• 한국연소학회:학술대회논문집
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• 1999.10a
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• pp.21-26
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• 1999

Liquefied petroleum gas(LPG) has been used as motor fuel due to its low emissions and low cost. The fuel feeding system has been improved with stringent requirement for exhaust emissions. LPG carburation system was firstly introduced, then the system changed into a gas injection system controlled precisely, but those gas feeding system has a limitation on improving power output. In order to improve an engine performance, a multi-point port injection system was introduced recently, and a liquid direct injection system into a cylinder was suggested as a next generation system to maximize a fuel economy as well as a power. This study addresses the analysis of the LPG spray from diesel injectors. The spray images are visualized and compared with diesel sprays in a wide injection pressure range. The photographs show much wider dispersion of LPG sprays.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.33-35
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• 2012

This study has been mainly motivated to numerically model the supercritical mixing and combustion processes encountered in the liquid propellant rocket engines. In the present approach, turbulence is represented by the extended k-e model. To account for the real fluid effects, the propellant mixture properties are calculated by using generalized cubic equation of state. In order to realistically represent the turbulence-chemistry interaction in the turbulent nonpremixed flames, the flamelet approach based on the real fluid flamelet library has been adopted. Based on numerical results, the detailed discussions are made for the effects of swirl number on flame structure of supercritical kerosene/LOx double swirl coaxial injector.

• Journal of ILASS-Korea
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• v.8 no.3
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• pp.1-9
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• 2003

The objective of this study is to compare atomization characteristics for differently made an ultrasonic twin-fluid nozzle. A spray system, an ultrasonic system, and three different type(Nozzle type, Tube type. Conventional type)are made and compared experimental and numerical results. In this investigation, the measurement and numerical analysis of spray droplet are to analyze the effects of ultrasonic energy on the agricultural atomization spray system in order to protection of dispersion droplets. It is clarified that ultrasonic energy forcing into a nozzle is valid to obtain atomization enchancement. As the result of comparing the experimental and numerical result, it is confirmed that nozzle type is highest efficiency than that of tube type and conventional type, also well fit, respectively.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.551-554
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• 2006

Inhibition of propellant temperature rising in liquid propulsion rocket using cryogenic fluid as a propellant is very important. Especially propellant temperature rising during stand-by after filling and pre-pressurization can bring into cavitation in turbo-pump. One of the method preventing propellant temperature rising in cryogenic feeding system is recirculating propellant through the loop composed of propellant tank, feed pipe, and recirculation pipe. The circulation of propellant is promoted through gas-lift effect by gas injection to lower position of recirculation pipe. In this experiment liquid oxygen and gas helium is used as propellant and injection gas. Under atmospheric and pressurized tank ullage condition, helium injection flow-rate is varied to observe the variation of recirculating flow-rate and propellant temperature in the feed pipe. There is appropriate helium injection flow-rate for gas-lift recirculation system.

• Journal of ILASS-Korea
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• v.25 no.2
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• pp.74-80
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• 2020

The jet in crossflow is a spray method used in the various air-breathing engine. In order to understand the spray characteristics in various environments, many prior studies have been conducted. However, there is a lack of understanding of the low-temperature liquid spray characteristics below 273 K. With this in mind, we tried to enhance the knowledge of the low-temperature liquid spray characteristics by identifying the penetration height of low-temperature ethanol. The experiment was conducted under phase pressure, and 273 K of air and 293, 263, and 233 K of ethanol was used. Shadowgraphy was employed to measure the liquid penetration, and Otsu's method was used to analyze the penetration height. The heights tend to decrease as the temperature of the liquid jet decreases. A correlation for the penetration height in the experimental conditions was derived and presented.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.6
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• pp.16-23
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• 2001

Spray dispersion in high pressure diesel engines have been simulated experimentally with a special emphasis on the effect of swirl by using a liquid injection technique. A constant volume chamber was designed to be rotatable in order to generate a continuous swirl and to have the flow field closely resembling a solid body rotation. Emulsified fuel was injected into the chamber and the developing process of fuel sprays was visualized. The effect of swirl on the spray dispersion was quantified by calculating non-dimensionalized dispersion area according to the spray tip penetration length. The results show that the effect of swirl on the spray dispersion is different between short and long spray penetrations. For short range of spray tip penetration, the effect of swirl on spray dispersion is quite small. However, as the spray tip is penetrated into longer distance in spray chamber, the effect of swirl on spray dispersion becomes larger. These results can be used as a basic data for designing combustion chamber and injection system of direct injection diesel engine.

• Journal of ILASS-Korea
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• v.8 no.4
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• pp.1-8
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• 2003

The objective of this study is to investigate experimentally atomization characteristics for differently made an ultrasonic twin-fluid nozzle. A spray system, an ultrasonic system, and three different type(Nozzle type, Tube type, Conventional type)are made and tested by applied with ultrasonic energy. In this investigation, the measurement and calculation of spray droplet are to analyze the effects of ultrasonic energy on the agricultural atomization system. Through the measurement of suray angle, spray column using, high speed camera and PDA, it is found that nozzle type is highest efficiency than that of tube type and conventional type. It was found that the ultrasonic energy increased the atomization efficiency of spray droplets about 9% respectively and spray angle was wide spray.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.9
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• pp.863-871
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• 2004

The use of fossil fuels like coal, oil and natural gases around the world causes an increase of the carbon dioxide content in the atmosphere. In order to reduce the concentration of the greenhouse gas, the idea of carbon dioxide sequestration in the ocean is proposed to be an effective mitigation strategy to counteract potential global warming due to the greenhouse effect. Therefore, in the present study, calculations of the dissolution behavior of carbon dioxide when liquid carbon dioxide is released at 1,000m and 1,500m in depth by fixed pipeline are performed. The results show that carbon dioxide droplets change to carbon dioxide bubbles in gas phase around 500m in depth, and the droplets are completely dissolved below 500 m in depth if the liquide carbon dioxide is released both at 1,000 m in depth with the initial diameter of 0.007m or less and at 1,500m in depth with the diameter of 0.011m or less.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1999.10a
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• pp.9-9
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• 1999

액체로켓 엔진의 분사기와 연소실 설계에 사용될 재생냉각형 칼로리미터의 냉각유로를 설계하였다. 사용할 펌프의 수두는 5기압이며 이로써 끓는점 아래에서 작동할 수 있고 동시에 넓은 냉각 면적을 가지는 유로의 형상을 결정하였다. 유로에서의 압력강하와 온도분포는 전산유동해석에 의하여 구하였고 열부하는 기존의 연소 해석과 1차원해석에 의한 결과를 적용하였다. 해석결과로서 유로의 폭이 4mm에서 2.5mm까지 2단계로 줄었다가 다시 2단계로 늘어나는 냉각유로를 설계하였으며 이 때 높이는 2mm로 일정하게 유지하였다. 유량 변화에 의한 레이놀즈 수는 1.9$\times$$10^4$, 2.4$\times$$10^4$, 2.9$\times$$10^4$이며 세 경우 모두 주어진 펌프수두 이내의 압력강하를 보였으나 온도상승과 성능상의 여유를 고려하여 레이놀즈 수 2.4$\times$$10^4$인 경우를 최종 설계안으로 결정하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.594-596
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• 2010

Hot-firing tests were performed on a sub-scale gas generator for development of a 75 ton-class liquid rocket engine. This paper deals with the analysis results of low-frequency combustion instability that encountered during combustion tests of the gas generator.