Gas-liquid flow of sub-millimeter bubbles at low void fractions: Void fraction prediction using drift-flux model

2018 ◽  
Vol 98 ◽  
pp. 195-205 ◽  
Author(s):  
Sotiris P. Evgenidis ◽  
Thodoris D. Karapantsios
Author(s):  
Peter Toma

Offspring of the nuclear reactor industry and gas-oil production, multiphase fluids handling technology appears to have matured into an entirely new field of inquiry, most notably following broad acceptance of the drift flux and flow pattern concepts and their widespread integration into engineering calculations. The drift flux model (DFM), first suggested by Nicklin in 1962 and, soon after, adapted and developed by Professor Zuber’s research group at General Electric, enables calculation of “locally averaged” phase velocity. Further progress made in selection of the flow patterns, calculated for each section of the pipe, provided the key to properly assessing the terminal velocity of the discrete phase and the local phase distributions. The flow pattern concept was first introduced by Canadian Charles Govier to describe oil-water laboratory experiments, then by Hewitt-Roberts and Baker in 1954. A decade later, the team of Dukler-Taitel-Barnea developed the qualitative flow pattern concept into a quantitative roadmap procedure leading to rational calculations of the local (cross-section averaged) gas-liquid flow geometry, or flow pattern. The homogeneous gas-liquid flow, presuming the equality of gas and liquid velocities, a simplification broadly accepted during the early days of two-phase flow engineering, came to be regarded, due to Hinze’s work (Shell, 1955), as an identifiable region in the local flow map, reflecting turbulent and high-shear breakup of the discrete phase. To illustrate the usefulness, validity, and importance of the DFM, and mechanistic modeling using the DFM, as well as the salient work of Prof. Zuber on boiling instability this paper discuses reduction of potential explosive droplet boiling risk during multiphase pumping of high–gas-oil ratio mixtures. To assess critical operating conditions of the multiphase pumps, the Ishi-Zuber criteria developed during 1970 for assessing potential boiling instabilities were adapted to multiphase pumping/compression equipment and the results compared to field instability data. The elucidation of this problem relies heavily on the DFM and on salient research performed during 70s by Prof. Zuber’s team.


Author(s):  
Marcos Penteado ◽  
Saon Vieira ◽  
Marcelo Castro ◽  
Antonio Bannwart

Centrifugal pumps are used in several industrial processes. It is common the operation of this equipment with gas-liquid mixtures, which is the case of the electrical submersible pumping artificial lift method used in the oil industry. The increase of free gas fraction inside the pump may lead to unstable operation and problems such as surging and gas locking phenomena to occur. In this study a drift-flux model is proposed for the gas-liquid flow subjected to centrifugal fields using the impeller as an example. The model is closed with experimental data of bubble diameter, displacements and velocities acquired via high-speed camera at several different rotational speeds and gas mass flow rates using water as the continuous medium. From the modeling and the forces balance in the bubbles, a quantitative criterion for the start point of surging and gas locking conditions was proposed.


AIChE Journal ◽  
2021 ◽  
Author(s):  
Marcos R. M. Penteado ◽  
Saon C. Vieira ◽  
Marcelo S. Castro ◽  
Antonio C. Bannwart

2000 ◽  
Author(s):  
Boštjan Končar ◽  
Ivo Kljenak ◽  
Borut Mavko

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.


Author(s):  
Takashi Hibiki ◽  
Mamoru Ishii

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.


Author(s):  
Ulf Jakob F. Aarsnes ◽  
Florent Di Meglio ◽  
Steinar Evje ◽  
Ole Morten Aamo

We present a simplified drift-flux model for gas-liquid flow in pipes. The model is able to handle single and two-phase flow thanks to a particular choice of empirical slip law. A presented implicit numerical scheme can be used to rapidly solve the equations with good accuracy. Besides, it remains simple enough to be amenable to mathematical and control-oriented analysis. In particular, we present an analysis of the steady-states of the model that yields important considerations for drilling practitioners. This includes the identification of 4 distinct operating regimes of the system, and a discussion on the occurrence of slugging in underbalanced drilling.


Author(s):  
Y. S. Lim ◽  
Simon C. M. Yu

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.


2021 ◽  
Vol 39 (4) ◽  
pp. 1343-1350
Author(s):  
Tat Thang Nguyen

The drift-flux model is widely used in study, calculation and design of two-phase flow. It is a highly efficient model that requires little computation resources. In the model, accurate calculation of the distribution parameter C0 and the drift velocity Vgj is a critically important factor. The calculation requires simultaneously measured data of phase velocity and void fraction distributions or profiles. By using currently widely used methods for two-phase flow measurement, satisfying the requirement is highly difficult. This paper presents novel results of simultaneous measurement of the phase velocity and void fraction profiles in a vertical round tube of 50 mm inner diameter. A combination measurement method has been developed. It comprises the multiwave Ultrasonic Velocity Profile (multiwave UVP) method and the Wire Mesh Tomography (WMT). Based on the measured data, C0 and Vgj have been calculated. They have been compared with those of the published experimental data and correlations. Analyses of the measured data have been carried out. For the first time, the analysis results reveal the variation of C0 and Vgj in the measured flow conditions. More importantly, the data obtained are also useful for the development and validation of the computational codes for two-phase flow.


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