• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.6
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• pp.83-88
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• 2014

LTC(Low Temperature Combustion) technology has been studied to see feasibility of the combustion technology applied to heavy-duty engines on the laboratory scale. This study succeeded to develop a demo engine including realized low temperature combustion under partial load conditions. To find the best feasible LTC strategy, various LTC combustion methods such as PPCI, MK and highly diluted mixing controlled LTC were conducted on 6.0L heavy duty diesel engine. Air management system was re-designed to make these combustion scheme stable and the re-designed air system helped expand LTC operating range. This study finally revealed plausible LTC concept to maximize benefit of the alternative combustion technology while overcoming handicaps of the LTC strategy.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.1
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• pp.180-188
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• 1992

By means of the compatibility according to solving environmental pollution and energy problem due to the emissions of NOx and smoke from diesel engine this paper experimentally inspected the effect of using emulsified fuel, gas oil-water, for combustion characteristic, that is combustion pressure, pressure rise rate, heat generating rate, the period of ignition delay and specific fuel consumption, and CO, HC, NOx concentration and smoke density. When using emulsified fuel, as a water addition rate was increased, combustion pressure, pressure rise rate and heat generating rate was increased, the period of ignition delay was lengthening, the specific fuel consumption was some what increased in contrast to diesel fuel in low load, but deceased in high load region. And NOx concentration was decreased, CO concentration was increased in low load, but decreased in high load region, HC concentration was increased in contrast to diesel fuel in all region.

• Journal of the Korean Society of Combustion
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• v.15 no.4
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• pp.53-57
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• 2010

The purpose of the present work is to investigate the effect of gasoline-premixing on a combustion and emissions characteristics in a compression ignition engine. For studying combustion characteristics, a combustion pressure and rate of heat release (ROHR) were measured using a single-cylinder DI compression ignition engine with a common-rail injection system and premixed fuel injection system. In addition, exhaust emissions characteristics were studied using emission analyzers and smoke meter. The experimental results showed that the case of gasoline-premixing had longer ignition delay and lower combustion pressure compared to the cases of diesel direct injection. Furthermore, premixed gasoline-air mixture reduced NOx emissions due to low peak of ROHR.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.6
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• pp.46-52
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• 2011

Homogeneous charge compression ignition (HCCI) is the best concept able to provide low NOx and PM in diesel engine emissions. This new alternative combustion process is mainly controlled by chemical kinetics in comparison with the conventional combustion in internal combustion engine. However, HCCI engine's operation have an excessive rate of pressure rising during the combustion process. In this study, stratification condition of EGR exhaust gases was used to reduce the pressure rising during the combustion process in HCCI engine. Also, combustion characteristics and emissions characteristics were investigated using the detailed diesel surrogate reaction mechanism.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.5
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• pp.635-644
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• 1986

A Compuressible turbulent boundary layer effect of the high temperature, accelerating gas flow through the De-Laval nozzle on combustion chamber pressure is numerically investigated. For this purpose, the coupled momentum integral equation and energy integral equation are solved by the Bartz method, and 1/7 power law for both the turbulent boundary layer velocity distribution and temperature distribution is assumed. As far as the boundary layer thicknesses are concerned, we can obtain reasonable solutions even if relatively simple approximations to the skin friction coefficient and stanton number have been used. The effects of nozzle wall cooling and/or mass flow rate on the boundary layer thicknesses and the combustion chamber pressure are studied. Specifically, negative displacement thickness is appeared as the ratio of the nozzle wall temperature to the stagnation temperature of the free stream decreases, and, consequently, it makes the combustion chamber pressure low.

• 한국연소학회:학술대회논문집
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• 2005.10a
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• pp.255-260
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• 2005

To achieve efficient combustion within a manageable length, a successful fuel injection scheme must provide rapid mixing between the fuel and airstreams. The aim of the present numerical research is to investigate the flame holding and combustion enhancement. Additional fuel into the cavity prevents shear flow impingement on the trailing edge of the cavity. The high temperature freestream flow mixes with the cold hydrogen fuel that is injected into the cavity and raises the fuel temperature remarkably and become to start combustion. The high pressure in the cavity due to the cavity structure and combustion leads the hydrogen fuel to upstream. The shock in the cavity to be generated by the fuel injection joins together and reflects off the ceiling wall. This makes high pressure and low mach number region and makes a small recirculation in this region. This high stagnation temperature is nearly recovered in the shear layer in front of the cavity and leads to start combustion. In the downstream of the cavity, the wall pressure drops significantly. This means that the combustion phenomenon is diminished. Because fuel lumps at the trailing edge of the cavity then it spreads after the cavity so, in this region there is a strong expansion.

• 한국연소학회:학술대회논문집
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• 2007.05a
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• pp.31-36
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• 2007

The supersonic combustion experiments are carried out using T3 free-piston shock tunnel. Hydrogen Fuel is injected in the cavity parallel with air(or nitrogen fuel) flow. The equivalence ratios in this study are 0.132 and 0.447. Experimental measurements use OH-PLIF near the cavity and pressures in the combustor. For parallel fuel injection case, direct fuel add into cavity leads to increase of cavity pressure. And Flame exists just near the bottom wall for low equivalent ratio. There is no flame in the cavity because of no mixing in it. Compared to the inclined fuel injection, ignition delay length is longer for low equivalence ratio in both case. OH distribution is not a single line but a repeatable fluctuation flame structure by turbulence. Pressure distributions have nothing to do with the fuel injection position.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1994.11a
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• pp.39-45
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• 1994

Combustion characteristics of the solid composite propellants were studied from burning rate, ignition and steady combustion processes, and structure of the extinguished surfaces. Optical Vacuum Strand Burner (OVSB) system was desisted and configured to study those. Burning rates of the propellants were measured by OVSB at low pressure range by developed ten method. video camera(30 frames/s) was used to take potographs of the phenomena of ignition and combustion of propellant within the test cell of the OVSB. Burning surfaces of the propellants that were extinguished by rapid depressurization method were analyzed with Scanning Electron Microscope. (SEM).

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.55 no.4
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• pp.411-418
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• 2019

In this study, to investigate the effect of physical and chemical properties of butanol on the engine performance and combustion characteristics, the coefficient of variations of IMEP (indicated mean effective pressure) and fuel conversion efficiency were obtained by measuring the combustion pressure and the fuel consumption quantity according to the engine load and the mixing ratio of diesel oil and butanol. In addition, the combustion pressure was analyzed to obtain the pressure increasing rate and heat release rate, and then the combustion temperature was calculated using a single zone combustion model. The experimental and analysis results of butanol blending oil were compared with the those of diesel oil under the similar operation conditions to determine the performance of the engine and combustion characteristics. As a result, the combustion stabilities of D.O. and butanol blending oil were good in this experimental range, and the indicated fuel conversion efficiency of butanol blending oil was slightly higher at low load but that of D.O. was higher above medium load. The premixed combustion period of D.O. was almost constant regardless of the load. As the load was lower and the butanol blending ratio was higher, the premixed combustion period of butanol blending oil was longer and the premixed combustion period was almost constant at high load regardless of butanol blending ratio. The average heat release rate was higher with increasing loads; especially as butanol blending ratio was increased at high load, the average heat release rate of butanol blending oil was higher than that of D.O. In addition, the calculated maximum. combustion temperature of butanol blending oil was higher than that of D.O. at all loads.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.7
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• pp.951-962
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• 2010

An experimental study was performed to investigate the improvement of response performance of a turbocharged diesel engine under the operating conditions of low speed and fast acceleration. In this study, the experiment for improving the low speed and acceleration performance is performed by means of injecting air into the intake manifold of compressor exit during the period of low speed and application of a fast acceleration from low speed. The effects of air injection into the intake manifold on the response performance were investigated at various applicant parameters such as air injection pressure, accelerating rate, accelerating time, engine speed and load. The experimental results show that air injection into the intake manifold at compressor exit is closely related to the improvement of turbocharger lag under low speed and accelerating conditions of a turbocharged diesel engine. During the rapid acceleration period, the air injection into the intake manifold of turbocharged diesel engine indicates the improvement of the combustion characteristics and gas pressure in the cylinder. At low speed range of the engine, the effect of air injection shows the improvement of the pressure distribution of turbocharger and combustion pressure during the period of gas exchange pressure.