Experimental Observation of Bubbles Released in Horizontal Water Flow

2018 ◽  
Author(s):  
Can Kang ◽  
Yanguang Ji ◽  
Lili Zhang ◽  
Wei Zhang
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
Bubble Size ◽  
Cross Flow ◽  
Water Velocity ◽  
Bubble Velocity ◽  
Bubble Shape ◽  
Stagnant Water ◽  
Water Flow Velocity ◽  
Eotvos Number

To investigate the characteristics of the bubble which is exposed to the liquid cross flow, the method of ventilation was adopted and air was injected into the water flow. A water tunnel was used to provide uniform water flow with variable velocity magnitude. A high speed camera was used to record instantaneous bubble images. An image-processing code was developed to identify bubble profile and to calculate bubble parameters. The effects of water flow velocity and the flow rate of the injected air were considered. The results indicate that bubble size decreases as the water velocity increases; meanwhile, ellipsoidal bubble shape is transformed into rounded shape. The variation in the air flow rate leads to a slight change of bubble size as well the bubble shape. The bubble velocity fluctuates with the movement of the bubble, and the fluctuations are intensified as the water velocity decreases. As the balance between the forces exerted on the bubble is reached, an approximately linear relationship between the bubble velocity and the water flow velocity is proven. For a given bubble equivalent diameter, the bubble terminal velocity with the liquid cross flow is higher than that associated with stagnant water. For small Eötvös number, the consistency of the bubble aspect ratio in the cross flow and the stagnant water is manifested; however, large Eötvös number obtained here is beyond the range associated with the stagnant water, and the existing relationship is extended.

Micro-scale simulation of bubble-water flow in coal seams by the lattice Boltzmann method

2016 ◽  
Vol 56 (2) ◽  
pp. 608
Author(s):  
Jie Yi ◽  
Huilin Xing ◽  
Tianwei Sun ◽  
Victor Rudolph
Keyword(s):  
Coal Seam ◽  
Water Flow ◽  
Flow Rate ◽  
Bubble Size ◽  
Lattice Boltzmann ◽  
Water Flow Rate ◽  
Bubble Flow ◽  
Coal Seam Gas ◽  
Two Phase ◽  
Flow Process

The production of coal seam gas initially requires pumping and removing significant amounts of water to sufficiently reduce the hydrostatic pressure in the subsurface, so that methane can desorb from the matrix and diffuse into the cleat systems; majority of the methane molecules gather into nucleation or bubbles. During the depression, the flow pattern of gas in cleats changes from bubble flow to slug flow, and finally forms circular flow. The significance of the bubble flow process—during which the liquid phase is continuous while the gas phase exists as small bubbles randomly distributed within the liquid—has not been emphasised because of its complexity. In this study, a free energy based two-phase lattice Boltzmann model is used to simulate the gas bubble/water flow behaviour in micro-cleats of a coal seam gas reservoir. The model was validated by comparison with analytical results based on dimensionless numbers, and good agreement was found in general. The influences of bubble shape, bubble size, and coal surface wettability on gas water two-phase flow in micro-cleats are discussed. The simulation results indicate that the bubble size and wettability of gas have significant impacts on the flow capacity of both gas and water. A decrease of the water flow rate is observed when large bubbles occur, and the gas flow rate decreases when the gas wettability becomes stronger. The bubble flow process significantly influences the drainage of water and the further gas production.

scholarly journals Studi Kecepatan Aliran Air dengan Menggunakan Tabung Pitot

2018 ◽  
Vol 5 (1) ◽  
pp. 14
Author(s):  
Muhammad Taufik Iqbal ◽  
Zulvyah Faisal
Keyword(s):  
Flow Velocity ◽  
Water Flow ◽  
Flow Rate ◽  
Open Channel ◽  
Flow Analysis ◽  
Distribution Channel ◽  
Research Process ◽  
Flow Speed ◽  
Water Flow Velocity ◽  
Speed Distribution

The tools and methods used in the measurement of water flow velocity are now very diverse, such as by using Venturi Meter, Orifice, Current Meter, Pitot Tube, and so forth. To learn more about water flow velocity measurement method, in order to improve professionalism in the field of water resources can be done research at Hydraulics Laboratory by researching Water Flow Analysis by Using Pitot Tubes. The research process will be carried out using three varied channel basis samples: reviewing the velocity of the water flow at the bottom of the channel with slippery base, reviewing the flow rate of the water on the gravel base channel, and reviewing the flow rate of the water on the channel with the decking concrete base. The expected result of this research is knowing the distribution of velocity in a cross section such as drainage channel, irrigation channel and river, so construction of water structure can be adjusted position placement in the open channel section. In addition it can be used as a reference in planning an open channel. One of the benefits to construction cofferdam construction speed distribution is to determine the dewatering system to be carried out during construction.Keywords— Flow Speed, Speed Distribution. Channel Basic Variations

scholarly journals Study on the Motion Characteristics of Residual Air Mass in Pipelines in Water Transfer Project

2018 ◽  
Vol 246 ◽  
pp. 01113
Author(s):  
Huang Haocheng ◽  
Jiang Jin ◽  
Chen Qi ◽  
Liao Zhifang ◽  
Liu Laiquan
Keyword(s):  
Flow Velocity ◽  
Water Flow ◽  
Flow Rate ◽  
Water Flow Rate ◽  
Water Transfer ◽  
Long Distance ◽  
Water Flow Velocity ◽  
Air Mass ◽  
Motion Characteristics ◽  
Residual Air

For long-distance water transfer projects, the residual air mass in the pipeline will not only reduce the efficiency, but also be detrimental to the safety of the system. In order to study the influence of the water flow velocity of the pressurized water pipeline and the pipeline angle of the hump on the motion characteristics of the residual air mass, an experimental platform with Particle Image Velocimetry (PIV) measuring system was constructed to analyse the flow field. The RSM turbulence model was combined with the VOF multiphase flow model to construct a local high-point gas-liquid two-phase fluid dynamics model for numerical simulation. The results showed that with the increase of water flow velocity, the local hump residual air mass would go through three states, namely, no bubble generation, air bubble was generated and partial discharged, and air mass discharge at one time. If the gas was greater than a certain volume, the increase in the water flow rate required to carry the air mass out of the hump at one time would slow down; the larger the local hump angle was, the greater the water flow rate was required to carry the gas out of the local hump part.

scholarly journals Performance test of Pikohidro Cross flow Water Turbine using multilevel double penstock

Teknomekanik ◽  
2019 ◽  
Vol 2 (2) ◽  
pp. 76-80
Author(s):  
Purwantono Purwantono ◽  
Bahrul Amin ◽  
Abdul Aziz ◽  
Jasman Jasman ◽  
Andre Kurniawan
Keyword(s):  
Water Flow ◽  
Performance Test ◽  
Flow Analysis ◽  
Cross Flow ◽  
Water Velocity ◽  
Small Scale ◽  
Excess Water ◽  
Water Turbine ◽  
The Stability ◽  
Turbine Construction

This study aims to examine the performance of pico hydro scale cross flow water turbines using multilevel double penstock as a conductor of water flow.  Multilevel double penstock is used to reduce the transportation process from highways that are affordable to four-wheeled vehicles / cars to the location of the installation of the turbine.  This condition causes the need for small-scale water turbine designs with lightweight construction with a kock down system.  Overall the picohidro scale turbine construction is needed relatively cheaper transportation costs, so that people who have not been reached by the PLN network can be touched by small and cheap electricity. Turbine construction data has a runner diameter of 170 mm, body dimensions 200 mm x 300 mm x 250 mm, frame 250 mm x 800 mm. Pool tando 600 mm x 1200 mm and penstock length 16m. The power produced is theoretically around 2500 watts, with a data flow of 50 liters / second and a water level of 8 m. 65% efficiency. The research method is analyzing the double penstock water flow, by making paralon pipes in stages, ranging from 5 incci diameter, 4 inches and 3 inches, flow analysis approach using a gradient line, where the incoming water velocity and water velocity come out until entering the transmitting pipe. The performance results of this turbine provide an average actual power of up to 2000 watts. The stability of the inlet water condition is used by the Tando pond as a water bath. If there is excess water in the sediment tank, the water gate is used out, where excess water will automatically flow into the exhaust channel.

scholarly journals Auto-Aspirated DAF Sparger Study on Flow Hydrodynamics, Bubble Generation and Aeration Efficiency

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1498
Author(s):  
Dmitry Vladimirovich Gradov ◽  
Andrey Saren ◽  
Janne Kauppi ◽  
Kari Ullakko ◽  
Tuomas Koiranen
Keyword(s):  
Size Distribution ◽  
Water Flow ◽  
Flow Rate ◽  
Bubble Size ◽  
Transfer Rate ◽  
Pure Water ◽  
Water Flow Rate ◽  
Bubble Size Distribution ◽  
Bubble Generation ◽  
Aeration Efficiency

A novel auto-aspirated sparger is examined experimentally in a closed-loop reactor (CLR) at lab scale using particle image velocimetry, high-speed camera and oxygen mass transfer rate measurements. State-of-the-art 3D printing technology was utilized to develop the sparger design in stainless steel. An insignificant change in the bubble size distribution was observed along the aerated flow, proving the existence of a low coalescence rate in the constraint domain of the CLR pipeline. The studied sparger created macrobubbles evenly dispersed in space. In pure water, the produced bubble size distribution from 190 to 2500 μm is controlled by liquid flow rate. The bubble size dynamics exhibited a power-law function of water flow rate approaching a stable minimum bubble size, which was attributed to the ratio of the fast-growing energy of the bubble surface tension over the kinetic energy of the stream. Potentially, the stream energy can efficiently disperse higher gas flow rates. The oxygen transfer rate was rapid and depended on the water flow rate. The aeration efficiency below 0.4 kW/m3 was superior to the commonly used aerating apparatuses tested at lab scale. The efficient gas dissolution technology has potential in water treatment and carbon capture processes applications.

The Effect of Nozzle Shape and Configuration on Bubble Formation in a Liquid Cross Flow

2012 ◽  
Author(s):  
Mona Hassanzadeh Jobehdar ◽  
Aly H. Gadallah ◽  
Kamran Siddiqui ◽  
Wajid A. Chishty
Keyword(s):  
Liquid Flow ◽  
Bubble Size ◽  
High Speed ◽  
Waste Water Treatment ◽  
Bubble Formation ◽  
Cross Flow ◽  
Bubble Velocity ◽  
Two Dimensional ◽  
Flow Rates ◽  
Nozzle Shape

Gas injection into a liquid cross flow from a nozzle causes bubble formations which have potential applications in industry such as chemical plants, waste water treatment and bio- and nuclear-reactors. The purpose of this study is to experimentally investigate the effects of nozzle shape and configuration with respect to the liquid cross-flow direction, on the bubbly flow characteristics such as bubble formation, detached bubble size and frequency at different gas and liquid flow rates. The experiments were conducted in a Plexiglas two-dimensional rig using a high speed camera. High speed imaging and an image processing algorithm were used to track each individual bubble and to quantify the bubble growth as well as the detachment frequency and the bubble velocity. Back light shadowgraphy which utilizes a low intensity diffuse light source to illuminate the background was used to image bubbles. Nozzles were mounted in the test section which was designed such that the flow in this section has a two-dimensional profile. The results showed that the bubble size increases with an increase in GLR (gas to liquid flow rates ratio). Furthermore, the bubble formations and detached bubble size were strongly influenced by the nozzle shape and configuration.

Numerical study of single bubble rising dynamics using the phase field lattice Boltzmann method

2018 ◽  
Vol 29 (11) ◽  
pp. 1850111 ◽  
Author(s):  
Ting Su ◽  
Yang Li ◽  
Hong Liang ◽  
Jiangrong Xu
Keyword(s):  
Reynolds Number ◽  
Bubble Size ◽  
Lattice Boltzmann ◽  
Viscosity Ratio ◽  
Density Ratio ◽  
Terminal Velocity ◽  
Single Bubble ◽  
Bubble Shape ◽  
Bubble Rising ◽  
Eotvos Number

In this paper, the rising dynamics of a two-dimensional single bubble in the duct is systematically studied by using an improved phase field lattice Boltzmann (LB) multiphase model. This model enables to handle multiphase flows with mass conservation and high density ratio, up to the order of [Formula: see text], which are unavailable in the LB community. The model is first validated by simulating bubble rising problem with the density ratio of 1000 and numerical solutions for bubble shape and position agree well with the previous literature data. Then, it is used to study single bubble rising through a quiescent liquid. The dynamic behavior of the bubble and rising velocity are shown, and the influences of several important physical quantities, including the Eotvos number, Reynolds number, density ratio, viscosity ratio, bubble size and initial bubble shape, are investigated in detail. The numerical results show that the bubble undergoes a great deformation with the increase of the Eotvos number or Reynolds number, and even could break up into multiple satellite bubbles at a sufficiently large value of Eotvos number or Reynolds number. Several classic terminal bubble shapes are also successfully produced in the system. The terminal rising velocity of bubble at equilibrium shows to present an initial increase with the Eotvos number and finally decreases with it, while increasing the Reynolds number could enhance the bubble rising velocity. Both the density ratio and viscosity ratio have less influence on the terminal shape of the bubble, while a greater influence on the rising velocity is reported for the density ratio smaller than 20 and it seems to be independent of the viscosity ratio. At last, we discuss the effects of the bubble size and initial bubble shape. It is found that bubble size has little influence on terminal bubble shape, but decreasing the bubble size can improve the bubble terminal velocity. On the other hand, both the deformation and terminal velocity of the bubble are found to no longer change much with its initial shape.

STUDY OF WATER FLOW RATE IN THE GATES OF HYDROPOWER AND IRRIGATION FACILITIES

2016 ◽  
Vol 6 (2) ◽  
pp. 135-139
Author(s):  
Muradulla M. MUKHAMMADIEV ◽  
Shavkat I. KLYCHEV ◽  
Kurbon S. DZURAEV ◽  
Farkhodzhon E. MADALIEV ◽  
Sulton BEKMURODOV ◽  
...  
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
Average Velocity ◽  
Vertical Section ◽  
Water Flow Rate ◽  
Experimental Studies ◽  
Water Velocity ◽  
Vertical Speed ◽  
Average Water ◽  
Water Rate

The results of the calculated and experimental studies of water velocity distribution in the central vertical crosssection of flow in the plane of the shutter are introduced. Shutter model allowing to investigate the water rate for conventional planar gate and the gate to the guide flap is presented. It is shown that the relative coordinate section characterizing the average water flow rate is not independent on the height of the water level and the shutter opens, but only on their ratio. Experimental graphical dependence of the average velocity of the water in the central vertical section shutter and coordinates of its position are introduced. Experiments showed that the water flow in the gates has a vertical speed component.. The obtained results enable us to develop methods for measuring the water flow in the gate.

Study on Enhancement of Sub-Cooled Flow Boiling Heat Transfer and Critical Heat Flux of Solid-Water Two-Phase Mixture

2002 ◽  
Author(s):  
Yasuo Koizumi ◽  
Tomoyuki Suzuki ◽  
Hiroyasu Ohtake
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Water Flow ◽  
Flow Rate ◽  
Boiling Heat Transfer ◽  
Water Flow Rate ◽  
Flow Region ◽  
High Water ◽  
Water Velocity ◽  
Rate Region

The influence of particle introduction into a subcooled water flow on boiling heat transfer and critical heat flux (CHF) was examined. When the water velocity was low, the particles crowded on the bottom wall of the flow channel and flowed just like sliding on the wall. When the water velocity was high, the particles were well dispersed in the water flow. In the non-boiling region, the heat transfer was augmented by the introduction of the particles into the water flow. As the introduction of the particles were increased, the augmentation was also increased in the high water flow rate region. However, it was independent upon the particle introduction rate in the low water flow rate region. The onset of boiling was delayed by the particle inclusion. The boiling heat transfer was enhanced by the particles. However, it was rather decreased in the high heat flux fully-developed-boiling region. The CHF was decreased by the particle inclusion in the low water flow region and was not affected in the high water flow region.

Radon removal by aeration: observations on testing, installation and maintenance of domestic treatment units

2009 ◽  
Vol 9 (4) ◽  
pp. 469-475
Author(s):  
T. Turtiainen
Keyword(s):  
Water Quality ◽  
Water Flow ◽  
Removal Efficiency ◽  
Flow Rate ◽  
Test Protocol ◽  
Household Water ◽  
Medium Flow ◽  
Removal Efficiencies ◽  
Frequent Sampling

Radon is one of the contaminants that sometimes impair the water quality of wells, especially those drilled in bedrock. Domestic radon removal units based on aeration have been commercially available for more than ten years. In order to determine how effectively these units remove radon a new test protocol applying frequent sampling while letting 100 litres of water flow, was developed. This way, removal efficiencies can be more accurately calculated and possible malfunctions detected. Seven models of domestic aerators designed for removing radon from household water were tested. The aerators were based on diffused bubble aeration, spray aeration or jet aeration. The average removal efficiencies for 100 litres with a medium flow rate were 86–100% except for a unit that circulated the aerated water back to the well that had removal efficiency of 80% at the maximum. By conducting a questionnaire study usual problems related to the aeration units were localized and recommendations on maintenance and installation are given accordingly.

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