Influence Mechanism of Gas–Containing Characteristics of Annulus Submerged Jets on Sealing Degree of Mixing Zone

Abstract

The introduction of air into a submerged annular jet will result in dispersion of the jet, which will affect the degree of enclosure of the gas–water mixing zone in the annular jet nozzle, and then have a significant impact on air suction and the formation of the foam system in the floatation process. A numerical simulation method is used to analyze the characteristics of the distribution of the axial flow velocity of annular jets, gas–phase volume, and turbulence intensity in the gas–water mixing zone in the nozzle with different air–liquid ratios, and thereby reveal the mechanism whereby gas–containing in annular jets affects the degree of enclosure of the gas–water mixing zone. The results show that as the air–liquid ratio increases, the degree of air–liquid mixing will increase and the radial flow velocity will decrease gradually, resulting in the effective enclosure of the gas–water mixing zone. Meanwhile, the dissipation of jet energy, the range of turbulent flow and the vorticity intensity will increase, but the turbulence intensity will decrease. When the gas–water mixing zone is fully enclosed, as gas–containing continues to increase, the degree of dispersion of the annular jet will further increase. Consequently, the area of the gas–water mixing zone with bounced–back water will become larger, resulting in a higher axial flow velocity, larger local turbulence intensity and larger vorticity intensity. This will lead to the dissipation of jet energy, which is not favorable for air suction.