• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.6
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• pp.1529-1538
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• 1995

In this study, a liquid sheet type co-axial nozzle has been used to investigate the turbulent atomization characteristics which could result in the experimental data to be used in designing a jet nozzle with high performance. Image processing technique and immersion sampling method were employed to measure droplet size. In atomizing characteristics, droplet size distributions and absolute droplet sizes, SMD(Sauter Mean Diameter) have been investigated in the wide ranges of flow field depending upon the air-water mass ratios. And the comparisons between the present data and the semi-empirical curves have been conducted semi-empirical correlation for SMD has been derived in the present analysis.

• Journal of Biosystems Engineering
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• v.35 no.3
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• pp.158-162
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• 2010

The effect of fuel injection characteristics on engine performance has been known for improving fuel economy and emission reduction. In this study, the spray characteristics of crude palm oil blended fuel with conventional diesel fuel was investigated. The experiments were performed to evaluate the effect of crude palm oil blending ratio and injection pressure on the spray behavior. The droplet size of injected fuel was analyzed through laser diffraction particle analyzer (LDPA). Also, spray atomization characteristics were investigated in terms of Sauter mean diameter (SMD) and droplet distribution at various injection conditions. Fuel containing crude palm oil has different spray pattern on account of the high viscosity. Through those experimental results, we found that the increase of blending ratio made droplet size larger, SMD of biodiesel 100% was increased 30.2% than that of diesel fuel 100% under injection pressure of 60 MPa.

• Journal of ILASS-Korea
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• v.9 no.3
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• pp.1-7
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• 2004

This experiment was undertaken to investigate the atomization characteristics of the low viscosity biodiesel blended fuel and ultrasonic energy added one. Test fuels were conventional diesel fuel and biodiesel fuel. We compared to the characteristics of viscosity and surface tension, SMD between low viscosity biodiesel blended fuel and ultrasonic energy added one. Sauter mean diameter was measured under the variation of the spray distance. Viscosity and surface tension was measured under the variation of the time trace. To measure the droplet size, we used the Malvern system 2600C. Droplet size distribution was analyzed from the result data of Malvern system. Through this experiment, we found that the condition of the ultrasonic energy added situation had smaller Sauter mean diameter of droplet, viscosity and surface tension than that of the conventional situation.

• Journal of Advanced Marine Engineering and Technology
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• v.19 no.4
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• pp.17-26
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• 1995

In general existing air conditioning devices, which are carried out by convection heat transfer, are very popular compared with the radiation type air conditioning devices. But perconal convection tpe air conditioning units are unuseful air conditioning type because it handles amount of surrounded air to meet the temperature and humidity. In this view, this study is intended to develope personal dir conditioning units using a radiation type radiator. Liquid Droplet Radiator(L.P.R.) radiates the energy by means of thermal radiation. Radiative energy from L.P.R. is the infrared rays which heat the objects without lose of energy. It is a desirable heating method for the local area within the large room. In this study, the analysis uses the Monte Carlo methd to predict the temperature distribution in the droplet sheet and the net heat flux from the L.D.R.. And for this study and experiment was carried out to analyse the radiative and convective heat transfer characteristics in the L.D.R.. And the experiment was investigated the effects of inlet temperature, feed rate, optical thickness and droplet diameter on heat transfer characteristics of L.D.R.. The obtained results from the numerical and experimental studies of L.D.R. were as follows ; (1) The heat flux of L.D.R. was effected by extinction coefficient of droplet sheet, optical thickness and droplet temperature, surface area and emissivity of the droplet. And it was increased with the temperature, feed rate and optical thickness, on the other hand decreased with increasing of droplet diameter. (2) The experimental results for heat flux was ecalucted below 20% than that of the numerical solution by Monte Carlo method, but the tendency of the variation shows relatively good agreement.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.10
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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.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.79-84
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• 2001

The effect of spray characteristics on desulfurization yield was evaluated by performing experiments with pilot spray drying sorber (SDS). Among the variables of operating conditions, the slurry-spraying conditions were chosen as major parameters; Stoichiometric ratio and Sauter mean diameter of slurry droplet were varied for the different gas temperatures and $SO_{2}$ concentrations in the inlet gas flow. From the experimental results, we proposed semi-empirical models of desulfurization yield for both Stoichiometric ratio and Sauter mean diameter of droplets. The optimal condition of spray can be determined based on these results, which might be applied to the design or scale-up of SDS systems.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.4
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• pp.1039-1049
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• 1994

The intermitternt and transient fuel spray have been investigated from the simultaneous measurement of droplet sizes and velocities by using Phase/Doppler Particle Analyzer(PDPA). Measurement have been done on the spray axis and at the edge of the spray near nozzle at various gas-to-liquid density ratios(.rho./sub g//.rho./sub l/) that ranges from those found in free atmospheric jets to conditions typical of diesel engines. Probability density distributions of the droplet size and velocity were obtained from raw data and mathematical probability density functions which can fit the experimental distribations were extracted using the principle of maximum likelihood. In the near nozzle region on the spray axis, droplet sizes ranged from the lower limit of the measurement system to the order of nozzle diameter for all (.rho./sub g/ /.rho./sub l/) and droplet sizes tended to be small on the spray edge. At the edge of spray, average droplet velocity peaked during needle opening and needle closing. The rms intensity is greatly incresed as the radial distance from the nozzle is increased. The probability density function which can best fit the physical breakage process such as breakup of fuel drops is exponecially decreasing log-hypebolic function with 4 parameters.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.1
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• pp.1-8
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• 1994

This study carried out to investigate the spray characteristics of diesel oil through out ultrasonic fuel supply system in comparison with conventional. Size of the droplets comprising diesel spray was measured by immersed liquid method at different positions along the spray axis. Droplets distribution diagram was ploted and Sauter Mean Diameter(SMD) was also calculated. The effects of the ultrasonic vibration and injection pressure on the droplet size distribution and SMD were investigated. As the ultrasonic vibration supply SMD decreases on the same injection pressure conditions with conventional injector's. But the effect of ultrasonic vibration decreases with injection pressure increasing.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.258-263
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• 2010

An experimental study was performed to understand spray characteristics of the V type rotating fuel nozzle with orifice diameters by using high speed rotational system. The experimental apparatus consist of a high speed rotational system, fuel injection system and acrylic case. The droplet size and velocity were measured by PDPA(Phase Doppler Particle Analyzer) and spray was visualized by using Nd-Yag laser-based flash photography. From the test results, droplet diameters are reduced with increasing orifice diameter and the optimum injection orifice diameter is 2.6 mm. When increasing orifice diameter over than 2.6 mm, droplet diameter is not decreased with increasing orifice diameter. This is due to the irregular distribution of the liquid sheet around the inner surface of injection orifice.

• Journal of ILASS-Korea
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• v.10 no.2
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• pp.18-31
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• 2005

This study was performed to explore the liquid breakup and atomization characteristics for the classification of drop formation mode and background of uniform droplets generation in electrohydrodynmaic atomization according to the change of experimental parameters such as nozzle material (stainless steel. teflon). fluid flow rate, applied electrical field and intensity, and frequency. In results, from the classification map of drop formation modes according to the variation of applied AC voltage and frequency at a stainless nozzle, the droplet size was smaller than the outer diameter of the nozzle tip relatively in the spindle mode. The transition points became clearly to be moved toward the high applied voltage by rising the applied AC frequency beyond 450Hz. Also the droplet radius can be observed quite small in the frequency bandwidth of $350{\sim}450Hz$. The droplet radiuses decrease as the applied voltage increases for a fixed applied AC frequency within the range from 50Hz to 400Hz Over 400Hz, the relation between the power intensity and the droplet size was not consistent with a continuous mechanism of liquid breakup. Thus, it is showed that the droplet size distribution using the teflon nozzle was analogous to the results of stainless steel, but the droplet size was bigger than that of stainless steel relatively in case of a teflon nozzle.