涡流空气分级流场中颗粒运动及分布规律研究

Study of particle motion and distribution laws in the turbo airclassification flow field

为探究粗细颗粒在分级机内分离过程,基于颗粒-涡相互作用模型和离散元软球模型研究了涡流空气分级流场中湍流脉动对颗粒运动及切割粒径d_(50)的影响,探索了分级过程中颗粒的分布规律。湍流脉动主要影响小颗粒的运动轨迹,对大颗粒运动轨迹影响不大,对切割粒径d_(50)无明显影响;在风速12 m·s^(-1),转笼转速1200 r·min^(-1)工况下,从径向分布来看,小于20μm的细颗粒主要分布在转笼区,接近切割粒径d_(50)的颗粒在环形区内做旋流运动,大于25μm的粗颗粒会在靠近导叶的区域聚集,由于颗粒间的相互作用导致一些较细的颗粒会掺混在这些粗颗粒中,从而产生“鱼钩效应”;从轴向分布来看,小于20μm的细颗粒主要分布在分级机内靠近顶部区域,粗颗粒会逐渐向下沉降,粒径越大沉降越快。

To probe into the separation process of coarse and fine particles in the classifiers,based on the particle-eddy interaction model and the discrete element soft sphere model,the influence of turbulent fluctuation in the turbo air classification flow field on particle motion and cut size d_(50 )are investigated.The distribution laws of particles in the classification process are also explored.Turbulent fluctuation mainly influences the trajectory of small particles.It has little effect on the trajectory of large particles,and has no significant effect on cut size d50.At an inlet air velocity of 12 m·s^(-1) and a rotor cage rotating speed of 1200 r·min^(-1),for the radial distribution,the fine particles less than 20μm are mainly distributed in the rotor cage area,particles with size near d50 move with swirling flow in the annular region,and the coarse particles larger than 25μm gather in the area near the guide blade.Due to the interaction between particles,some fine particles may be mixed with the coarse particles,resulting in a“fish-hook effect”.For the axial distribution,the fine particles less than 20μm are mainly distributed in the classifier near the top area,the coarse particles gradually settle downward and the larger the particle size the faster the settlement.