Paula D. Pico, Juan P. Valdés, Nicolás Ratkovich, Eduardo Pereyra
Abstract: The objective of this study is to analyze the influence of the physical properties of Newtonian and Non-Newtonian fluids, such as density, effective viscosity and surface tension, as well as operational parameters of the piping, such as diameter, length and angle of inclination, on the drift velocity for twophase gas-liquid flow. This study comprises a Computational Fluid Dynamics (CFD) approach for Newtonian fluids and an experimental approach for both, Newtonian and NonNewtonian fluids. The simulation model consisted of half a section of a circular pipe with a symmetry plane. This model was calibrated through a mesh independence test, which considered experimental and literature data as benchmarking values for both low and high viscosity Newtonian fluids. The results obtained through the CFD model showed good agreement with the experimental data gathered for the present study, keeping the experimental deviations under 10% for most (roughly 95%) of the cases considered. The relationship between the Froude number (Fr) and the Viscosity number (Nvis) was studied and an inverse exponential tendency was found for all the parameters and fluids tested, which agrees with the models proposed in literature. The data gathered for all fluids on the drift velocity’s behavior against operational parameters such as length, diameter and inclination, showed the influence of the governing forces for each case based on dimensionless analysis using Eötvös (Eö) and Reynolds (Re) numbers. For dominant capillary or viscous forces on the system, the drift velocity changed with the variation of these parameters. However, it was found that for dominant inertial and gravitational forces, the drift velocity maintained a constant value regardless of the operational settings. Finally, it was observed that the rheological nature found for the Non-Newtonian fluids has a significant influence on the drift velocity’s behavior, deviating its patterns from the Newtonian fluids as the effective viscosity changed.
Keywords: Drift Flux, CFD, Froude Number, Viscosity Number, Two-phase.
Date Published: October 1, 2018 DOI: 10.11159/jffhmt.2018.006
View Article