Fluid Flow And Mixing Mechanism Of A New Eccentric Three-screw Extruder

As a new type of multi-screw extruder,the eccentric three-screw extruder has important research value in the mixing and extrusion of polymer.In the actual production and processing process,both the structure of the common single screw and double screw extruder have certain limitations,which can not meet the requirements of the production and processing of new materials.Eccentric single screw and twin screw extruder can meet the needs of new materials processing,but it can not be widely spread due to low working efficiency.In order to meet the requirements of production and processing and improve production efficiency,the paper takes the eccentric three-screw extruder as the research object.The flow and mixing mechanism of eccentric twin screw extruder is relatively complex due to the different screw combination and arrangement.Compared with the eccentric three-screw extruder,the mixing mechanism and structure are more complex,and the internal flow becomes more variable.In order to study the mechanism of internal mixing flow and to control the eccentric three-screw extruder better,the paper makes a deep study.In this paper,a new type of eccentric three-screw extruder is taken as the research object.In order to explore the flow rule and mixing mechanism,the internal flow characteristics and mixing characteristics are analyzed and studied.Firstly,in order to ensure the rationality of the structure,the eccentric meshing disc is selected as the component of the eccentric screw according to the chaos mechanism.Secondly,in order to observe the internal flow and mixing directly,the particle tracer technology was used to release different color particles at the entrance of the eccentric three-screw extruder.It was found that the mixing effect of particles was obvious under the action of screw rotation.The trajectory of a single particle is complex and changeable.Finally,in order to explore the influence of external conditions on the eccentric three-screw extruder,the eccentric three-screw extruder composed of meshing disks with different eccentricity and the eccentric three-screw extruder with different rotating speeds were simulated and analyzed.In order to further explore the flow and mixing mechanism of eccentric three-screw extruder.The flow and mixing in the barrel were studied by changing the number of screws and the arrangement of screws.First of all,the common eccentric twin-screw extruder is compared with the new eccentric tri screw extruder.The eccentric three-screw extruder has multiple meshing areas and the triangular arrangement has a central area.The mixing efficiency of the material increase effectively under the same rotating speed.Secondly,explore the mixing and flow characteristics of the in-line and triangular eccentric three-screw extruders by changing the arrangement structure of the screws.And through the extension logarithm,instantaneous shear rate,axial shear rate,probabilistic mixing index and other mixing parameters,it is found that the in-line eccentric three-screw extruder has a better shearing effect on the internal melt,while the triangular eccentric three-screw extruder has a more obvious effect on the internal melt stretching.