During the nozzle’s spraying from the pipe to the outside (Fig. 1), a spraying-induced suction mechanism is formed when the spray’s radius is equal to or larger than the inner diameter of the pipe. To be specific, the air in front of the nozzle would be pushed out by the outpouring spray and an under-pressure is formed behind it. Accordingly, a negative pressure (below atmospheric) is formed at the nozzle, which makes the dusty airflow enter the pipe. In the nozzle, the entrained dusts collide with the water droplets and forced to coagulate. Simul-taneously, the mixture composed of the purified air and water mist is ejected by the nozzle at a high speed, and a negative pressure field is formed at the ejection end. The surrounding airflow containing dusts is entrained into the spraying field, where the dusts in the airflow are further purified so as to achieve a secondary dust suppression (Zhou et al., 2012; Li,2010; Ren et al., 2013; Xie et al., 2007).