Abstract: In order to study the cut size of a superfine classifier, computational fluid dynamics was used to simulate the gas-solid two-phase flow in the classifier. The RNG k-ε turbulence model was adopted to describe the gas phase, and the particle stochastic trajectory model was used to describe the solid phase. The physical mechanism of particle movement and the classification process in a superfine classifier was revealed by analyzing the relationship between particle tracks and cut size. By analyzing the change of cut size, the effects of rotational speed, air volume, feeding concentration and material density on cut size were established. The results showed that in the theoretical calculation of cut size, ignoring the effect of blade thickness would lead to overly small calculated value. When rotational speed was low （450 r/min，600 r/min）, the simulation value and calculated value had a large difference due tor the effect of local turbulence, and the max error was 13.58%. Compared with air volume, the effect of rotational speed on cut size was much more significant. The simulation cut size value agreed well with theoretical calculation. The results provide a new method of obtaining the cut size of a superfine classifier.

Key words: superfine classifier, cut size, particle tracks, numerical simulation

摘要： 为研究超细分级机的切割粒径，采用计算流体力学技术对分级机气固两相流进行了数值模拟。计算中气相采用RNG k-ε湍流模型，颗粒相采用随机轨道模型。通过分析颗粒轨迹与切割粒径的关系，揭示了颗粒在分级机内运动的物理机制；通过分析切割粒径随转子转速、风量、喂料浓度和物料密度的变化规律，阐述了各参数对切割粒径的影响。结果表明：切割粒径的理论推算中，忽略叶片厚度的影响将导致计算值偏小；低转速（450 r/min，600 r/min）时，受局部涡流的影响，切割粒径模拟值与理论计算值相差较大，最大误差为13.58%；与风量相比，转速对切割粒径的影响更为显著。模拟结果与理论计算值吻合较好，为求取分级机的切割粒径提供了一种新方法。

关键词: 超细分级机, 切割粒径, 颗粒轨迹, 数值模拟