等截面垂直管道中气粉的临界管长彭一川，韩 考虑重力和摩擦力的影响，建立了描述垂直管道中气粉流行为的数学模型．采用马赫数检验法，确定了产生摩擦里塞时的临界管长．计算表明，当气粉流以不同方式喷入相同的冶金熔池时，底吹垂直管道比顶吹垂直管道需要更大的临界管?.. Critical tube length of gas powder in vertical pipe with equal cross section Peng Yichuan, Han Considering the influence of gravity and friction, a mathematical model describing the behavior of gas flow in vertical pipe was established. The Mach number test was used to determine the critical tube length when friction licker was generated. Calculations have shown that the bottom-blown vertical pipe requires a larger critical pipe than the top-blown vertical pipe when the powder flow is injected into the same metallurgical bath in different ways.