• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.5
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• pp.53-58
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• 1998

This paper concentrates on the development of a computational design program to determine nozzle size in water jet, combing the numerical optimization technique with the flow analysis code. To achieve the above objective, a two-dimensional model was developed for investigating the fluid flow in water jet and calculating the velocity and pressure distributions. The mathematical formulation as a standard ${k}-\varepsilon$ model was solved employing a general thermo fluid-mechanics computer program, PHOENICS code, which is based on the Semi-Implicit Method Pressure Linked Equations(SIMPLE) algorithm. The developed code was applied to water jet design to determine the nozzle size, and investigated the effect of the change of nozzle location. Calculated results showed that the flow pattern is not changed as the change of nozzle location.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.7
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• pp.79-86
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• 2010

The environment-friendly abrasive materials of starch series has a wide range of application value such as deburring of plastic injection products, paint exfoliation and surface treatment of painted products and polishing, etc. In this study, an experiment of paint exfoliation was performed by using the environment-friendly abrasive materials made of cheap starch, and its performance was reviewed. By adjusting the grit size of abrasive materials, nozzle pressure, nozzle feed and number of nozzle repetition, paint could be exfoliated effectively. In this experiment, it was found that the most suitable condition was grit size 0.75~1.0 mm, nozzle pressure 0.4 MPa, nozzle feed 5 mm/min and number of processing repetition 2 times.

• Journal of ILASS-Korea
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• v.27 no.4
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• pp.173-180
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• 2022

Cooling fog is being used in various parts of society such as fine dust reduction, cleanliness, and temperature drop. Cooling fog has the advantage of low flow rate and ease of use compared to other spray systems. In the case of cooling fog, it was confirmed that the injection angle increased as the pressure increased and the nozzle diameter increased. In this study, the minimum injection angle was 33.61 degrees and the maximum injection angle was 107.38 degrees. It was confirmed that the larger the nozzle diameter and the smaller the pressure, the larger the droplet size. In addition, it was confirmed that the Sauter Mean Diameter (SMD) increased along the X and Y axis directions. It was confirmed that the size of the droplet decreases as it approaches the nozzle tip due to the characteristics of the nozzle design factor.

• Journal of the Korean Society of Radiology
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• v.14 no.7
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• pp.891-898
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• 2020

As the problem of shields made of lead has recently emerged, research on replacement shields is essential, and studies on the manufacture of diagnostic X-ray shields with 3D printers are also being actively conducted. Recently, with the development of metal mixed filaments, it has become possible to manufacture shielding materials easily, but studies on the nozzle size and output setting of 3D printers are insufficient. Therefore, this study aims to compare and analyze the results through a shielding rate experiment using a brass filament and a 3D printer, outputting the shield according to the nozzle size and layer height, and using a diagnostic radiation generator. The nozzle size was changed to 0.4, 0.8 mm, layer height 0.1, 0.2, 0.3, 0.4 mm, and output. The shielding rate test was fixed at 40 mAs, and the shielding rate was analyzed by experimenting with 60, 80, and 100 kVp, respectively. As a result of the analysis, it was analyzed that the printing time could be reduced to 1/10 according to the nozzle size and the layer height, and the shielding rate could be increased by 1% or more.

• Journal of ILASS-Korea
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• v.20 no.2
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• pp.82-87
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• 2015

A nozzle with vortex generator was used to develop the low pressure nozzle with high atomization performance and the nozzle atomized the liquid by centrifugal shear forces. In order to analyze the atomization characteristics, a shadowgraphy method was used and the measurement of droplet size was performed by using laser diffraction analyzer. The liquid injection pressure was fixed as 0.03 bar which is very low pressure and the gas injection pressures were changed from 0 bar to 2.0 bar. As a result, the breakup was achieved at the air injection pressure of 0.25 bar and over. The nozzle with the orifice diameter of 0.4 mm and the orifice gap of 0.25 mm presented small droplet diameters under 50 at the air injection pressure of 0.75 bar.

• Journal of ILASS-Korea
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• v.10 no.1
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• pp.24-34
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• 2005

Injection technology is one of the important technologies in a diesel engine. Many studies have done on the injection system. In this study, the fuel chamber geometry, the orifice ratio and the needle lift of the injection valve for a marine diesel engine are varied, and simulated. The result shows that the nozzle hole size has influence on the rail pressure and injection duration sensitively. The decrease of the static pressure at the nozzle hole entrance and the increase of the dynamic pressure on the outlet surface are occurred with the increase of the nozzle hole diameter. The highest dynamic pressure of the outlet was occurred at the needle lift of 0.4mm and the nozzle hole diameter of 0.328mm in this test nozzle.

• 한국연소학회:학술대회논문집
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• 2002.06a
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• pp.16-23
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• 2002

Electrostatic pressure-swirl nozzle for practical oil burner application has been designed. The charge injection method has been used in this design, where the nozzle consists of a sharp pointed tungsten wire as a charge injector and the nozzle body grounded. The spray characteristics of the nozzles have been investigated by using an insulating liquid, i.e. kerosene without active surface agent. Breakup length of liquid decreased with an increase in applied voltage and injection pressure, while the spray angle increased with an increased in both applied voltage and injection pressure. An empirical equations have been suggested to predict the breakup length for electrostatic pressure-swirl atomizer. The experimental result was within the range of the predicted equations. The SMD decreased between the ranges of 2.8 ${\sim}$ 33% when the conventional nozzle was compared to the electrostatic with -10 kV applied to the electrode at a radial distance from 5 to 20 mm.

• Journal of Advanced Marine Engineering and Technology
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• v.8 no.2
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• pp.88-97
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• 1984

The combustion process and the performance of a diesel engine are considerably affected by the characteristics of fuel spray. It is known that the spray of swirl nozzle for diesel engine injector of small orifice ratio becomes soft spray that has no core, therefore its penetration, one of the characteristics of spray becomes werse inspite of its good dispersion. In this paper, the spray characteristics of variously designed swirl nozzle for diesel injector were investigated by the photographic method. The nozzles, used in this experiment, vary in the diameter of swirl chambers and orifice ratio. From the results of the study, the sprays of this type nozzle of optimum swirl chamber and orifice ratio show that penetration decreased slightly but dispersion and spray volume increased remarcably, compared with unswirled single hole nozzle of the same size. It was suggested as a reason for the results, that the spray of this type swirl nozzle is similar to hard spray, therefore the core of the spray sustains good penetration considerably.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.16 no.1
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• pp.89-102
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• 1987

Experiments have been carried out to study the atomisation characteristics of superheated liquid(water) jet injected into the atmosphere through a single-hole nozzle. In present experi-mental range, superheated liquid jet has been observed to be atomised in two-phase effluent type; that is, spray formed by the bubble nucleation in the nozzle. In case of liquid injection through a long nozzle (L/D=29.09), the critical superheat for occurrence of two-phase effluent atomisa-tion can be determined from sudden change of spray angle. Sauter mean diameter of the spray droplets decreases as the degree of superheat increases. For the short nozzle (L/D=7.27), mean diameter increases with the injection pressure, while it decreases for the long nozzle; however for the long nozzle the effect of injection pressure is not significant compared with the short nozzle. For the short nozzle the uniformity of drop size distribution increases with increasing the degree of superheat, but for the long nozzle the effect of superheat on the uniformity is not appreciable.

• Korean Journal of Materials Research
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• v.12 no.1
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• pp.58-67
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• 2002

In this study copper chloride(CuCl$_2$) solution was used as raw material to produce the fine copper oxide powder which has less than 1 $\mu\textrm{m}$ average particle size and has uniform particle size distribution by spray pyrolysis process. In the present study, the effects of reaction temperature, the injection speed of solution and air, the nozzle tip size and the concentration of raw material solution on the properties of produced powder were studied. The structure of the powder became much more compact with increasing the reaction temperature regardless of copper concentration of the raw material solution. The particle size of the powder increased accordingly with increasing the reaction temperature in case of 30 g/$\ell$ copper concentration of the solution. The particle size of the powder increased accordingly, and the surface structure of the powder became more porous with increasing the copper concentration of the raw material solution. When copper concentration in raw material solution was more than 100 g/$\ell$, all produced powder was CuCl regardless of reaction temperatures. When copper concentration in solution was below 30 g/$\ell$ and reaction temperature was higher than 90$0^{\circ}C$, CuO was the main phase. The surface of the powder tended to become porous with increasing the injection speed of solution. Particle size was increased and the surface of the powder showed severely disrupted state with increasing the nozzle tip size. The particle size was decreased and the particle size distribution was more uniform with increasing the air pressure through the nozzle.