• 한국분무공학회지
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• 제2권2호
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• pp.24-34
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• 1997

This paper describes the investigation of combustion characteristics of gasoline-methanol blend in constant volume combustion chamber. A constant volume combustion chamber was used to elucidate a basic combustion characteristics and the premixer was installed to control temperature and equivalence ratio. And the maximum pressure, combustion duration and flame propagation according to the evaporation rate were measured to determine the optimal temperature range for evaporating a blend fuel. These experimental results indicate that the combustion characteristics such as combustion chamber pressure and combustion were deteriorated by decreasing surrounding temperature of fuel. These experimental results indicate that the combustion characteristics such as combustion chamber pressure and combustion were deter orated by decreasing surrounding temperature of fuel injected. It was also found that the overall gasification process for methanol blend fuel was influenced by a combustion chamber temperature rather than a premixer temperature.

• 대한기계학회논문집B
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• 제32권7호
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• pp.513-517
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• 2008

A parametric study was made to understand the fundamentals of combustion of CNG fuel in a constant volume chamber in the respect of swirl effect, and the numbers of spark ignition. Optical devices were applied for the visualization of the physics of combustion, and combustion pressures and exhaust emission were measured at several equivalence ratios by controlling speeds of a swirling motor. When the speed of a swirling motor was raised the combustion conditions were improved. The corresponding maximum combustion pressure and heat release rate were increased and the speed of flame propagation was getting faster. This research may contribute to improve the performance of CNG engine and reduce emissions in future.

• 대한기계학회논문집
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• 제19권6호
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• pp.1510-1517
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• 1995

A theoretical method is described to simulate the propagation of turbulent premixed flames in a closed vessel. The objective is to develop and test an efficient technique to predict the propagation speed of flame as well as the geometric structure of the flame surfaces. Flame is advected by the statistically generated turbulent flow field and propagates as a wave by solving twodimensional Hamilton-Jacobi equation. In the simulation of the unburned gas flow field, following turbulence properties were satisfied: mean velocity field, turbulence intensities, spatial and temporal correlations of velocity fluctuations. It is assumed that these properties are not affected by the expansion of the burned gas region. Predictions were compared with existing experimental data for flames propagating in a closed vessel charged with hydrogen/air mixture with various turbulence intensities and Reynolds numbers. Comparisons were made in flame radius growth rate, rms flame radius fluctuations, and average perimeter and fractal dimensions of the flame boundaries. Two dimensional time dependent simulation resulted in correct trends of the measured flame data. The reasonable behavior and high efficiency proves the usefulness of this method in difficult problems of flame propagation such as in internal combustion engines.

• 한국자동차공학회논문집
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• 제3권3호
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• pp.129-139
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• 1995

This study investigates the combustion characteristics of methane-hydrogen-air premixture in a constant volume combustion chamber. Primary factors of the combustion characteristics of methane- hydrogen-air premixture are the equivalence ratio and hydrogen supplement rate. In the case of $\phi$= 1.1, maximum combustion pressure and heat release rate have peaks, and they increase as the initial pressure and hydrogen supplement rate increase. The total burning time is also the shortest at the $\phi$= 1.1, it shorten by lowering the initial pressure and by increasing the hydrogen supplement rate. The maximum flame temperature is shown at the $\phi$= 1.0, and increasing the initial pressure and hydrogen supplement rate, it increases. The concentration of NO reveals the highest value at the $\phi$= 0.9, and it increases by increasing the initial pressure and hydrogen supplement rate. It is also found that the limit of lean inflammability of methane-hydrogen-air premixture is greatly widened by increasing the hydrogen supplement rate.

• 대한기계학회논문집B
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• 제27권6호
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• pp.685-692
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• 2003

A numerical simulation of flame propagation in a micro combustor was carried out. Combustor has a sub -millimeter depth cylindrical internal volume and axisymmetric one-dimensional was used to simplify the geometry. Semi-empirical heat transfer model was used to account for the heat loss to the walls during the flame propagation. A detailed chemical kinetics model of $H_2/Air$ with 10 species and 16 reaction steps was used to calculate the combustion. An operator-splitting PISO scheme that is non-iterative, time-dependent, and implicit was used to solve the system of transport equations. The computation was validated for adiabatic flame propagation and showed good agreement with existing results of adiabatic flame propagation. A full simulation including the heat loss model was carried out and results were compared with measurements made at corresponding test conditions. The heat loss that adds its significance at smaller value of combust or height obviously affected the flame propagation speed as final temperature of the burnt gas inside the combustor. Also, the distribution of gas properties such as temperature and species concentration showed wide variation inside the combustor, which affected the evaluation of total work available of the gases.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2002년도 제25회 KOSCI SYMPOSIUM 논문집
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• pp.231-235
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• 2002

A theoretical and experimental study on the combustion process in a constant volume micro combustor is described. Unlike in a macro scale constant volume combustor, the heat loss to the wall plays a major role in flame propagation in a micro micro combustor. In order to analyze the effect of heat loss on combustion phenomena, pressure transition from ignition was measured. A number of cylindrical micro combustors with different diameter and depth were used for experiment to study the effect of length scales and shape factor. The diameter of combustor ranged from 7.5mm to 22.5 mm and the height of cylinder was from 1mm to 4mm. Initial pressure was also varied for the experiment. The diagnostic methods were severely limited due to the size of the apparatus and uncertainties of certain quantities to be measured in a small-scale environment. An analytical method to derive physical quantities that are essential for performance prediction from the pressure measurements is described.

• 한국추진공학회지
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• 제4권3호
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• pp.19-28
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• 2000

고체추진 로켓모타의 개발이나 성능평가 때에는 추진기관의 추력, 연소실 압력, 온도, 연소시간 등 정적연소시험을 통해서 필요한 데이터론 측정한다. 그러나 휴대용 대공 유도무기의 경우에는 추진기 관의 화염으로부터 사수를 보호하기 위해 대단히 까다로운 안전규정을 요구하고 있다. 이러한 안전 규정들을 만족시키기 위해 설계된 분리장치나 점화안전장치의 개발 및 성능평가를 위해서는 이들 장치들이 결합된 추진기관에 대해 실제 비행 환경 하에서 설계목표의 신뢰도를 시험하기 위한 동적연소시험이 수행되어야 한다. 본 연구에서는 이러한 휴대용 대공 유도무기 추진시스템의 개발이나 성능평가를 위한 동적연소시험 기법 및 동적시험대의 설계 및 제작에 관한 연구를 수행하였다.

• 동력기계공학회지
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• 제21권3호
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• pp.12-18
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• 2017

Diesel and gasoline engines will be used as main power system of automobiles. Recently, engine downsizing is widely applied to both gasoline and diesel engines in order to improve fuel economy and exhaust emissions. Engine downsizing means small engine combustion chamber with higher combustion pressure. Therefore, spray and combustion process should be investigated under these high pressure and temperature conditions. In this study, constant volume combustion chamber which enables easy optical access from six directions was developed. Combustion chamber was designed to resist maximum pressure of 15 MPa and maximum temperature of 2,000 K. Combustible pre-mixed mixture was introduced into combustion chamber and ignited by spark plugs. High pressure and temperature were implemented by combustion of pre-mixed mixture. Three initial conditions of different pressure and density were tested. High repeatability of combustion process was implemented which was proven by low standard deviation of combustion pressure.

• 한국항공우주학회지
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• 제41권10호
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• pp.796-804
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• 2013

연소 및 추진 기관 공학 교육 과정의 일부로써 간단한 형태의 열기관인 감자총 (Potato Gun)의 제작, 시험 및 해석을 수행하였다. 정적 연소실의 화학 평형 해석을 이용하여 연소실의 압력을 계산하고, 팽창과정의 열역학 해석을 통하여 열에너지의 운동에너지로 변환되는 내탄도 과정을 계산하였다. 공기역학적 지식을 도입한 구형 탄도 궤적 해석을 통하여 비행거리를 추정할 수 있었으며, 이를 통하여 감자총의 에너지 변환 효율 및 혼합기의 당량비를 추정하였다. 본 과제는 재활용 자재를 이용하여 학부 수준에서 열-유체역학공학 지식을 활용하여 실습하고 학생들의 관심을 유발할 수 있는 적당한 예로 여겨진다.

• 융합정보논문지
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• 제11권7호
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• pp.111-117
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• 2021

본 연구는 LFG(Land Fill Gas)의 주성분인 메탄(CH₄) 60%와 이산화탄소(CO₂) 40%로 구성된 매립지가스를 활용하여 정적연소 환경에서 연소의 초기 불안정성을 해결할 수 있는 실험적인 연구결과를 제안하는 것이다. 실험조건은 공기과잉율 0.9~1.6, 초기연소를 위한 압축압력 3bar, 실험주변온도 25℃, 실험용 연료가스 메탄, 예연소실 화염 분출구 직경 2.5, 3.0, 3.5, 4.0, 4.5mm로 설정하였다. 실험결과 M3.0 모델에서 초기화염의 확산성이 매우 증가된 특성을 확인할 수 있으며, 이와 같은 증가의 특성은 공기 과잉률이 0.9, 1.0, 1.2에서 오리피스의 효과가 극도로 향상하게 되었다는 점을 알 수 있었다. 결과적으로, 본 실험을 통하여 M3.0으로 설계된 예연소실 화염 분출구 치수를 LFG에 적용할 경우 기존의 점화 플러그 특성 보다 부분적인 연소의 성능을 높일 수 있다는 점을 확인할 수 있었다.