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Shigeo Hosokawa
Kobe University

Akio Tomiyama
Graduate School of Engineering, Kobe University, 1-1 Rokkodai-cho, Nada, Kobe, 657-8501, Japan


One of the key issues in two-phase turbulence modeling is the turbulence modification due to the interaction between the shear-induced turbulence and the turbulence induced by the dispersed phase. As for the gas-liquid two-phase flows in vertical pipes, Serizawa and Kataoka carried out detailed measurement of turbulence intensity and detected the turbulence modification. Gore and Crowe pointed out that the modification is well correlated with the ratio of a particle diameter to a turbulence length scale (d/lt). However the modification may depend not only on the length scales but also on the eddy viscosities of shear-induced and particle-induced turbulence. Hosokawa et al. proposed the ratio Ø of the eddy viscosity induced by the dispersed phase to the shear-induced eddy viscosity and confirmed that measured turbulence modification for gas-solid two-phase flow was well correlated with Ø.
In this study, we examined whether or not Ø is also applicable to gas-liquid and solid-liquid two-phase dispersed upflows in vertical pipes. Using the eddy viscosity ratio instead of d/lt, we obtained much better correlation. The critical point at which no modification occurred was close to Ø = 1 irrespective of a type of two-phase dispersed flow. Consequently, we could confirm that the eddy viscosity ratio is a more appropriate parameter for correlating the turbulent modification than the conventional critical parameter d/lt.