Structure effect of a suction pipe on slag-discharging performance in a shaft boring machine

The efficiency and stability of shaft boring machines depend critically on the slag-discharging system. In this study, we simulate the slagging process by using the coupled computational fluid dynamics/discrete element method and validate the method’s reliability through experiments. We investigate the impact of outlet diameter, inlet diameter, and outlet section length on slag-discharging performance. We establish the slag-discharging principle of the suction pipe by analyzing the particle motion trajectory. The flow field close to the suction pipe can be classified into collecting and lifting zones on the basis of the main flow direction velocity. Furthermore, we propose pipes with seven typical types, among which the straight-conical type exhibits the most favorable slag-discharging performance. The straight-conical pipe enhances the slag-discharging mass by 22.49 % compared with the straight pipe.