Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
Numerical Predictions of the Liquid Film Thickness for Gas-Liquid Flows on Separated Pattern
Submission Author:
Vinicius Sylvestre Simm , PR
Co-Authors:
Vinicius Sylvestre Simm, Luiz Eduardo Muzzo, Luiz Eduardo Melo Lima
Presenter: Vinicius Sylvestre Simm
doi://10.26678/ABCM.COBEM2021.COB2021-0324
Abstract
Multiphase flows occur in various industry branches, as seen in power plants, nuclear reactors, and oil and gas production. Several flow patterns arise according to the spatial distribution of the phases, which depend on flow rates, physical properties of the fluids, and geometrical characteristics of the pipe. Stratified and annular flows constitute an important two-phase flow pattern in ducts, called separated (or separated phases) flow, which has a variety of practical applications, for example, the core flow. For gas-liquid flows, this pattern presents itself as a liquid film in contact with the pipe wall flowing parallel with a gas core that can drag liquid droplets. In horizontal flows, the interface is flat. But with the increase in gas velocity, waves appear at the interface, the gas core drags the liquid droplets, and the film “scales” the walls, tending to form an eccentric annular pattern. On the other hand, a concentric annular pattern appears in vertical flows. The experimental determination of the film thickness is difficult and limited. Therefore, the mathematical models based on the physical aspects of the phenomenon are developed and employed for this parameter estimation. These models are dependent on several parameters, such as the entrainment fraction of the droplets, for example, which depends on the atomization and deposition rates of these droplets, and is often modeled through empirical correlations. In the present work, the influence of droplets entrainment fraction and interfacial friction factor on the film thickness prediction was evaluated. To this end, a computational code was developed to solve the implicit equation of the film model. The results obtained for the film thickness were compared with two experimental literature databases: one for horizontal stratified and the other for vertical annular. It was possible to identify the precision of the droplets entrainment fraction correlations analyzed from the obtained deviations. The gas-liquid ratio influences the correlations for entrainment fraction of droplets, and the correlations for interfacial friction factor are dependent on flow pattern (stratified and annular).
Keywords
multiphase flow, liquid film thickness, modeling
