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Xu B.,Technology Development Center for polymer Processing Engineering of Guangdong Province | Yu H.,Hunan University of Technology
Advanced Materials Research | Year: 2012

This work aims at simulation of the mixing performance in the novel co-rotating non-twin screw group developed by the authors. The simulation concerns the incompressible fluid obeying Carreau flow model. Using the mesh superposition technique, the mixing performance in such novel mixing sections, as well as in the conventional twin screw groups with one and two tips, are simulated. Adopting the particle tracking technique, distributive mixing is visualized by the evolution of the mixing of a cluster of particles in addition to using the segregation scale. Dispersive mixing is evaluated using mixing index in combination with the probability distributions of cumulative mixing index. The computational results reveal that the novel screw group is superior in mixing ability. © (2012) Trans Tech Publications, Switzerland. Source


Xu B.,Technology Development Center for polymer Processing Engineering of Guangdong Province | Xu B.,Hunan University of Technology | Yu H.,Technology Development Center for polymer Processing Engineering of Guangdong Province | Yu H.,Hunan University of Technology | And 3 more authors.
Huagong Xuebao/CIESC Journal | Year: 2012

A new approach to mixing enhancement in regular single screw extruder was presented with axial reciprocating motion of barrier to generate chaotic mixing. Such a model with the barrier lower than the screw channel was proposed and the corresponding mathematical model was developed. The periodic flow and mixing performance of Newtonian fluid in such an extruder were numerically simulated. The finite volume method was used and flow domain was meshed by staggered grids with the periodic boundary conditions of the barrier motion being imposed by mesh supposition. Fluid particles tracking was carried out by the fourth order Runge-Kutta scheme. Distributive mixing was visualized by the evolution of passive tracer initially located in different positions. The growth of interface stretch of the tracers with time and cumulative residence time distribution (RTD) were also obtained. The Poincaré section was used to reveal the geometrical scale of chaotic mixing, and the results confirmed that the axial reciprocating motion of the barrier could lead to chaotic mixing to enhance mixing performance. The new approach could make the broadening of RTD much narrower than that in fixed barrier geometry along with the much smaller mean residence time. In contrast, the mixing performance in the conventional single extruder with a fixed barrier was also investigated. © 2012 All Rights Reserved. Source


Wang X.,Hunan University of Technology | Wang X.,Technology Development Center for polymer Processing Engineering of Guangdong Province | Xu B.,Technology Development Center for polymer Processing Engineering of Guangdong Province | Liu Y.,Hunan University of Technology | And 3 more authors.
Gaofenzi Cailiao Kexue Yu Gongcheng/Polymeric Materials Science and Engineering | Year: 2012

The numerical simulations of three-dimensional isothermal flow in a embedded planet-screw is carried out using finite-volume approach. The boundary conditions of planet screws were imposed by user define function (UDF) developed by ourselves. The distributions of the velocity, pressure obtained from the strain rate and residence time distribution (RTD) are investigated for single-screw and planet-screw. Compared with the conventional single-screw extruder, the planet-screw leads to perturbation on the flow field and the material elements are suffered higher strain rate and elongation effect. After analysis the residence time distribution curve, it is found that the residence time distribution in the planet-screw is narrower than in the conventional single-screw extruder, so the planet-screw can has a higher output with the better extrusion characteristic performance. Source

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