A Proposed Calculational Model for Two-Phase Countercurrent Flow Limitation in Channels with Abrupt Area Change

1990 ◽  
Vol 89 (2) ◽  
pp. 227-232
Author(s):  
Tanvir Salim ◽  
Woon-Shing Yeung ◽  
R. Thomas Fernandez
Keyword(s):  
Countercurrent Flow ◽  
Flow Limitation ◽  
Two Phase ◽  
Area Change

Mechanism and Effects of Predominant Parameters Regarding Limitation of Falling Water in Vertical Countercurrent Two-Phase Flow

1996 ◽  
Vol 118 (3) ◽  
pp. 715-724 ◽  
Author(s):  
Y. Sudo
Keyword(s):  
Water Mass ◽  
Two Phase Flow ◽  
Water Injection ◽  
Momentum Equation ◽  
Wall Friction ◽  
Countercurrent Flow ◽  
Phase Flow ◽  
Flow Limitation ◽  
Two Phase ◽  
Channel Configuration

In this study, an investigation was carried out to clarify the mechanism of countercurrent flow limitation (CCFL) or flooding, that is, limitations in the falling water mass flux in countercurrent two-phase flow in vertical channels, and to identify the effects of predominant parameters regarding CCFL, adopting the criterion that the CCFL condition be given by an envelope of momentum equation applied for the entire length of the channel with respect to any void fraction. As a result, it was found that the analytical model proposed could adequately predict all existing experimental results investigated in this study. In the channel configuration, circular, rectangular, and annular or planar channels, channel dimensions of diameter, gap size, width or circumference, and length, interfacial and wall friction, water injection mode, and inlet water subcooling were dominant parameters. Therefore, both the mechanism and the quantitative effects of CCFL have been identified.

scholarly journals Countercurrent Flow Limitation at the Junction between the Surge Line and the Pressurizer of a PWR

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Taiga Doi ◽  
Takashi Futatsugi ◽  
Michio Murase ◽  
Kosuke Hayashi ◽  
Shigeo Hosokawa ◽  
...  
Keyword(s):  
Gas Flow ◽  
Low Frequency ◽  
Water Levels ◽  
Countercurrent Flow ◽  
Flow Limitation ◽  
Cylindrical Tank ◽  
Two Phase ◽  
Surge Line ◽  
Cylindrical Tanks ◽  
Tank Geometry

An experimental study on countercurrent flow limitation (CCFL) in vertical pipes is carried out. Effects of upper tank geometry and water levels in the upper and lower tanks on CCFL characteristics are investigated for air-water two-phase flows at room temperature and atmospheric pressure. The following conclusions are obtained: (1) CCFL characteristics for different pipe diameters are well correlated using the Kutateladze number if the tank geometry and the water levels are the same; (2) CCFL occurs at the junction between the pipe and the upper tank both for the rectangular and cylindrical tanks, and CCFL with the cylindrical tank occurs not only at the junction but also inside the pipe at high gas flow rates and small pipe diameters; (3) the flow rate of water entering into the vertical pipe at the junction to the rectangular upper tank is lower than that to the cylindrical tank because of the presence of low frequency first-mode sloshing in the rectangular tank; (4) increases in the water level in the upper tank and in the air volume in the lower tank increase water penetration into the pipe, and therefore, they mitigate the flow limitation.

Countercurrent flow limitation in inclined channels with bends

1994 ◽  
Vol 152 (1-3) ◽  
pp. 379-388 ◽  
Author(s):  
S.M. Ghiaasiaan ◽  
R.E. Turk ◽  
S.I. Abdel-Khalik
Keyword(s):  
Countercurrent Flow ◽  
Flow Limitation ◽  
Inclined Channels
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