NUMERICAL SIMULATION OF UPRISING TURBULENT FLOW BY 2D RANS FOR FLUIDIZED-BED CONDITIONS

Abstract

2D RANS (Reynolds Average Navier Stokes) equations are used for numerical modeling of uprising particulate (gas-solid particle) turbulent flow in conditions of fluidized beds. The two-fluid model approach was used in giving numerical simulations. The flow domain is a round pipe with diameter of 1 m and height of 6 m (a real industrial object). The flow of mean velocity 4 m/s carries solid particles (material density 2000 kg/m; sizes of 0.3, 1 and 1.5 mm) with mass flow ratio 10 kg/kg. The mathematical model pertains to gravitational and viscous drag forces, Magnus and Saffman lift forces, effects of inter-particle collisions as well as particle interaction with the wall, effect of turbulence modulation (turbulence enhancement) at particles’ presence. The fluidized-bed conditions consider that flow conditions were set for high-temperature flow, density of the carrier fluid 0.329 kg/m, and kinematic viscosity 1.55·10 m/s. The results are presented in the form of distribution of axial and radial velocity components of gaseous and solid phases, particle mass concentration and kinetic turbulent energy along the flow height at the flow exit (highest downstream position) and in the middle cross-section (intermediate position) in order to observe development of particulate flow. As shown by the results, the 2D RANS model qualitatively and quantitatively describes the real-time distribution of flow in a real flow domain, i.e. the model covers reasonable physical phenomena occurring in fluidized-bed conditions.