• Journal of Biosystems Engineering
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• v.17 no.1
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• pp.5-17
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• 1992

To develop an analytic method of combustion characteristics in a small sized and single cylinder type diesel engine for a power tiller, 1) the theoritical analysis of combustion gas in engine cylinder was performed based on thermoscience and 2) the computer program which could be used to calculate those values of the apparent burning rate, the heat loss, the gas temperature and the fuel-air equivalence ratio with the experimental cylinder pressure data, was developed. This method would provide the practical and quantative data for the diesel combustion process. Through the use of this method, following details would be obtained: 1) the application in the modeling of combustion process without detail knowledeg of combustion process, 2) the basis for the complete modeling of diesel engine, and 3) the basic information for the design of combustion chamber by the prediction of engine performance.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.6
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• pp.96-103
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• 2014

Liquefied Petroleum Gas(LPG) has attracted attention as a alternative fuel. The lean-burn LPG direct injection engine is a promising technology because it has an advantage of lower harmful emissions. This study aims to investigate the effect of combustion strategy and excess air ratio on combustion and emission characteristics in lean-burn LPG direct injection engine. Fuel consumption and combustion stability were measured with change of the ignition timing and injection timing at various air/fuel ratio conditions. The lean combustion characteristics were evaluated as a function of the excess air ratio with the single injection and multiple injection strategy. Furthermore, the feasibility of lean operation with stratified mixture was assessed when comparing the combustion and emission characteristics with premixed lean combustion.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.10
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• pp.3381-3386
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• 1996

The engine performance and combustion characteristics of methanol blended fuel in spark ignition engine were discussed on the basis of experimental investigation. The effects of methanol blending fuel on combustion in cylinder were investigated under various conditions of engine cycle and blending ratio. The results showed that the engine performance was influenced by the methanol blending ratio and the variations of operating conditions of test engine. The increase of fuel temperature brought on the improvement of combustion characteristics such as cylinder pressure, the rate of pressure rise and heat release in an engine. The burning rate of fuel-air mixture, the exhaust emissions and the other characteristics of performance were discussed also.

• Journal of Power System Engineering
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• v.12 no.4
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• pp.12-17
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• 2008

The purpose of this study is to analyse and compare the fuel combustion characteristics between LPG and gasoline on SI engine. Pressures of combustion chamber were measured on the state that engine speed was 2000rpm and BMEP was 2.0bar And we measured pressures of combustion chamber regarding variation of the MBT We could know that the combustion pressure of LPG fuel use engine is appeared lower than that of gasoline fuel use engine. At the lean mixture ratio area we could blow that Ignition timings are pulled very forward, and ignition timing of LPG fuel is advanced to $5\sim12^{\circ}$ CA than gasoline fuel. We learned that the value of coefficient of variation of LPG fuel is higher than gasoline fuel.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.4
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• pp.104-111
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• 2019

Staged combustion cycle engines exhibit higher combustion performance compared with open cycle engines with a gas generator. An advanced research of the staged combustion cycle engine is going on for the next program following the KSLV-II program. Various experiments have been carried out for the technology demonstration model, TDM0A and TDM0B. The experiments on the combustion performance are aimed to understand the engine start condition and combustion characteristics. They also aim to develop the oxidizer-rich pre-burner and the combustor of the staged combustion cycle engine. The engine-shaped model, TDM1A is fabricated based on the experimental data. The combustion experiment of the TDM1A shows that the combustion pressure of the combustor is approximately 91 bar and the turbine rotation is approximately 28,00 rpm. The result is stable and satisfies the development requirements. The present paper reports on the development process and characteristics of engine models from TDM0A to TDM1A.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.1
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• pp.67-75
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• 2002

A study to investigate the influence of combustion chamber shape, especially piston top face configuration, on the combustion stability is presented with CFD analysis and single cylinder GDI engine test. Initial configuration of the piston bowl was designed with CFD analysis and further parametric studies of the design factors on the piston top face were carried out through the single cylinder GDI engine test. It was found that both the geometry of piston top face and the compression ratio have great influences on the combustion stability. Of interest is that the design factors of the GDI piston to prevent mixture diffusion out of the piston bowl have important roles for the stable combustion at the stratified mixture condition. Also the relationship between spray impingement and flow pattern in a GDI piston bowl should be considered to design an optimal bowl configuration for stable stratified combustion.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.649-653
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• 2006

Engine Noise is composed of the mechanical and combustion noise. The contribution of combustion noise is generally bigger than the contribution of the mechanical noise at idle condition in DI diesel engine. That noise usually makes a roughness problem at the fundamental engine order. It is difficult to remove the modulation frequency so we have to directly reduce the combustion noise. The key effect of combustion noise reducing solution is the modification of the combustion pressure profile. It is accomplished by the multiple injection method and we solved the 400Hz combustion noise and improved the sound quality at idle condition in DI diesel engine.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.4
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• pp.19-27
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• 2021

In this study, a high-pressure subsacle thrust chamber was developed to verify the core technology for KSLV-II performance enhancement. The core technologies are the design of an injector for high-pressure combustion, development of a combustion stabilization device using the additive manufacturing technique, and the design and fabrication of mixing head and regeneratively cooled combustion chamber. The core technologies, which have been verified through the development of high-pressure subscale thrust chamber, will be used to develop large engine liquid rocket engine thrust chamber in the future.

• Journal of Advanced Marine Engineering and Technology
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• v.26 no.1
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• pp.37-47
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• 2002

Recently gasoline direct injection method has been applied to gasoline engine to reduce fuel consumption rate by controlling fuel air mixture on lean condition by means of stratified charging, and to reduce simultaneously. Pollutant emissions especially NOx and CO by lowering the combustion temperature. But difficulty of controling local fuel air ratio at ignition area in flammability limit unavoidably appeared, because it is merely controlled by injection timing with spatial and temporal distribution of fuel mixture. In this study, the authors devised a uniquely shaped combustion chamber so called three-chamber GDI engine, intended to keep the more reliable fuel air ratio at ignition area. The combustion chamber is divided into three regions. The first region is in the rich combustion division, where the fuel is injected from the fuel injection valve and ignited by the spark plug. The second region is in the lean combustion division, where the combustion gas from the rich combustion division flows out and burns on lean condition. And the last region is in the main combustion division ie in the cylinder, where the gas from the above two combustion divisions mixed together and completes the combustion during expansion stroke. They found that the stable range of operation of three-chamber GDI engine on low-load condition exists in the lean area of average equivalence ratio. And they also found that the reformed engine reveals less specific fuel consumption and less pollutant emissions compared with conventional carburettor type gasoline engine.

• Journal of Mechanical Science and Technology
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• v.15 no.10
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• pp.1442-1450
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• 2001

The EGR system has been widely used to reduce nitrogen oxides (NO$\_$x/) emission, to improve fuel economy and suppress knock by using the characteristics of charge dilution. However, as the EGR rate at a given engine operating condition increases, the combustion instability increases. The combustion instability increases cyclic variations resulting in the deterioration of engine performance and emissions. Therefore, the optimum EGR rate should be carefully determined in order to obtain the better engine performance and emissions. An experimental study has been performed to investigate the effects of EGR on combustion stability, engine performance,70x and the other exhaust emissions from 1.5 liter gasoline engine. Operating conditions are selected from the test result of the high speed and high acceleration region of SFTP mode which generates more NO$\_$x/ and needs higher engine speed compared to FTP-75 (Federal Test Procedure) mode. Engine power, fuel consumption and exhaust emissions are measured with various EGR rate. Combustion stability is analyzed by examining the variation of indicated mean effective pressure (COV$\_$imep/) and the timings of maximum pressure (P$\_$max/) location using pressure sensor. Engine performance is analyzed by investigating engine power and maximum cylinder pressure and brake specific fuel consumption (BSFC)