Numerical Simulation Research On Particle Slip Velocity Under Turbulent Flow

The difficulty of floating fine particles is an urgent problem to be solved in the utilization of minerals.Flotation equipment is the main process to achieve froth flotation.In the flotation dynamics model,the collision of particles and bubbles is an important basis for mineralization process.The accuracy of collision rate prediction has an important influence on the design and optimization of flotation equipment.The velocity of movement can effectively affect the accuracy of collision rate prediction,but the existing prediction formulas of slip velocity are mostly based on theoretical derivation,which have certain restrictions and lack practical applications.The study of particle slip velocity in turbulent flow has great significance for the prediction of flotation collision process and the optimization of flotation equipment design.In view of this,this paper uses numerical simulation and experiment methods to study the influence of different turbulence intensity and different particle parameters(shape,diameter,density)on particle slip velocity and slip velocity fluctuation.The main content and conclusions of the paper are as follows:Firstly,a square grid with a blocking ratio of 0.42 was selected,and the grid independence,time independence and mean value of grid turbulence were verified by numerical simulations,and a stable,nearly uniform,isotropic,turbulent flow field under grid turbulence was constructed.It provides a basis for solid-liquid two-phase flow calculation.Secondly,in the solid-liquid two-phase flow,the influence of particles on the turbulence intensity of the flow field in the control body was studied.An experimental platform for particle movement observation under grid turbulence was built.Highspeed dynamic camera and PIV technology research methods were used to obtain the slip velocity in different turbulence intensities.The particle slip velocity below verifies the reliability of the FLUENT-EDEM coupling method for calculating slip velocity.Then the FLUENT-EDEM coupling is used to calculate the influence of different turbulence intensity,particle shape,diameter and density on particle slip velocity and slip velocity fluctuation.It is found that for fine particles,the effect of turbulence is greater.As the intensity of turbulence increases,the particle slip velocity and the slip velocity fluctuation increase.While the effect on the density of larger diameter particles is greater,as the density increases,the sliding velocity of particles increases accordingly.Finally,the law of particle slip velocity is analyzed based on the Stokes number of the particles,and the predictive relationship between the Stokes number,turbulence intensity,particle diameter,density,and the ratio of slip velocity to the average velocity is obtained.It provides a certain theoretical guiding significance for further accurately predicting the particle collision process and optimizing the mineral flotation process.