不同螺槽深度下异向双螺杆挤出机流道仿真分析

Simulation analysis of flow channel of different twin-screw extruder with different groove depth

目的:讨论聚乳酸在异向双螺杆挤出机不同螺槽深度下的流道分布规律。方法:使用Solidworks软件建立3种不同螺槽深度的螺杆元件及其对应的流道模型,运用Polyflow流体仿真软件进行数值模拟,借助FieldView软件对后处理结果进行数值分析;并对3种不同螺槽深度状态下的异向双螺杆挤出机的聚乳酸流体的压力场、剪切速率场和黏度场,以及停留时间分布曲线RTD进行对比分析。结果:通过改变螺杆元件的齿根圆直径及其对应的流道直径可实现螺槽深度的改变,在其他条件相同的情况下,螺槽深度越浅,压力波动越大,剪切速率波动越大,但黏度波动越小;螺槽深度越深,轴向混合性能越高。结论:螺槽深度的变化对流场混合性能存在影响并具有一定的规律性,可根据试验选择混合性能全面的双螺杆挤出机进行实际生产。

Objective:The flow channel distribution of polylactic acid(PLA)in different groove depths of a double screw extruder was discussed.Methods:Three kinds of screw elements with different depth of screw groove and their corresponding flow channel models were established by Solidworks software.Polyflow fluid simulation software was used for numerical simulation,and FieldView software was used for numerical analysis of post-processing results.The pressure field,shear rate field,viscosity field and residence time distribution curve(RTD)of polylactic acid(PLA)in three different screw extruders with different groove depths were studied.Results:The depth of the screw groove was changed by changing the diameter of the root circle of the screw element and the corresponding diameter of the flow channel.Under the same condition,the shallower the depth of the screw groove,the greater the fluctuation of pressure and shear rate,but the smaller the fluctuation of viscosity.The deeper the screw groove,the higher the axial mixing performance.Conclusion:The change of screw groove depth has influence on the mixing performance of flow field and has certain regularity.The twin-screw extruder with comprehensive mixing performance can be selected according to the experiment for practical production.