Modeling of Fluid Turbulence Modification Using Two-time-scale Dissipation Models and Accounting for the Particle Wake Effect*

摘要

Presently developed two-phase turbulence models under-predict the gas turbulent fluctuation,because their turbulence modification models cannot fully reflect the effect of particles.In this paper,a two-time-scale dissipation model of turbulence modification,developed for the two-phase velocity correlation and for the dissipation rate of gas turbulent kinetic energy,is proposed and used to simulate sudden-expansion and swirling gas-particle flows.The proposed two-time scale model gives better results than the single-time scale model.Besides,a gas turbulence augmentation model accounting for the finite-size particle wake effect in the gas Reynolds stress equation is proposed.The proposed turbulence modification models are used to simulate two-phase pipe flows.It can properly predict both turbulence reduction and turbulence enhancement for a certain size of particles observed in experiments.