Flow characteristics in porous jet spouted bed with LBM-DEM coupled model

It is important to study the flow characteristics of particles in spouted bed for the design and optimization. Based on the lattice Boltzmann method ( LBM)-discrete element method ( DEM),considering the influence of solid motion on the flow field comprehensively,the gas phase is calculated by the modified lattice Boltzmann equation,the collision between particles and particle-wall is calculated by the soft sphere model of discrete element method,the gas drag force of particles is modeled by the Gidaspow drag force model,and the fluid-solid coupling is based on the New-ton’s third law. The flow mechanism of porous jet in the dense gas-solid fluidized bed is analyzed from the mesoscopic point of view. The above model is solved by Fortran language programming. The accuracy of LBM-DEM coupling model is validated effectively by reproducing the evolution process of bubbles in bubbling bed. The variation of void fraction, particle pseudo-temperature,bed expansion height,particle kinetic energy and potential energy of single-nozzle system and multi-nozzle system at different jet velocities are studied. The results show that with the increase of gas velocity of single nozzle jet,the carrying capacity of gas to particles increases,the fountain area enlarges,the voidage distribution in the bed increases,the velocity fluctuation increases,the pseudo-temperature of particles increases,and the expansion height of the bed increases. In multi-nozzle system,there is strong lateral disturbance between adjacent nozzles,and ob-vious jet coalescence occurs in the fountain area at the bottom of the bed,which is located at the center of the jet. With the increase of nozzle number,the bed expansion height increases by 27. 50% ,the time-averaged voidage range enlar-ges,the particle pseudo-temperature increases,the jet merging height decreases by 28. 57% ,the particle potential en-ergy increases by 66. 07% ,and the kinetic energy decreases by 48. 48% . The above analysis results show that the coupled model based on the modified lattice Boltzmann method and discrete element method can be used as an effec-tive tool to analyze the internal mechanism of dense gas-solid two-phase flow.