• International Journal of Automotive Technology
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• 제6권6호
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• pp.555-561
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• 2005

This experimental study was executed to obtain basic data for actual engine operation using radical induced ignition method (RI) which can achieve emission reduction and high efficiency due to the rapid bulk combustion. In this study, a direct injection diesel engine was converted into SI type engine with a sparkplug. The modified SI type engine can be divided into two classes. One is the SI engine with a sparkplug only at the cylinder head, and the other is the SI engine with the sparkplug which is enveloped in a sub-chamber. Also, a basic experimental was conducted in order to investigate combustion mechanism of radical induced injection before the experiment execution for actual engine using the modified SI engine. The bulk combustion phenomenon of radical induced ignition method was analyzed from the basic experiment by using a constant volume chamber. Volume value of sub-chamber used in this experiment is approximately $0.2\%$ of one of the main combustion chamber. In this paper, combustion characteristics using radical induced injection method was compared with that of using spark ignition method according to change in the engine speed and equivalence ratio. As a result, in the case of the radical induced injection engine, the combustion duration and cycle variation were respectively reduced ranged from $\Phi$(equivalence ratio)=0.8 (lean mixture ratio) to $\Phi$=1.0 (stoichiometric ratio).

• 한국자동차공학회논문집
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• 제10권1호
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• pp.17-23
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• 2002

In order to reduce exhaust emissions from diesel engine under wide operating range, an experimental study based on a new concept of combustion called HCDC(Homogeneous Charge Diesel Combustion) was conducted. In this concept, most of the fuel is supplied as premixed homogeneous charge and the rest is directly injected into a cylinder to ignite. In this study we compared combustion characteristics of an HCDC engine with those of conventional diesel engines. At high premixed fuel ratio and high load range, it was observed that premixed combustion heat release rate was low and diffusion combustion duration was shorten. from this experiment, it was found that NOx is reduced by the lower maximum temperature and soot is reduced by rapid combustion during diffusion combustion phase.

• 한국기계가공학회지
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• 제10권5호
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• pp.125-130
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• 2011

The characteristics of unsteady combustion were experimentally investigated using confined premixed flames stabilized by a rearward-facing step. The unsteady combustion used in this experiment plays an important role in controlling self-excited combustion oscillations and it has usually desirable performance such as high load combustion and low pollutant emission. It is known that combustion oscillation is occurred if Rayleigh's criterion is satisfied. The pressure fluctuation and OH-emission fluctuation were measured using pressure transducer and OH optical fiber respectively and then cross-corelation and phase difference were calculated to apply Rayleigh's criterion.

• 한국연소학회지
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• 제10권4호
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• pp.1-9
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• 2005

The usefulness of unsteady combustion was experimentally investigated using confined premixed flames stabilized by a rearward-facing step. For this purpose, apparatus of forced pulsating mixture supply, which could be modulated its amplitude and frequency, was designed. The unsteady combustion used in this experiment plays an important role in controlling self-excited combustion oscillations and furthermore it exhibits desirable performance, from a practical point of view, such as high load combustion and reduction of pollutant emission like nitric oxide.

• 한국추진공학회지
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• 제15권5호
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• pp.19-26
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• 2011

초음속 연소에서 연료를 분사하는 분사구의 형태에 따른 연소 성능의 변화를 파악하기 위하여 실험과 준일차원 해석(Quasi-One Dimensional Analysis)을 수행하였으며, 결과 값을 본 팀에서 2008년에 수행한 데이터와 비교해 보았다. 시험은 일본 JAXA에서 보유하고 있는 불어내기식 풍동을 사용하였으며, 온도조건을 맞추기 위하여 Vitiated Heater가 사용되었다. 시험을 위하여 2008년 수행하였던 시험모델에서 사용한 연료 분사구의 크기를 줄이고 개수를 증가시켰다. 연료 분사구의 크기 및 개수는 동일한 연료 압력에서 연료의 분사량과 침투깊이가 동일하도록 결정되었다. 실험결과 공동이 없을 시에는 연료 분사구의 크기를 줄이고 개수를 늘렸을 때 연소성능이 큰 폭으로 증가하였지만, 일자형 공동에서 는 그 영향이 미미하였다. 지그재그형 공동에서는 연료 분사구의 크기를 줄이고 개수를 늘렸을 때 오히려 연소성능의 저하가 관찰되었다.

• 한국분무공학회지
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• 제13권4호
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• pp.206-211
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• 2008

In this research, combustion and spray characteristics were investigated experimentally in a constant volume chamber by applying bio-diesel fuel to a common-rail system in which precise control is available for utilizing environmentally friendly properties of bio-diesel fuel. The experiment was conducted at fuel temperatures $20^{\circ}C$ and $-20^{\circ}C$ to investigate combustion characteristics of bio-diesel fuel provoking problems in fluidity specially in a low temperature. For the visualization, the experiment was carried out under various conditions of ambient pressure, injection pressure and fuel temperature. The test was made by three different types of diesel fuels, conventional diesel, BD20 and BD100. In summary, this research aims to investigate combustion characteristics in the application of bio-diesel fuels and compare the results with performance of conventional diesel fuel. This experimental data may provide fundamentals of spray and combustion of bio-diesel fuels at a low temperature and contribute to the development of bio-diesel engines in future.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제35회 추계학술대회논문집
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• pp.423-431
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• 2010

초음속 연소에서 연료를 분사하는 분사구의 형상에 따른 연소 성능의 변화를 파악하기 위하여 실험과 준일차 해석(Quasi-One Dimensional Analysis)을 수행하였으며, 결과 값을 본 팀에서 동일 설비 및 조건으로 2008년에 시험을 수행한 데이터와 비교해 보았다. 연료 분사구 형상은 2008년 수행하였던 시험모델과 비교하여 연료 분사구의 크기를 줄이고 개수를 증가시켰으며, 연료 분사구의 크기 및 개수는 동일한 연료 압력에서 연료의 분사량과 침투깊이가 동일하도록 결정되었다. 실험결과 공동이 없을 시에는 연료 분사구의 크기를 줄이고 개수를 늘렸을 때 연소성능이 큰 폭으로 증가하였지만, 일자형 공동에서는 그 영향이 미미하였다. 하지만 지그재그형 공동에서는 연료 분사구의 크기를 줄이고 개수를 늘렸을 때 오히려 연소성능이 저하되었다.

• 대한기계학회논문집B
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• 제27권8호
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• pp.1089-1096
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• 2003

An experiment was performed to investigate lift-off, blow-off and combustion characteristics of a lifted coaxial diffusion flame according to fuel jet and air velocity. A jet diffusion flame which is attached on the nozzle rim begins to be lifted with increase of air velocity, and finally becomes blow-off at higher air velocity. In experiment, blow-off limit increased with increase of fuel jet velocity, however lift-off occurred at lower air velocity. Flame structure and combustion characteristics were examined by schlieren photos, temperature distributions and emission concentration distributions. Flame temperature became higher at midstream and its RMS became larger at up and downstream with increase of air velocity. Local NO concentration decreased but $CO_2$concentration increased with increase of air velocity, which shows combustion reaction becomes close to be stoichiometric at higher air velocity in spite of lift-off.

• 한국연소학회지
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• 제7권3호
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• pp.32-36
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• 2002

A numerical study was carried out to investigate combustion phenomena in a model Scramjet engine, which had been experimentally studied at the University of Tokyo using a high-enthalpy supersonic wind tunnel. The main airflow was Mach number 2.0 and the total temperature of hot flow was 1800K. Equivalence ratio was set to be 0.26 which is higher than that of experiment to investigate the effect of strong precombustion shock. The results showed that self-ignition occurred at the rear bottom wall of the combustor and combined with the shear layer flame between fuel jet and main airflow. Then, precombustion shock was generated at the step location and reversely enhanced the mixing and combustion process behind the shock. Due to the high equivalence ratio, the precombustion shock moved upstream of the step compared with that of experiment.

• 한국항공운항학회지
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• 제19권1호
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• pp.7-14
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• 2011

In this study, the measurement uncertainty of combustion experimental system and experimental parameters for hybrid rocket were evaluated by B type evaluation method. The measurement uncertainty of all experimental parameters was lower than 3%. The highest value of expanded uncertainty was characteristic velocity efficiency with 2.83% and the expanded uncertainty of regression rate which is the design and performance parameter was indicated to 0.03%. These results shown that the reliability of hybrid combustion system was located within allowed limits.