螺杆构型对啮合异向双螺杆流场影响的仿真分析

Simulation analysis of the influence of screw configuration on the flow field of meshing twin screw

以聚乳酸(PLA)为例,讨论异向双螺杆挤出机3种不同螺杆构型(阴阳转子螺杆头数比分别为2∶2、3∶2、4∶2)下的流道分布规律。依据理论端面曲线方程在Solidworks中创立上述3种不同螺杆构型的三维模型,使用Workbench软件对3种螺杆构型进行网格模型的建立,再使用Polyflow流体仿真软件进行模拟实际流场情况,得到后处理结果,使用后处理分析软件FieldView进行最终结果的分析;研究PLA流体的在不同螺杆构型下的压力、剪切速率以及黏度。同时使用Polystat统计模块对停留时间分布曲线RTD以及分布混合特性进行对比研究。结果表明,在螺杆转速为60 r/min和阳转子螺杆头数一定的条件下,随着阴转子螺杆头数的增加,压力波动减小,剪切作用提高,停留时间增加,分布效果提高,有利于材料的输出和混合。

The flow channel distribution of three different screw configurations was discussed by taking polylactic acid(PLA)in a twin⁃screw extruder with different directions at ratios of screw heads to rotor of 2∶2,3∶2,4∶2.The 3D mod⁃els for these three screw configurations were established by the SolidWorks software according to a theoretical end curve equation.The mesh models of the three screw configurations were established using the Workbench software,and the ac⁃tual flow field was simulated using the Polyflow fluid simulation software to obtain the post⁃processing results.The final result was analyzed by using the FieldView post⁃processing analysis software.The pressure,shear rate,and viscosity of the PLA fluid were studied under different screw configurations.Meanwhile,the residence time distribution curve and distribution mixing characteristics were compared by using the Polystat statistical module.The results indicated that the pressure fluctuation decreased,the shear effect increased,the residence time increased,and the distribution effect in⁃creased with an increase in the number of screw heads of the negative rotor at a screw speed of 60 rpm with the certain number of screw heads of the positive rotor.There are advantageous to the output and mixing of materials.