Flow Configure in Vertical 180 Degree Turning Duct

2001 ◽  
Author(s):  
Lu Yuanwei ◽  
Zhou Fangde ◽  
Wang Yueshe ◽  
Qian Huanqun ◽  
Hu Zhihua
Keyword(s):  
Flow Pattern ◽  
Liquid Flow ◽  
Two Phase Flow ◽  
Vertical Tube ◽  
Experimental Result ◽  
Phase Flow ◽  
Two Phase ◽  
Vertical Part ◽  
Flow Situation ◽  
Gas Liquid Flow

Abstract Bend is applied in many industries, which exert an influence on fluid and make the flow complicate. The second flow caused by the bend is strong enough that the flow behind it very long can be affected, so it is hard to make the flow in it steady. The long-term unsteady flow can make the pipe fatigue, so make the tube crack and leak. It is important to improve this situation. In this paper a throttle is built in the exit of the bend to control the non-homogeneous flow inside the bend, which can overcome the disadvantage of bend in industrial application. Through computed the flow field behind the bend by water, we can see that the throttle can improve the flow situation and make the flow steady behind it. Applying this method to the gas-liquid flow, the experimental result showed that the void fraction behind the bend is alike the fully developed flow. It means that the throttle can improve the two-phase flow situation in the invert U bend. At last the gas-liquid flow pattern in-bend was studied by experiment and built the flow pattern map in the vertical parts of the invert U bend. It was found that the flow pattern in the vertical part of invert U bend is different from the fully developed gas-liquid flow in vertical tube. The throttle built in the bend make the unsteady region of two-phase flow being reduced.

Flow Pattern Transition in Pipes Using Data-Driven and Physics-Informed Machine Learning

2020 ◽  
Author(s):  
André M. Quintino ◽  
Davi L. L. N. da Rocha ◽  
Roberto Fonseca Jr. ◽  
Oscar M. H. Rodriguez
Keyword(s):  
Machine Learning ◽  
Experimental Data ◽  
Flow Pattern ◽  
Liquid Flow ◽  
Two Phase Flow ◽  
Data Driven ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Pattern Transition ◽  
Gas Liquid Flow

Abstract Flow pattern is an important engineering design factor in two-phase flow in the chemical, nuclear and energy industries, given its effects on pressure drop, holdup, and heat and mass transfer. The prediction of two-phase flow patterns through phenomenological models is widely used in both industry and academy. In contrast, as more experimental data become available for gas-liquid flow in pipes, the use of data-driven models to predict flow-pattern transition, such as machine learning, has become more reliable. This type of heuristic modeling has a high demand for experimental data, which may not be available in some industrial applications. As a consequence, it may fail to deliver a sufficiently generalized transition prediction. Incorporation of physics in machine learning is being proposed as an alternative to improve prediction and also to reduce the demand for experimental data. This paper evaluates the use of hybrid-physics-data machine learning to predict gas-liquid flow-pattern transition in pipes. Random forest and artificial neural network are the chosen tools. A database of experiments available in the open literature was collected and is shared in this work. The performance of the proposed hybrid model is compared with phenomenological and data-driven machine learning models through confusion matrices and graphics. The results show improvement in prediction performance even with a low amount of data for training. The study also suggests that graphical comparison of flow-pttern transition boundaries provides better understanding of the performance of the models than the traditional metric

Behavior of the Two-Phase Gas-Liquid Flow at the Inlet of a Catalytic Reactor

2019 ◽  
Vol 19 (2) ◽  
pp. 123-131
Author(s):  
O. P. Klenov ◽  
A. S. Noskov
Keyword(s):  
Liquid Phase ◽  
Uniform Distribution ◽  
Liquid Flow ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Catalytic Reactor ◽  
Two Phase ◽  
Gas Consumption ◽  
Flow Diagrams ◽  
Gas Liquid Flow

The work was aimed at studying the behavior of the two-phase gas-liquid flow at the inlet pipe of a catalytic reactor. Apart from the classical approach using literature flow diagrams, methods of computational hydrodynamics were used for 3D simulation of the space propagation of phases in the pipeline. The results obtained demonstrated non-uniform distribution of the liquid phase through the outlet section of the pipeline and the time-unsteady mass consumption of the liquid phase. The maximal peak consumptions were ca. 3 times as high as the average values. With the data on the flow diagrams, the CFD simulation demonstrated that variations in the gas consumption within the range under study do not cause changes in the behavior of the two-phase flow but an increase in the gas consumption results in smoothening of the non-uniform distribution of the liquid phase at the outlet pipe. The data on the flow behavior are necessary for designing catalytic reactors to provide uniform propagation of the two-phase flow over the catalyst bed, for example, hydrotreatment reactors used in refineries.

Numerical Simulation of the Gas-Liquid Flow in a Rotary Gas Separator

1998 ◽  
Vol 120 (1) ◽  
pp. 41-48 ◽  
Author(s):  
G. Lackner ◽  
F. J. S. Alhanati ◽  
S. A. Shirazi ◽  
D. R. Doty ◽  
Z. Schmidt
Keyword(s):  
Void Fraction ◽  
Liquid Flow ◽  
Two Phase Flow ◽  
Numerical Procedure ◽  
Phase Flow ◽  
Two Phase ◽  
Free Gas ◽  
Gas Separator ◽  
Gas Liquid Flow ◽  
Gas Void Fraction

The presence of free gas at the pump intake adversely affects the performance of an electrical submersible pump (ESP) system, often resulting in low efficiency and causing operational problems. One method of reducing the amount of free gas that the pump has to process is to install a rotary gas separator. The gas-liquid flow associated with the down hole installation of a rotary separator has been investigated to address its overall phase segregation performance. A mathematical model was developed to investigate factors contributing to gas-liquid separation and to determine the efficiency of the separator. The drift-flux approach was used to formulate this complex two-phase flow problem. The turbulent diffusivity was modeled by a two-layer mixing-length model and the relative velocity between phases was formulated based on published correlations for flows with similar characteristics. The well-known numerical procedure of Patankar-Spalding for single-phase flow computations was extended to this two-phase flow situation. Special discretization techniques were developed to obtain consistent results. Special under relaxation procedures were also developed to keep the gas void fraction in the interval [0, 1]. Predicted mixture velocity vectors and gas void fraction distribution for the two-phase flow inside the centrifuge are presented. The model’s predictions are compared to data gathered on a field scale experimental facility to support its invaluable capabilities as a design tool for ESP installations.

Frictional Pressure Drop and Two-Phase Flow Pattern of Gas-Liquid Two-Phase Flow in Circular and Rectangular Minichannels

2006 ◽  
Author(s):  
Hiroyasu Ohtake ◽  
Hideyasu Ohtaki ◽  
Yasuo Koizumi
Keyword(s):  
Flow Pattern ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Experimental Result ◽  
Phase Flow ◽  
Two Phase ◽  
Pressure Drops ◽  
Circular Tubes ◽  
Rectangular Channels ◽  
Inner Diameter

The frictional pressure drops of gas-liquid two-phase flow in mini-pipes and mini-rectangular channels were investigated experimentally. The following test channels were used in the present experiments: commercial stainless-steel circular tubes with 0.6, 0.5 and 0.25 mm in inner diameter, FEP circular tube of 0.4 mm in inner diameter and rectangular channels, made of Acrylic resin, with 0.39 × 20.4 mm, 0.21 × 9.75 mm, 0.26 × 4.28 mm and 0.18 × 1.87 mm in height and width, respectively. The pressure drops of straight pipe, sudden enlargement and sudden contraction of gas-liquid two-phase flow in mini-pipes were measured for the test mini-channels. The pressure drops of rectangular minichannel were also measured. Experimental result showed that measured two-phase friction multipliers agreed well with a conventional Lockhart-Martinelli correlation for circular tubes and Mishima-Hibiki’s correlation for rectangular channels. Observed flow patterns by visualization were bubbly, slug, churn, ring and annular flow; the flow patterns in the present experiments were reproduced well by Baker’s flow pattern map.

3-D Numerical Simulation of Gas-Liquid Flow in a Minichannel With a Non-Uniform GDL Surface

2010 ◽  
Author(s):  
Yulong Ding ◽  
Xiaotao T. Bi ◽  
David P. Wilkinson
Keyword(s):  
Fuel Cell ◽  
Flow Pattern ◽  
Liquid Flow ◽  
Two Phase Flow ◽  
Operating Conditions ◽  
Phase Flow ◽  
Two Phase ◽  
Corner Flow ◽  
Side Walls ◽  
Simulation Results

Gas-liquid two-phase flow in rectangular minichannels of polymer-electrolyte membrane fuel cells (PEMFCs) has a major impact on the fuel cell performance and durability. Different from traditional two-phase flow in other applications, water in the PEMFCs is introduced into the minichannel from the gas diffusion layers (GDLs) through random pores of different sizes. Meanwhile, the four channel surfaces may have different wettabilities due to the different materials used. Thus, the microstructure of GDLs and the surface wettability should be considered in investigating the two-phase flow in PEMFC channels. One challenge in simulating PEMFCs is that, full consideration of detailed microstructure of GDL needs extremely large computational time. In this work, we simplified the microstructure of GDL to a number of representative pores on the 2D GDL surface. A 3-D minichannel with 1.0 mm × 1.0 mm square cross section and 100 mm long was used in the simulation. Operating conditions and material properties were selected according to realistic fuel cell operating conditions. Volume of fluid (VOF) method was employed to explicitly track the droplet surfaces emerging from the non-uniform GDLs. Simulation results show that, as the flow develops along the channel, the flow pattern evolves from corner flow on the bottom and side wall to corner flow on the top wall, annular flow and slug flow. The effects of liquid injection rates were studied, and it is found that the high liquid flow rate would accelerate the flow pattern development. The effect of wall surface material wettability was also studied by changing the hydrophobicity of GDL surface and side walls, separately. Simulation results show that the material wettability has a strong impact on the two-phase flow pattern, with a more hydrophilic side walls and/or a more hydrophobic GDL surface being more beneficial for expelling water out of the channel.

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