啮合同向双螺杆挤出机不同螺杆构型对其流场的影响

目的：探究啮合同向双螺杆挤出机不同螺杆构型对流场的影响，改善聚乳酸的材料性能。方法：应用Solidworks软件建立双头螺纹元件的几何模型，在Polyflow中进行数值模拟，借助Fieldview软件对仿真结果进行后处理分析，并对比剪切速率场、压力场、速度场、黏度场以及停留时间分布曲线RTD，得出螺槽深度对流场的影响。结果：在中心距相同的情况下，通过改变螺纹元件的外径和内径之比改变螺槽深度，在相同的工艺条件下，同向双螺杆流道内各物理场以及混合性能均存在较大差异；与构型二相比，构型一的剪切作用更强，但构型二的建压能力更好；挤出过程中，构型二轴向混合能力较好但自清洁能力较差，而构型一轴向混合能力较差、自清洁能力较好。结论：螺槽深度的改变对流道混合性能有着一定影响且存在规律性，可有效指导双螺杆挤出机螺纹元件的设计。

Influence of different screw configurations on the flow field of intermeshing co-rotating twin-screw extruder

Objective:To explore the influence of different screw configurations of intermeshing co-rotating twin -screw extruder on the flow field and improve the material properties of PLA.Methods:The geometric model of double threaded element was established by using Solidworks software, and the numerical simulation was carried out in Polyflow. The post-processing analysis of the simulation results was carried out with the help of Fieldview software. The shear rate field, pressure field, velocity field, viscosity field and the residence time distribution RTD were compared to obtain the influence of screw groove depth on the flow field.Results:When the center distance was the same, the depth of the screw groove was changed by changing the ratio of the outer diameter to the inner diameter of the threaded element, physical fields and mixing performance had great differences in the flow field of intermeshing co-rotating twin-screw extruder under the same process conditions. Compared with configuration 2, configuration 1 had stronger shear effect, but configuration 2 had better pressure building ability. In the extrusion process, configuration 2 had good axial mixing ability but poor self-cleaning ability, while configuration 1 had poor axial mixing ability and good self-cleaning ability.Conclusion:The change in screw groove depth has certain effects and rules on the mixing performance of the flow field, which can effectively guide the design of threaded element for twin-screw extruder.