Critical Suspension Of Multi-particle In Solid-liquid Stirred Tank

The main object of solid-liquid suspension is to make the solid particles completely disperse in the liquid medium,and then increase the contact area,effectively strengthen the solid-liquid mass transfer,heat transfer and chemical reaction.Regarding the mechanism of solid-liquid suspension,the critical suspension of multiple solid particles in laminar flow driven by standard Rushton(RT)impeller is studied in this paper.In this paper,the movement of solid particles at different critical suspension speeds is tracked from the bottom and the side by a camera,and the centers of solid particles are identified by Matlab to obtain the trajectory and velocity of each solid particle.In this paper,the lattice Boltzmann method(LBM)is used to simulate the experimental system directly.The trajectories of solid particles,the force and torque applied by fluid on solid particles are obtained,and the force model is established.According to the comparison of the critical suspension speeds,it can be found that solid particles can start to suspend at a lower speed under the multi-particle condition,and the effects of the particle size and density are also investigated.Meanwhile,the simulation results of LBM better reproduce the multi-particle suspension process,and the obtained trajectories of solid particles are in good agreement with trajectories of experiment.In this paper,we study the force and torque of the fluid subjected to solid particles.It is found that although the lift force acting on solid particles is smaller than the net weight thereof except for the last suspended solid particles,these solid particles could still be suspended.Through the established force model,it can be seen that the torque is a key factor in the suspension of solid particles,which is often overlooked in solid-liquid two-phase studies.