• 제목/요약/키워드: Droplet size and velocity distribution

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

  • 문석수;최재준;배충식
    • 대한기계학회논문집B
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    • 제31권7호
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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.

디젤 분무(噴霧) 액적(液滴)의 크기와 속도(速度) 동시계측(同時計測)에 관한 연구(硏究) (A Study on the Simultaneous Measurement of Droplet Size and Velocity in a Diesel Fuel Spray)

  • 장영준;전충환;박호준;김현규;김상진
    • 한국자동차공학회논문집
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    • 제2권5호
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    • pp.11-22
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    • 1994
  • The pupose of this study is to measure droplet size and velocity simultaneously for a transient diesel fuel spray in a quiescent chamber at atmospheric temperature and pressure. Generally, diesel combustion phenomena is mainly governed by characteristics of injection system and fuel spray. Therefore we need to clarify these characteristics for developing more economical diesel systems. In this study, correlation between droplet size and velocity was measured at downstream distance from nozzle. Governing parameters are pump speed and fuel quantity for the detailed nature in this transient diesel fuel spray. It is observed effect to the droplet size and velocity distribution. Velocity(peak, mean, rms), number density and droplet size were investigated simulaneously using PDA in the spray. Various results are presented to illustrate the effects of operation factors and correlation between the droplet diameter and velocity.

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이중분무의 중첩영역과 단일분무에서 액적의 거동 특성 (Characteristics of the Droplet Behavior in the Overlap Region of Twin Spray and in Single Spray)

  • 정지원;차건종;김덕줄
    • 대한기계학회논문집B
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    • 제24권10호
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    • pp.1300-1308
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    • 2000
  • The objectives of this study was to investigate the spray characteristics of single spray and twin spray in the overlap region such as mean axial velocity, mean radial velocity, mean droplet size and probability density function of droplet size. A phase doppler anemometer was used as the measurement system for droplet size and velocity. In case of single spray, injection pressure was varied from 0.2MPa to 0.7MPa. Mean axial velocity, mean radial velocity and droplet size were decreased as the distance below nozzle tip was increased. In case of twin spray, the spray characteristics were measured by varying the distance between two nozzles from 127mm to 155mm. In the overlap region, the boundary of the overlap region was determined by obtaining the distribution of mean axial and radial velocity. Droplet size was increased as the distance from nozzle tip was increased. It was found that the distribution of droplet size for twin spray in the overlap region was different to single spray.

DME 연료의 분무 특성에 관한 연구 (Fuel Spray Characteristics of Dimethyl Ether)

  • 이상훈;전문수
    • 융복합기술연구소 논문집
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    • 제3권2호
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    • pp.51-56
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    • 2013
  • This paper describes the atomization characteristics, as well as the velocity and size distribution, of DME spray based on common-rail injection system. To analyze the possibility of using DME fuel as an alternative fuel of diesel, spray atomization characteristics were investigated. For this investigation, two-dimensional phase Doppler analyzer system was used to obtain droplet size and velocity distribution simultaneously. Velocity and droplet size measurements were performed at various injection pressures. Results showed that increasing pressure from 25MPa to 50MPa leads to higher spray droplet velocities and smaller droplet diameter but injection pressure above 40MPa, no signifiant reduction was observed. With the droplet velocity and SMD comparison between diesel and DME fuel, it can be observed that DME has smaller SMD and droplet velocity due to its low surface tension.

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An Experimental Study on Angled Injection and Droplet Size Characteristics of Liquid Jets in Subsonic Crossflow

  • Kim, Min-Ki;Song, Jin-Kwan;Hwang, Jeong-Jae;Yoon, Young-Bin
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2008년 영문 학술대회
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    • pp.486-491
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    • 2008
  • The spray characteristics and drop size measurements have been experimentally studied in liquid jets injected into subsonic crossflow. With water as fuel injection velocity, injection angle and atomizer internal flows were varied to provide of jet operation conditions. The injector internal flow was classified as three modes such as a non-cavitation flow, cavitation, and hydraulic flip flows. Pulsed Shadowgraph Photography measurement was used to determine the spatial distribution of the spray droplet diameter in a subsonic crossflow of air. And this study also obtains the SMD(Sauter Mean Diameters) distribution by using PLLIF(Planar Liquid Laser Induced Fluorescence) technique. The objectives of this research are getting a droplet distribution and drop size measurement of each condition and compare with the other flows effect. As the result, This research have been showed the droplet size were spatially dependent on air-stream velocity, fuel injection velocity, injection angle effects and normalized distance from the injector exit length.(x/d, y/d)There are also different droplet size characteristics between cavitation, hydraulic flip and the non-cavitation flows.

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와류형 고압 분무의 속도 및 입경분포에 관한 연구 (A Study on the Distribution of Droplet Velocity and Diameter in a High-Pressure Swirl Spray)

  • 최동석;류경훈;차건종;김덕줄
    • 대한기계학회논문집B
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    • 제23권10호
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    • pp.1310-1319
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    • 1999
  • High-pressure swirl injectors have usually been employed in Gasoline direct injection engines due to their spray characteristics and the feasibility of their control. Thus the microscopic characteristics of high-pressure swirl spray were investigated by PDA. The correlation between axial and radial velocities and the correlation between droplet size and axial velocity were examined with different axial and radial positions. Two dimensional droplet velocity and its number distribution with size-classified droplets were illustrated. The mean droplet velocity and its SMD were also analyzed at the center of spray, the position having maximum mean axial velocity, and the spray periphery using time dividing method. Finally, the structure of high-pressure swirl spray was presented with the size distribution and velocity profile of droplets.

SPRAY STRUCTURE OF HIGH PRESSURE GASOLINE INJECTOR IN A GASOLINE DIRECT INJECTION ENGINE

  • Lee, Chang Sik;Chon, Mun Soo;Park, Young Cheol
    • International Journal of Automotive Technology
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    • 제2권4호
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    • pp.165-170
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    • 2001
  • This study is focussed on the investigation of spray characteristics from the high pressure gasoline injector for the application of gasoline direct injection engine. For the analysis of spray structure of high pressure gasoline injector; the laser scattering method with a Nd-Yag laser and the Phase Doppler particle analyzer system were applied to observe the spray development and the measurement of the droplet size and velocity of the spray, respectively. Also spatial velocity distribution of the spray droplet was measured by use of the particle image velocity system. Experimental results show that high pressure gasoline injector shapes the hollow-cone spray, and produce the upward ring shaped vortex on the spray surface region. This upward ring shaped vortex promotes the secondary atomization of fuel droplets and contributes to a uniform distribution of fuel droplets. Most of fuel droplets are distributed under 31$\mu m$ of the mean droplet size (SMD) and the frequency distribution of the droplet size under 25$\mu m$ is over 95% at 7 MPa of injection pressure. According to the experimental results of PIV system, the flow patterns of the droplets velocity distribution in spray region are in good agreement with the spray macroscopic behaviors obtained from the visualization investigation.

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직분식 가솔린 기관 고압 인젝터의 연료 무화 특성 (Spray Characteristics of High-Pressure Injector in Direct-Injection Gasoline Engine)

  • 이창식;최수천;김민규
    • 한국자동차공학회논문집
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    • 제7권8호
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    • pp.1-6
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    • 1999
  • An experimental study was carried out to investigate the global spray behavior and spray characteristics of high-pressure fuel injector in the direct-injection goasoline enginet. The atomization characteristics of fuel spary such as mean droplet size, mean velocity , and velocity distribution were measured by the phase Doppler particle analyzer. The spray tip penetration and spray width were investigated by the result fo visualizaiton experiment. The quantitiative spary characteristics of injector spray were measured under various sparay conditions and ambient pressures. The results of experiment show that the increase in ambient pressure have influence on the spray tip penetration and spray development process. Also, the influence of injection pressure and measuring location on the mean velocity and droplet size distribution were discussed.

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아음속 수직분사제트에서 액적크기 특성에 대한 실험적 연구 (An Experimental Study on Droplet Size Characteristics of Liquid Jets in Subsonic Crossflow)

  • 김민기;손진관;김진기;황용석;윤영빈
    • 한국분무공학회지
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    • 제12권2호
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    • pp.115-122
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    • 2007
  • The spray characteristics and drop size measurements have been experimentally studied in liquid jets injected into subsonic crossflow. With water as fuel injection velocity, injection angle and atomize. internal flows were varied to provide of jet operation conditions. The injector internal flow was classified as three modes such as a non-cavitation flow, cavitation, and hydraulic flip flows. Pulsed Shadowgraph Photography measurement was used to determine the spatial distribution of the spray droplet diameter in a subsonic crossflow of air. And this study also obtains the SMD (Sauter Mean Diameters) distribution by using Planar Liquid Laser Induced Fluorescence technique. The objectives of this research are get a droplet distributions and drop size measurements of each condition and compare with the other flow effects. As the result, This research has been showned that droplet size were spatially dependent on air-stream velocity, fuel injection velocity, injection angle effects, and normalized distance from the injector exit length(x/d, y/d). There are also different droplet size characteristics between cavitation, hydraulic flip and the non-cavitation flows.

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내부 온도분포를 고려한 Coal-Water Slurry의 점화현상에 관한 이론적 해석 (Theoretical Analysis of Ignition of a Coal-Water Slurry Droplets with Interior Temperature Distribution)

  • 최창은;백승욱;김종욱
    • 대한기계학회논문집
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    • 제17권7호
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    • pp.1823-1832
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    • 1993
  • CWS(coal-water slurry) is used for application in power plants, boilers, industrial furnaces. A single coal-water slurry droplet ignition has been examined to reveal the basic nature of their evaporation, volatilization and heating processes. The interior droplet temperature distribution has been considered. The effect of coal thermal conductivity, droplet size, water fraction in the slurry, gas temperature and velocity and radiation on the ignition phenomena were also studied. Either increasing the velocity and gas temperature or decreasing the droplet size and water fraction in the slurry may reduce the time for evaporation and ignition delay time.