Abstract Ribbon mixers are widely used in practice because they are capable of providing high speed convective mixing. Here, the discrete element method (DEM) is used to investigate the effects of impeller speed and fill level on the mixing behaviors of mixtures of particles with different cohesion in two-bladed and four-bladed ribbon mixers, each having a horizontal cylindrical vessel. The mixing behaviors are characterized by a particle-scale mixing index. Simulations show that the mixing rate increases with the impeller speed for both the cohesive and non-cohesive particle mixtures up to a certain speed, beyond which it shows a reduction. The mixing rate becomes poorer at higher impeller speeds for mixing of cohesive particles in the 2-bladed mixer. Inspection of velocity fields shows that many localized recirculation flows exist when the mixing non-cohesive particles, preventing the overall mixing. By contrast, when mixing cohesive particles, there exist circumferential flow about the shaft axis and convective flow in the horizontal axial direction, improving the particle mixing. The mixing rate deteriorated with an increase of the fill level in both the two-bladed and four-bladed mixers. The mixing rate of the particles is higher in the four-bladed mixer compared to the two-bladed mixer. With the increase of fill level, the particle flow changes successively from the sliding type of flow to recirculation flow and then to cascading flow for non-cohesive particles. The four-bladed mixer performs better for mixing at high fill levels and stronger cohesion, consolidating its advantage for mixing cohesive particles.

中文翻译：

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螺带混合机的混合性能：操作参数的影响

摘要 带式混合器在实践中被广泛使用，因为它们能够提供高速对流混合。在这里，离散元方法 (DEM) 用于研究叶轮速度和填充水平对两叶片和四叶片螺带混合器中具有不同内聚力的颗粒混合物的混合行为的影响，每个螺带混合器都有一个水平圆柱形容器。混合行为的特征在于颗粒级混合指数。模拟表明，内聚和非内聚颗粒混合物的混合速率随着叶轮速度的增加而增加，直至达到一定速度，超过该速度则显示降低。在较高的叶轮速度下混合速度变差，用于在 2 叶片混合器中混合粘性颗粒。速度场的检查表明，当混合非粘性颗粒时，存在许多局部再循环流，阻止了整体混合。相比之下，在混合粘性颗粒时，存在绕轴的圆周流动和水平轴向的对流，改善了颗粒混合。在双叶片和四叶片混合器中，混合速率随着填充水平的增加而恶化。与双叶混合器相比，四叶混合器中的颗粒混合速率更高。随着料位的增加，颗粒流由滑动流向循环流，再到非粘性颗粒的级联流依次变化。四叶混合器在高填充水平和更强的内聚力下混合表现更好，