Improvement of horizontal stratification criteria in the SPACE code. (November 2019)

• Record Type: Journal Article
• Authors: Lee, Jong Hyuk; Kim, Byoung Jae; Kim, Kyung Doo
• Is Part Of: Annals of nuclear energy. Volume 133(2019)
• Page Start: 122
• Page End: 128
• Publication Date: 2019-11
• Subjects: Horizontal stratification -- Kelvin-Helmholtz instability -- Ill-posedness -- Two-phase flow -- System code -- SPACE; Nuclear energy -- Periodicals; Nuclear engineering -- Periodicals; 621.4805
• DOI: 10.1016/j.anucene.2019.05.014
• Languages: English
• ISSNs: 0306-4549

Abstract

Highlights: The criteria of horizontal stratified flow were modified by adopting with inviscid/viscous Kelvin-Helmholtz analyses. These criteria are implemented into the SPACE code. The simulation results show the predictability of horizontal stratification is further improved. Abstract: The flow regime for two-phase flow plays an important role in nuclear safety analysis, because different physical models for two-phase flow are used depending on the flow regime. This paper deals with the flow regime criteria for horizontal stratification, which frequently occurs in the hot or cold leg during a loss-of-coolant accident (LOCA). Although there are several horizontal stratification criteria based on the Kelvin-Helmholtz theory, the condition for the onset of waves leading to a wavy-stratified flow or a non-stratified flow is still unclear. This study approached the horizontal stratification criteria from the perspective of viscous/inviscid flow instability theories. The criterion between smoothly stratified flow and transition region was adopted with viscous Kelvin-Helmholtz (VKH) analysis. The onset of ill-posedness for the governing equation set, which is related to the inviscid Kelvin-Helmholtz (IKH) analysis, was used to determine the transition criterion between the transition region and non-stratified flow. These criteria were incorporated into the SPACE thermal-hydraulic system code. Simulation results show good agreements with experimental data, and the predictability of horizontal stratification is thereby further improved.