TWO-DIMENSIONAL NONISOTHERMAL NUMERICAL ANALYSIS OF SPEED RATIO EFFECTS ON DISPERSION AND DISTRIBUTION IN HIGH-VISCOSITY PARTIALLY FILLED RUBBER MIXING

Abstract

ABSTRACT Two-dimensional, transient, and nonisothermal computational fluid dynamics simulations are conducted for high-viscosity rubber mixing in a two-wing rotor-equipped partially filled chamber of fill factor 75%. Calculations presented assess the effect of three differential speeds or speed ratios of the two rotors for the rubber mixing process: 1.0 (also called even speed), 1.125, and 1.5. A Eulerian multiphase model, the volume of fluid technique, is employed to simulate two different phases, rubber and air, by calculating the free surface between the two phases, in addition to the main governing equations such as the continuity, momentum, and energy equations. To characterize the non-Newtonian, highly viscous rubber under nonisothermal conditions, the shear rate–dependent Carreau-Yasuda model along with an Arrhenius function are employed. A set of massless particles is introduced into the chamber to calculate several parameters related to dispersive and distributive mixing characteristics. Specifically, the mixing index and maximum shear stress are analyzed for the dispersive nature, whereas cluster distribution index and length of stretch are calculated for investigating the distributive nature of the mixing process. Also, the temporal viscous heat generation rate, a good indication of the temperature rise throughout the domain, which is critical in the process and equipment design, is analyzed here. Results showed that the 1.125 speed ratio was the most efficient in terms of distributive mixing and heat generation.