• 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.

• Journal of ILASS-Korea
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• v.17 no.4
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• pp.192-196
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• 2012

This paper reports on breakup characteristics of fuel droplet which includes metal nanoparticles. In order to develop a new injection system for nanoparticle-coated layers overcoming the conventional flame spray system, fundamental experiments were conducted to examine the interaction between a fuel droplet with nanoparticles and the external energy induced by the laser. In the experiments, this study used nickel nanoparticles whose size was under 100 nm to mix with kerosene as the fuel, and utilized a syringe pump and a metal needle to inject a fuel droplet. In particular, the Nd-YAG laser was adopted to give additional energy to the nanoparticles for evaporation of a fuel droplet containing nanoparticles. When the laser energy as 96 mJ was irradiated during the injection, it was observed that such an explosive evaporation occurred to break up a fuel droplet including nanoparticles, making the rapid increase in the ratio surface area to liquid volume. From this work, we suggest the possibility that the laser energy can be used for rapid evaporation of a fuel droplet.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.4
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• pp.551-559
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• 1998

Evaporation and ignition characteristics of fuel droplet have major influences on the efficiency and performance of engine. In the present study the experiment of evaporation and self-ignition of single fuel was performed under the various ambient conditions. An individually suspended droplet of n-heptane n-hexadecane ethyl-alcohol and light oil were employed as a liquid droplet. Evaporation and ignition characteristics were measured by using the video-camera and image processing technique under the various ambient temperatures (up to 1000310 OC)and partial pressure of oxigen(up to 60%) The evaporation curve shows that the droplet life time ignition delay time decreases as the ambient temperature and partial pressure of oxigen increase, The temperature variations of droplet were also reported for various fuel and ambient temperatures. The numerical simulations were carried out to predict droplet diameter and temperature with favorable agreement.

• Journal of the Korean Society of Combustion
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• v.3 no.2
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• pp.1-11
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• 1998

Experimental investigation on flame spread of blended fuel droplet arrays has been conducted for droplet diameters of 1.0mm and 0.75mm using high-speed chemiluminescence images of OH radical. The flame spread rate is measured with blended fuel composition, droplet diameter, and droplet spacing. Flame spread is categorized into two: a continuous mode and an intermittent one. There exist a limit droplet spacing, above which flame does not spread, and a droplet spacing of maximum flame spread, which is closely related to flame diameter. It is seen that flame spread rate is mainly dependent upon the relative position of flame zone within a droplet spacing. In case of large droplet, the increase of % volume of Heptane induces the shift of limit droplet spacing to a larger spacing since volatile Heptane plays a role of an enhancer of flame spread rate. In case of small droplet, the increase of % volume of Heptane leads to the shift of limit droplet spacing to a smaller droplet spacing. This is so because of the delayed chemical reaction time by the rapid increase of mass flux of fuel vapor for small droplet.

• Journal of the Korean Applied Science and Technology
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• v.31 no.3
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• pp.492-499
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• 2014

The objectives of this study was to examine experimentally the microexplosion phenomena of single droplet W/O(water-in-oil) type emulsified fuel. Also, measured the combustion characteristics of single droplet emulsified fuel for microexplosion phenomena in atmospheric pressure condition. The larger quantity of adding water makes microexplosion phenomenon with higher intensity of sound level, because larger water droplet has better coalescence for emulsified fuel. The small quantity of adding water makes puffing with lower sound level intensity. In latter period of extinction, large size droplet of the emulsified fuel breaks down rapidly to small size droplet, and microexplosion phenomenon occurs with multi step combustion.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.2
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• pp.49-56
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• 2006

The single droplet combustion characteristics of multicomponent fuel such as diesel-oxygenate and diesel-paraffin blends under high ambient temperature and atmospheric pressure were investigated in the study. The results of the study may be concluded as follows : In the combustion of diesel fuel droplet with additive of oxygenate and paraffin, the dimensionless droplet size of $(D/D_o)^2$ was linearly decreased with time. A fuel droplet with low boiling temperature additives and in high boiling temperature diesel fuel evaporates and burns faster than usual diesel fuel. This rapid burning may result from so-called "micro-explosion" and its burning intensity varies with the types of additives. The results above may suggest that rapid evaporation of oxygenate additive in the middle stage of combustion can contribute much to combustion improvement of blended fuels. When compared to ordinary diesel fuel, neat oxygenate and paraffin fuels show blue flame during entire combustion which prove smokeless combustion.

• Journal of Energy Engineering
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• v.11 no.1
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• pp.74-80
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• 2002

In this study, a numerical method for fuel droplet evaporation in cylinder of S.I. engine is presented. This study was newly defined non-dimensional critical droplet lifetime and modeled heating and evaporation processes of fuel droplet during intake and compression stroke of gasoline engine. The simulation results show that simultaneous increase of gas temperature and pressure in compression stroke seems to have compensative effect on droplet gasification rate. The environment variations in cylinder have little effect on the fuel droplet gasification process. The droplet size for full evaporation at the end of compression stroke can be estimated using this program.

• International Journal of Safety
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• v.3 no.1
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• pp.20-26
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• 2004

The system considered in this model consists of a single, semi- transparent, diesel fuel droplet, which is immobile in the heating area and surrounded by a quiescent air. A uniform external radiation field surrounds the droplet. Results from mathematical simulation suggest that because of the higher surface temperature, the external radiative heating of the droplet can promote an earlier ignition of the fuel vapour/air mixture. The radiative heating of the droplet increases the mass transfer from the droplet to the surrounding gas-phase, thus, decreasing the heterogeneity of the fuel droplet/air system.

• Journal of the Korean Applied Science and Technology
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• v.28 no.1
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• pp.95-101
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• 2011

We estimated on the stability of W/O type emulsified fuel using by capacitance sensor, so it concluded the following conclusions. For the first 24 hours, prepared emulsified fuel reveals phase separation ratio of 5%, maintains stable status which verifies the stability of emulsified fuel. Adding more water increases the phase separation ratio rapidly, and adding more surfactant displays stable emulsification. Adding water causes larger size of water droplet diameter, and adding surfactant mixture causes smaller size of water droplet diameter. In conclusion, the size of W/O type emulsified fuel water droplet diameter is directly related to the volume of surfactant, and density of water droplet diameter changes thedistribution according to water contents.

• 한국연소학회:학술대회논문집
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• 2000.12a
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• pp.194-201
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• 2000

This paper is intended to analyze the macroscopic behavior and transient atomization characteristics of the high-pressure gasoline injector in direct-injection gasoline engine. The global spray behavior of fuel injector was visualized by shadowgraph technique. Time-resolved droplet axial and radial velocity components and droplet diameter were measured at many probe positions in both axial and radial directions by a two-component phase Doppler particle analyzer (PDPA). In order to obtain the influence of fuel injection pressure, the macroscopic visualization and experiment of particle measurement on the fuel spray were investigated at 3,5 and 7 MPa of injection pressure under different surrounding pressure in the spray chamber. The results of this work show that the fuel injection pressure of gasoline injector in GDI engine has influence upon the mean droplet diameter, mean velocity of spray droplet, the spray tip penetration, and spray width under the elevated ambient pressure.