高层住宅主支式排烟道的主烟道中烟气流动可看作是一维定常垂直摩擦管流。通过计算管流流动相与颗粒相的物理参数沿管程分布情况，确定了颗粒相流动情况，进而判断烟气排放情况。这受到排烟系统高度、烟道管径，及材料组成等因素的影响，通过预设排烟系统高度并保证良好排放情况，求得主烟道管径应满足的条件。这使得布设排烟道时可以找到一个较好的横截面尺寸，既满足烟气排放条件，又节约修建材料。

Flue collector of master-slave mode discharging system in domicile kitchen can be taken as one dimensional vertical steady flow with friction. By calculation of the distributional condition of the physical parameter of mobile phase and particle phase of flow, it can ascertain the flow condition of particle phase and further decide the discharging condition of fume. And it is affected by some conditions, such as highness of discharging system, diameter of flue and composition of material and so on. Through presetting the highness of discharging system and ensuring a well discharging condition, the diameter of master flue can be got to fit the condition. So a better size of cross section can be found for pipe laying, which both meets the discharging condition of fume aiwl economizes the construction material.