scholarly journals Numerical Modelling and Simulation of Two-Phase Flow Flushing Method for Pipeline Cleaning in Water Distribution Systems

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2470
Author(s):  
Zhaozhao Tang ◽  
Wenyan Wu ◽  
Xiaoxi Han ◽  
Ming Zhao ◽  
Jingting Luo ◽  
...  
Keyword(s):  
Numerical Modelling ◽  
Distribution Systems ◽  
Water Distribution ◽  
Two Phase Flow ◽  
Growth Ring ◽  
Water Distribution Systems ◽  
Water Phase ◽  
Phase Flow ◽  
Two Phase ◽  
Secondary Pollution

Secondary pollution by microorganisms and substances peeling off from the “growth ring” causes clean water deterioration during the water distribution process. In order to reduce the secondary pollution, our previous research investigated the best settings of a two-phase flow flushing method for pipeline cleaning in water distribution systems experimentally, and a case study was carried out for comparison of the efficiencies between two-phase and single-phase flow methods. In this paper, based on the results of the experimental study, numerical modelling and a simulation study are carried out by FLUENT to evaluate the performance of the two-phase flow flushing method for removal of the “growth ring”. Results: the simulation results match the experimental results; pressure, water-phase flow velocity and water-phase volume ratio distributions in a section of pipe are simulated and analysed; the shear force against time in a period is obtained; elbow pipes cause flushing energy loss, and therefore, at most one section of elbow pipe is flushed in one flushing period.

Imaging and Resistivity Studies of Saturation Gradients in Two-Phase Flow in 3-D Porous Media

1996 ◽  
Vol 464 ◽  
Author(s):  
E. H. Kawamoto ◽  
Po-Zen Wong
Keyword(s):  
Computed Tomography ◽  
Porous Media ◽  
Two Phase Flow ◽  
Water Saturation ◽  
Glass Beads ◽  
Water Phase ◽  
Phase Flow ◽  
Two Phase ◽  
Vertical Column ◽  
X Ray

ABSTRACTWe have carried out x-ray radiography and computed tomography (CT) to study two-phase flow in 3-D porous media. Air-brine displacement was imaged for drainage and imbibition experiments in a vertical column of glass beads. By correlating water saturation Sw with resistance R, we find that there is a threshold saturation S* ≈ 0.2, above which R(SW) ∼ Sw−2, in agreement with the empirical Archie relation. This holds true for both drainage and imbibition with littlehysteresis, provided that Sw remains above S*. Should Sw drop below S* during drainage, R(Sw) rises above the Archie prediction, exhibiting strong hysteresis upon reimbibition. This behavior suggests a transition in the connectivity of the water phase near S*, possibly due to percolation effects.

Turbulence Structure of a Liquid-Solid Two-Phase Jet by Means of Laser Techniques

2003 ◽  
Author(s):  
Toshimichi Arai ◽  
Naoki Kudo ◽  
Tsuneaki Ishima ◽  
Ismail M. Youssef ◽  
Tomio Obokata ◽  
...  
Keyword(s):  
Particle Size ◽  
Single Phase ◽  
Two Phase Flow ◽  
Volume Ratio ◽  
Water Phase ◽  
Phase Flow ◽  
Size Discrimination ◽  
Single Phase Flow ◽  
Particle Volume ◽  
Two Phase

Characteristics on particle motion in a liquid-solid two-phase jet flow were studied in the paper. The water jet including glass particle of 389 μm in mean diameter was injected into water bath. The experimental conditions were 0.21% of initial particle volume ratio, 5mm in pipe diameter and 1.84 m/s of mean velocity on outlet of the jet. A laser Doppler anemometer (LDA) with size discrimination was applied for measuring the time serious velocities of the single-phase flow, particle and water phase flow. A particle image velocimetry (PIV) was also applied in the two-phase flow. The normal PIV method can hardly measure the particle size and perform the particle size discrimination. In the experiment, using the gray scales related with the scattering light intensity, measuring method with size discrimination in two-phase flow was carried out. The experimental results show less difference between velocities of single-phase flow and water-phase flow under this low particle volume ratio condition. Particles have the relative motion with the water-phase and large rms velocity. The PIV used in this experiment, which is called multi-intensity-layer-PIV: MILP, can measure water-phase velocity with good accuracy.

Water Condensation and Two-Phase Flow Modeling for a Plate Heat Exchanger Channel

2007 ◽  
Author(s):  
Charlotte Wilhelmsson ◽  
Jinliang Yuan ◽  
Bengt Sunden
Keyword(s):  
Phase Change ◽  
Two Phase Flow ◽  
Plate Heat Exchanger ◽  
Water Phase ◽  
Phase Flow ◽  
Governing Equations ◽  
Two Phase ◽  
Plate Heat ◽  
Total Enthalpy ◽  
Vapour Condensation

There are water vapour condensation and two-phase flow in plate heat exchangers when they are used as condensers. Water phase change and flow dynamics modelling is an important but complicated task due to large change in water physical/transport properties across the water liquid-vapour interface boundary. In particular, singular-link behaviour in governing equations is present due to the large step change in the density when computational fluid dynamics (CFD) is employed. Conventional methods using ensemble averaged parameters such as void fraction are impossible to be applied to cases where high-resolution calculations and detailed analysis are required. In this study, a CFD approach is employed to model water vapour condensation and two-phase flow in a channel relevant for plate heat exchanger parallel plates. The developed model is based on the governing equations which are directly solved for the entire single- and two-phase fields. The water phase change and two-phase flow are treated by employing a water liquid-phase fraction factor based on the total enthalpy in each computational cell. The factor is defined as the ratio of the total enthalpy differential to the latent heat of condensation. The thermal-physical properties, such as density, viscosity and conductivity of the two-phase region, are calculated and updated based on the calculated value of the liquid-phase fraction factor until a converged result is reached. It is concluded that, among others, the inlet vapour velocity has significant effects on the water phase change and two-phase flow in the channel, in terms of liquid-water fraction factor distribution.

scholarly journals SmartCrawler: An In-pipe Robotic System with Novel Low-frequency Wireless Communication Setup in Water Distribution Systems

2021 ◽  
Author(s):  
Saber Kazeminasab ◽  
M.Katherine Banks
Keyword(s):  
Wireless Communication ◽  
Radio Frequency Identification ◽  
Distribution Systems ◽  
Water Distribution ◽  
Phase 1 ◽  
Water Distribution Systems ◽  
Robotic System ◽  
Experimental Results ◽  
Circuit Board ◽  
Two Phase

Water Distribution Systems (WDS) are critical infrastructures that deliver potable water to residential areas. Water quality monitoring is one of the requirements for utility managers to ensure the health of the water. However, it is challenging to access all parts of the WDS since they are long and comprise different configurations. In this paper, we propose a size-adaptable in-pipe robot so-called “SmartCrawler”. We develop two-phase control algorithm that enables reliable motion in different configurations of pipelines. The controller in phase 1 stabilizes the robot in the straight paths and tracks the desired velocity with high-level linear quadratic regulator (LQR) and low-level proportional-integral-derivative (PID) based controllers. The controller in phase 2 enables the robot to have reliable change of direction in the non-straight paths. The performance of the two-phase controller is evaluated with experimental and simulation results. Wireless underground communication is a challenging task for underground applications. To facilitate wireless communication, we propose an active radio frequency identification (RFID) based communication working in 434MHz carrier frequency and evaluate its performance with experimental results. At the end of this work, we design the printed circuit board (PCB) for the SmartCrawler. The simulation and the experimental results prove the proposed robotic system can be used for in-pipe missions where wireless communication is needed to communicate with the robot during operation. <br>

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