椭球颗粒搅拌运动及混合特性的数值模拟研究

为探讨在强制搅拌下同属性颗粒由分层到分布均匀状态的运动特征及规律, 本研究利用三维离散单元法模拟不同转速下U形罐体内等粒径椭球颗粒的混合过程. 从单颗粒随机运动轨迹、宏观颗粒流运动矢量图的角度分析颗粒混合过程的宏观混合规律及局部混合特征, 定量描述混合度与搅拌叶片旋转圈数的数学关系. 结果表明, 强制搅拌下同属性分层颗粒的混合是在对流混合及四个局部混合共同作用下实现的; 分层颗粒的混合度与搅拌轴的转速无关, 而与搅拌轴旋转圈数直接相关; 混合度与圈数的关系符合指数增长模型. 研究结果可为散体物料增混行业的设备改进及操作控制提供依据和参考.

Numerical simulation on stirring motion and mixing characteristics of ellipsoid particles

To investigate the motion characteristics and the law of identical property for particles obtained under segregation to uniform distribution conditions in forced agitation mixing, the mixing process of the same sized ellipsoidal particles at different rotating speeds in a U-tank is simulated using three-dimensional discrete element method. Macroscopic mixing law and partial mixing characteristics in particle mixing process are analysed in the view of single particle random motion trajectory and motion vector diagram of macroscopic particle flow. And the mathematical relation between mixability and revolutions of agitating blades is described quantitatively. Results show that convective mixing and four partial mixing characteristics control the mixing homogeneity process of identical property of segregation particles in forced agitation mixing. Mixability of segregation particles is independent of rotating speed of the agitating shaft, but has a direct correlation with revolutions. The relation between mixability and revolutions agrees with the exponential growth model. Research results can provide the basis and reference for equipment improvement and operating control of bulk material in the industry of the augmenting of mix.