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.