• Title, Summary, Keyword: Atomizing particles

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Flying Trajectories of Fine Powder during Centrifugal Atomizing

  • Chonglin, Wang
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • pp.444-445
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    • 2006
  • Flying trajectories of fine particles within a size range of $10{\sim}60{\mu}m$ were studied during centrifugal atomizing processes. A FORTRAN program was written by using increment method. Calculation results revealed that the drag force might reach very high value of 522-7800 g for fine powder of $10{\sim}60{\mu}m$. Flying distance in horizontal direction could be shortened if the particles fly obliquely due to the huge drug force. On the other hand, very fine powder could be projected to far distances when the atmosphere flow velocity is much stronger. Fortunately such particles could be contracted within a cylinder closed to the atomizer when the atmosphere flow was weaken or retained in a limited diameter.

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Compositing Modes and Microstructures of $Cu-X(=Al_2O_3,W)_p$ Composite by Centrifugal Spray-Cast Deposition (원심분사주조법에 의한 $Cu-X(=Al_2O_3,W)_p$ 복합재료의 미세조직 및 복합화)

  • Bae, Cha-Hurn;Jeong, Hae-Yong
    • Journal of Korea Foundry Society
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    • v.17 no.5
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    • pp.480-487
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    • 1997
  • Particle reinforced metal matrix composites(MMCs) via a centrifugal spray-cast deposition(CSD) process were fabricated by injecting second phase particles($Al_2O_3$<40${\mu}m$, W<17.3${\mu}m$) into copper melt on the atomizing disc. Compositing modes were investigated by combining microstructures and mathematical modeling between Cu droplets and the reinforced particles injected. The $Cu/W_P$ powders were shown that the W particles penetrate and get embedded in the Cu droplets. It is considered that the W particles composite preferentially in Cu melt on the atomizing disc. On the other hand, the $Al_2O_3$, particles did not penetrate into the Cu droplets on the atomizing disc but get attached in surface of Cu droplets during the flight. It is considered that the compositing may be attained in the flight distance which the relative velocity between Cu droplet and $Al_2O_3$, particle is maximum. The microstructure of the $Cu/W_P$ and the $Cu/(Al_2O_3)_p$ composite preform was strongly influenced by compositing modes of droplets, and after subsequent deposition it was comprised as it is called the dispersed type and the cell type of microstructure, respectively.

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Pulverized Coal Particle Presence Inside CWM Droplet (CWM 방울안의 미분탄 존재)

  • 김종호;김성준
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.14 no.5
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    • pp.1211-1221
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    • 1990
  • The purpose of this study is to get experimental data on the distribution of CWM (Coal- Water Mixture) droplets size and the presence of pulverized coal particles inside CWM droplets. Atomization of CWM is done by Twin-Fluid Atomizer. The operational parameters are atomizing air pressure, coal particle loading, mean size of pulverized coal particles and sampling positions across spray. Th data analysis is initiated by Impression Sampling Method(Magnesium Oxide Technique) and Photo-technique and counting works are followed. Experimental work induces following research results. The variation of particle loadings in slurry makes no appreciable effects on the mean size of CWM droplets. It is evident that atomizing air pressure has very strong effect on the atomization of slurry. The mean size of atomized fuel droplets is dramatically reduced with the increasing air pressure. The population ratio of droplets without coal particles to total number of droplets is decreased as atomizing air pressure or loading rises and the same trend is obtained as the mean size of coal particles becomes smaller but a certain tendency of coal particle presence inside droplets could not be found from the change of sampling positions.

Coal particle distribution inside fuel droplets of high loading CWM (고부하도 CWM 연료방울안에 존재하는 미분탄 분포)

  • 김성준;유영길
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.15 no.2
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    • pp.618-629
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    • 1991
  • The purpose of this experiment is to understand the distribution of coal particles inside CWM droplet which is believed to be a very important factor controlling the flame stability. CWM slurry is atomized by an air assisted twin fluid nozzle. An experimental rig is designed and fabricated. The mean size of coal particle distribution in CWM slurry, atomizing air pressure, coal particle loading in slurry and sampling position inside spray are main experimental variables. The atomized CWM droplets are sampled on the thin white layer of magnesium oxide by the emergency sampling shutter. The sampled coal particles on magnesium oxide layers are collected into test tubes and dispersed completely by Ultra-Sonicator. The size distribution of coal particles inside droplets are measured by Coulter Counter. The presence of coal particle inside the impressions of droplets on magnesium oxide layer are investigated by photo technique. There are quite many droplets which do not have any coal particles. Those are just water droplets, not CWM droplets. The population ratio of droplets without coal particles to toal number of droplets is strongly affected by the mean size of coal particle distribution in slurry and this ration becomes bigger number as the mean size of coal particles be larger. The size distribution of coal particles inside CWM droplets is not even and depends on the size of droplet. Experimental results show that the larger CWM droplets has droplets has bigger mean value of particle size distribution. This trend becomes more evident as the atomizing air pressure is raised and the mean size of coal particles in CWM slurry is bigger. That is, the distribution of coal particles inside CWM dropolets is very much affected by the atomizing air pressure and the mean size of pulverized coal particles in CWM slurry.

A study on the improvement of coating film characteristic in arc spraying by using the inert gas (아크용사시 불활성가스에 의한 피막밀착강도 향상에 관한 연구)

  • 김영식;여욱종
    • Journal of Welding and Joining
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    • v.5 no.2
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    • pp.17-26
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    • 1987
  • In this study, the experiments were carried out for the purpose of establishment of the arc sparing method which reducing oxides or oxide film by using the inert gas as the carrier gas of atomizing particles. Main results obtained are as follows; 1. Oxides and oxide film which lower the adhesion strength are largely reduced by using the inert gas as the carrier gas of atomizing particles, and adhesion strength of coating film are improved. 2. The coating film characteristics appear to be no difference between the inert gas arc spraying in air environment and that in argon gas environment. 3. Inert gas arc spraying using argon as the carrie gas has higher reduction rate of composition element in coating film than compressed air spraying does.

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Flow and Performance Analysis of Atomizing Nozzle (아토마이징 노즐의 유동 및 성능해석)

  • Kim, Bong-Hwan;Ryu, Kwang-Hyun;Jung, Eun-Ik;Cho, Eun-Man;Lee, Jung-Eun
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.9 no.3
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    • pp.42-48
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    • 2010
  • The aim of this study is to investigate the influence of driving atomizing nozzle position, the slope of sludge entering tube and supplying air flow rate on the performance of sludge air dryer. This paper deals with optimization of the geometry of the atomizing nozzle for sludge drying using computational fluid dynamics and drying performance test using pilot air dryer. The air drying system was composed of the atomizing nozzle which made high-speed fluid field. dewatered cake was crushed at the high-speed zone as the first step and formed intto dried powder of sphere shape by the collision between particles at the circling zone. The CFD analysis results show when the slope of entering sludge tube is smaller, suction air amount is increased. It is shown that the developed atomizing nozzle is very excellent in the drying performance through pilot test.

An experimental study on the atomizing characteristics of liquid column type coaxial sprays (액주형 동축노즐 분무의 무화특성에 관한 실험적 연구)

  • 노병준;강신재;오제하
    • Journal of the korean Society of Automotive Engineers
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    • v.14 no.5
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    • pp.41-53
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    • 1992
  • The main purpose of this study is to investigate the atomizing characteristics of a two phase spray by using a liquid column type coaxial nozzle. The experiments have been carried out to analyze the atomization behavior, the droplet size distributions, and the statistical properties of droplet size distributions. Immersion sampling method and the image processing technique were adapted for the measurements of particles, and the distributions of the droplet sizes were statistically analyzed. In the experiments, the mass ratio defined as Mr= $M_{\sigma}$/ $M_{1}$ has been changed from 1.0 to 3.4 and the measurements have been performed along the axis of the spray. As a result of this experimental study, the distributions of droplet size were satisfied with the Log-Normal distributions and arithmetic mean diameter and deviation of mass ratio. Droplet volume-surface mean diameter was denoted by a exponential function of mass-ratio and the exponent was denoted by linear relation according to the central axis from the nozzle. Dispersions, skewness factors and flatness factors had comparatively constant values regardless of mass ratio and location.

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The Characteristics of an Ultrasonic Sprayer by using Piezoelectric Ceramic Resonator (압전 세라믹 진동자를 이용한 초음파 분무기의 분무 특성)

  • Bae, Sang-Tae;Lee, Su-Ho;Sug, Jeong-Young;Kim, Cheol-Hwan;SaGong, Geon
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.22 no.5
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    • pp.405-410
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    • 2009
  • The conventional ultrasonic nozzle produces a mist by applying an ultrasonic vibration into a non-flowering liquid. In this paper, we first present a novel designed nozzle type sprayer that is able to apply an ultrasonic vibration directly to the moving liquid and generate a mist instantly. For the novel nozzle, a ring-type actuator of the novel nozzle was designed and built using the PZW-PMN-PZT ceramics. This paper will describe a variety of physical, mechanical, and electrical characteristics of the ultrasonic nozzle. The characteristics of the mist particles was also measured as the amount of the outflow liquid was varied.

Development and Performance Evaluation of a Liquid Particle Generator (액적 발생 장치 개발 및 성능 평가)

  • Heo, Jung-Hyuk;Kim, Dae-Seong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.9
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    • pp.4334-4340
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    • 2012
  • In this work, we developed and evaluated the Liquid Particle Generator for generating fine particles in the air. The Liquid Particle Generator, which was based on the spray-evaporation method, had two kinds of orifices: 0.3 mm and 0.5 mm. The Liquid Particle Generator was operated at different pressure between 1 bar and 4 bars to find relationship between input pressure and droplet output rate. In addition, the size distribution of the droplets generated by the Liquid Particle Generator with different orifices was measured by the SMPS system and the optical particle counter. As a result, it was shown that the Liquid Particle Generator with 0.3 mm orifice generated droplets of around 0.3 ${\mu}m$ and atomized particles very stably. The Liquid Particle Generator having 0.5 mm orifice generated bigger droplets, compared with the Liquid Particle Generator with 0.3 mm orifice. Additionally, in these Liquid Particle Generators (0.3 mm and 0.5 mm orifice), little coagulation of particles did occur because of fine droplets atomized by the jet. Therefore, the Liquid Particle Generator could be used as an aerosol generator for atomizing fine particles.

A Study on the Characteristics of Microstructures in the Semi-solid State of Aluminum Powder Alloys (알루미늄 분말 합금의 반응고 미세조직 특성 연구)

  • Lee, Sang-Yong
    • Journal of the Korean Society for Heat Treatment
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    • v.21 no.4
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    • pp.205-212
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    • 2008
  • Characteristics of microstructures, mechanical properties and formability of two Al-20Si-5Fe-2Ni alloys produced by gas atomizing (P/M) and spray forming (S/F) respectively were compared at temperatures up to $560^{\circ}C$. Room temperature hardness values and tensile strengths of both alloys were increased in accordance with temperature after heat treatment above $300^{\circ}C$. The highest values of hardness and tensile strength of both alloys were obtained at $490^{\circ}C$. It was interpreted that increase in hardness and tensile strength according to heating temperature between $300{\sim}490^{\circ}C$ was mainly related to increase in internal stress between Al matrix and reprecipitated particles. S/F alloys showed better formability and wear property than P/M alloys due to the homogenity of microstructures above $300^{\circ}C$.