scholarly journals Evaluation of slip ratio correlations in two-phase flow

2021 ◽  
Vol 10 (1) ◽  
pp. 21-30
Author(s):  
Tram Tran Thanh ◽  
Hyun-Sik Park
Keyword(s):  
Critical Flow ◽  
Accident Analysis ◽  
Phase Flow ◽  
Two Phase ◽  
Slip Ratio ◽  
Flow Prediction ◽  
Ratio Correlation ◽  
Computer Codes ◽  
Very High ◽  
Key Parameter

Critical flow is one of the essential parameters in LOCA accident analysis in which pressure difference is very high. Void fraction (α), in another term, slip ratio, s, is the key parameter that could affect critical flow prediction. Henry-Fauske (HF) model is the model for critical flow calculation existing in current computer codes such as MARS, RELAP, TRACE. However, the limitation of this model is slip ratio s=1. By modified the slip ratio correlation, the paper focuses on evaluating the HF model. Among the chosen correlations for slip ratio, Smith correlation is the best option for this purpose. The results in our paper showed that while the original Smith correlation with k=0.4 is suggested for horizontal tests, the modified one with k=0.2 could be applied for vertical tests.

Flow prediction of a heat pipe using gas-liquid two-phase flow simulation

2019 ◽  
Vol 2019.32 (0) ◽  
pp. 270
Author(s):  
Kaoru TAKEMURA ◽  
Yuki KAWAMOTO ◽  
Hiroaki NAGASHIMA ◽  
Shun TAKAHASHI ◽  
Manami KONDO ◽  
...  
Keyword(s):  
Heat Pipe ◽  
Two Phase Flow ◽  
Flow Simulation ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Prediction

Two-Phase Flow Modeling in a Pipe Related to Flow-Induced Vibration

2005 ◽  
Author(s):  
W. G. Sim ◽  
N. W. Mureithi ◽  
M. J. Pettigrew
Keyword(s):  
Void Fraction ◽  
Power Law ◽  
Slug Flow ◽  
Momentum Flux ◽  
Two Phase Flow ◽  
Liquid Velocity ◽  
Fluid Dynamic ◽  
Phase Flow ◽  
Two Phase ◽  
Slip Ratio

To understand the fluid dynamic forces acting on a structure subjected to two-phase flow, it is essential to get detailed information about the characteristics of two-phase flow. The distributions of flow parameters across a pipe, such as gas velocity, liquid velocity and void fraction, may be assumed to follow a power law (Cheng 1998, Serizawa et al. 1975). The void fraction profile is, for example, uniform for bubbly flow while it is more or less parabolic for slug flow. In the present work, the average values of momentum flux, slip ratio, etc. are derived by integral analysis, based on approximate power law distributions. A parametric study with various distributions was performed. The existing empirical formulations for average void fraction, proposed by Wallis (1969), Zuber et al. (1967) and Ishii (1970), are considered to obtain the present results. In particular, the unsteady momentum flux for slug flow is approximated.

Transition of Bubbly to Slug Flow in a Short Vertical Channel of Gas-Liquid Two-Phase Flow

2014 ◽  
Vol 881-883 ◽  
pp. 721-725
Author(s):  
Mohd Zamri Zainon ◽  
Mohd Ardan Zubir ◽  
Rahizar Ramli
Keyword(s):  
Slug Flow ◽  
Two Phase Flow ◽  
Vertical Channel ◽  
Superficial Velocity ◽  
Phase Flow ◽  
Flow Loop ◽  
Two Phase ◽  
Slip Ratio ◽  
Wide Range ◽  
Simple Flow

Transitions of bubbly to slug flow have been investigated for wide range of flow conditions via visualization technique. The effects of velocities of both phases were examined with variety of combinations and the experimentations were focused on the air-water flow with an industrial scale two-phase flow loop. The results show that the formations of slugs were easy with the increasing gas superficial velocity during a fixed liquid superficial velocity and were difficult when velocity of the liquid phase increases. These transitions were then evaluated using the ratio of velocities of both phases or called the slip ratio and from there a simple flow pattern map was constructed.

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.

scholarly journals Non-Invasive Evaluation of Wavy Liquid Film

2013 ◽  
Vol 34 (2) ◽  
pp. 241-252 ◽  
Author(s):  
Krystian Czernek ◽  
Stanisław Witczak
Keyword(s):  
Liquid Film ◽  
Experimental Method ◽  
Liquid Flow ◽  
High Viscosity ◽  
Phase Flow ◽  
Optoelectronic System ◽  
Two Phase ◽  
Non Invasive ◽  
Invasive Evaluation ◽  
Very High

The study presents the possible use of optoelectronic system for the measurement of values specific for hydrodynamics of two-phase gas very-high-viscosity liquid flow in vertical pipes. An experimental method was provided, and the findings were presented and analysed for selected values which characterise the two-phase flow.

Simulation Model for Helical Rotor Expanders

1991 ◽  
Author(s):  
Larry D. Simmons
Keyword(s):  
Experimental Data ◽  
Computer Model ◽  
Phase Flow ◽  
Performance Potential ◽  
Nitrogen Gas ◽  
Two Phase ◽  
New Applications ◽  
Very High ◽  
Good Agreement ◽  
Fluid Characteristics

Abstract The objective of this project was to develop a computer model for the helical rotor expander which can be used to determine performance potential and to facilitate optimization of expander design. Testing has shown that this energy conversion device has substantial potential advantages over conventional turbines in very high temperature cycles and for two-phase flow. However, the tests have been limited to particular non-optimized designs, and a model is badly needed to assess viable design improvements and their effects on performance. A computer model was developed to simulate the geometric and thermal/fluid characteristics of the expander to give power output, mass flow rate, and efficiency versus rotational speed for any chosen design configuration. The model has been tested against experimental data from expanders running on nitrogen gas and two-phase steam with good agreement. It is now ready and available for use in developing and evaluating designs for new applications of the helical rotor expander.

scholarly journals Study of Critical Flow : Completely Separated Gas-Liquid Two-Phase Flow

1973 ◽  
Vol 16 (101) ◽  
pp. 1741-1749 ◽  
Author(s):  
Yoshiro KATTO ◽  
Yukio SUDO
Keyword(s):  
Two Phase Flow ◽  
Critical Flow ◽  
Phase Flow ◽  
Two Phase
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