• Title/Summary/Keyword: Atomizer

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Numerical Study on the Atomization Process of a Supersonic Gas-Metallic Liquid Atomizer (초음속기체-금속액체 분사기의 미립화 과정에 대한 수치해석)

  • Hwang, Won-Sub;Kim, Kui-Soon;Choi, Jeong-Yeol
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.44 no.7
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    • pp.593-602
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    • 2016
  • Numerical simulations on the close-coupled supersonic gas atomizer for metallic powder production were performed in this study. A proper turbulence model was chosen and then VOF(Volume of Fluid) and DPM(Discrete Phase Model) methods were sequentially applied for the simulations of primary and secondary break-up processes of liquid metal. Diameters of parent droplets were calculated by analyzing Level-Set function contour from the VOF result. Finally, the distribution of particle diameter was obtained from the DPM result at exit of the computational domain.

The change of spray characteristics on hydraulic acoustic wave influence and prediction of low combustion instability (수력파동에 의한 분무변화 및 저주파 연소불안정에의 영향 예측)

  • Kim, Tae-Kyun;Lee, Sang-Seung;Yoon, Woong-Sup
    • 한국연소학회:학술대회논문집
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    • 2004.11a
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    • pp.152-160
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    • 2004
  • Studies to investigate the influence on hydraulic acoustic wave were conducted using pressure swirl atomizer under making frequency range from 0 to 60Hz using water as a propellant. Pressure oscillation from hydraulic sources gives a strong influences on atomization and mixing processes. The ability to drive these low frequency pressure oscillations makes spray characteristics changeable. The effect of pressure perturbation and its spray characteristics showed that low injector pressure with pressure pulsation gives more significantly than high injector pressure with pressure perturbation in SMD, spray cone angle, breakup length. Moreover, this data could be used for prediction of low combustion instability getting G factor.

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The Effect of Water Droplets on the Nano Particle Size Distribution using the SMPS System (SMPS 시스템에서 용매(물)가 나노입도측정결과에 미치는 영향)

  • Hwangbo, Seon-Ae;Chu, Min-Cheol
    • Journal of Powder Materials
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    • v.20 no.2
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    • pp.129-133
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    • 2013
  • In this paper we have studied the effect of water droplet size on nano-particle size distribution using SMPS(Scanning Mobility Particle Sizer)system. It can be seen that the unknown peak at >100 nm was caused by water droplets which did not dry completely when DI water was used as a solvent in the SMPS system. Therefore, it is important to dry water droplets generated from atomizer in the SMPS system when measuring the particle size distribution using less than 100 nm nano-particles in diameter. From this study, It can be concluded that the napion was a useful material as dryer ones and using EAG(Electro Aerosol Generator) as a particle generator was the most effective in reducing the effect of water droplets.

The improvement of surface roughness of cast-iron pipe (주철관의 표면조도 개선)

  • Park, Seong-Yoo;Park, Myung-Ho;Kim, Sung-Joon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.21 no.9
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    • pp.1491-1497
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    • 1997
  • The purpose of this research is to improve the surface roughness of cast-iron pipe porduced by the centrifugal casting. A twin-fluid atomizer of mold-wash slurry is designed for this project. New atomizer is equipped with the existing manufacturing facility to produce pipes. Cast-iron pipes (.cent.125*L3000mm) are produced and the surface roughnesses of those are analysed by UBM. The average surface roughness of new products is 6.7.mu.m while the old products of sand-resin coating method have 17.0.mu.m of average surface roughness. The surface roughness of cast-iron pipe is improved very much than before.

A Study on the Prediction of the Drop Size Distribution of Pressure-Swirl Atomizer (압력식 스월 노즐의 액적 크기분포 예측에 관한 연구)

  • Cho, D.J.;Yoon, S.J.;Kim, D.W.
    • Journal of ILASS-Korea
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    • v.1 no.1
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    • pp.44-54
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    • 1996
  • A theoretical and experimental study was carried out on the prediction of drop size distribution of the pressure swirl atomizer. Drop size distribution was obtained by using maximum entropy formal ism. Several constraints in the form of the definition of mean diameter were used in this formulation in order to avoid the difficulties of the estimating source terms. In this study $D_{10}$ was only introduced into the formulation as a constraint. A drop size obtained by using linear Kelvin-Helmholtz instability theory was considered as an unknown characteristic length scale. As a result, the calculated drop size was agreed well with measured mean diameter, particularly with $D_{32}$. The predicted drop size distribution was agreed welt with experimental data measured wi th Malvern 2600.

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Atomization Characteristics of Coal-Water Mixture Fuel (석탄-물 혼합연료(CWM)의 분무 특성)

  • 노남선;신대현;김광호
    • Journal of Energy Engineering
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    • v.3 no.2
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    • pp.130-150
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    • 1994
  • Coal-water mixture(CWM) fuel has attracted much attention as a substitute fuel for oil by which high economics and short-term commercialization might be realized in comparison with other coal conversion technologies. There are many factors that affect the CWM combustibility, such as the physical properties of CWM, the performance of atomizer and burner, operating conditions, capacity and load of the boiler, etc. Particularly, atomization quality is extremely critical to achieving acceptable carbon conversion efficiency of CWM fuel and maintaining the flame stability, because the coal particles in the CWM droplets burn as agglomerates. This paper presents the R&D results about the CWM atomization characteristics, including the significance of CWM atomization the R&D results about the CWM atomization characteristics, including the significance of CWM atomization quality, the atomization and combustion mechanism, the type of CWM atomizer, size and size distribution of CWM droplets and some factors that influence the atomization performance.

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Lead Determinaiton in $25{\mu}l$ Whole Blood Sample by Atomic Absorption Spectrophotometer with Furnace Atomizer (Furnace Atomizer를 이용(利用)한 미량혈액중(微量血液中) Pb검출(檢出)에 관(關)한 연구(硏究))

  • Kim, Hyung-Suk;Park, Yang-Won;Koo, Do-Seu
    • Journal of Preventive Medicine and Public Health
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    • v.15 no.1
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    • pp.111-114
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    • 1982
  • To determine Pb level in blood, we usually .used to pull out about 5ml blood from venous vessel and this sample was digested with acids to decompose organic matter and then determined the Pb contents by Atomic Absorption Spectrophotometer with flame. But recent trend in quan titating Pb in small amount of sample is very much recommended in clinical chemistry specially pediatrics, and industrial hygiene and occupational health area. Authors tried to determine Pb contents in small amount blood of $25{\mu}l$ by using capillary tube method and got the possibility of determination of ng amount of Pb in $25{\mu}l$ whole blood sample without any pretreatment of sample.

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Numerical Analysis of Gas Atomizer Flow using the Compressible Navier-Stokes Equations (압축성 Navier-Stokes 방정식을 이용한 가스 분무기 유동의 수치적 해석)

  • 윤병국
    • Journal of Powder Materials
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    • v.2 no.2
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    • pp.120-134
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    • 1995
  • The behavior of the flow about gas atomizers with a supersonic nozzle containing an under-expanded or over-expanded jet is very important with respect to performance and stability characteristics. Since detailed experiments are expensive, computational fluid mechanics have been applied recently to various relating flow field. In this study, a higher order upwind method with the 3rd order MUSCL type TVD scheme is used to solve the full Reynolds Wavier-Stokes equations. To delineate the purely exhaust jet effects, the melt flow is not considered. Comparison is made with some experimental data in terms of density fields. The influence of the exhaust-jet-to freestream pressure ratio and the effect of the protrusion length of the melt orifice are studied. The present study leads us to believe that the computational fluid mechanics should be considered as powerful tool in predicting the gas atomizer flows.

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A Study on the Characteristics of an Oscillating Fluidic Atomizer

  • Kim, K.H.;Kiger, K.;Lee, W.
    • Journal of ILASS-Korea
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    • v.11 no.2
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    • pp.105-112
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    • 2006
  • A unique feature of fluidic atomizers is that the nozzle geometry produces a thin capillary Jet which is forced to oscillate on a 2-dimensional plane through the use of a passive feedback mechanism. The objective of the current work is to characterize the influence of the stagnation pressure at the nozzle exit, jet oscillation and stretching on the breakup properties of the capillary ligament. To achieve this, shadow graph technique is used to measure size, shape, velocity and the number density of the droplets as a function of the position within the spray fan. The breakup length, defined as the radial distance from the breakup point, is analyzed as a function of the non-dimensional parameters. Finally, a kinematic model is developed to simulate the breakup of the oscillating jets at low stagnation pressures. Using the existing jet breakup theories, the model is used to predict the size and diameter distribution of the droplets after primary atomization.

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A numerical analysis and experimental study on the prediction of spray characteristics (분무특성 예측을 위한 이론적 접근과 실험적 연구)

  • Yoon, S.J.;Cho, D.J.
    • Journal of ILASS-Korea
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    • v.3 no.2
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    • pp.1-13
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    • 1998
  • A theoretical and experimental study was carried out to predict the drop size distribution of the pressure swirl atomizer. Various analytical methods using the Kelvin-Helmholtz instability theory were tried to examine the wave growth on cylindrical liquid sheets. Cylinderical liquid sheets were extended to the case with the conical sheets. Perturbations due to tangential motion as well as longitudinal one were taken into account. And it was assumed that the breakup occurs when amplitude ratio exceeds exp(12), drop sizes were predicted only by theoretical approach. Drop size distribution was obtained by using maximum entropy formalism. Seven constraints in the form of the definition of mean diameter were used in this formulation in order to avoid the difficulties of estimating source terms. In this study $D_{10}$ only was introduced into the formulation as a constraint. The predicted drop size and drop size distribution agreed well with the measured data.

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