• Journal of Advanced Marine Engineering and Technology
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• 제10권3호
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• pp.107-118
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• 1986

The presenet research attempts to examine the combustion characteristics and the structure of the flame in turbulent premixed flames and thus enhance the combustion performance that leads to the design of the effective combustion system (untilizing LNG). Following experimental investigations for several stabilized premixed flames were attempted to identify the interactive mechanism between flame structures and flow fields; Visualization by Schlieren method, measurement of flow velocity by LDV, detection of ion current by ion probe, measurement of fluctuating temperature by thermocouple having compensation circuit, average values with respect to time of fluctuating amount for flow velocity, temperature, ion current, etc., variable RMS values, PDFs, autocorrelation, crosscorrelation, spatial macroscale, power spectra, and velocity scale. Continuing the authors published studies whose flame dominated by coherent structures and the characteristics of combustion reaction for irregular three dimensional flame and stabilized flame by step were investigated with obtained experimental quantities. Results of this research are following : The most turbulent flames support the structure of a Wrinkled laminar flame or laminar flamelets. It also observed that combustion reaction is related to small tubulence microscales of the turbulent flow fields closly.

• 한국수산과학회지
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• 제8권3호
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• pp.150-156
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• 1975

Diesel 기관의 연소는 매우 복잡한 현상이다. 이 복잡한 연소과정을 각운전조건하에서 구한 열발생율에 의해 해석했으며 그 결과 다음 사항이 밝혀졌다. 1. Diesel기관의 연소기간은 예혼합기연소기관과 황산연소기관으로 나누어 생각할 수 있다. 2. 예혼합기연소부분이 클수록 효율은 양호하나 최고압력이 높아져 정숙한 운전이 되지 못하고 확산연소기간이 길수록 운전은 정숙하나 효율은 떨어지고 배기온도는 상승한다. 3. 예혼합기 연소부분은 주로 발화지연에 지배되나 확산연소기간은 산소의 확산에 지배된다. 4. 실험범위내에서 기관의 효율은 분사량과 회전수가 일정하면 분사시기가 빠를수록 효율은 증가했으나 압력의 상승은 효율의 증가보다 높았다.

• 에너지공학
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• 제17권2호
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• pp.100-106
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• 2008

매트형태의 연소촉매를 사용하는 촉매연소 버너는 발생 열을 원적외선 형태로 피 가열체에 공급할 수 있기 때문에 저온 공정에서 효율적으로 열을 사용할 수 있다. 매트형태 촉매연소 버너의 활용 가능성을 높이기 위해 촉매연소버너를 제작하고 구조에 따른 연소성능에 대해 고찰하였다. 확산식 촉매연소에서는 연소면의 방향이 연소반응에 많은 영향을 주며, 촉매 주위 온도변화에 따른 산소의 확산속도 차이가 촉매 연소 반응 속도에 많은 영향을 주는 것을 알았다. 예혼합 촉매연소에서 연소공기는 이론공기량 보다 조금 많게 공급하는 것이 최적이고, 연소열의 70% 이상이 복사로 전달됨을 알았다.

• 한국수소및신에너지학회논문집
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• 제21권6호
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• pp.561-569
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• 2010

The present study deals with experimental investigations on the syngas-oxygen combustion characteristics of a swirl-stabilized premixed flame in a 10 kW combustor. The effect of hydrogen in syngas has been investigated with different swirl angles to identify the role of hydrogen and swirl strength on the flame stability and CO emissions. The results show that hydrogen addition extended the blowout limit while narrowing the flashback limit. The dependence of blowout on the swirl angle is negligible while the dependence of flashback on the swirl angle is evidenced by two regimes depending on the amount of hydrogen. CO emission is decreased with increasing excess $O_2$ supply or increasing hydrogen content. Chemiluminescence diagnostics is utilized to provide information on the structure of a swirl-stabilized premixed flame. The OH chemiluminescence intensity is more concentrated near the burner exit with an increase in the hydrogen content, which results from high reactivity of hydrogen.

• 한국자동차공학회논문집
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• 제22권1호
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• pp.157-164
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• 2014

Dual fuel combustion strategy with di-methl ether (DME) and gasoline was tested in a compression ignition engine. Characteristics of combustion and emissions were analyzed with the variation of engine operating parameters such as fuel proportion, DME injection timing, intake oxygen concentration, DME injection pressure and so forth. Gasoline was injected into the intake manifold to form the homogeneous mixture with intake charge and DME was injected directly into the cylinder at the late compression stroke to ignite the homogeneous gasoline-air mixture. Dual fuel combustion strategy was advantageous in achievement of higher thermal efficiency and low NOx emission compared with DME single fuel combustion. Higher thermal efficiency was attributed to the lower heat tranfer loss from the decreased combustion temperature since the amount of lean premixed combustion was increased with the larger amount of gasoline proportion. Lower NOx emissions were also possible by lowering the combustion temperature.

• 한국연소학회지
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• 제18권4호
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• pp.44-52
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• 2013

Important role of chemical interaction in flame extinction was numerically investigated in downstream interaction among lean(rich) and lean(rich) premixed as well as partially premixed $H_2$-air and CO-air flames. The strain rate varied from 30 to $5917s^{-1}$ until interacting flame could not be sustained anymore. Flame stability diagrams mapping lower and upper limit fuel concentrations for flame extinction as a function of strain rate are presented. Highly stretched interacting flames were survived only within two islands in the flame stability map where partially premixed mixture consisted of rich $H_2$-air flame, extremely lean CO-air flame, and a diffusion flame. Further increase in strain rate finally converges to two points. Appreciable amount of hydrogen in the side of lean $H_2$-air flame also oxidized the CO penetrated from CO-air flame, and this reduced flame speed of the $H_2$-air flame, leading to flame extinction. At extremely high strain rates, interacting flames were survived only by a partially premixed flame such that it consisted of a very rich $H_2$-air flame, an extremely lean CO-air flame, and a diffusion flame. In such a situation, both the weaker $H_2$-air and CO-air flames were parasite on the stronger diffusion flame such that it could lead to flame extinction in the situation of weakening the stronger diffusion flame. Particular concerns are focused on important role of chemical interaction in flame extinction was also discussed in detail.

• 한국자동차공학회논문집
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• 제21권3호
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• pp.43-49
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• 2013

This work investigated the effects of engine speed and injection timing on combustion and emissions characteristics in a partially premixed charge compression ignition (pPCCI) engine fueled with DME. pPCCI engine especially has potential to achieve more homogeneous mixture in the cylinder, which results in lower NOx and smoke emission. In this study single cylinder engine was equipped with common rail and injection pressure is 700 bar. Total injected fuel mass is 64.5 $mm^3$ per cycle. The amount of pilot injection of the entire injection 12.5% is tested. Results show that NOx emission is decreased while IMEP is increased as the retard of injection timing. Besides, NOx emissions are slightly rised as well as IMEP is increased with the increase of engine speed.

• 수산해양기술연구
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• 제45권2호
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• pp.114-121
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• 2009

There are increased in using the bio-ethanol, as the carbon neutral attracts many researchers due to a reduction in carbon dioxide spotted as the global warming gas. A gasoline engine with 100% of the bioethanol was developed and used in Brazil already, but researches of using the bio-ethanol in diesel engines are lack. In this study, combustion tests with blend fuel of the gas oil and bio ethanol by 50% maximally due to a low cetane number of bio-ethanol were accomplished as a basic study of introduction of using the bioethanol in diesel engines. The result was that smoke emission was decreased with increase in proportion of the bio-ethanol, due to the increase of a amount of pre-mixed combustion with ignition delay. Although the amount of $CO_2$ is reduced according as the bio-ethanol is used(carbon neutral), the emission of $CO_2$ with increase in the proportion of the bio-ethanol was more increased due to lower a heat value of bio-ethanol than gas oil.

• 한국연소학회지
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• 제7권1호
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• pp.31-36
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• 2002

Vortical structures are investigated numerically for both cold and combusting flows from a two-dimensional bluff-body burner in the transitional flow regime from steady to unsteady state. The Reynolds number of the central fuel flow is varied from 10 to 230 at a fixed air Reynolds number of 400. The flame sheet model of infinite chemical reaction and unit Lewis number are assumed in the simulation. The temperature dependence of the viscosity and diffusivity of the gas mixture is also considered. The vortex shedding is observed depending on the fuel flow. For cold flow, four different types of vortical structure are identified. However, for combusting flow of methane-air system the vortical structures change significantly due to a large amount of heat release during the combustion process, in contract to cold flow.

• 한국연소학회지
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• 제16권1호
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• pp.58-65
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• 2011

Thermal spray technology has been used in many industrial application. Especially, thermal spray coating have been employed with the purposes of achieving better resistances in abrasion, heat and corrosion. In the previous studies on the thermal spray coating, thermal spray characteristics from the perspective of combustion engineering have not been investigated sufficiently, while the material characteristics of the coated substrates have been investigated widely. In this study, the effect of spray particles on the flame behavior was experimentally investigated. The amount of the injected particles was measured using the light scattering method and the temperature of the particles was estimated using a two-color method. Various flame-spray interactions were observed and it was found that the high temperature zone near the flame is elongated by particles density. Based on these results, the applicability of the light scattering method and the two-color method was discussed.