摘要：气流分级机分级粒径的不稳定是造成精度下降的根本原因。本文对不均匀气流速度场导致分级粒径沿涡轮轴向的空间波动，湍流脉动导致分级粒径的时间波动，范德华引力产生的假大颗粒导致鱼钩效应而影响细粉的分级以及与一次风、二次风均不发生作用的物料直接进入粗粉，相当于分级粒径为０，而使分级精度明显下降等因素进行了分析，推导出的各影响因素作用的数学方程可用于定性分析。

关键词：气流分级机;分级精度;速度场;涡流;

Abstract：The precision of cut of air classifier is decreased by the flunctuation of cut - size.The non - uniformity of air velocity field leads to spacial change of cut - size along the rotor axis,the turbulent pulsation leads to time change of cut - size, the false big particle formed by the Vander Waals force leads to the fish - hook effect which affects the classification of the finer powders,the powders uncontacted with the first and secondary air are separated into coarse product directlywhich makes the classification effeciency decrease. The mathematical formulae are developed inthis paper can analyse the influence of some factors qualitively

Key words：air classifier; precision of cut; velocity field; turbulent flow