Effect of empirical coefficients on simulation in two-scale second-order moment particle-phase turbulence model

Abstract

A two-scale second-order moment two-phase turbulence model accounting for inter-particle collision is developed, based on the concept of particle large-scale fluctuation due to turbulence and particle small-scale fluctuation due to collision. The proposed model is used to simulate gas-particle downer reactor flows. The computational results of both particle volume fraction and mean velocity are in agreement with the experimental results. After analyzing effects of empirical coefficient on prediction results, we can come to a conclusion that, inside the limit range of empirical coefficient, the predictions do not reveal a large sensitivity to the empirical coefficient in the downer reactor, but a relatively great change of the constants has important effect on the prediction. Nomenclatureαp-particle volume fraction β-drag coefficient U -mean velocity(m/s) u,v -fluctuating velocity (m/s) uu, vv-Reynolds stress or fluctuation velocity correlation(m 2 /s 2 ) e-restitution coefficient d -particle diameter(m) k -kinetic energy(m 2 /s 2 ) ε-kinetic energy dissipation rate(m 2 /s 3 ) Subscripts: 1-large-scale fluctuation 2-small-scale fluctuation p-particle f-gas