Numerical prediction of dense gas-particle flows in downer using second-order-moment and frictional stress model

Yang Liu *, XueLiu , Guohui Lil

1 Marine Engineering College, Dalian Maritime University, Dalian,116026,China

2Performance Test Center, Harbin Power System Engineering and Research Institute, Harbin, 150046,China

3Schoolof Electronic and Information Engineering, Dalian Jiaotong University, Dalian, 116028, China

ABSTRACT

A unified second-order-moment two-phase turbulence model combining the kinetic theory of particle collisions on the basis of the Euler-Euler two-fluid approach (USM-θ) is developed for simulating the dense gas-particle flows in downer. A new frictional stress model incorporated with the friction particle-particle collision by introducing an effective coefficient of restitution is proposed. The interaction between gas and particle turbulence is simulated by the transport equation of two-phase stress correlation. Effects of the frictional stress model on the simulated results are discussed. Flow behaviors of particle in high-density in downer are predicted. The simulated results are in good agreement with experimental data. The typical dense ring of particle near wall region is observed. Considering the realistic energy dissipation by frictional stress model, particle concentration and particle axial averaged velocity are closely the measured and is better than those of without frictional stress model, and particle temperature is reduced. It leads to the redistribution of Reynolds stress. Effect of frictional stress model for increasing collision frequency is obviously at the outlet and inlet region and not in the fully development flows region. Meanwhile, frequency of particle collisions is observed on the order of 102 magnitudes.

Keywords Unified second-order-moment, Frictional stress; downer gas-particle flows; numerical simulation