• Title/Summary/Keyword: Air Bubble

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Comparison of Dissolved Air and Micro-Bubble Concentration by a Micro-Bubble Generating Pump (미세기포 발생 펌프에서 생성되는 기포농도와 용존공기농도의 비교)

  • Lee, Chang-Han;Ahn, Kab-Hwan
    • Journal of Environmental Science International
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    • v.23 no.11
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    • pp.1835-1842
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    • 2014
  • The goal of this study was to evaluate micro-bubble concentration ($C_{air}$) in water by air/water ratio (A/W ratio) with a micro-bubble generating pump. The estimation of micro-bubble concentration is based on the balance of inlet/outlet air and water flow rate. On net A/W ratio to be generated micro-bubble, we found that the obtained the $C_{air}$ are shown as a function of discharge pressure ($P_g$) of the micro-bubble generating pump. The correlation of the $C_{air}$ and the $P_g$ ($C_{air}=3.261P_g-1.754$) was adequately described by the least square methods with a high correlation coefficient (r = 0.9459) and calculated values fit the experimental data quite well. The $C_{air}$ was lower than theoretical dissolved air concentration ($C_{aq}$) calculated by Henry's law. The $C_{air}$ for being operated the micro-bubble generating pump was 6.75 - 39.53 mL/L, however, we found that the optimum of the $C_{air}$ to generate micro-bubble was the range from 10 to 12 mL/L.

Prediction of Micro-Bubble Releasing Concentration with the Retention Time of a Micro-Bubble Generating Pump (미세기포 발생펌프 내 체류시간에 따른 미세기포의 발생 농도 예측)

  • Ambrosia, Matthew Stanley;Lee, Chang-Han
    • Journal of Environmental Science International
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    • v.25 no.6
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    • pp.829-837
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    • 2016
  • The mechanism of micro-bubble generation with a pump is not clarified yet, so the design of water treatment systems with a micro-bubble generating pump is based on trial and error methods. This study tried to explain clearly quantitative relationships of experimental micro-bubble concentration ($C_{air}$) of continuous operation tests with a micro-bubble generating pump and theoretical air solubility. Operation parameters for the tests were discharge pressure ($P_g$), water ($Q_{w0}$) and air ($q_0$) flow rates, orifice diameter ($D_o$), and retention time (t). The experimental micro-bubble concentrations ($C_{air}$) at 4.8 atm of discharge pressure ($P_g$) were in the range of 21.04 to 25.29 mL/L. When the retention time (t) by changing the pipe line length ($L_p$) increased from 1.22 to 6.77s, the experimental micro-bubble concentrations ($C_{air}$) increased from 25.86 to 30.78 mL air/L water linearly. The dissolved and dispersed micro-bubble concentrations ($C_{air}$) are approximately 4 times more than the theoretical air solubility.

Acoustic insertion loss by a bubble layer for the application to air bubble curtain and air masker (기포층 음향 삽입손실 연구: 기포커튼과 에어마스커)

  • Park, Cheolsoo;Jeong, So Won;Kim, Gun Do;Moon, Ilsung;Yim, Geuntae
    • The Journal of the Acoustical Society of Korea
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    • v.39 no.4
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    • pp.227-236
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    • 2020
  • This paper derives the insertion loss for the bubble layer of an air bubble curtain and an air masker which are used to reduce ocean anthropogenic noise such as the piling noise and the ship noise. The air bubble curtain is considered as a 'fluid-air bubble layer-fluid' model and the environment for the air masker is simplified as an 'vacuum-thin plate-fluid-air bubble layer-fluid' model. The air bubble layer in each model is assumed as the effective medium which has the complex wavenumber and the complex impedance corresponding to the bubble population distribution. The numerical simulations are performed to examine the insertion loss depending on the bubble population, the void fraction, and the thickness of the layer.

A Study on Bubble Behavior Generated by an Air-driven Ejector for ABB (Air Bubble Barrier) (II): Comparison of Bubble Behavior with and without Ejector (공기구동 이젝터를 이용한 ABB (Air Bubble Barrier)의 기포거동 특성 연구 (II): 기포거동 특성의 비교 분석)

  • Seo, Hyunduk;Aliyu, Aliyu Musa;Kim, Hyogeum;Kim, Kyung Chun
    • Journal of the Korean Society of Visualization
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    • v.15 no.2
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    • pp.59-67
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    • 2017
  • To verify floatability of ABB (Air bubble barrier), we compared bubble swarm behavior with and without the air-driven ejector. Experiment was conducted using the fabricated air-driven ejector with 5 mm nozzle on the bottom of 1 m3 water tank. Reynolds number of air in the nozzle was ranged 1766-13248. We analyzed data with statistical method using image processing, particle mage velocimetry (PIV) and proper orthogonal decomposition (POD) analysis. As a result of POD analysis, there was no significant eigenmode in bubbly flow generated from the ejector. It means that more complex turbulent flows were formed by the ejector, thereby (1) making bubbles finer, (2) promoting three-dimensional energy transfer between bubble and water, and (3) making evenly distributed velocity profile of water. It is concluded that the air-driven ejector could enhance the performance of ABB.

Noise Reduction Effect of an Air Bubble Layer on an Infinite Flat Plate (무한 평판 주위에 형성된 수중 기포층의 방사소음 감소 효과)

  • Kim, Jong-Chul;Oh, Joon-Seok;Cho, Dae-Seung
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.17 no.2 s.119
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    • pp.168-176
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    • 2007
  • The mixture sound speed in bubbly fluids is highly dispersive due to differences of the density and compressibility between bubbles and fluids. The dispersion range in bubbly fluids expands to a higher frequency than the resonance frequency of an air bubble. A theoretical model was developed to compute the reduction of radiation noise that is generated by a force applied on an infinite flat plate using a bubble layer as a compliant baffle. For evaluating the effectiveness of a bubble layer in reducing the structure-borne noise of an infinite elastic plate, the noise reduction levels for various parameters such as the thickness of bubble layers, the volume fractions and the distribution types of bubbly fluids are calculated numerically. The noise reduction effect of an air bubble layer on an infinite flat plate is considerable level and similar to the tendency of dispersion of bubbly fluids. It is recommended that the thickness of a bubble layer should be increased with keeping an appropriate volume fraction of an air bubble for the most effective reduction of the radiation noise.

A Study on Bubble Behavior Generated by an Air-driven Ejector for ABB (Air Bubble Barrier) (I): Development of Image Processing Method and Statistical Analysis (공기구동 이젝터를 이용한 ABB (Air Bubble Barrier)의 기포거동 특성 연구 (I): 영상처리 및 통계적분석방법 개발)

  • Seo, Hyunduk;Aliyu, Aliyu Musa;Kim, Minkyun;Kim, Kyung Chun
    • Journal of the Korean Society of Visualization
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    • v.15 no.2
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    • pp.48-58
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    • 2017
  • To analyze bubbles generated by an ABB (Air Bubble Barrier), we developed image processing procedure and statistical analysis method. Air was discharged from 5 mm nozzle as swarm form at the bottom of 1 m3 water tank. Flow rates of discharged air are ranged from 2 L/min to 20 L/min and these are corresponding to Reynolds number of 1766-17663. Rise velocity of bubble is extracted by using image process pretending intrusive method. Mean equivalent velocity was calculated using void fraction weighting factor. Bubble diameter is obtained and compared with correlations in the literature. Also, we present a correlation according to the result of this study. Mean velocity and mean diameter of bubbles increase with increasing gas Reynolds number. But these parameters show an asymptotic trend when they approach to high Reynolds number.

Flow Visualization of Bubble Jet Loop Heat Pipe (Bubble Jet Loop Heat Pipe의 유동 가시화)

  • Lee, Hyun-Jik;Kong, Sang-Woon;Ha, Soo-Jung;Hwang, Jong-Ho;Jang, Jeong-Wan;Son, Kil-Jae;Kim, Jong-Soo
    • Proceedings of the SAREK Conference
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    • 2009.06a
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    • pp.279-283
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    • 2009
  • Bubble jet loop heat pipe is what heat pipe operate in the horizontality. It is consist of one heating part creating bubble and one rounded U tube type radiator. This study shows whether the heat pipe operates well in the horizontality or not, and what optimized refrigerant charging rate is in the tube. But flow visualization of bubble jet heat pipe was not known. The purpose of this study is to visualize bubble jet loop heat pipe. The experiment was performed by changes of charging rate. Working fluid was R-141b. And heater of 220 V & 100 W was used. we take a photograph of flow visualization of bubble jet loop heat pipe in slow motion.

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Flow visualizations and analysis on characteristics of bubbly flows exhausted from a venturi-type bubble generator with an air vent (공기유입구를 가진 벤츄리 형상의 기포발생기에서 토출되는 기포 유동 특성의 가시화 측정 분석)

  • Bae, Hyunwoo;Lee, Seungmin;Song, Moonsoo;Sung, Jaeyong
    • Journal of the Korean Society of Visualization
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    • v.17 no.1
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    • pp.60-68
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    • 2019
  • Flow visualizations have been carried out to analyze the characteristics of bubby flows exhausted from a venturi-type bubble generator with an air vent. For various design parameters and operating conditions of the bubble generator, the images of bubbly flows was recorded using a high-speed camera and a microscope. Then the amount and size distribution of bubble was evaluated by an image processing technique. The results show that for increasing the amount of bubble, it is more effective to reduce the venturi throat than to enlarge the air vent diameter. If the water flow rate increases, the bubble generation rate increases but reaches a status of saturation, whose condition depends on Reynolds number at a given air vent diameter. The bubble size increases as the diameter of venturi throat decreases and Reynolds number increases. However, the air vent diameter is not a significant factor on bubble size.

Experimental study to minimize the air bubble during the imprinting process in UV nanoimprint lithography (UV nano imprint 공정에서 air bubble area 최소화에 대한 연구)

  • Choi, Seung-Woong;Lee, Dong-Eon;Lee, Woo-Il
    • Proceedings of the KSME Conference
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    • 2008.11a
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    • pp.1934-1938
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    • 2008
  • Formation of air bubble is the one of common defects in UV nano imprint lithography. Location of dispensing and volume of droplets are among the most important parameters in the process. ]n this study, UV curable resin droplets with different volumes were dispensed at different locations and pressed to investigate air bubble formation. By varying volume of droplet and dispensing location, process conditions were found for minimum air bubble area.

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Interaction between a rising toroidal bubble and a free surface (상승하는 원환형 기포와 자유수면의 상호작용)

  • Moon, Eunseong;Kim, Daegyoum
    • Journal of the Korean Society of Visualization
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    • v.20 no.2
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    • pp.55-62
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    • 2022
  • We experimentally investigate a rising toroidal bubble impacting a free surface. The toroidal bubble is created by releasing pulsed air. By adjusting the volume and circulation of the toroidal bubble, the characteristics of interactions between the toroidal bubble and the free surface are identified. Because of the impact by the toroidal bubble, the free surface is convexly deformed upwards above the center point of the toroidal bubble, while the edge of the deformed free surface is pulled down. When the circulation of the bubble becomes stronger, the surface which was pulled down breaks eventually, and air above the free surface is entrained into water, forming an unstable toroidal bubble. The deformations at the center and edge of the free surface are in a linear relationship with the Froude number and the Weber number, respectively.