• Title, Summary, Keyword: Droplet size

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The Droplet Size Distribution of Fan Spray at Different Surrounding Conditions (팬형분무의 주변조건에 따른 입자분포 변화)

  • Moon, Seok-Su;Choi, Jae-Joon;Bae, Choong-Sik
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.31 no.7
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    • pp.611-619
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    • 2007
  • In this study, the droplet size distribution of a slit injector at different surrounding conditions, such as air flow and fuel temperature, were investigated. Phase Doppler anemometry (PDA) was utilized to investigate the initial droplet size distribution and the effect of fuel temperature and air flow on droplet size distribution. The entrained air motion was also evaluated by the temporal velocity profile of droplets. When the air flow velocity increased, the small droplets were more entrained to the upper and central parts of the spray and this tendency was confirmed by plotting the temporal velocity profile of droplets. This entrainment of small droplets at high airflow velocities caused relatively small mean droplet size at upper and central parts of the spray and the large mean droplet size at downstream and edge of the spray, compared to that of low airflow velocities. The total mean droplet size, obtained by averaging the size of all droplets measured at all test locations, decreased when the high airflow velocities were applied. The increased fuel temperature, with an airflow velocity of 10m/s, caused reduced droplet size at all test locations. However, the decreased value of mean droplet size at high fuel temperatures was relatively higher at upper parts of the spray, compared to downstream, as a result of enhanced entrainment of small droplets to upper parts of the spray.

Droplet Size Distribution Effect on the Electro-Optical Properties of Emulsion Type Polymer Dispersed Liquid Crystal (에멀전 방식의 고분자 분산형 액정의 전기 광학 특성에 미치는 액적 크기 분포의 영향)

  • Yoo, Hee Sang;Oh, Nam-Seok;Yan, Jin;Kwon, Soon-Bum
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.28 no.7
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    • pp.439-445
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    • 2015
  • We established the emulsion method using membrane filter with precise control of LC droplet distribution in PDLC. PDLC cells with various LC droplet size distributions such as single droplet sizes of $1.0{\mu}m$, $1.9{\mu}m$ and $3.5{\mu}m$, the mixture of two different LC droplet sizes and the mixture of three different LC droplet sizes were fabricated and the electro-optical properties of the emulsion type PDLC cells with various droplet size distribution were investigated. In the appropriate droplet size range, the PDLCs with the single droplet sizes distributions have good electro optical properties than those with the mixture of three different LC droplet sizes. In addition, the PDLC cells with the mixture of two different LC droplet sizes have the better electro optical properties than those with single droplet sizes distribution. The PDLC cell with dual droplet size distribution of $1.0+1.9{\mu}m$ shown the best electro optical properties than the PDLC cells with other size distributions. This method enabled us to find the proper LC droplet size distribution for achieving both high transmittance and contrast ratio.

Wall Impingement Behavior and Droplet Size Measurement in Diesel Spray (디젤분무의 벽면충돌거동 및 분무입경측정)

  • 이장희;김태권;최인수
    • Transactions of the Korean Society of Automotive Engineers
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    • v.2 no.4
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    • pp.39-49
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    • 1994
  • An experimental investigation was undertaken in a diesel spray to evaluate wall impingement behavior and droplet size distribution. Emphasis is placed on the possibility of the application for new combustion type which is based on OSKA-D type. Visualization were employed using optical scheme which was a spark shadowgraphy to observe the behavior of wall impingement caused by diesel spray vertically injected at the center of the combustion chamber. Droplet size measurements using Malvern system were made to quantify the visual observations with surface diameter of impingement. The effects of the surface dia. variation on the droplet size during injection with the wall impingement spray are discussed. It was found that for the wall impingement spray the droplet size becomes greatly small rather than the spray without the wall impingement and the droplet deposition rate of the injection fuel is decreased as the surface area of impingement becomes small.

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Droplet size measurement using image processing method (이미지프로세싱 기법을 이용한 액적크기 측정)

  • Lim Byoungjik;Jung Kihoon;Khil Taeock;Yoon Youngbin
    • Journal of the Korean Society of Visualization
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    • v.2 no.1
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    • pp.25-31
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    • 2004
  • Droplet size is one of the most important parameter which controls the performance of the combustion system using liquid fuel or oxidizer. Droplet formation and its size are mainly affected by the injection velocity and ambient gas density. Recently, droplet size measurement was conducted by PDPA or Malvern particle analyzer using laser light. But at this paper image processing method was developed to measure droplet size. And its validation was investigated with reticle.

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Droplet size prediction model based on the upper limit log-normal distribution function in venturi scrubber

  • Lee, Sang Won;No, Hee Cheon
    • Nuclear Engineering and Technology
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    • v.51 no.5
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    • pp.1261-1271
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    • 2019
  • Droplet size and distribution are important parameters determining venturi scrubber performance. In this paper, we proposed physical models for a maximum stable droplet size prediction and upper limit log-normal (ULLN) distribution parameters. For the proposed maximum stable droplet size prediction model, a Eulerian-Lagrangian framework and a Reitz-Diwakar breakup model are solved simultaneously using CFD calculations to reflect the effect of multistage breakup and droplet acceleration. Then, two ULLN distribution parameters are suggested through best fitting the previously published experimental data. Results show that the proposed approach provides better predictions of maximum stable droplet diameter and Sauter mean diameter compared to existing simple empirical correlations including Boll, Nukiyama and Tanasawa. For more practical purpose, we developed the simple, one dimensional (1-D) calculation of Sauter mean diameter.

Spray Characteristics of Fuel Injector in DI Diesel Engine (직접 분사식 디젤 기관 인젝터의 연료 분무 특성)

  • 이창식;김민규;전원식;진다시앙
    • Transactions of the Korean Society of Automotive Engineers
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    • v.9 no.5
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    • pp.75-81
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    • 2001
  • This paper presents the atomization characteristics of single hole injector in the direct injection type diesel engine. The spray characteristics of fuel injector such as the droplet size and velocity were measured by phase Doppler particle analyzer. In this paper, the atomization characteristics of fuel spray are investigated for the experimental analysis of the measuring data by the results of mean diameter and mean velocity of droplet. The effect of fuel injection pressure on the droplet size shows that the higher injection pressure results in the decrease of mean droplet diameter in the fuel spray. The minimum size of fuel spray droplet appears on the location of 40mm axial distance from nozzle exit of diesel injector. Based on the experimental results, the correlation between the droplet diameter and mean velocity of the diesel spray due to the change of axial and radial distance from the nozzle tip were investigated.

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Bioaccessibility of β-Lactoglobulin Nanoemulsions Containing Coenzyme Q10: Impact of Droplet Size on the Bioaccessibility of Coenzyme Q10

  • Ha, Ho-Kyung;Lee, Mee-Ryung;Lee, Won-Jae
    • Food Science of Animal Resources
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    • v.38 no.6
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    • pp.1294-1304
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    • 2018
  • The aims of this research were to examine the effect of heating temperature (65, 75, and $85^{\circ}C$) and $CaCl_2$ concentration level (3, 4, and 5 mM) on the physicochemical properties of ${\beta}$-lactoglobulin (${\beta}$-lg) nanoemulsions (NEs) and to study how the droplet size of NEs affects the bioaccessibility (BA) of coenzyme $Q_{10}$ ($CoQ_{10}$). The droplet size of NEs and BA of $CoQ_{10}$ was assessed by particle size analyzer and UV-Vis spectrophotometer, respectively. An increase in heating temperature and $CaCl_2$ concentration level resulted in a significant (p<0.05) increase in the droplet size of NEs while there were no significant differences in polydispersity index and zeta-potential of NEs. When NEs containing $CoQ_{10}$ were incubated in simulated small intestinal phases, an increase in the droplet size and polydispersity index of NEs was observed. This indicated that NEs were not stable in small intestine and digestion of NEs occurred. As heating temperature and $CaCl_2$ concentration level were decreased, a significant (p<0.05) increase in BA of $CoQ_{10}$ was observed. There was a significant (p<0.05) increase in BA of $CoQ_{10}$ with a decrease in the droplet size of NEs. In conclusion, heating temperature and $CaCl_2$ concentration level were key-parameters affecting the initial droplet size of NEs and BA of $CoQ_{10}$ was negatively correlated with initial droplet size of NEs.

The Effects of Droplets Arrangement and Size Difference on the Vaporization and Combustion Characteristics of Liquid Fuel Droplets (액체 연료 액적들의 배열 및 크기차이가 증발 및 연소특성에 미치는 영향)

  • Lee, Dong-Jo;Kim, Ho-Young;Cho, Chong-Pyo;Yoon, Suk-Goo
    • 한국연소학회:학술대회논문집
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    • pp.107-113
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    • 2007
  • The burning characteristics of interacting droplets with internal circulation in a convective flow are numerically investigated at various particle arrangement and size difference. In this simulation some conditions are fixed, surround gas temperature is 1250K, pressure is 10 atm and drolet's initial temperature is 300K. The transient combustion of arranged droplets, the fixed droplet distances of 4 radii to 20 radii horizontally, is studied. And the range of size of droplet is 75${\mu}m$ to 100${\mu}m$. The results obtained from the present numerical analysis reveal that the transient flame configuration and retardation of droplet internal motion with the horizontal spacing substantially influence lifetime of interacting droplets. At a Reynolds number 10, lifetime of the three droplets with decreasing horizontal droplet spacing increases monotonically. But when droplet spacing decreases further to 4radii, Lifetime of interacting droplets are increase. So Lifetime of interacting droplets exhibits a strong dependence on the horizontal droplet spacing and size difference. It can be investigated well with these conditions to that of single burning droplet.

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Analysis on the Relations of Droplet Size Distribution and Optical Depth in Water Curtain (워터커튼에서 액적의 크기 분포와 광학 두께의 상관관계 분석)

  • You, Woo Jun;Ryou, Hong-Sun
    • Fire Science and Engineering
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    • v.30 no.2
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    • pp.62-67
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    • 2016
  • In this study, the optical depth is analyzed with the effects of droplet size distribution of the water curtain nozzle to attenuate the radiative heat transfer. The HELOS/VARIO equipment is used for the measurement of the droplet size distributions. The spray characteristics are quantified by the investigation of Deirmenjian's modified gamma distribution function. The distribution constant of the nozzle can be obtained as ${\alpha}=1$ and ${\gamma}=5.2$. The generalized equation of the optical depth related with the droplet size distribution is introduced. These results will be applicable to the analysis of the design condition of the water curtain nozzle.

Experimental Study on the Relationship between Ink Droplet Volume and Inkjet Waveform (잉크젯 파형과 잉크 액적 체적의 관계 실험적 분석)

  • Kwon, Kye-Si;Myong, Jae-Hwan
    • Journal of the Korean Society for Precision Engineering
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    • v.26 no.4
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    • pp.141-145
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    • 2009
  • Recently, inkjet technology has emerged as one of the most powerful tools for patterning electronics devices, such as large area display applications, RFID, PCB patterning, etc. By using the Inkjet technology, the droplet speed as well as the size can be controlled precisely. In this paper, the relationship between waveform and droplet size will be investigated by means of experiment. Also the relationship between inkjet speed and droplet size will be discussed. It was shown from experimental results that ink droplet size from the nozzle diameter of $50{\mu}m$ can be varied from 37 to $58{\mu}m$ by modifying the inkjet waveform when the speed of the droplet is 1m/sec. Finally, experimental results indicate that small drops are more difficult to generate than large drops since the jetting conditions for making small drops are sensitively affected by the dwell time variation.