to 'zero' as the materials adhere to the barrel wall, and it is equal to the surface velocity of the twin screw while the materials adhere to the twin screw's surface. Pressure boundary conditions are chosen for the inflow section and outflow section of the twin screw extruder. ANSYS, the software involves with finite element method, was adopted for solving the flow models and gaining results of the velocity flied, pressure filed, and viscosity field. Through deduction to the constitutional equation of viscosity, field and shear stress field of the runner were achieved. An idiographic measure was brought forward, as well as some compiled post processor programs were used to closely calculate elongation rate, shear rate and shear stress. A measure, in connection with flow and circulatory flow, which is simple to compute with and easy to comprehend, was adopted in this thesis.In order to fully explain the relationship between extrusion characteristics and analytical parameters, the method of connecting figure with table was chosen in this thesis. Analytical parameters including screw rotate speed, press difference between inflow section and outflow section, clearance between barrel wall and screw surface, mass peculiarity and non-dimensional depth of screw groove, etc, were carefully analyzed. The effect on the extrusion characteristics such as flow, circulatory flow, elongation rate, shear rate, shear stress and mean shearing intensity, etc, caused by the parameters mentioned above was analyzed, too.