• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.2
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• pp.48-55
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• 2003

The effects of pressure charge on combustion stability and emissions have been analyzed using a GDI single cylinder engine. A late injection mode of stratified condition at the air-fuel ratio of 40:1 for 1200∼2400 rpm was tested while the boosted pressure ratio was increased up to 1.5:1. In-cylinder CFD analysis was also performed for better understanding of in-cylinder flow and fuel spray behavior. With a higher boosted pressure ratio the IMEP was increased greatly due to the increased engine load, and the ISFC was improved by more than 10% at all engine speeds. The regime of stable stratified combustion was extended to a higher engine speed, but the spark ignition angle had to be more advanced for stable combustion. The emissions of ISHC and ISNOx did not show a particular trend for the increased engine speed but a general trend of lower ISHC and higher ISNOx for a gasoline engine.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.3
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• pp.38-43
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• 2011

A CNG/diesel dual-fuel engine uses CNG as the main fuel and injects a small amount of diesel as an ignition priming. This study proposed the modification of the existing diesel engine into a dual-fuel engine that injects diesel with a high pressure by common rail direct injection (CRDI) and by injecting CNG at the intake port for premixing. And experiment was progressed for understanding about effect of CNG mixing ratio. The CNG/diesel dual-fuel engine showed equally satisfactory coordinate torque and power regardless of CNG mixing ratio. The PM emission was low at any CNG mixing ratio because of very small diesel pilot injection. In case of NOx and HC, high CNG mixing ratio showed low NOx and HC emissions at low speed. At medium & high speed, low CNG mixing ratio showed low NOx and HC emissions. Therefore, it would be optimized by controlling CNG mixing ratio.

• Aerospace Engineering and Technology
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• v.12 no.1
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• pp.111-119
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• 2013

Conceptual design of RBCC (Rocket Based Combined Cycle) engine is performed through the thermodynamic cycle analysis. The engine is designed to take off at sea level and accelerate to Mach 8 at 30 km altitude. According to the flight speed, the engine operating modes are categorized into 3 modes : Ejectorjet (~ Mach 3), Ramjet (Mach 3~6), Scramjet (Mach 6~8). As a design result, the engine has a diameter of 1 m and a length of 6.7 m. In the prediction results, its maximum thrust is 16.5 ton. In Ramjet and Scramjet modes, design condition of the engine intake influence the engine thrust according to the flight speed.

• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2769-2772
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• 2003

This paper presents results of the development of the Turbo-generator system with structure which is HSG(High Speed Generator) installed to high speed gas-turbine engine directly. Turbo-generator with high speed motor-generator directly has many advantages aspects of weight, size, lubrication system and complexity of the system compared of conventional turbo-generator system with gear-box. But because of direct high speed operation of the high speed generator, we have to need stable high speed motor driving algorithm for perfect engine ignition when gas turbine starting. Also we have to need design of the PCU(Power Conditioning Unit) for converting high speed AC output power to conventional AC power or needed DC power.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.3
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• pp.63-70
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• 1998

According to the stringent exhaust emission regulation control of air fuel ratio is one of the most important issues on gasoline engine. Although many researches have been carried out to identify the fuel transport phenomena in a port fueled gasoline engine, complexity of fuel film behavior in the intake port makes it difficult. The fuel film behavior was investigated recently by using visualization method and these gave us qualitative understanding. In this paper, the quantitative measurement method for the port fuel film is studied by using Fast Response Flame Ionization Detector(FRFID). The mass of fuel film on the port wall was measured by using the methods of fuel injection off, injection on and regression. The Fuel film mass was increased with incresing load at the same engine speed.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.3
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• pp.37-45
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• 1995

Effect of reentrant type bowl geometry on combustion characteristics was investigated in a D.I. diesel engine. The main factor was the cupola height of bowl center and the reentrant angle of combustion chamber, and the cylinder pressure, engine performance and emissions of the engine using the total 11 kinds of the combustion chamber were measured by test. The results are as follows. The NOx decreases by increasing the cupola height of bowl center because it makes the decreasing of maximum combustion pressure by the heat loss and smooth combustion from good airflow. The smoke increases by increasing the reentrant angle at high speed range of the engine, but decrease at low and medium speed range until the reentrant angle becomes $15^{\circ}$.

• Journal of Power System Engineering
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• v.2 no.3
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• pp.68-73
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• 1998

The propulsion diesel engine have been widely applied with a mechanical governor to control the truck speed for a long time. But it was recently very difficult for mechanical governor to control the speed of long stock and diesel engine of truck because of hunting by dead time between fuel injection and power output. This study is aimed to configure the modeling for performance simulation regarding to diesel truck operation which could be suppressed for hunting. The modeling have been made on the base of dynamic characteristic such as electronic governor, injection of fuel system and operating states of diesel engine truck. Real model system have been introduced for deciding reacting parameters and for the comparison of resulting performance in simulation. In results of simulation, we obtained items which diesel truck drives for suppressed hunting.

• Journal of Advanced Marine Engineering and Technology
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• v.19 no.3
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• pp.9-23
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• 1995

To analyze the spray and flame in D.I. diesel engine, the visualizing methods by schlieren photograph and diffused background illumination photograph with high speed camera are applied to optically accessible D.I.diesel engine. Wcaporating spray, spray droplets and brightness flame are taken with high speed camera by visuallizing method in accordance with various suction air temperature and injection time. The spray and flame image on the film was analyzed by image analyzer. The optically accessible D.I. diesel engine had the similar pressure characteristic to the real D.I. diesel engine. Experimental results showed that shadow areas of the evaporating spray were extended at higher suction air temperature, spray droplets had a max. Penetration length and their penetrating patterns were dependent on the surrounding gas temperature, and flame size after ignition was largely governed by the evaporated fuel quantity at ignition point and by the surrounding gas condition due to piston motion.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.554-559
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• 2007

The cylinder cover stud for assembling the combustion chamber components of low-speed marine diesel engine is one of the main structural components in engine. To understand the structural behavior of the stud is quite important for safe and economic design of it. In this paper, the structural behavior and design adequacy of the stud have been evaluated through strain measurement and structural analysis for the world's two largest engine types. Moreover, a feasibility study for design modification was carried out based on fatigue test and calculation. The results showed that 1) the stud experiences very high stress ratio under normal operating conditions, 2) the fatigue strength of the stud is sufficient, and 3) results from strain measurement and structural analysis were quite close each other.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.6
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• pp.628-636
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• 2005

In this paper. the effects of a WI(Water Injection) in the intake pipe for a 4-cylinder Dl(Direct Injection) diesel engine are investigated experimentally, The WI system was controlled by the duty cycle from the intake manifold's temperature and MAF(Manifold Air Flow) First. effect of EGR on NOx reduction was investigated. Then WI system was applied to reduce NOx As the results. we can make the NOx map and visualize the NOx results by variation of engine speed and engine load It was known that effect of WI system on NOx reduction without the EGR was better than the with EGR base engine except of low load and speed condition.