• Title/Summary/Keyword: Liquid Atomization

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Influence of AC Frequency on the Liquid Breakup in Electrohydrodynamic Atomization (전기수력학적 미립화에서 교류 주파수가 액적 분열에 미치는 영향)

  • Sung, K.A.;Lee, C.S.
    • Journal of ILASS-Korea
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    • v.9 no.2
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    • pp.41-49
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    • 2004
  • Liquid breakup under the variation of AC frequency has been studied experimentally in the electrohydrodynamic atomization. The effect of parameters such as charging voltage, flow rate, nozzle tip inner diameter and power frequency have been considered. This work was performed to investigate the experimental analysis for the effect of AC frequency on breakup process, the mapping of occurrence of disintegration region, and the relationship between the applied power and the droplet radius. The experimental results show that the increase of applied voltage in a certain frequency band leads to a reduction in the droplet size within the limits from 50Hz to 400Hz. The transition phenomena from dripping mode to spindle mode were observed under the band of sudden fall of droplet radius changing ratio, and the synchronous region were produced within the range of applied voltage from 5kV to 6kV.

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Spray characteristics of twin-fluid atomization using external-mixing sonic nozzles (외부혼합형 음속노즐을 사용한 2유체 미립화의 분무특성)

  • Park, Byeong-Gyu;Lee, Jun-Sik
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.21 no.1
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    • pp.132-139
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    • 1997
  • Spray characteristics of external mixing sonic twin-fluid atomization nozzles are investigated experimentally. Particle sizes are measured by the Fraunhofer diffraction method using the Malvern particle analyzer, and their radial distributions are obtained using the tomographical transformation technique. The spatial distribution of SMD shows that the drop size increases in the radial direction at a fixed liquid flow rate, and the distribution is getting uniform rapidly as the atomizing gas pressure increases. The SMD decreases as the liquid flow rate increases at a fixed GLR. It is found that the atomization efficiency of the flush type sonic nozzle is superior to that of protrusion type. The effect of laser beam diameter of the particle analyzer on the spatial SMD distribution is minor at present experimental conditions.

Spray and Atomization Technologies in Pesticides Application: A Review

  • No, Soo-Young
    • Journal of ILASS-Korea
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    • v.6 no.4
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    • pp.1-13
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    • 2001
  • In the pesticides sprays, spray and atomization technologies to increase the deposition and reduce the drift are briefly reviewed. Further research is needed to deduce a measure of drift risk in sprays with different structures, velocity profiles. For flat fan nozzles, the data of breakup length and thickness of liquid sheet are essential to understand the atomization processes and develop the transport model to target. In the air-assisted spray technology to reduce drift, further works on the effect of application height on drift and air assistance on droplet size should be followed. In addition, methods for quantifying included air in the air inclusion techniques are required. A few researches on the droplet size of fallout can be found in the literature. A combined technology with electrostatic method into one of method for the reduction of drift may be an effective strategy for increasing deposition and reducing drift.

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An Experimental Study on the Electrohydrodynamic Atomization of Conducting Liquid Using the AC High Voltages (교류 고전압을 이용한 대전액체의 전기수력학적 미립화에 관한 실험적 연구)

  • Sung, K.A.
    • Journal of ILASS-Korea
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    • v.13 no.2
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    • pp.73-78
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    • 2008
  • An experimental study was performed to explore the drop formation and atomization characteristics in electrohydrodynarnic atomization with flow rate, power supply, voltage frequency, and nozzle size. A basic electrohydrodynarnic atomizer equipment was developed for the analysis of spray visualization and tested for the exploration of relationship between several experimental parameters. In results, the varicose wave had been taken place and the small droplets had been generated less than outer diameter of nozzle on the conditions of 25G of nozzle, flow rate of 2 mL/min, and applied frequency of 50kV at AC power over 5kV voltage. The whipping motion had been grown at applied frequency of 400kV and AC power around 2kV voltage

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Spray Characterization and Flow Visualization of the Supersonic Liquid Jet by a Projectile Impingement (발사체 충돌에 의한 초음속 액체 제트의 분사 특성 및 유동 가시화)

  • Shin, Jeung-Hwan;Lee, In-Chul;Koo, Ja-Ye;Kim, Heuy-Dong
    • Journal of the Korean Society of Visualization
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    • v.9 no.2
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    • pp.27-33
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    • 2011
  • Supersonic liquid jet discharged from a nozzle has been investigated by using a ballistic range which is composed of high-pressure tube, pump tube, launch tube and liquid storage nozzle. High-speed Schlieren optical method was used to visualize the supersonic liquid jet flow field containing shock wave system, and spray droplet diameter was measured by the laser diffraction method. Experiment was performed with various types of nozzle to investigate the major characteristics of the supersonic liquid jet operating at the range of total pressure of 0.8 from 2.14 GPa. The results obtained shows that shock wave considerably affects the detailed atomization process of the liquid jet and as the nozzle diameter decreases, the shock wave angle and the averaged SMD of spray droplet tends to decrease.

Generation of uniform Fine Droplets Under Spindle Mode in Electrohydrodynamic Atomization (스핀들 모드하의 전기수력학적 미립화를 통한 균일 미세액적 생성)

  • Lee, Sang-Yong;Kim, Myeong-Chan;Kim, Sang-Su;Kim, Yu-Dong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.25 no.7
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    • pp.923-932
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    • 2001
  • A series of experiments were conducted to generate fine liquid(water) drops through the electrohydrodynamic atomization process. The atomization mode depended on flow rate and DC voltage input. For water, having electric conductivity larger than 10(sup)-7S/m, the spindle mode turned out to be the only mode to generate uniform-size drops within the range of 30-450 microns that have wide applications. Within this mode, both the uniformity and the fineness of drops were improved at an optimum voltage input for a given flow rate. This optimum voltage increased with increasing of the liquid flow rate. Another important parameter considered was the nozzle material with different electric conductivity and liquid wettability. A stainless-steel nozzle (the material with high electric conductivity and high liquid wettability) and a silica nozzle (the electrically non-conducting material with low liquid wettability) were tested and compared; and more uniform drops could be obtained with the silica nozzle.

SPH Code Development and Validation for Numerical Simulation of Liquid-Liquid Swirl Coaxial Injector (액체-액체 동축형 스월 인젝터의 수치적 모사를 위한 SPH 코드 개발 및 검증)

  • Kim, You-Cheon;Sirotkin, Fedir V.;Yoh, Jai-Ick
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.43 no.1
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    • pp.8-22
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    • 2015
  • Most jet spray and atomization simulations are done with the Eulerian method which has inherent disadvantage in representing jet breakups and droplets. Full Lagrangian particles method called Smoothed Particle Hydrodynamics(SPH) is used in this work. We develop the SPH code and perform validations that confirm the suitability of our SPH method for simulating liquid jet atomization problem. Then, we conduct the simulation of liquid-liquid swirl coaxial injector for comparison against the experimental data.

An Experimental Study on the Effect of Electrohydrodynamic Monodisperse Atomization According to Nozzle Characteristics (노즐 특성에 따른 전기수력학적 단분산 미립화 효과에 관한 실험적 연구)

  • Sung, K.A.;Lee, C.S.
    • Journal of ILASS-Korea
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    • v.10 no.2
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    • pp.18-31
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    • 2005
  • This study was performed to explore the liquid breakup and atomization characteristics for the classification of drop formation mode and background of uniform droplets generation in electrohydrodynmaic atomization according to the change of experimental parameters such as nozzle material (stainless steel. teflon). fluid flow rate, applied electrical field and intensity, and frequency. In results, from the classification map of drop formation modes according to the variation of applied AC voltage and frequency at a stainless nozzle, the droplet size was smaller than the outer diameter of the nozzle tip relatively in the spindle mode. The transition points became clearly to be moved toward the high applied voltage by rising the applied AC frequency beyond 450Hz. Also the droplet radius can be observed quite small in the frequency bandwidth of $350{\sim}450Hz$. The droplet radiuses decrease as the applied voltage increases for a fixed applied AC frequency within the range from 50Hz to 400Hz Over 400Hz, the relation between the power intensity and the droplet size was not consistent with a continuous mechanism of liquid breakup. Thus, it is showed that the droplet size distribution using the teflon nozzle was analogous to the results of stainless steel, but the droplet size was bigger than that of stainless steel relatively in case of a teflon nozzle.

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Spray Characteristics for Recess Length in a Swirl Coaxial Injector to use GCH4/LOx (가스메탄/액체산소를 추진제로 하는 스월 동축형 인젝터의 리세스 길이에 따른 분무특성)

  • Min, Ji-Hong;Lee, Yang-Suk;Ko, Young-Sung;Kim, Sun-Jin;Kim, Yoo
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2011.04a
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    • pp.20-23
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    • 2011
  • The spray and atomization characteristics of swirl coaxial injectors which use gas methane and LOx as propellants are investigated experimentally with a recess length variation. Mass distribution and spray angle are measured by a patternator and droplet size to find atomization characteristics are measured by GSV(Global Size and Velocity) system. As a result, when the liquid sprayed, the spray angle decreased and the atomization characteristic was improved with the recess length increase. When the gas and liquid injected simultaneously, the spray angle was decreased and the atomization characteristic was improved comparing to only the liquid injection.

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Analysis of spray cone angle of air assisted flash atomization (공기보조식 (air-assisted) 플래쉬 분무의 분무 각 확대 특성 연구)

  • Yu, Tae-U;Kim, Sae-Won;Bang, Byong-Ryeol
    • Journal of ILASS-Korea
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    • v.10 no.1
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    • pp.1-9
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    • 2005
  • When the water jets heated up to the saturation temperature at a high line pressure are sprayed into a reduced (atmospheric) pressure through an air-assisted nozzle, the jets experience sudden exposure into a reduced pressure, get superheated and produce steam bubbles while atomization processes of jets are taking place. This process is called flash atomization. In this study the flash atomization of superheated water jets assisted by air has been studied. Sprays with flash atomization have been photographed at various water and air flow rates and water superheats. It has been found that the spray angle with flash atomization increases with water superheat and water flow rate but decreases with air flow rate. The degree of change of spray angle has been analyzed and correlated as a function of superheat, air and water flow rates.

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