双螺杆中啮合块、螺杆元件混合过程及混合性能的研究

以双螺杆挤出机中的啮合块、螺杆元件作为研究对象,对其混合过程及混合性能进行研究,分析物料与添加剂的相互运动及变化过程。利用网格重叠技术和Ployflow软件对啮合块、螺杆元件的混合性能进行仿真,研究螺杆元件及不同转速下啮合块对应流体区域内的最大剪切应力,粒子在流体区域内的停留时间分布、分布指数、分离尺度等。结果表明:在啮合块流道内的混合过程中,啮合区域的两种粒子进行分布混合,其他区域的粒子在轴向运动到第2片啮合块时开始被带入啮合区,与另一种粒子进行分布混合;在相同转速下,啮合块的混合性能优于螺杆元件,随着转速的提高,啮合块的分散混合性能逐渐增强。

Study on Mixing Process and Mixing Performance of Meshing Block and Screw Element in Twin Screw

The meshing block and screw element in the twin-screw extruder were selected as the research object, and the mixing process and mixing performance were studied to analyze the mutual movement and change process of materials and additives. By using the overlapping grid technique, the mixing performance of the meshing block and the screw element was simulated by the use of the Ployflow software. The maximum shear stress in the fluid region corresponding to the screw element and the meshing block at different speeds, the residence time distribution, distribution index and separation scale of the particles in the fluid region were studied.The results show that during the mixing process of the two particles in the flow channel of the meshing block, the two particles in the meshing region are first distributed and mixed, and the particles in other regions are brought into the meshing region when the axial movement to the second meshing block, where particles are distributed and mixed. At the same rotating speed, the mixing performance of the meshing block is better than that of the screw element. As the rotating speed increases, the dispersion mixing performance of the meshing block gradually increases.