• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.311-313
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• 2014

High pressure combustion with multiphase--liquid, gas, and supercritical phase--mixtures are widely used technology in the high efficiency liquid propellent rocket engine. This is the typical characteristics differentiate from the combustor of conventional air-breathing engines. Therefore, successful research of high pressure combustion at supercritical condition is essential to develope a high efficiency liquid rocket engine. Numerical studies have been carried out to explore capabilities of numerical method for LOx-CH4 non-premixed flames at high pressure. In this paper, corresponding numerical results are presented and compared with experimental result of MASCOTTE facility.

• Journal of the Korean Society of Combustion
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• v.17 no.2
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• pp.24-31
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• 2012

Diesel engines exhaust much more NOx(Nitrogen Oxides) and PM(Particulate Matter) than gasoline engines, and it is not easy to reduce both NOx and PM simultaneously because of the trade-off relation between two components. This study investigated flame characteristics of the partial premixed compression ignition known as new combustion method which can reduce NOx and PM simultaneously. The investigation was performed through the analysis of the flame images taken by a high speed camera from the visible engine which is the modified single cylinder diesel engine. The results obtained through this investigation are summarized as follows; (1) The area of the luminous yellow flame was reduced due to the decrease of flame temperature and even distribution of temperature. (2) The darkish yellow flame zone caused by the shortage of the remaining oxygen after the middle stage of combustion was considerably reduced. (3) Since the ignition delay was shortened, the violent combustion did not occur and the combustion duration became shortened.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.5
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• pp.24-29
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• 2007

This study aims to provide a fundamental data for directly injected hydrogen fuel engines. Spray, ignition and combustion characteristics of hydrogen were studied using constant volume chamber. For spray visualization, hydrogen was vertically injected into a combustion chamber at various condition, for example, injection pressure, ambient pressure. And an argon laser was used for the shadowgraph photography by applying optical method. Also, to investigate heat-release rate and flame propagations, spark was ignited on hydrogen injected at the different time after injection and the duration of injection was also changed. Processes of ignition and combustion were analyzed by heat-release rate calculated by pressure history and were observed by shadowgraph photography The results gave much knowledge of spray, ignition and combustion characteristics of hydrogen.

• Journal of the Korean Society of Safety
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• v.2 no.1
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• pp.11-16
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• 1987

A study was performed on combustion rates of three kinds of combustible substances under a few different combustion conditions. To measure the combustion rates by weight method, I contrived an apparatus using a sensitive load cell. The experimental results by the combustion tests of various combustible substances shows that the combustion circumstances, eg., air supply condition and the existence of flammable oil. And it is found that the time constant T in case of oil absence is smaller than that in case of oil existence, and the time constant T in case of enforced air-entrained condition is greater that in case of natural air-entrained condition.

• Journal of Mechanical Science and Technology
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• v.19 no.9
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• pp.1821-1832
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• 2005

This study realizes the conceptual method to predict combustion instability in actual full-scale combustion chamber of rocket engines by experimental tests with model (sub-scale) chamber. The model chamber was designed based on the methodologies proposed in the previous work regarding geometrical dimensions and operating conditions, and hot-fire test procedures were followed to obtain stability boundaries. From the experimental tests, two instability regions are presented by the parameters of combustion-chamber pressure and mixture (oxidizer/fuel) ratio, which are customary for combustor designers. It is found that instability characteristics in the chamber with the adopted jet injectors can be explained by the correlation between the characteristic burning or mixing time and the characteristic acoustic time: In each instability region, dynamic behaviors of flames are investigated to verify the hydrodynamically-derived characteristic lengths of the jet injectors. Large-amplitude pressure oscillation observed in upper instability region is found to be generated by lifted-off flames.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.1
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• pp.60-67
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• 2005

Mild combustion or Flameless oxidation(FLOX) have been considered as one of the most prospective clean-combustion technologies to meet both the targets of high process efficiency and low pollutant emissions. A mild combustor with high air preheating and strong internal exhaust gas recirculation is characterized by relatively low flame temperature, low NOx emissions, no visible flame and no sound. In this study, the Steady Flamelet Approach has been applied to numerically analyze the combustion processes and NOx formation in the mild combustor. The detailed discussion has been made f3r the basic characteristics of mild combustor, numerical results and limitation of the present combustion modeling.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.8
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• pp.99-106
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• 1999

The present study deals with the effect of combustion chamber shape on in-cylinder soot oxidation characteristics of a D.I . diesel engine. The analysed combustion chambers were a toroidal and a reentrant with a projection(Complex). The two-color method was used to measure in-cylinder flame temperature and KL value which is approximately proportional to the soot amount along the optical path. In addition, heat release rate was calculated from the in-cylinder pressure data. From these investigations , the soot oxidation of the reentrant and the complex which were strengthen squish flows went worse in late combustion period under heavy-load operation compared to that of the toroidal at retarded fuel injection timing . It might be the cause of the flame holding that squish lip depress the outflow of flame from the bowl to the entire combustion space.

• Journal of the korean Society of Automotive Engineers
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• v.9 no.4
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• pp.50-60
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• 1987

Combustion characteristics of opposed-jet-flames spouting out from dual prechambers of a divided combustion chamber were investigated by using high speed schilieren photography and chamber pressure measurement. Result shows that opposed-jet-flames are characterized by the parameter ( $A_{ori}$/ $V_{p}$) and there exists a certain critical value of ( $A_{ori}$/ $V_{p}$)c which distinguishes flame propagation patterns in the main chamber. Also higher chamber pressure and shorter total burning time can be derived by adopting this dual prechamber divided combustion chamber, which would lead a possibility of an appropriate combustion method of high load and low emissions.ons.ons.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.3
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• pp.113-122
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• 1994

This paper describes the effects of combustion parameters on the characteristics of combustion products in swirling flow furnace. The concentration of combustion products and temperature distribution of flow field in the furnace have been investigated by numerical method. The fuel was injected into the furnace and the swirling device was constructed with three kinds of vane swirler at inlet port of furnace. The results of this study showed that the effect of combustion parameters on the concentration characteristics of carbon monoxide and nitrogen monoxide of combustion products. It was found that the pollutant formation wad dependent on the equivalence ratio and swirl intensity level.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.326-330
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• 2011

Development and validation of performance analysis model for dual combustion ramjet engines has been performed. A typical performance model for hypersonic intake flow and supersonic mixing and combustion was demonstrated; Taylor-Maccoll equation for coaxial intakes and a quasi-one dimensional reacting flow analysis with CEA chemical equilibrium for supersonic combustion. The results, thermodynamic data of intake and supersonic combustor were validated with CFD numerical results.