• Transactions of Materials Processing
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• v.3 no.1
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• pp.110-119
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• 1994

In this paper, a new forming process of large-size forgings of converged nozzle-shape is developed by the experimental study using the incremental forging method and combined forming method. The development of the forming process is focused on the manufacturing of large-size forgings by the press with medium load capacity. Various related processes are proposed and modelling experiments using plasticine are carried out. Thus, the incremental forging method for expanding is recommanded from the study of formability and forming load, etc. The selected process is then subjected to modelling experiments of lead and the design parameters such as preform for final process, die-width of the upper die and reduction amount of each stroke are determined. In order to verify the effectiveness of the selected process, 1/7 scale prototype experiment of the real material is carried out. Forgings of converged nozzle shape can be produced by the developed process within the limit loads and with the simple tools.

• Journal of ILASS-Korea
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• v.1 no.1
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• pp.21-27
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• 1996

This experimental study was to investigate spray angles and drop sizes in an external mixed twin-fluid swirl jet nozzle. Twin-fluid swirl jet nozzle with swirlers designed four swirl angles such as $0^{\circ},\;22.5^{\circ},\;45^{\circ},\;64.2^{\circ}$ was employed. A PDA system was utilized for the measurement of drop size and mean velocity. Water and air were used as the working fluids in this experiment. The mass flow rate of water was fixed as 0.03 kg/min, and air flow rates were controlled to have the air/liquid mass ratio from 1.0 to 6.0. As a result, swirl angle controlled to spray angles and drop sizes. It was found that swirl angle was increased with spray angle and with decreased SMD. However, the effect of swirl angle was reduced at large air/liquid mass ratio(Mr=6.0).

• Journal of Biosystems Engineering
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• v.18 no.2
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• pp.100-109
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• 1993

The aim of this study was to provide the reasonable data for design of the nozzle which produces finer droplets on the same level of the effective travel distance or which transports droplets to the farther target on the reasonable atomization in comparison with the commercial nozzles being used much in Korean rural areas. Newly designed twin-fluid atomizers with some commercial nozzles were tested in this study, and their results were as follows : 1. The characteristics of the spray deposit distribution of No.1 nozzles for farther target were nearly same in the near or nearer travel distance less than 8m. Therefore it was reasonable to combine the characteristics of the spray deposit distributions of No.2 and No.3 nozzles to those of No.1 nozzle. 2. The effective travel distance was increased with increase of the sectional area of the jet ligament, and the maximum effective travel distance was reached to about 17m. 3. The droplet size was increased with increase of the sectional area of the jet ligament, and the maximum droplet size was produced in the front of the point of the maximum spray deposit distribution. 4. The atomization was excellent in the twin-fluid atomizer in comparison with the hydraulic atomizer and also the effective travel distances were nearly same level in both atomizers.

• 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.

• Journal of Energy Engineering
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• v.18 no.4
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• pp.258-263
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• 2009

Jet Loop Reactor(JLR), in which a two-phase nozzle is installed, is the new design technique for the treatment of high concentration wastewater by accelerating of oxygen contacting between substrate and surrounding bacteria. This numerical study of the two phase jet flow was conducted to find the optimum design of JLR. It was shown that there was a minimum velocity in the nozzle for continuous circulation of wastewater. The optimum location and the size of the draft tube for continuous circulation were examined. It was certain that the smaller the air size is, the more the effect of the mixing increases. The relation between the mixing effect and the turbulence was confirmed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.365-369
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• 2007

The solid rocket interacts circumscriptively in terms of is many more than liquid rocket. It is uncontrollable than liquid rocket because all part of combustion is decided such as Mixture ratio of propellant, burning time and area. However, production cost is cheap and because authoritativeness security can be easy and enlarge the early speed that follow thrust-to-weight ratio, it is used comprehensively by small size rocket. Considered about nozzle cooling to control phenomenon that burn by thermal conduction in interior wall of nozzle that follow in thrust increase of solid rocket and erosion phenomenon by combustion gas of high speed.

• Journal of ILASS-Korea
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• v.22 no.2
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• pp.96-102
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• 2017

In order to reduce the NOx, SCR technology is most suitable. In this study, we focused on studying the injector part of urea-SCR system. When stoichiometric 1 mole of urea is injected, 2 moles of $NH_3$ are created. $NH_3$ causes a SCR reaction by reacting with NOx. However, urea is decomposed by the side reaction of coming out HNCO, deposit formation is formed. In this study, it was to design a nozzle that can spray the optimal spray flow rate. Test nozzle used in this experiment is efferverscent type. The result of the experiment, liquid flow rate was confirmed to be that they are dominated by the exit orifice diameter. The area ratio is defined by ratio of the area of exit orifice hole and that of aerorator. The droplet size was measured by varying the area ratios. In addition, it was also confirmed that there is no change of the liquid flow rate and air flow rate to change the aerorator at the same exit orifice. Further, It was confirmed that the droplet size was relatively uniform even though the area ratio was different. Finally, there is little change in the SMD that air flow rate increases in 0.3 or more ALR.

• 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.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.303-306
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• 2002

Liquid atomization by means of a spinning cup is widely used as a device for combustion, in cooling and spray drying. In this study, the blowing type rotary atomizer was experimental carried out the investigations on the characteristics of the blowing type rotary atomizer which is an air flow energy of blower instead of an electric motor most commonly used to a driven energy. The analysis on the rotary cup speed, air velocity with the blower conditions was performed and also the drop size was measured using LDPA. It was tried to analyzed on air-nozzle size and liquid flowrate as the result. It was found that the increase of the relative velocity between liquid and air improve significantly atomization liquid, and decrease of the liquid flowrate improved the maximum drop size though the mean drop size is really the same.

• Journal of Power System Engineering
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• v.2 no.1
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• pp.25-30
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• 1998

In order to investigate the droplet size distribution and Sauter Mean Diameter in a ultra high pressure diesel spray, fuel was injected with ultra high pressure into the environments of high pressure and room temperature by an Electronic Hydraulic Fuel Injection System. Droplet size was measured with the immersion liquid sampling technique. The immersion liquid was used a mixture of water-methycellulose solution and ethanol. The Sauter Mean Diameter decreased with increasing injection pressure, with a decrease environmental pressure (back pressure) and nozzle diameter. Increasing the injection pressure makes the fuel density distribution of the spray more homogeneous. An empirical correlation was developed among injection pressure, air density, nozzle diameter and the Sauter Mean Diameter of spray droplets.