Reply to ‘discussion of “drift flux model for large diameter pipe and new correlation for pool void fraction”’

1988 ◽  
Vol 31 (9) ◽  
pp. 1956-1957
Author(s):  
Kataoka Isao ◽  
Ishii Mamoru
Keyword(s):  
Void Fraction ◽  
Large Diameter ◽  
Drift Flux Model ◽  
Large Diameter Pipe ◽  
Drift Flux ◽  
New Correlation ◽  
Diameter Pipe ◽  
Flux Model

Analysis of RELAP5 Drift-Flux Model for Vertical Subcooled Boiling Flow at Low Pressure Conditions

2000 ◽  
Author(s):  
Boštjan Končar ◽  
Ivo Kljenak ◽  
Borut Mavko
Keyword(s):  
Void Fraction ◽  
Drift Velocity ◽  
Bubbly Flow ◽  
Low Pressure ◽  
Subcooled Boiling ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Boiling Flow ◽  
Flux Model ◽  
Relap5 Code

Abstract The RELAP5/MOD3.2.2 Gamma code was assessed against low pressure boiling flow experiments performed by Zeitoun and Shoukri (1997) in a vertical annulus. The predictions of subcooled boiling bubbly flow showed that the present version of the RELAP5 code underestimates the void fraction increase along the flow and strongly overestimates the vapor drift velocity. It is shown that in the calculations, a higher vapor drift velocity causes a lower interphase drag and may be a possible reason for underpredicted void fraction development. A modification is proposed, which introduces the replacement of the EPRI drift-flux formulation, which is currently incorporated in the RELAP5 code, with the Zuber-Findlay (1965) drift-flux model for the experimental low pressure conditions of the vertical bubbly flow regime. The improved experiment predictions with the modified RELAP5 code are presented and analysed.

scholarly journals Void fraction development in gas-liquid flow after a U-bend in a vertically upwards serpentine-configuration large-diameter pipe

2017 ◽  
Vol 54 (1) ◽  
pp. 209-226 ◽  
Author(s):  
Almabrok A. Almabrok ◽  
Aliyu M. Aliyu ◽  
Yahaya D. Baba ◽  
Liyun Lao ◽  
Hoi Yeung
Keyword(s):  
Void Fraction ◽  
Liquid Flow ◽  
Large Diameter ◽  
Large Diameter Pipe ◽  
Diameter Pipe ◽  
Gas Liquid Flow

Distribution Parameter and Drift Velocity of Drift-Flux Model in Bubbly Flow

2002 ◽  
Author(s):  
Takashi Hibiki ◽  
Mamoru Ishii
Keyword(s):  
Constitutive Equation ◽  
Void Fraction ◽  
Drift Velocity ◽  
Bubble Size ◽  
Bubbly Flow ◽  
Distribution Parameter ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Flow Parameters ◽  
Flux Model

In view of the practical importance of the drift-flux model for two-phase flow analysis in general and in the analysis of nuclear-reactor transients and accidents in particular, the distribution parameter and the drift velocity have been studied for bubbly-flow regime. The constitutive equation that specifies the distribution parameter in the bubbly flow has been derived by taking into account the effect of the bubble size on the phase distribution, since the bubble size would govern the distribution of the void fraction. A comparison of the newly developed model with various fully-developed bubbly-flow data over a wide range of flow parameters shows a satisfactory agreement. The constitutive equation for the drift velocity developed by Ishii has been reevaluated by the drift velocity obtained from local flow parameters such as void fraction, gas velocity and liquid velocity measured under steady fully-developed bubbly flow conditions. It has been confirmed that the newly developed model of the distribution parameter and the drift velocity correlation developed by Ishii can also be applicable to developing bubbly flows.

Experimental Investigation of Two Phase Flow in Micro-Sized Circular Tubes

2012 ◽  
Author(s):  
Y. S. Lim ◽  
Simon C. M. Yu
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Transitional Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Slip Ratio ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Glass Tubes ◽  
Flux Model

Single phase and two phase flow characteristics in micro-sized glass tubes with i.d. (inner diameter) of 300 and 500 μm have been examined experimentally. Single phase pressure drop measurements are found generally in good agreement with Poiseulle flow theory. Transitional flow is found to start earlier at Reynolds number about 1600 as compared to the onset of transitional flow at Reynolds number of 2300 for macro-scale tubes. In addition, these glass tubes are employed for the investigation of adiabatic two phase flow characteristic by introducing gas phase via a stainless steel tube inserted at the center of the glass tube. Real time flow visualization obtained under the same flow condition are analyzed by both cross sectional void fraction (one dimensional drift flux model) and volumetric void fraction (image processing method). The analysis shows that the void fraction estimated by drift flux model (DFM) agrees with homogeneous correlation (α = β) and Armand correlation (α = 0.833β). However image processing method seems to reveal that the slip ratio for the two phase flow is more significant and that the void fraction results are clustering between slip ratio of 3 and 7. Additionally, two phase frictional pressure losses are compared with the convention correlation for macro-sized tube (Lockhart-Martinelli model). It is found that measurements of the two phase frictional pressure drop can serve as a flow map to predict the flow patterns when the flow in the channel is not transparent.

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