料仓内稠密粉体卸料流动特性研究

Study on Flow Characteristics of Dense Powder Discharge in Hopper

为了研究料仓内粉体卸料流动及混合特性,采用实验与模拟相结合的方法,利用粉体的溶解性质获得两种粉体卸料过程的混合曲线,并建立能够进行大规模数值计算颗粒间固相作用力的三维数学模型。该模型基于欧拉与拉格朗日相结合的方法,利用相邻网格间固相颗粒浓度梯度与颗粒平均速度梯度来描述颗粒间的固相作用力。结果表明:料仓半顶角与卸料口径对粉体卸料流率的影响的模拟结果与实验结果及Brown经验关联式预测值吻合较好。两种粉体卸料过程的混合指数随料仓半顶角的增加而减小,减小卸料口径时混合指数有所减小但减幅不大,表明增加料仓半顶角以及减小卸料口径均会促进两种粉体在卸料过程的混合。

In order to study the powder discharge flow and mixing characteristics in the hopper,the dissolution properties of powders were used in experiments to obtain the mixing curve of two kinds of powder during discharge processes.A three-dimensional numerical model was established for large-scale numerical calculation of solid-phase interaction between particles.The model was based on the combination of Euler and Lagrange methods.The interaction forces between particles were described as the concentration gradient of solid phase and the average speed gradient between adjacent grids.The results show that the simulation results of the influences of the half angle and the outlet size of hopper on the discharge rate of the powder are in good agreement with the experimental results and the Brown empirical correlation.The mixing index of two kinds of powder decreases with the increase of the half angle of the hopper.When the outlet diameter is reduced,the mixing index decreases but the decrement is small.It indicates that increasing the half angle of hopper and reducing the outlet diameter will enhance the mixing of the two kinds of powder during the discharge process.