针辊式高压静电分选电场的数值模拟

Numerical Simulation of Electric Field for Needle-roller High Voltage Electrostatic Separation

直接测量静电分选电场非常困难。为形象直观地表达分选电场的分布特征,利用MATLAB软件模拟了针辊间高压放电过程。建立针辊式分选机实验装置的简化模型,选取装置周围1 m3正方体空间为初始边界。采用有限差分法求解模型、用迭代法求解差分方程组、用插值法进行函数逼近,分别对单针、单针与转辊、5针、5针与转辊的静电场进行了模拟。结果表明:针电极附近等势线密集,越往外等势线越稀疏;相邻放电针间距较小时,同性电荷互相排斥,针间电场强度明显减弱;针与转辊之间的等势线密集,转辊之外及针电极上部的等势线衰减迅速。模拟结果准确地描绘出了静电场分布规律,为静电分选机的实际设计提供了理论依据。

It is difficult to measure the electric field of electrostatic separation directly. In order to illustrate the electric field distribution intuitively, we simulated the high voltage electrostatic discharge process of needle-roller using MATLAB. Firstly we established a simplified model of the needle-roller device, with initial boundary of one cubic meters around. Using finite difference method in electromagnetic field numerical analysis, the iteration method for solving differential equations and the interpolation method of function approximation, we simulated the electrostatic field of four electrode structures, namely single-needle, single-needle and roller, five needles, and five-needles and roller. The results showed that equipotential lines are intensive near the needle electrode, but they are sparse in other regions. Since charges repel each other, the electric field among multiple needles decreases significantly when adjacent needles spacing is small. Equipotential lines are intensive between needles and roller, and they decay rapidly outside the roller and the upper needle electrodes. The simulation depicts the distribution of electrostatic field accurately and provides a theoretical foundation for electrostatic separator design.