• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.636-640
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• 2011

Film cooling technique has been applied to effectively reduce thermal load on liquid rocket combustion chambers by direct injection of a portion of propellant, which flows through the regeneratively cooling channels, into the chamber wall. This study developed a comprehensive model to quantitatively predict the effects of kerosene film cooling on propulsive performance and wall cooling at supercritical pressure conditions, and assessed the predictive capability against hot-firing tests of an actual combustor. The present model is expected to be utilized as a design and analysis tool to meet the conflicting requirements in terms of performance, cooling, pressure loss and weight.

• Journal of the Korean Society of Combustion
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• v.15 no.4
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• pp.29-36
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• 2010

An experimental study was conducted for three different fuels($CH_4$, $C_2H_4$ and $C_3H_8$) to investigate the combustion characteristics and the local reaction intensity with combustor pressure(-30kpa~30kpa). Regardless of fuel composition, EINOx decreased with reducing pressure decreased. Structure and combustion characteristics were also largely affected by the combustor pressure. In addition, reaction intensity in terms of the changing combustor pressure and equivalence ratio was investigated. Combustion reaction in higher than atmospheric pressure was very active than the lower combustor pressure. When the combustor pressure is lower than the atmospheric pressure, the overall reactivity is noticeably enhanced due to the elevated diffusion process of unburned mixture. It was found that the combustion characteristics of the methane and propane flames are considerably influenced by the pressure while those of ethylene flame are less sensitive to the combustor pressure.

• Journal of the Korean Society of Combustion
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• v.16 no.3
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• pp.33-40
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• 2011

Combustion experiments were conducted at three different fuels ($CH_4$, $C_2H_4$ and $C_3H_8$) to investigate the effects of combustor pressure (30 ~ -30 kPa) on combustion charateristics and reaction zone structure. Regardless of the fuels, emission index of CO (EICO) increased with decreasing combustor pressure, and EICO of $C_2H_4$ was mostly affected by changing combustor pressure at subatmospheric pressure. In order to observe reaction zone, $OH^*$, $CH^*$ and ${C_2}^*$ chemiluminescence intensity were measured. The sequence of the chemiluminescence intensity peak position was affected by chemical characteristics of fuels rather than changing combustor pressure. The emission zone thickness of $C_2H_4$ and $C_3H_8$, defined by the full width at half maximum (FWHM) of $CH^*$ intensity profile, were increased with decreasing combustor pressure. however, the thickness of $C_2H_4$ exhibited the opposite tendency due to the characteristics of the fuel as the bond structure.

• Journal of the Korean Ceramic Society
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• v.38 no.6
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• pp.545-550
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• 2001

본 연구에서는 분사연소합성(SCS)을 위한 기초단계로서 용액연소합성에 대한 거동을 살펴보고자 알루미나 합성을 모델로 하였으며 이를 위해 전구체에 대한 열분해거동, 그리고 각 온도에서의 평형종 분압 계산 및 합성과정을 조사하였다. 각각의 열중량 분석(TGA) 결과 산화제와 환원제(연료)의 열분해 이력이 서로 다르게 나타났으며, 열역학 응용 프로그램인 ChemSag에 의한 평형종 분압의 계산에서 연소속도를 저하시킬 수 있는 $CO_2$와 수증기 가스 분압이 상당부분 존재하였다. 산화제/환원제 혼합물의 열분석(DTA/TG) 결과 산화제와 환원제의 열분해 거동의 차이, 그리고 매우 작은 시료의 양으로 인해 263$^{\circ}C$에서 발열피크가 매우 작게 나타났다. 열분석 시료에 비해 발열 에너지를 높이기 위해 산화제와 환원제 혼합 전구체를 비이커에서 증기압을 조절하며 가열시켜 본 결과 27$0^{\circ}C$에서 $\alpha$-Al$_2$O$_3$생성물을 얻을 수 있었다. 따라서 분사연소합성 반응을 통해 세라믹 원료를 합성하기 위해서는 연소과정 중 열분해 거동과 평형종의 분압을 고려하여야 한다.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.1
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• pp.93-100
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• 2017

Four-stroke cycles in an automobile engine are suction stroke, compression stroke, combustion stroke and exhaustion stroke. A normal operation of engine in compression and power stroke must be processed in optimal fuel-air pressure. In this paper we describe a development of measuring equipment for engine cylinder pressure with observing supply current to self motor(start motor). By comparing the current wave on pressure of the 4 or 6 cylinder in engine, a abnormal cylinder state will be found. The validity of the proposed measuring equipment was shown by experiment for real automobile.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.4
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• pp.614-621
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• 2002

This study was performed to investigate the behavior of vapor phase of fuel mixtures with different piston bowl shapes(F, B and R-type) in a optically accessible engine. The images of liquid and vapor phases were captured in the motoring engine using exciplex fluorescence method. Fuel was injected into atmospheric nitrogen to prevent quenching phenomenon by oxygen. Injection pressure was 5.1MPa. Two dimensional spray fluorescence image of vapor phase was acquired to analyze spray behaviors and fuel distribution inside of cylinder. Four injection timings were set at BTDC 90$^{\circ}$, 80$^{\circ}$, 70$^{\circ}$, and 60$^{\circ}$. With a fuel injection timing of BTDC 90$^{\circ}$, fuel-rich mixture level in the center region was highest in a B-type piston. With a fuel injection timing of BTDC 60$^{\circ}$, R-type piston was best. R-type piston shape was suitable under enhanced swirl ratio and late injection condition and B-type piston shape was right in a weak swirl ratio. It was found that the piston bowl shape affected the mixture stratification inside of cylinder.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.704-709
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• 2000

Laminar burning velocities of propane- and iso-octane-air mixtures have been numerically modelled over a wide range of equivalence ratio, pressure and temperature. These correlations are applicable to the modelling of stratified charged combustion like that of lean bum and GDI engine combustion. The numerical models are based on the results calculated by PREMIX code with Sloane's detailed chemical reaction mechanism for propane and FlameMaster code with Peters' for iso-octane. Laminar burning velocity for two fuels showed a pressure and temperature dependence in the following form, in the range of $0.1{\sim}4MPa$, and $300{\sim}1000K$, respectively. $S_L={\alpha}\;{\exp}[-\xi({\phi}-{\phi}_m)^2-{\exp}\{-{\xi}({\phi}-{\phi}_m)\}-{\xi}({\phi}-{\phi}_m)]$ where ${\phi}_m=1.07$, and both of ${\alpha}$ and ${\xi}$ are functions of pressure and temperature. Compared with the results of the existing models, those of the present one showed the good agreement of the recent experiment data, especially in the range of lean and rich sides. Judging from the calculated results of the stratified charged combustion by using STAR-CD, the above modelling prove to be more suitable than the other ones.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.12
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• pp.992-999
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• 2009

The focus of this study is placed on the behavior characteristics of gasoline spray under condition field of room temperature and pressure. To analyze the behavior and flow characteristics of injected fuel spray is important in speculation of mixture formation process. Also the exhausted emissions from actual engines can be controlled by the analyzed results. The ${\varphi}$(degree of freedom) and K(energy ratio of particle motion) are selected as the simulation parameter. The factors affect characteristics of spray structure, and the factors are included in the sub-program of the KIVA-II code. In this study, the simulation study by modified KIVA-II code was conducted and the calculated results obtained by the modified KIVA-II code show good agreements with experimental results. As a result, applying the improved TAB model with ${\varphi}$=8 and K=2 to simulation analysis of the KIVA-II code is sufficiently useful for analyzing the macro characteristics in spray structure, such as the spray tip penetration of injected fuel spray.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.915-920
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• 2001

This study was performed to investigate the behavior of vapor phase of fuel mixtures with different piston bowl shapes(F, B, and R-type) in a optically accessible engine. The images of liquid and vapor phases were captured in the motoring engine using exciplex fluorescence method. Fuel was injected into atmospheric nitrogen to prevent quenching phenomenon by oxygen. Injection pressure is 5.1MPa. Two dimensional spray fluorescence image of vapor phases was acquired to analyze spray behaviors and fuel distribution inside of cylinder. Four injection timings were set at BTDC $90^{\circ},\;80^{\circ},\;70^{\circ},\;and\;60^{\circ}$. With a fuel injection timing of BTDC $90^{\circ}$, fuel-rich mixture level in the center region was highest in a B-type piston. With a fuel injection timing of BTDC $60^{\circ}$, R-type piston was best. R-type piston shape was suitable under enhanced swirl ratio and late injection condition and B-type piston shape was right in a weak swirl ratio. It was found that the piston bowl shape affected the mixture stratification inside of cylinder.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.75-78
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• 2007

천연가스의 수증기 및 이산화탄소 복합 개질은 탄화수소화합물과 이산화탄소를 원료로 사용하여 수소를 생산하는 공정으로, 온실가스로 지목되고 있는 주요 화합물을 수소와 일산화탄소 혼합 가스로 전환시켜 합성 반응 또는 연료전지에 사용할 수 있도록 해준다. 본 연구에서는 $MgAl_2O_4$를 지지체로 하는 니켈계 촉매를 제조하여 수증기 및 이산화탄소 복합 개질 반응에 사용하였으며, 기존의 수증기 개질촉매 적용 시 문제가 되었던 탄소 침적에 의한 촉매 비활성화를 피할 수 있었다. 개발된 촉매 레시피를 바탕으로 펠릿 촉매를 제조하여 0.1 bpd규모의 Fischer-Tropsch 합성 반응에 적용 가능한 튜브형 반응기에 적용하여 수증기 및 이산화탄소 복합 개질 반응을 실시하였으며, 반응기의 온도 구배, 가스 조성 변화를 관찰하였다. 반응 조건에 따른 촉매 및 반응기의 성능 최적화를 실시하여 최적 촉매 및 반응기 성능을 모색하고자 하였다.