分级轮叶片结构和转速对分级性能影响的仿真

Simulation on Influence of Blade Structure and Speed of Classification Wheel on Classification Performance

运用Fluent软件,采用液-固两相流的数值模拟方法,对超细粉体湿法离心分级机分级腔内流场进行数值模拟仿真;选用重整化群k-ε湍流模型和欧拉多相流模型,利用多重参考坐标系法,在稳态条件下,分析不同形状分级轮叶片分级腔内流体的速度分布情况,研究不同形状分级轮叶片对分级机分级性能的影响;选用离散相模型,在非稳态条件下,分析分级腔内颗粒轨迹的规律,研究分级轮转速对分级粒径的影响。结果表明:相比于直叶片和斜叶片,弧形叶片分级效果更好;采用弧形叶片结构,当分级轮转速为1 000 r/min时,分级粒径大于1μm,分级轮转速为2 000 r/min时,分级粒径接近1μm,当分级轮转速为3 000 r/min时,分级粒径小于1μm,增大分级轮转速有利于减小分级粒径。

Fluent software and the method of numerical simulation of liquid-solid two-phase flow were used to analyze the flow of fluid in classification chamber of ultrafine powder wet centrifugal classifier. Under the condition of steady state, renormalization group （RNG） κ-ε model, Eulerian multiphase flow model and multiple reference frame method were used to analyze the velocity distribution of the fluid in classification chamber of different shape classification wheel blades, in order to study the influence of different shape classification wheel blades on classification performance. Under the condition of unsteady state, the discrete phase model was used to analyze the rule of particle track in classification chamber, in order to study the influence of different rotate speed of classification wheel on cut size. The results indicate that comparing with straight blades and oblique blades, the classification oerformance of curved blades is the best. Using curved blades, the cut sizeis greater than 1 /xm when the grading wheel speed is 1 000 r/min, the cut size is close to 1 txm when classification wheel speed is 2 000 r/rain, and the cut size is smaller than 1/,Lm when the classification wheel speed is 3 000 r/min. Improving the classification wheel rotary speed is helpful to reduce the cut size.