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.

Behavior of Bubbles Separated by a Cross-Shaped Obstacle Placed in a Circular Flow Channel

2017 ◽  
Author(s):  
Kazuyuki Takase ◽  
Hiep H. Nguyen ◽  
Gaku Takase ◽  
Yoshihisa Hiraki
Keyword(s):  
High Speed ◽  
Nuclear Reactor ◽  
Two Phase Flow ◽  
Flow Direction ◽  
Flow Behavior ◽  
Bubbly Flow ◽  
Wire Mesh ◽  
Phase Flow ◽  
Two Phase ◽  
Validation Data

Clarifying two-phase flow characteristics in a nuclear reactor core is important in particular to enhance the thermo-fluid safety of nuclear reactors. Moreover, bubbly flow data in subchannels with spacers are needed as validation data for current CFD codes like a direct two-phase flow analysis code. In order to investigate the spacer effect on the bubbly flow behavior in a subchannel of the nuclear reactor, bubble dynamics around the simply simulated spacer was visually observed by a high speed camera. Furthermore, the void fraction and interfacial velocity distributions just behind the simulated spacer were measured quantitatively by using a wire-mesh sensor system with three wire-layers in the flow direction. From the present study, bubble separation behavior dependence upon the spacer shape was clarified.

Experimental Analysis of a Liquid-Gas Two-Phase Flow in a Flow Distributor

2019 ◽  
Author(s):  
Luiz H. M. Lino ◽  
Henrique K. Eidt ◽  
Carolina C. Rodrigues ◽  
Cesar Y. Ofuchi ◽  
Paulo H. D. Santos ◽  
...  
Keyword(s):  
Distribution System ◽  
High Speed ◽  
Two Phase Flow ◽  
Flow Distribution ◽  
Experimental Tests ◽  
Wire Mesh ◽  
Liquid Volume ◽  
Phase Flow ◽  
Two Phase ◽  
Operational Conditions

Abstract The main goal of this work is to analyze the efficiency of a two-phase flow distribution system for different operational conditions, which was designed and built by the Multiphase Flow Research Center (NUEM). The distribution system is composed of a two tangential inlets, a cyclonic chamber, and four outlets. The working principle of this apparatus is based on the combined action of centrifugal and gravitational forces, which causes the development of a liquid film, facilitating the flow distribution. Four outlets are located perpendicularly to the cyclonic chamber in order to distribute the flow equally to some extent. Experimental tests were performed using water and air in a vertical 52-mm ID acrylic pipe. Two flow patterns (bubble and slug) at the input of the inlets were visually identified through the use of a high-speed camera. To verify the flow distribution, wire-mesh sensors were installed at each outlet and graduated beakers and a timer was used in order to estimate the liquid volume flowing at the outlets. The results showed that the flow distribution system has a satisfactory efficiency of distribution.

Characterisation of Air-Water Two-Phase Flow Using a Wire-Mesh Sensor

2011 ◽  
Author(s):  
Carlos E. F. do Amaral ◽  
O´liver B. S. Scorsim ◽  
Eduardo N. Santos ◽  
Marco Jose´ da Silva ◽  
Marco Germano Conte ◽  
...  
Keyword(s):  
High Speed ◽  
Gas Flow ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Industrial Applications ◽  
Wire Mesh ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Rates ◽  
Piping Systems

Two phase flow occurs in many industrial applications, mainly in the transport of mixtures. Many patterns can be produced according to the liquid and gas flow rates. The identification of these patterns is very important in the design of piping systems and equipments. This work proposes an experimental study to identify multiphase flow patterns of water and air in horizontal pipes. The study was developed using an experimental circuit of 26 mm diameter and 9.2 m length pipe, at Thermal Sciences Lab (LACIT) at the Federal University of Technology - Parana´. To characterize the flow patterns, an intrusive mesh electrodes sensor was used, which allows the detailed visualization of the phases distribution. Tests were made using several experimental settings of water and gas flow rates. Measurements were compared to images obtained by high speed camera and the temporal void fraction series which were analyzed with the use of PDF and PSD functions, showing the singularities for each two-phase flow pattern.

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.

Local characteristic of horizontal air–water two-phase flow by wire-mesh sensor

2016 ◽  
Vol 40 (3) ◽  
pp. 746-761 ◽  
Author(s):  
Weiling Liu ◽  
Chao Tan ◽  
Feng Dong
Keyword(s):  
Void Fraction ◽  
Transient Flow ◽  
Two Phase Flow ◽  
Wire Mesh ◽  
Local Characteristic ◽  
Phase Flow ◽  
Flow Conditions ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Local Flow

Two-phase flow widely exists in many industries. Understanding local characteristics of two-phase flow under different flow conditions in piping systems is important to design and optimize the industrial process for higher productivity and lower cost. Air–water two-phase flow experiments were conducted with a 16×16 conductivity wire-mesh sensor (WMS) in a horizontal pipe of a multiphase flow facility. The cross-sectional void fraction time series was analysed by the probability density function (PDF), which described the void fraction fluctuation at different flow conditions. The changes and causes of PDFs during a flow regime transition were analysed. The local structure and flow behaviour were characterized by the local flow spectrum energy analysis and the local void fraction distribution (horizontal, vertical and radial direction) analysis. Finally, three-dimensional transient flow fluctuation energy evolution and characteristic scale distribution based on wavelet analysis of air–water two-phase flow were presented, which revealed the structural features of each phase in two-phase flow.

scholarly journals Experimental Investigation of the Performance and Spray Characteristics of a Supersonic Two-Phase Flow Ejector with Different Structures

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1166 ◽  
Author(s):  
Shizhen Li ◽  
Wei Li ◽  
Yanjun Liu ◽  
Chen Ji ◽  
Jingzhi Zhang
Keyword(s):  
High Speed ◽  
Two Phase Flow ◽  
Fire Suppression ◽  
Cone Angle ◽  
Water Mist ◽  
Pulsation Period ◽  
Phase Flow ◽  
Two Phase ◽  
Half Cone ◽  
Half Cone Angle

A two-phase flow ejector is an important part of a water mist fire suppression system, and these devices have become a popular research topic in recent years. This paper proposes a supersonic ejector that aims to improve the efficiency of water mist fire suppression systems. The effects of ejector geometric parameters on the entrainment ratio (ER) were explored. The effects of primary flow pressure (PP) on the mixing process and flow phenomena were studied by a high-speed camera. The experimental results show that the ER first increases and then decreases with increasing PP. ER increases with increasing ejector area ratio (AR). The PP corresponding to the maximum ER of ejectors with a different nozzle exit position (NXP) is 3.6 bar. The ejector with an NXP of +1 and AR of 6 demonstrate the best performance, and the ER of this ejector reaches 36.29. The spray half-cone angle of the ejector increases with increasing ER, reaching a maximum value of 7.07°. The unstable atomization half-cone angle is mainly due to a two-phase flow pulsating phenomenon. The pulsation period is 10 ms. In the present study, a general rule that provides a reference for ejector design and selection was obtained through experiments.

Sign in / Sign up

Export Citation Format

Share Document