Experimental investigation of threshold velocities for air-water two-phase flow in a vertical tube and annular channels
This work presents an experimental study of five threshold velocities for air-water flow in three different vertical channels. The measured threshold velocities included onset flooding (OF), end flooding (EF), onset deflooding (OD), end deflooding (ED), and minimum pressure (MP) velocities. The expe...
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| Language: | English |
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Elsevier
2025-02-01
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| Series: | Nuclear Engineering and Technology |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S1738573324004315 |
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| author | Almog Biton Evgeny Rabinovich Erez Gilad |
| author_facet | Almog Biton Evgeny Rabinovich Erez Gilad |
| author_sort | Almog Biton |
| collection | DOAJ |
| description | This work presents an experimental study of five threshold velocities for air-water flow in three different vertical channels. The measured threshold velocities included onset flooding (OF), end flooding (EF), onset deflooding (OD), end deflooding (ED), and minimum pressure (MP) velocities. The experimental system includes a transparent vertical tube of 52.5 mm inner diameter and 1500 mm length. The test channel can be easily changed from a tube to an annular shape by inserting a cylindrical test element. A counter-current or concurrent upward flow was achieved by blowing air upward from the channel's bottom and flowing water from its top. The threshold velocities were determined by analyzing the pressure drop versus air superficial velocity. Findings revealed evident hysteresis between the end flooding and onset deflooding velocities. In contrast, the end deflooding and onset flooding velocities were found to be identical. The end flooding velocity was indifferent to the water's superficial velocity for all three channel geometries. A generalized gas-liquid flow state diagram for vertical channels is developed based on the present empirical analysis for different threshold velocities. |
| format | Article |
| id | doaj-art-2dcc18e4960e4f16b75b6fe76a0a7ae8 |
| institution | Kabale University |
| issn | 1738-5733 |
| language | English |
| publishDate | 2025-02-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Nuclear Engineering and Technology |
| spelling | doaj-art-2dcc18e4960e4f16b75b6fe76a0a7ae82025-01-31T05:11:02ZengElsevierNuclear Engineering and Technology1738-57332025-02-01572103183Experimental investigation of threshold velocities for air-water two-phase flow in a vertical tube and annular channelsAlmog Biton0Evgeny Rabinovich1Erez Gilad2Nuclear Research Center Negev (NRCN), P.O.Box 9001, Beer Sheva, 84190, Israel; The Unit of Nuclear Engineering, Ben-Gurion University of the Negev, P.O.Box 653, Beer Sheva, 8410501, IsraelNuclear Research Center Negev (NRCN), P.O.Box 9001, Beer Sheva, 84190, IsraelThe Unit of Nuclear Engineering, Ben-Gurion University of the Negev, P.O.Box 653, Beer Sheva, 8410501, Israel; Corresponding author.This work presents an experimental study of five threshold velocities for air-water flow in three different vertical channels. The measured threshold velocities included onset flooding (OF), end flooding (EF), onset deflooding (OD), end deflooding (ED), and minimum pressure (MP) velocities. The experimental system includes a transparent vertical tube of 52.5 mm inner diameter and 1500 mm length. The test channel can be easily changed from a tube to an annular shape by inserting a cylindrical test element. A counter-current or concurrent upward flow was achieved by blowing air upward from the channel's bottom and flowing water from its top. The threshold velocities were determined by analyzing the pressure drop versus air superficial velocity. Findings revealed evident hysteresis between the end flooding and onset deflooding velocities. In contrast, the end deflooding and onset flooding velocities were found to be identical. The end flooding velocity was indifferent to the water's superficial velocity for all three channel geometries. A generalized gas-liquid flow state diagram for vertical channels is developed based on the present empirical analysis for different threshold velocities.http://www.sciencedirect.com/science/article/pii/S1738573324004315Onset flooding velocityEnd flooding velocityOnset deflooding velocityEnd deflooding velocityMinimum pressure velocityGas-liquid two-phase flow |
| spellingShingle | Almog Biton Evgeny Rabinovich Erez Gilad Experimental investigation of threshold velocities for air-water two-phase flow in a vertical tube and annular channels Nuclear Engineering and Technology Onset flooding velocity End flooding velocity Onset deflooding velocity End deflooding velocity Minimum pressure velocity Gas-liquid two-phase flow |
| title | Experimental investigation of threshold velocities for air-water two-phase flow in a vertical tube and annular channels |
| title_full | Experimental investigation of threshold velocities for air-water two-phase flow in a vertical tube and annular channels |
| title_fullStr | Experimental investigation of threshold velocities for air-water two-phase flow in a vertical tube and annular channels |
| title_full_unstemmed | Experimental investigation of threshold velocities for air-water two-phase flow in a vertical tube and annular channels |
| title_short | Experimental investigation of threshold velocities for air-water two-phase flow in a vertical tube and annular channels |
| title_sort | experimental investigation of threshold velocities for air water two phase flow in a vertical tube and annular channels |
| topic | Onset flooding velocity End flooding velocity Onset deflooding velocity End deflooding velocity Minimum pressure velocity Gas-liquid two-phase flow |
| url | http://www.sciencedirect.com/science/article/pii/S1738573324004315 |
| work_keys_str_mv | AT almogbiton experimentalinvestigationofthresholdvelocitiesforairwatertwophaseflowinaverticaltubeandannularchannels AT evgenyrabinovich experimentalinvestigationofthresholdvelocitiesforairwatertwophaseflowinaverticaltubeandannularchannels AT erezgilad experimentalinvestigationofthresholdvelocitiesforairwatertwophaseflowinaverticaltubeandannularchannels |