不同振动模式下颗粒分离行为的数值模拟

Numerical simulation of particle segregation behavior in different vibration modes

利用三维离散元法对垂直方向上的直线、圆和椭圆振动模式颗粒分离过程进行了数值模拟研究,对直线振动时上层大颗粒的波动及圆和椭圆振动时出现的聚集、循环等现象的形成机理进行了分析,并讨论了振动强度对各振动模式下颗粒分离形态的影响规律.研究表明,综合运用空隙填充、侧面驱动的颗粒运动和能量非均匀分布三种机理,并结合颗粒群的速度矢量分布情况能够较好地解释各振动模式下的颗粒分离行为.振动强度对圆和椭圆振动模式的分离形态具有显著的影响,并在振动强度约为3时,各种振动模式均具有良好的颗粒分离效果和稳定的颗粒运动状态.

Particle segregation processes in different vibration modes are simulated based on 3D discrete element method（DEM）.The phenomena of wave motion of large particles in upper layer that appears in the segregation processes of linear vibration mode,accumulation and circulation that appear in circular and elliptical vibration mode are analyzed.And the influences of vibration intensity on the segregation pattern of the circular and elliptical mode were also discussed.The results show that the segregation behaviors in different modes can be well explained by a combination of three mechanisms：void filling,sidewall-driven transport of particles and nonequipartition of energy,and the distribution of particle velocity vectors.The vibration intensity has a great effect on the segregation pattern of circular and elliptical mode.For each vibration mode,fine particle segregation effect and stable particle moving state is obtained when the value of vibration intensity is about 3.