A Two-Fluid Turbulence Model for Gas-Solid Two-Phase Flows.

On the basis of a two-equation turbulence model of single-phase flows, two-fluid turbulence models, namely, the k–ε–kp–εp model and the k–ε–kp model are developed to describe turbulent gas-solid two-phase flows. Governing equations for the turbulent kinetic energy and the kinetic energy dissipation rate of the particulate phase are derived from their momentum equations, and unknown terms at two-equation closure level are modeled. The developed models show that the turbulence intensity of the particulate phase is often larger than that of the gaseous phase in the gas-solid flow in a 90° bend, which is quite in accordance with the experimental results. The conventional k–ε–Ap model using a k–ε turbulence model for the carrier fluid and Tchen-Hinze’s formula for the eddy viscosity of the particulate phase, however, shows that the particulate turbulence intensity is always smaller than that of the gaseous phase. Therefore, the two-phase turbulence models developed here are superior to the conventional turbulence model. The turbulence models are also applied to predict the effect of particles on gaseous phase turbulence in the gas-solid flow in a vertical pipe. The predicted results are favorably compared with the available experimental data.