Comparison of turbulent flow characteristics of liquid-liquid dispersed flow between CFD simulations and direct measurements with particle image velocimetry

Abstract

For the purpose of investigating the effect of dispersed phase on turbulence characteristics, both CFD simulation and experiments from particle image velocimetry (PIV) on flow field at different dilute liquid-liquid dispersion are performed. CFD simulation is established by coupling mixture model and empirical mean drop size for two phase mixing. Turbulent kinetic energy (TKE) and energy dissipations rate (EDR) are discussed as key parameters. With the addition of dispersed phase, CFD results indicate that TKE decrease when EDR increase in impeller region and both decrease in circulation region; while experimental results shows both TKE and EDR increase in the full flow range. Trend reflected from CFD results is supposed to be the suppression on velocities fluctuation by enlarged density and viscosity of the dispersed phase, and the enhancement of energy dissipation rate by viscosity. Further work concerning the dynamics of drop distribution evolution (coupling Population Balance Equations, PBE) in CFD simulation is particularly demanded, where the effect of drop behaviors including random motion, breakage and coalescence on turbulence intensity could be discussed.