Theoretical Analysis of Pressure Distribution in an Oval Type Mixer for Polymeric Material

Abstract

In order to perform a behavior analysis of polymeric material in a mixer with oval or wing type rotors, it was necessary to find a theoretical solution of the pressure distribution in the material along the circuit direction of the rotor. We considered a behavior model in which the material flowed from a wide channel that tapered down into a narrow one corresponding to a space between the rotor and chamber of the mixer. Using this model, the pressure distribution throughout the whole circuit of the rotor was theoretically analyzed under the following two conditions: 1) the material behaved as a Newtonian fluid, 2) the material behaved as a non-Newtonian fluid of a power-law type. Through this analysis, the necessary theoretical solution for pressure distribution of the two types of fluids were obtained, and the theory of pressure distribution in a mixer was then completed.
These analyses showed that the maximum pressure along the circuit of the rotor did not occur in the tip area, but rather at the front face of the rotor. They also showed that pressure distributions differred when all conditions except fluid type (Newtonian and non-Newtonian) were held constant. The pressure distribution curves, which indicated pressure increasing in the direction of flow at the front face of the rotor, were shown to be closer to linear for the non-Newtonian fluid than for the Newtonian fluid.