scholarly journals Review on Microbubbles and Microdroplets Flowing through Microfluidic Geometrical Elements

Micromachines ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 201 ◽  
Author(s):  
Ana T. S. Cerdeira ◽  
João B. L. M. Campos ◽  
João M. Miranda ◽  
José D. P. Araújo
Keyword(s):  
Steam Generators ◽  
Two Phase Flows ◽  
Two Phase ◽  
Industrial Systems ◽  
Interphase Interactions ◽  
Pass Through ◽  
Liquid Flows ◽  
And Control ◽  
Oil Gas ◽  
Numerical Approaches

Two-phase flows are found in several industrial systems/applications, including boilers and condensers, which are used in power generation or refrigeration, steam generators, oil/gas extraction wells and refineries, flame stabilizers, safety valves, among many others. The structure of these flows is complex, and it is largely governed by the extent of interphase interactions. In the last two decades, due to a large development of microfabrication technologies, many microstructured devices involving several elements (constrictions, contractions, expansions, obstacles, or T-junctions) have been designed and manufactured. The pursuit for innovation in two-phase flows in these elements require an understanding and control of the behaviour of bubble/droplet flow. The need to systematize the most relevant studies that involve these issues constitutes the motivation for this review. In the present work, literature addressing gas-liquid and liquid-liquid flows, with Newtonian and non-Newtonian fluids, and covering theoretical, experimental, and numerical approaches, is reviewed. Particular focus is given to the deformation, coalescence, and breakup mechanisms when bubbles and droplets pass through the aforementioned microfluidic elements.

scholarly journals INTELLIGENT SYSTEM FOR THE TWO-PHASE FLOWS DIAGNOSIS AND CONTROL ON THE BASIS OF RAW 3D ECT DATA

2017 ◽  
Vol 7 (1) ◽  
pp. 17-23 ◽  
Author(s):  
Paweł Fiderek ◽  
Tomasz Jaworski ◽  
Robert Banasiak ◽  
Jacek Nowakowski ◽  
Jacek Kucharski ◽  
...  
Keyword(s):  
Fuzzy Inference ◽  
Intelligent System ◽  
Fuzzy Classification ◽  
Control Panel ◽  
Random Errors ◽  
Two Phase Flows ◽  
Two Phase ◽  
Control Module ◽  
Inference System ◽  
And Control

In this paper the new intelligent system for two-phase flows diagnosis and control is presented. The authors developed a fuzzy inference system for two phase flows recognition based on the raw 3D ECT data statistical analysis and fuzzy classification which identify the flow structure in real-time mode. The non-invasive three-dimensional monitoring is possible to conduct even in non-transparent and non-accessible parts of the pipeline. Presented system is also equipped with the two phase gas-liquid flows installation control module based on fuzzy inference which includes the feedback information from the recognition module. The intelligent control module working in a feed-back loop keep the sets of required flow regime. Presented in this paper fuzzy algorithms allow to recognize the two phase processes similar to the human expert and to control the process in the same, very intuitively way. Using of the artificial intelligence in the industrial applications allows to avoid any random errors as well as breakdowns and human mistakes suffer from lack of objectivity. An additional feature of the system is a universal multi-touched monitoring-control panel which is an alternative for commercial solution and gives the opportunity to build user own virtual model of the flow rig to efficiently monitor and control the process.

scholarly journals Computer methods for non-invasive measurement and control of two-phase flows: a review study

2019 ◽  
Vol 48 (3) ◽  
pp. 464-486
Author(s):  
Radosław Wajman
Keyword(s):  
Energy Saving ◽  
Flow Regime ◽  
Main Trend ◽  
Two Phase Flows ◽  
Two Phase ◽  
Computer Methods ◽  
Non Invasive ◽  
Flow Parameters ◽  
And Control ◽  
Invasive Measurement

Nowadays, the application of advanced technologies in modern production systems is the main trend of development and technological progress in many industrial sectors. It is due to the still growing trends of energy-saving and production quality enhancement. Wherever in the production process the phase mixture is transported and it is not optimal or not economic, there is a need to develop a system which would be able to prevent any construction disaster, unexpected production line stopping or situation where for reasons of bad flow parameters, the final product is defective. This paper studies various sensors, measurement techniques and computer methods for signal processing and analysis to diagnose and control two-phase flows. Due to the possibility that the invasive measurement disturbs the process and changes it parameters and behavior especially in the location just after the measurement point and simultaneously does not provide any information about these changes it is unreliable for the diagnosis or control. Therefore, the non-invasive techniques commonly used for measurement of flows parameters are described. Depending on the industrial demands many of applications examples for non-invasive two-phase flows measurement and monitoring are given. This description for identifying the flow parameters is divided into features categories of this phenomena as void fraction distribution, velocity profile and flow regime. However, from these methods the high accuracy and short processing time is expected. The continued observation and monitoring of the process abnormalities can provide valuable information about its dynamic state and allow for real-time and automatic monitoring and control. Therefore, the development of advanced process control is one of the most important challenges to keep the flow regime on the given level and for instant and long-term energy saving, quality improvement.

Calculation of Two-Phase Flows in an Oil Separator by Using a Cubic Interpolated Propagation Code on Unstructured Grid Spaces

2002 ◽  
Author(s):  
Eiji Ishii ◽  
Hirotaka Kameya ◽  
Atsushi Watanabe ◽  
Masayuki Urashin
Keyword(s):  
Finite Volume Method ◽  
Finite Volume ◽  
Unstructured Grid ◽  
Incompressible Flows ◽  
Critical Conditions ◽  
Two Phase Flows ◽  
Two Phase ◽  
Oil Separation ◽  
Liquid Flows ◽  
Volume Method

We have developed a cubic interpolated propagation (CIP) code combined with a finite volume method using unstructured grid spaces. The CIP code, which can solve both compressible and incompressible flows simultaneously, was used to calculate gas-liquid flows — in this case, waterspouts — in an oil separator. We found that waterspouts raise the oil at the bottom of the separator’s chamber and lower the efficiency of oil separation remarkably. We also found that the waterspouts can be classified as circulatory or non-circulatory and that they are caused by a low-pressure core in the discharge pipe. Furthermore, we predicted the critical conditions under which the waterspouts occur, and these predictions agree with measurements taken with a test separator.

Stability Analysis of Two-Phase Flows in Pipe-Riser Systems

2000 ◽  
Author(s):  
Erich Zakarian
Keyword(s):  
Hydrodynamic Instability ◽  
Momentum Balance ◽  
Quasi Equilibrium ◽  
Two Phase Flows ◽  
Two Phase ◽  
Drift Flux Model ◽  
Drift Flux ◽  
Differential Algebraic System ◽  
Flux Model ◽  
Liquid Flows

A differential-algebraic system is presented to model unstable two-phase flows in pipe-riser systems. Equations derive from the space integration of an isothermal drift-flux model assuming quasi-equilibrium momentum balance. A linear analysis of this system gives a new stability criterion for gas-liquid flows in pipe-riser systems. This criterion is validated by laboratory experiments. Then, a nonlinear analysis shows that the severe slugging phenomenon is a hydrodynamic instability coming from a supercritical Hopf bifurcation.

scholarly journals Two-phase flow separation in axial free vortex flow

2017 ◽  
Vol 9 (3) ◽  
pp. 105-113
Author(s):  
Mohammad Aghaee ◽  
Rouhollah Ganjiazad ◽  
Ramin Roshandel ◽  
Mohammad Ali Ashjari
Keyword(s):  
Vortex Flow ◽  
Two Phase Flow ◽  
Petroleum Industry ◽  
Tangential Velocity ◽  
Phase Flow ◽  
Two Phase Flows ◽  
Two Phase ◽  
Simple Method ◽  
Free Vortex ◽  
Liquid Flows

Multi-phase flows, particularly two-phase flows, are widely used in the industries, hence in order to predict flow regime, pressure drop, heat transfer, and phase change, two-phase flows should be studied more precisely. In the petroleum industry, separation of phases such as water from petroleum is done using rotational flow and vortices; thus, the evolution of the vortex in two-phase flow should be considered. One method of separation requires the flow to enter a long tube in a free vortex. Investigating this requires sufficient knowledge of free vortex flow in a tube. The present study examined the evolution of tube-constrained two-phase free vortex using computational fluid dynamics. The discretized equations were solved using the SIMPLE method. It was determined that as the liquid flows down the length of the pipe, the free vortex evolves into combined forced and free vortices. The tangential velocity of the free and forced vortices also decreases in response to viscosity. It is shown that the concentration of the second discrete phase (oil) is greatest at the center of the pipe in the core of the vortex. This concentration is at a maximum at the outlet of the pipe.

Bubble-driven liquid flows

1986 ◽  
Vol 170 ◽  
pp. 53-82 ◽  
Author(s):  
F. Durst ◽  
B. Schönung ◽  
K. Selanger ◽  
M. Winter
Keyword(s):  
Liquid Flow ◽  
Fluid Velocity ◽  
Experimental Studies ◽  
Vertical Direction ◽  
Experimental Information ◽  
Circular Cylinders ◽  
Two Phase Flows ◽  
Two Phase ◽  
Finite Difference Equations ◽  
Liquid Flows

Detailed information is provided in this paper on the physics of momentum transfer in bubble-driven liquid flows. Experimental information is obtained on the flow around bubbles and on the axisymmetric bubble-driven liquid flow inside liquid-filled cylinders located with their axes in the vertical direction. A laser-Doppler anemometer extended for particulate two-phase flows is employed for these measurements to yield local fluid velocity information as well as the rise velocity of bubbles. The bubble top radius and the bubble shape were also found from these measurements.Utilizing experimentally gained information and employing the basic equations for particulate two-phase flows, permits finite difference equations to be formulated that allow bubble-driven liquid flows to be computed. Results are presented for boundary conditions corresponding to those of the experimental studies. Comparisons of numerical and experimental results are shown to be in good agreement. This is taken as a justification to employ the developed computer programs to carry out parameter studies for bubble-driven liquid flow inside circular cylinders. Results of these studies are presented and discussed.

Implementation of a Level Set Interface Tracking Method in the FIDAP and CFX-4 Codes

2005 ◽  
Vol 127 (4) ◽  
pp. 674-686 ◽  
Author(s):  
Sergey V. Shepel ◽  
Brian L. Smith ◽  
Samuel Paolucci
Keyword(s):  
Finite Element ◽  
Level Set ◽  
Gaseous Phase ◽  
Two Phase Flows ◽  
Two Phase ◽  
Moving Interfaces ◽  
Computational Fluid Dynamics Cfd ◽  
Two Phases ◽  
Density Ratios ◽  
Liquid Flows

We present a streamline-upwind–Petrov-Galerkin (SUPG) finite element level set method that may be implemented into commercial computational fluid dynamics (CFD) software, both finite element (FE) and finite volume (FV) based, to solve problems involving incompressible, two-phase flows with moving interfaces. The method can be used on both structured and unstructured grids. Two formulations are given. The first considers the coupled motion of the two phases and is implemented within the framework of the commercial CFD code CFX-4. The second can be applied for those gas-liquid flows for which effects of the gaseous phase on the motion of the liquid phase are negligible; consequently, the gaseous phase is removed from consideration. This level set formulation is implemented in the commercial CFD code FIDAP. The resulting level set formulations are tested and validated on sample problems involving two-phase flows with density ratios of the order of 103 and viscosity ratios as high as 1.6×105.

Development of CUPID-SG for the analysis of two-phase flows in PWR steam generators

2014 ◽  
Vol 77 ◽  
pp. 132-140 ◽  
Author(s):  
Hyungrae Kim ◽  
Soo Hyoung Kim ◽  
Seung-Jun Lee ◽  
Ik Kyu Park ◽  
Han Young Yoon ◽  
...  
Keyword(s):  
Steam Generators ◽  
Two Phase Flows ◽  
Two Phase
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