OS9-5 Trial Measurement on Two-phase Flow using a Multi-wave Ultrasonic Velocity Profile Method : 3rd Report: Measurement of Slug Flow and Visualization using High-speed Camera

2007 ◽  
Vol 2007.12 (0) ◽  
pp. 109-110
Author(s):  
Hideki MURAKAWA ◽  
Hiroshige KIKURA ◽  
Masanori ARITOMI
Keyword(s):  
Velocity Profile ◽  
Ultrasonic Velocity ◽  
Slug Flow ◽  
High Speed ◽  
Two Phase Flow ◽  
Phase Flow ◽  
High Speed Camera ◽  
Two Phase ◽  
Profile Method

scholarly journals Application of RQA and SOM for identification of two-phase flow patterns during boiling in horizontal minichannel

2021 ◽  
Vol 321 ◽  
pp. 02008
Author(s):  
Hubert Grzybowski ◽  
Iwona Zaborowska ◽  
Romuald Mosdorf
Keyword(s):  
Pressure Drop ◽  
Liquid Flow ◽  
Slug Flow ◽  
High Speed ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Flow Patterns ◽  
Phase Flow ◽  
Two Phase ◽  
Inner Diameter

In the paper, numerical methods of data analysis recurrence quantification analysis (RQA) and self-organizing map (SOM) have been used to analyse pressure drop oscillations during the flow boiling in minichannel. The performed analysis allows us to identify flow patterns based on the character of the pressure drop oscillations. The following two-phase flow patterns have been identified: liquid flow, liquid flow with small vapour bubble, slug flow, long slug flow and confined bubble flow. In the experiment, the open-loop boiling system in a circular horizontal minichannel with an inner diameter of 1 mm was investigated. The two-phase flow patterns at the outlet of the heated section were observed through the glass tube (with an inner diameter of 1 mm) and recorded by a high-speed camera Phantom v1610.

scholarly journals Boiling Synchronization in Two Parallel Minichannels—Image Analysis

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1409 ◽  
Author(s):  
Gabriela Rafałko ◽  
Iwona Zaborowska ◽  
Hubert Grzybowski ◽  
Romuald Mosdorf
Keyword(s):  
Image Analysis ◽  
Liquid Flow ◽  
Slug Flow ◽  
High Speed ◽  
Annular Flow ◽  
Bubble Flow ◽  
Phase Flow ◽  
High Speed Camera ◽  
Two Phase ◽  
Time Period

In this paper, the boiling synchronization of two-phase flow patterns in two parallel minichannels of 1 mm in diameter with connected compressible volumes was analyzed. The analysis was performed using images recorded with a high-speed camera. The degree of synchronization between channels was evaluated by assessing the presence of liquid flow in the small part of the minichannels. It can be concluded that boiling is synchronized when small bubble flow or wavy annular flow occur in neighboring channels. The occurrence of slug flow in one channel causes the boiling in neighboring channels to become unsynchronized. The result of the image analysis shows that the correlation coefficient based on the evaluation of the presence of liquid flow in the small part of the minichannels over a long enough time period allows for the detection of boiling synchronization.

Development of Wire Mesh Sensor to Study Two Phase Flow and its Comparison With High Speed Camera

2017 ◽  
Author(s):  
Kamil Abbas ◽  
Lan Haijian ◽  
Yu Ting ◽  
Zhou Shiliang ◽  
Muhammad Ali Shahzad
Keyword(s):  
Data Acquisition ◽  
Spatial Resolution ◽  
High Speed ◽  
Two Phase Flow ◽  
Wire Mesh ◽  
Maximum Efficiency ◽  
Phase Flow ◽  
High Speed Camera ◽  
Two Phase ◽  
Data Acquisition Card

The main concern of this research is the two phase flow, which consist of air bubbles submersed in water in reactors cores. The understanding of these such flow activities is paramount to finding out about the efficiency of the process and for safety concerns. This knowledge is also important to control and monitor the flow at the spot or online. The employed method is based on the conductivity principle, and it was chosen because of the cheapness of the circuitry involved for implementation, as compared to other imaging techniques. Keeping this in mind, it provides an excellent temporal and spatial resolution for measurement. To fulfill this requirement, a small testing facility was designed and developed. The circuits were made and then tested by making PCBs. To prevent environmental noises and electromagnet disturbance, the apparatus was shielded to the best of ability, in accordance with the available resources. A wire mesh sensor with sixteen inputs and outputs respectively was made and put in a vertical glass section with water and air filled inside. The bubbles were generated by external means and the signal interference was noted in the collection section. The signals were collected by a data acquisition card and further manipulated in a software program. The data was first taken in the LabVIEW software and then transferred to MATLAB for analysis and image reconstruction. Basically, the main system included wire mesh, the circuit for excitation, the circuit for data collection and data acquisition card connected to a computer. The results were compared with a high speed camera which was linked in synchronization with the software. In these circuit designs, the maximum efficiency was ensured while keeping the cost low. The sensor is surrounded by glass so that the high speed camera could also be used to compare results. The use of the high speed data acquisition card also enabled to deal with real time acquisition without any problem. Unfortunately, this facility could not be tested in rigorous conditions like high temperature and pressure because of limited resources. The conclusions drawn from these experiments are that wire mesh sensors indeed provide temporal resolution of about 1000 frames/s with a good spatial resolution and is also a lot cheaper in comparison with other techniques.

On Instabilities in Horizontal Two-Phase Flow

1994 ◽  
Vol 59 (12) ◽  
pp. 2595-2603
Author(s):  
Lothar Ebner ◽  
Marie Fialová
Keyword(s):  
Differential Equation ◽  
Flow Regime ◽  
Slug Flow ◽  
Annular Flow ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Annular Flows ◽  
Flow Regime Maps

Two regions of instabilities in horizontal two-phase flow were detected. The first was found in the transition from slug to annular flow, the second between stratified and slug flow. The existence of oscillations between the slug and annular flows can explain the differences in the limitation of the slug flow in flow regime maps proposed by different authors. Coexistence of these two regimes is similar to bistable behaviour of some differential equation solutions.

High Speed Imaging and Two-Phase Flow Patterns During Flow Boiling in a Single Microchannel

2008 ◽  
Author(s):  
Jacqueline Barber ◽  
Khellil Sefiane ◽  
David Brutin ◽  
Lounes Tadrist
Keyword(s):  
High Speed ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Pressure Sensors ◽  
Flow Patterns ◽  
Bubble Nucleation ◽  
Phase Flow ◽  
Vapour Bubble ◽  
Two Phase ◽  
Over Time

Boiling in microchannels remains elusive due to the lack of full understanding of the mechanisms involved. A powerful tool in achieving better comprehension of the mechanisms is detailed imaging and analysis of the two phase flow at a fundamental level. We induced boiling in a single microchannel geometry (hydraulic diameter 727 μm), using a refrigerant FC-72, to investigate several flow patterns. A transparent, metallic, conductive deposit has been developed on the exterior of rectangular microchannels, allowing simultaneous uniform heating and visualisation to be conducted. The data presented in this paper is for a particular case with a uniform heat flux of 4.26 kW/m2 applied to the microchannel and inlet liquid mass flowrate, held constant at 1.33×10−5 kg/s. In conjunction with obtaining high-speed images and videos, sensitive pressure sensors are used to record the pressure drop profiles across the microchannel over time. Bubble nucleation, growth and coalescence, as well as periodic slug flow, are observed in the test section. Phenomena are noted, such as the aspect ratio and Reynolds number of a vapour bubble, which are in turn correlated to the associated pressure drops over time. From analysis of our results, images and video sequences with the corresponding physical data obtained, it is possible to follow visually the nucleation and subsequent both ‘free’ and ‘confined’ growth of a vapour bubble over time.

Analysis of Transient Two-Phase Flow in Pressure Safety Valve Outlet Headers

2018 ◽  
Author(s):  
Maral Taghva ◽  
Lars Damkilde
Keyword(s):  
Steady State ◽  
Shock Waves ◽  
High Speed ◽  
Two Phase Flow ◽  
Safety Valve ◽  
Strong Shock ◽  
Flow Property ◽  
Phase Flow ◽  
Transient Pressure ◽  
Two Phase

To protect a pressurized system from overpressure, one of the most established strategies is to install a Pressure Safety Valve (PSV). Therefore, the excess pressure of the system is relieved through a vent pipe when PSV opens. The vent pipe is also called “PSV Outlet Header”. After the process starts, a transient two-phase flow is formed inside the outlet header consisting of high speed pressurized gas interacting with existing static air. The high-speed jet compresses the static air towards the end tail of the pipe until it is discharged to the ambiance and eventually, the steady state is achieved. Here, this transient process is investigated both analytically and numerically using the method of characteristics. Riemann’s solvers and Godunov’s method are utilized to establish the solution. Propagation of shock waves and flow property alterations are clearly demonstrated throughout the simulations. The results show strong shock waves as well as high transient pressure take place inside the outlet header. This is particularly important since it indicates the significance of accounting for shock waves and transient pressure, in contrast to commonly accepted steady state calculations. More precisely, shock waves and transient pressure could lead to failure, if the pipe thickness is chosen only based on conventional steady state calculations.

Study of the 90° Elbows Performance as Phase Separators in an Air-Water Two-Phase Flow

2003 ◽  
Author(s):  
Valente Herna´ndez P. ◽  
Florencio Sa´nchez S. ◽  
Miguel Toledo V. ◽  
Georgiy Polupan
Keyword(s):  
Phase Separation ◽  
Slug Flow ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Pressure Gradients ◽  
Two Phase ◽  
Branch Diameter ◽  
Independent Variables ◽  
Inclination Angles ◽  
Phase Separator

In order to observe the 90° elbows performance as phase separators in an air-water two-phase flow, experimental results for the phase split which occurs at a 90° branched elbow are presented. The branched elbow geometry was varied in order to have three (branch diameter / elbow diameter) ratios and three branch inclination angles. Also the pressure was monitored at different points of the elbow with ramification in order to examine the pressure drop effect. The flow pattern upstream was mainly slug flow. First, the analysis of the main independent variables effect, (superficial velocities, branch inclination angle, ratio of diameters and pressure gradients) was carried out, then a correlation for the phase split was developed and, finally a comparison was made with data of phase separation in T junctions obtained by Azzopardi [1] and Soliman [2], as a result, a better behavior as phase separator was found for the elbow.

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