• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.8
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• pp.1097-1102
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• 2001

For the purpose of development of high performance gasoline engine, the design technique of the 5-valve(3 intake valves) combustion chamber for a subcompact vehicle has been studied. 3 intake valves cylinder heads were designed by using a 3-dimension CAD program, and steady state flow experiments have been performed with these model. The 5-valve engines, which have larger valve opening areas, have larger intake flow rates and higher flow coefficient than the 4-valve engines. The effects of intake port design parameters of a 5-valve engine on the intake flow rate and bore size were studied, and the design guidelines for the 5-valve engine were established.

• Journal of ILASS-Korea
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• v.7 no.3
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• pp.1-6
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• 2002

In this study numerical and experimental study on the spray atomization characteristics of a GDI injector is performed. To carry out numerical analysis, four hybrid models that are composed of conical sheet disintegration model, LISA model, DDB model, and RT model are used. The experimental results to evaluate the prediction accuracy of hybrid models are obtained by using phase Doppler particle analyzer and spray visualization system. It is shown that the prediction accuracy of hybrid model concerning spray developing process and spray tip penetration is good for all hybrid models, but the hybrid breakup models show different prediction of accuracy in the case of local radial SMD distribution.

• Journal of ILASS-Korea
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• v.3 no.1
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• pp.10-18
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• 1998

To investigate the in-cylinder phenomena in a SI engine with 3 valves and pent-roof type combustion chamber, flow fields, fuel distributions, and flame propagations were measured in a single c!'tinder visualized engine. Flow fields were visualized by PTV system during the intake and compression process. Fuel distributions were measured by PLIF at the various engine conditions including the cold and hot engine conditions and the effect of air-shrouded injector on the fuel distribution was investigated also. In addition, flame propagation patterns were characterized.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.6
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• pp.202-209
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• 1998

For development of SDI(Spark-ignited Direct Injection) engine, stratified mixture formation with adequate strength at spark plug was required in wide range of engine operating conditions. So, spray structure under high ambient pressure and spray distribution after impingement on piston bowl in motoring engine was visualized by using laser equipments. Also, incylinder bulk flow structure was measured by using PIV (Paiticle Image Velocimetry) system. Counter-rotating tumble port and bowl piston was found effective to conserve bulk motion directed to spark plug in compression stroke. In addition, mask attached near valve seat in intake port was proposed to attenuate conventional tumble component and enhance counter-rotating tumble component.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.8
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• pp.5082-5088
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• 2015

In this paper, durability test of 1000cc level gasoline engine has been carried out. Durability test set total 300 hours and WOT condition. Engine torque, power, fuel consumption, blow-by gas flow rate, and oil pressure are measured to analyse performance variation by time. As a result, engine performance of high rpm range gradually reduced by time but for relatively low rpm range shows stable performance. Blow-by gas flow rate shows 0.4% of averaged induction air flow rate, which is excellent rate for 1000cc level gasoline engine. Engine torque and fuel consumption data show the break-in upto 100 hours and aging trend after that. After 300 hours, engine is disassembled and each part is checked for the damage or crack.

• Current Industrial and Technological Trends in Aerospace
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• v.6 no.1
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• pp.35-43
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• 2008

Technical trends of propulsion system for small aircraft are investigated. Currently, most small aircraft are equipped with piston engine, turboprop and turbofan engines, and the technology development is going continuously. For piston engines, new diesel engines are arising besides gasoline engine. The diesel engines use relatively low-cost and easy to get fuel(Jet A), so the demand for small aircraft is getting increased, and new engines with high reliability and efficiency are being developed. For gas turbine engines, application of small turbofan is getting increased for newly arising VLJ market and the engine demand will be rapidly increased in the future. On the other hand, some electric propulsions without fossil fuels are being developed without high cost of fuel and environmental effects. In the future, propulsion system for small aircraft will be developed having enhancement of performance and efficiency with higher reliability and safety.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.765-770
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• 2020

The turbochargers used widely in diesel and gasoline engines are effective devices to reduce fuel consumption and emissions. In this study, the isentropic turbine efficiency of the steady flow in a twin-scroll turbocharger for the passenger vehicle gasoline engine was analyzed. The cold gas test bench was designed and made. The pressure and temperature of the inlet and exit of the turbine were measured at 60,000, 70,000, 90,000, and 100,000rpm under the steady-state flow. The isentropic turbine efficiency was calculated. The efficiency was the range of 0.53 to 0.57. The BSR and expansion ratio were changed from 0.71 to 0.84 and from 1.24 to 1.72, respectively. The isentropic turbine efficiency decreased with increasing BSR and expansion ratio. The operation of only scroll A or B was compared with that of the twin-scroll turbine. The isentropic efficiency of using only scroll B was higher than those of only scroll A at 60,000rpm. The isentropic efficiency of using only scroll A was higher than those of only scroll B at 100,000rpm. Therefore, the twin-scroll turbine used in this study is operating effectively in the wide speed range.

• Journal of the korean Society of Automotive Engineers
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• v.17 no.3
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• pp.11-18
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• 1995

본 논문에서는 주철 라이너를 삽입한 알루미늄 블럭 엔진 개발과정에서 주조 불량이 발생하였을때, 냉각계에 일어나는 제반 현상을 분석하고, 이를 해결해 나가는 과정을 기술하였다. 이를 위하여 주철 블럭과 알루미늄 블럭을 장착한 엔진의 피스톤 온도와 블럭의 열유속, 열정산을 측정하였다. 측정한 결과는 다음과 같다. 1. 알루미늄 블럭 제작시 주철 라이너와 알루미늄 블럭 사이에 공기층이 크거나, 용탕 충진이 불완전한 주조 불량이 발생하면 열접촉 저항이 커져 엔진 열전달 경로에 큰 영향을 준다. 2. 알루미늄 블럭 제작시 주조 불량이 발생하면 피스톤에서 라이너로의 전열량이 줄어듦에 따라 냉각수로의 전열량은 감소하는데, 6,000rpm, 전부하에서 알루미늄 블럭의 출력 대비 냉각수로의 방열량의 비는 38.3%이고, 주철 블럭은 44.1%이다. 3. 알루미늄 블럭 제작시 주조 불량이 발생하면, 피스톤 온도가 15-20.deg.C 정도 상승하여 피스톤 손상을 유발시킬 수 있다. 4. 알루미늄 블럭의 주조가 완벽하게 되어 주철 라이너와 알루미늄 몸체 사이에서의 열접촉저항이 없어지면, 스토로크 방향에 따른 금속면 온도 분포가 균일하게 된다. 5. 실린더 라이너의 주조상태 개선없이 오일젯을 사용한 결과 피스톤의 온도를 만족할 만한 수준으로 감소시켰다. 6. 6000rpm, 전부하에서 오일젯 적용시 출력 대비 냉각수로의 방열량의 비가 38.3%에서 36.2%로 감소하고, 출력대비 오일로의 방열량의 비는 9.6%에서 11.2%로 증가한다. 7. 오일젯 작용시 오일 펌프의 용량 증대와 오일 쿨러의 장착이 필수적이다.

• Journal of Energy Engineering
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• v.22 no.4
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• pp.399-405
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• 2013

The gas motion inside the engine cylinder plays a very important role in determining the thermal efficiency of an internal combustion engine. A precise information of in-cylinder three dimensional complex gas motion is crucial in optimizing engine design. Homogeneous charge compression ignition (HCCI) engine is a combustion concept, which is a hybrid between Otto and Diesel engine. The turbulent diffusion leads to increased rates of momentum, heat and mass transfer. The in-cylinder turbulence flow was found to affect the present HCCI combustion mainly through its influence on the wall heat transfer. This study investigates the effect of piston geometry shape on the turbulent flow characteristics of in-cylinder from the numerical analysis using the LES model and the results obtained can offer guidelines of the combustion geometries for better combustion process and engine performance.

• Journal of the Korean Institute of Gas
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• v.19 no.6
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• pp.22-27
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• 2015

Hydrogen features highest energy density per mass and is expected to be desirable as a fuel of HALE(High altitude long endurance) UAV(Unmanned aerial vehicle). A reciprocating internal combustion engine is known to be a reliable and economic power source for this kind of UAV. Therefore, the combination of hydrogen and engine is worth of doing research. Test bench with 2.4L Spark-Ignited engine was prepared for the experiment in which start and combustion characteristics at idle condition were examined in this study. Stable hydrogen supply system and a universal ECU(Engine control unit) were also utilized for the test engine. Equivalence ratio and spark timings at idle operation were investigated and compared to the data of gasoline engine. The results will be a starting point for full-scale research of hydrogen engine for HALE UAV.