Gas–liquid numerical simulation on micro‐bubble generator and optimization on the nozzle‐to‐throat spacing

Abstract

AbstractThe Cyclonic‐Static Micro‐bubble Flotation Column (CSMFC) has been widely used in fine mineral separation. The micro‐bubble generator, as a key unit of this flotation column, is used to produce micro‐bubble which designed based on the principle of gas liquid jet pump. Unlike the other jet pump, the performance of micro‐bubble generator not only focuses on the air suction volume flow rate, but also includes the size and distribution of bubbles. In this paper, the performance of bubble generator is studied both experimentally and numerically. Three‐dimensional numerical simulations employing the Eulerian two‐phase flow model and S–N drag model by Fluent 14.0 software is carried out. The experimental and Computational Fluid Dynamics results, of air volume flow rate, match closely with each other. The maximum relative error between experiment and numerical simulation is smaller than 7.6%. Then these numerical models are utilized in simulating the 3D flow field of micro‐bubble generator with different nozzle‐to‐throat spacing. Thirteen sets of simulations were conducted to explore the influence of the dimensionless nozzle‐to‐throat spacing (0–3) on air volume flow rate, bubble diameter and distribution. The results demonstrate that the performance of bubble generator is optimal when the dimensionless nozzle‐to‐throat spacing is over 1.25–2.5 while the water volume flow rate is fixed to 50 m3/h. In this range, the bigger air suction volume flow rate, the smaller bubble diameter and higher bubble distribution uniformity index, which are beneficial for fine minerals flotation, were obtained. © 2015 Curtin University of Technology and John Wiley & Sons, Ltd.