Research on flow field characteristic of close-coupled gas atomizing nozzle

The atomization nozzle is the core component of the close-coupled gas atomization method to prepare metal powder. The pressure at the tip of the melt delivery tube and the pressure at the stagnation point are very important for the smooth outflow of the molten metal during the atomization process. When the tip of the melt delivery tube is under positive pressure, the molten metal cannot flow out of the nozzle smoothly, and in severe cases, it will cause the back spray of the molten metal. The greater the pressure at the stagnation point, the greater the impact force of the atomized gas acting on the molten metal flowing out of the melt delivery tube, and the better the crushing effect. In this paper, the effects of atomization pressure, protrusion length and cone-apex angle on the pressure at the tip of the melt delivery tube and the pressure at the stagnation point are studied experimentally and numerically. The results show that with the increase of atomization pressure, the length of the negative pressure zone remains basically unchanged, while the pressure at the stagnation point increases; Increased protrusion length expands the negative pressure zone and reduces the pressure at the stagnation point; As the cone-apex angle of the melt delivery tube increases, the pressure at the tip of the tube will transition from negative pressure to positive pressure, resulting in the failure of atomization.