• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.354-358
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• 2007

An experimental study was performed to understand spray characteristics of the slinger injector. system for the micro turbojet engine. In this fuel injection system, fuel is sprayed and atomized in the combustor by centrifugal forces of engine shaft. This experimental apparatus consist of a high speed rotating Spindle, slinger injector, pressure tank 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, the droplet size(SMD) is largely affected to rotational speed, mass flow rate and the number of injection orifice. From the this experimental study, we could understand the spray characteristics of the slinger injection system and obtain the optimum shape of the slinger injector nozzle which is suitable for the micro turbojet engine.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.6
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• pp.2147-2159
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• 1991

The effects of principal dimensions of internal mixing twin-fluid atomized and operating conditions on the atomizing characteristics are experimentally investigated. The tests are conducted over the wide range of air/liquid ratio to predict influences of the diameter and length of nozzle, contacting angle between air and liquid in the mixing chamber, and air orifice diameter on the mean drop size(SMD), spray angle, distribution of drop size, and spray dispersion, And also, initial distribution of liquid column by air stream within the mixing chamber are observed through the transparent nozzles. A He-Ne laser particle sizer(MALVERN Model 2604) was used to measure the Sauter.s mean diameter( $D_{321}$) and droplet sizes distribution. In this experiment the air/liquid ratio, mixing length and nozzle diameter have a great influence on SMD, spray angle, droplet sizes distribution and spray dispersion.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.125-128
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• 2008

Atomization characteristics of small LRE-injector spray are investigated by using dual-mode phase Doppler anemometry (DPDA). Velocity, size, number density, and volume flux were measured at various injection pressures along the radial distance to make a close inquiry into spatial distribution characteristic of spray droplets. As the injection pressure increases, the velocity, turbulence intensity, number density, and volume flux of spray droplets become higher, whereas the droplet size ($D_{10}$ or $D_{32}$) gets smaller. Also, velocity and volume flux are proportional to Sauter mean diameter (SMD, $D_{32}$).

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.135-138
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• 2007

Two-dimensional distribution characteristics on the spray droplets emanating from an injector employed in a liquid-propellant thruster are investigated through dual-mode phase Doppler anemometry (DPDA). Spray-breakup characteristic parameters such as spray droplet velocity, turbulent intensity, Sauter mean diameter (SMD), number density, and volumetric flux are quantified to scrutinize the macroscopic behavior of injector-spray breakup. The present study will be able to contribute to the comprehension for performance features of the thruster in current use and to the design engineering of a brand-new thruster as well.

• Journal of the Korean Society of Propulsion Engineers
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• v.7 no.2
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• pp.23-35
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• 2003

"Backhole" is a new geometric parameter and is defined as an extra empty volume which is located behind the tangential entries at the rear part of the vortex chamber in the swirl injector. Backhole makes a difference to the spray characteristics of swirl injectors such as the spray angle, SMD, the mixing characteristics and so on. To find its characteristics, experiments are conducted by using a stroboscopic photography, a PDPA apparatus and a mechanical patternator. With the backhole, the mass flow rate of the swirl injector is increased and the center region of the injected flow has more large volume than that of without the backhole. Also the cone angle can be controlled by the backhole, so that the mixing efficiencies of swirl injectors are changed. Based on cold-flow tests, the swirl injector with the backhole may improve its performance.rformance.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.1
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• pp.140-152
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• 1989

The study on the penetration of sprays during the initial phase of injection period, i.e. ignition delay period, in high speed small D.I. diesel engines are strongly affected by such behavior. To investigate the penetration of the sprays injected through single cylinderical orifice, a mathematical model was developed and compared with experimental results. In this model, radial heterogeneity of fuel density in the spray, transiency of injection pressure difference, and spray outrunning phenomenon were considered simultaneously. Experiments on the behaviors of sprays in the high pressure air chamber were conducted at various injection pressure differences and different levels of back air pressure. The behaviors of sprays injected into the chamber through the conventional Bosch injection pump were visualized with side stroboscopic illumination. Comparison of the experimental results with predictions from the mathematical model confirmed the validity of the model. It was also found that during the initial phase of the injection period the penetration of sprays vs. time appeared to have two transition points; one corresponded to disintegration point of liquid fuel jet, the other to the beginning of steady state injection.

• Journal of ILASS-Korea
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• v.1 no.4
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• pp.1-7
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• 1996

• Journal of the Society of Cosmetic Scientists of Korea
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• v.37 no.1
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• pp.43-53
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• 2011

The conditions in fluid-bed processor for nanoencapsulation of azelaic acid-milk nano powder for acne nanocosmetics were optimized by response surface methodology (RSM). The maximum value of yield was 70.97 %. The yield was appreciably influenced by inlet air temperature, atomizing pressure, and feeding speed. The particle size increased with an increase in the feeding speed and a decrease in the atomizing pressure. The elution rate in saline solutions was appreciably influenced by inlet air temperature and atomizing pressure. The moisture content increased with higher atomizing pressure, which was demonstrated to be similar to the nanoencapsulation characteristics related to water activity. The Hunter's L and b values increased with an increase in the inlet air temperature. The optimum conditions estimated by RSM for the maximized values of yield, moisture content, particle size and elution rate in skin suitability were $67{\sim}73^{\circ}C$ of inlet air temperature, 0.6 ~ 0.8 mL/min feeding speed and 1.8 ~ 2.0 kg/$cm^2$ of atomizing pressure, respectively. These estimated values were in agreement with those measured by real experiments.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1998.10a
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• pp.7-7
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• 1998

액체 연료 분포의 균일성과 대칭성은 연소 효율을 높이고, 공해 물질을 줄이는데 있어서 필수적인 요소이기 때문에 분무 패턴을 정량적으로 해석하는 것은 매우 중요하다. 고전적으로 사용되고 있는 mechanical patternator는 ⅰ) 유동을 교란시키고, ⅱ) 공간 분해능이 떨어지며, ⅲ) 복잡한 재순환 유동이나 화학 반응이 있는 유동에서의 적용이 어렵다는 단점을 가지고 있다. 이러한 단점들을 극복하기 위하여 레이저를 이용한 optical patternator에 대한 연구가 진행되고 있다. Optical patternator는 유동을 교란시키지 않으면서 고해상도의 분무 패턴 측정을 할 수 있다. 형광 신호는 물질의 체적에 비례한다. 따라서, 레이저 평면광을 분무에 조사시켜 주어서 유도되는 형광 신호를 이용하는 평면액체 레이저 유도 형광법(PLLIF : Planar Liquid Laser Induced Fluorescence)은 분무패턴을 알아보는 매우 유용한 방법이다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.240-243
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• 2008

An experimental study was conducted to understand spray characteristics of rotating fuel nozzle by using high speed rotational system. The experimental apparatus consist of a fuel injection system, high speed rotational system, and acrylic case. The test is performed with several diameters and number of injection orifices. Spray characteristics such as droplet size and velocity are measured by PDPA(Phase Doppler Particle Analyzer). From the test results, we could understand the spray characteristics of rotating fuel nozzle with orifice number and diameter.