Abstract:

The Finite Element Method was used to study the flow field of different screw combination sections of single?screw extruder. The Polyflow software was used to calculate the pressure field, shear rate field, velocity vector, mixing index and other parameters of the flow field of ordinary screw, ordinary screw and pineapple head combined screw, ordinary screw and pin combined screw. The post?processing results were compared and analysed.The results show that the ordinary threaded screw can provide a greater axial velocity for the fluid; although the pineapple head screw has greater resistance, the more oblique section design can provide better axial and circumferential velocity for the fluid; the barrier effect of the screw causes a part of the fluid to flow back. The three new types of screws can effectively stretch and shear the fluid while providing a good linear velocity for the fluid to make its dispersion and mixing more uniform. According to the analysis of the curve results, the mixing effect of pin?screw is the best.

Key words: Single screw extruder, Mixing characteristic, Polyflow software, Numerical simulation

摘要：

采用有限单元法对单螺杆挤出机不同螺杆组合段流域进行研究。使用Polyflow软件计算普通螺纹螺杆、普通螺纹与菠萝头组合螺杆、普通螺纹与销钉组合螺杆流场的压力场、剪切速率场、速度矢量、混合指数等参数，并对后处理结果进行了比较分析。结果表明，普通螺纹螺杆能为流体提供较大的轴向速度；菠萝头螺杆虽然阻力较大，但是较多的斜截面设计能为流体提供较好的轴向分速度和周向分速度；销钉螺杆的屏障作用会使一部分流体回流。三种新型螺杆在为流体提供良好的线速度的同时，能有效地对流体进行拉伸和剪切，使其分散混合更加均匀，从其曲线分析结果来看销钉螺杆混合效果最佳。

关键词: 单螺杆挤出机, 混合特性, Polyflow软件, 数值模拟