A blade-free planetary mixer provides an effective and rapid mixing of cohesive powders due to its powerful centrifugal agitation capability to produce a swirling flow pattern in a mixing vessel. Despite its popular use in the powder processing industry, the dynamics and characteristics of blade-free planetary mixing are still not well understood because of a lack of experimental and numerical studies. This paper presents a discrete element study of the influence of operating parameters such as the steady-state revolution speed and the rotation-to-revolution speed ratio on bending of pharmaceutical powders with specific cohesiveness. The particle-level cohesive forces were calculated using the Johnson-Kendall-Roberts cohesion model. A series of discrete element simulation was carried out at some range of revolution and rotation speeds of a mixing vessel. The degree of mixing in each simulation was quantified with the mixing index and mixing time. The simulation results showed a faster rotation speed and a higher rotation-to-revolution ratio provided more effective mixing of the specific microcrystalline cellulose powder. The methodology and results of this numerical study can be used to determine the optimal operating conditions of a blade-free planetary mixer for effective mixing of cohesive powders.

中文翻译：

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无叶片行星式混合机工作条件对粘性粉末混合影响的数值研究

无叶片行星式混合器具有强大的离心搅拌能力，可在混合容器中产生涡旋流型，从而可有效，快速地混合粘性粉末。尽管它在粉末加工行业中得到了广泛的应用，但由于缺乏实验和数值研究，因此对无叶片行星式混合的动力学和特性仍然知之甚少。本文提出了离散参数研究，如稳态旋转速度和旋转/旋转速度比等操作参数对具有特定内聚性的药物粉末弯曲的影响。使用Johnson-Kendall-Roberts内聚模型计算颗粒级内聚力。在混合容器的某些转速和转速范围内进行了一系列离散元素模拟。通过混合指数和混合时间来量化每个模拟中的混合程度。模拟结果表明，更快的旋转速度和更高的旋转/旋转比提供了特定微晶纤维素粉末的更有效混合。该数值研究的方法和结果可用于确定无叶片行星式混合机的最佳运行条件，以有效地混合粘性粉末。