Mathematical modelling of stratified flow of polymer melts in an axisymmetric formulation
This study is about definition of rational geometry of the cable die, which effectively distributes polymer melt flows in channels; estimation of stability boundary flows of materials with different physical and rheological properties for the technological range of modes of processing; calculation and construction of the velocity fields, pressures, temperatures inside the channels of cable die; experimental determination of the dependence of the thickness of imposed layers of insulation and semiconducting materials from the linear velocity of pulling wires and expenses for each channel. In the modeling of the processes was used the cable die for joint overlay three layers of the polymer coating (layer semiconductive conductor screen, insulation, outer semiconductive screen) used in the production of modern electric cables of medium and high voltage. To analyze the processes of heat and mass in terms of stratified flows in channels of cable die real physical processes have been replaced by a mathematical model, which is a system of nonlinear differential equations, reflecting the basic conservation laws. The system was supplemented of boundary conditions and physical and rheological properties of the materials processed. In order to simplify the model offers a number of assumptions that allowed us, in particular, go to the axisymmetric formulation of the problem. To solve the formulated mathematical model the numerical method was applied, namely the finite element method, implemented through the Ansys set of software. Basing on the received results was made more effective geometry of the cable die, eliminating the effects of twist the polymer streams is developed; velocity, pressure and temperature distribution in the channels of the cable die were obtained; possible overheating of the material inside the channels is presented; the effect of certain parameters of overlay multilayer polymeric insulation process on layer thickness was assessed.