Nuclear Energy for New Europe 2009

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No: 201

Conference: Nuclear Energy for New Europe 2009

Title: Growth and Propagation of Interfacial Disturbances

Theme: Thermal Hydraulics

Author(s): François Henry, Yann Bartosiewitz, Michele Valette, Dominique Bestion

Contact : François Henry

E-mail: Francois.henry@uclouvain.be

Address: Université Catholique de Louvain, Louvain School of Engineering, Mechanical Engineering Department, Term Division
B-1348 Louvain-la-Neuve

Country: Belgium

This study is in the framework of CATHARE 3 developments and more precisely to present its ability to model growth and propagation of interfacial disturbances of a gas-liquid horizontal stratified flow.
During LOCA, transient phenomena appear locally. Among them a stratified vapor-liquid flow may occur in the hot leg of the primary loop. Interfacial waves which exist along the interface and the dynamics of droplet entrainment-deposition have a significant effect on the pressure drop characteristics of the system, particularly in the steam generator.
Consequently, the ability of system codes to predict the entrainment-deposition of droplets is interesting. However, there are no mechanistic models developed and validated for this flows but essentially semi-empirical correlations based on non-dimensional numbers. In this work, a first step in the attempt to develop such a model is conducted for the rate of droplet entrainment. The mechanisms used for the development of wavy regimes in the pipe are based on physical concepts and a realistic approach of apparition and growth of waves along the interface. Furthermore, a linear stability analysis is performed to determine flow regime transitions and the appearance of first waves. This study is achieved in the framework of a two-fluid model in conjunction with the closure relations used in CATHARE 3. The dispersion equation of interfacial waves is derived and compared to results from literature. The influence of the closure relations modelisation and the effect of flow parameters like gas or liquid flow rates and pipe diameter are mainly investigated.

No:	201
Conference:	Nuclear Energy for New Europe 2009
Title:	Growth and Propagation of Interfacial Disturbances
Theme:	Thermal Hydraulics
Author(s):	François Henry, Yann Bartosiewitz, Michele Valette, Dominique Bestion
Contact :	François Henry
E-mail:	Francois.henry@uclouvain.be
Address:	Université Catholique de Louvain, Louvain School of Engineering, Mechanical Engineering Department, Term Division B-1348 Louvain-la-Neuve
Country:	Belgium

This study is in the framework of CATHARE 3 developments and more precisely to present its ability to model growth and propagation of interfacial disturbances of a gas-liquid horizontal stratified flow. During LOCA, transient phenomena appear locally. Among them a stratified vapor-liquid flow may occur in the hot leg of the primary loop. Interfacial waves which exist along the interface and the dynamics of droplet entrainment-deposition have a significant effect on the pressure drop characteristics of the system, particularly in the steam generator. Consequently, the ability of system codes to predict the entrainment-deposition of droplets is interesting. However, there are no mechanistic models developed and validated for this flows but essentially semi-empirical correlations based on non-dimensional numbers. In this work, a first step in the attempt to develop such a model is conducted for the rate of droplet entrainment. The mechanisms used for the development of wavy regimes in the pipe are based on physical concepts and a realistic approach of apparition and growth of waves along the interface. Furthermore, a linear stability analysis is performed to determine flow regime transitions and the appearance of first waves. This study is achieved in the framework of a two-fluid model in conjunction with the closure relations used in CATHARE 3. The dispersion equation of interfacial waves is derived and compared to results from literature. The influence of the closure relations modelisation and the effect of flow parameters like gas or liquid flow rates and pipe diameter are mainly investigated.