Improved closure relations for the two fluid-model in flashing flows
type: CreativeWork
description: The two-fluid model is a widely used approach for the modeling of two-phase flows, consisted of two separate sets of mass, momentum, and energy conservation equations for the liquid and gas phases. In the two-fluid model, the interaction between the phases is determined by the mass, momentum, and energy transfer terms, which in turn are a function of the interfacial area concentration and the driving flux. Hence, it is important that the closure models for the interfacial area concentration and the driving fluxes are validated and benchmarked extensively for a wide range of flow conditions. Different approaches to predict the interfacial area concentration are available such as the static correlations and the Interfacial Area Transport Equation (IATE). In this work, the closure models of the two-fluid model, particularly those of the mass conservation equation, are studied and validated under flashing conditions with additional modifications proposed to improve the accuracy of the models. Three sets of experiments are performed in this work with a closed-loop test facility. Two-phase parameters are measured with four-sensor conductivity probes at five axial locations along the test section, consisted of 3 m of heated length, followed by 2 m of unheated length. Two-phase measurements such as void fraction, interfacial area concentration, and gas velocity, as well as flow parameters such as flow rate, fluid temperature, and pressure are measured in the experiments. The first set is a natural circulation experiment carried out with an annulus test section, while the second and third sets are forced convective flashing experiments carried out with an annulus and an annulus-to-pipe test section. In the natural circulation experiment, measurements are taken at three locations in the heated length and two in the unheated length to observe the change of two-phase parameters across the entire test section. On the other hand, for the forced convection experiments, all five me…
abstract: The two-fluid model is a widely used approach for the modeling of two-phase flows, consisted of two separate sets of mass, momentum, and energy conservation equations for the liquid and gas phases. In the two-fluid model, the interaction between the phases is determined by the mass, momentum, and energy transfer terms, which in turn are a function of the interfacial area concentration and the driving flux. Hence, it is important that the closure models for the interfacial area concentration and the driving fluxes are validated and benchmarked extensively for a wide range of flow conditions. Different approaches to predict the interfacial area concentration are available such as the static correlations and the Interfacial Area Transport Equation (IATE). In this work, the closure models of the two-fluid model, particularly those of the mass conservation equation, are studied and validated under flashing conditions with additional modifications proposed to improve the accuracy of the models. Three sets of experiments are performed in this work with a closed-loop test facility. Two-phase parameters are measured with four-sensor conductivity probes at five axial locations along the test section, consisted of 3 m of heated length, followed by 2 m of unheated length. Two-phase measurements such as void fraction, interfacial area concentration, and gas velocity, as well as flow parameters such as flow rate, fluid temperature, and pressure are measured in the experiments. The first set is a natural circulation experiment carried out with an annulus test section, while the second and third sets are forced convective flashing experiments carried out with an annulus and an annulus-to-pipe test section. In the natural circulation experiment, measurements are taken at three locations in the heated length and two in the unheated length to observe the change of two-phase parameters across the entire test section. On the other hand, for the forced convection experiments, all five me…
author: Ooi, Zhiee Jhia
language: en
keywords: Interfacial Area Transport Equation, Interfacial Mass Generation Rate, System Analysis Codes, Flashing, Two-Fluid Model
date published: 2021-03-05T21:37:58Z
date modified: 2026-07-22T22:24:50Z
provider: University of Illinois - Urbana-Champaign
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Illinois at Urbana-Champaign

PropertyValue
property ID: Handle
value: http://hdl.handle.net/2142/109368