• 대한기계학회논문집B
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• 제24권12호
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• pp.1608-1614
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• 2000

For the purpose of obtaining fundamental data which is needed to develope combustion system of LPG engine, we made constant volume chamber and analyzed flame propagation characteristics under different intial temperature, initial pressure and equivalence ratio which affect combustion of LPG. We investigated flame propagation speed of each fuel using laser deflection method and compared with the investigated flame propagation speed of each fuel using laser deflection method and compared with the results of image processing of flame. As a result, the maximum flame propagation speed was found at equivalence ratio 1.0 and 1.1 for LPG and gasoline, respectively. In the lean region, we can see that flame propagation speed of LPG surpasses that of gasoline. On the contrary, flame propagation speed of gasoline surpasses LPG in the rich region. As initial temperature and initial pressure were higher, flame propagation speed was faster. And, as equivalence ratio was larger and initial temperature was higher, combustion duration was shorter and maximum combustion pressure was higher.

• 한국연소학회지
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• 제21권1호
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• pp.1-7
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• 2016

This study was performed to provide the basic information of the combustion, CO and $NO_X$ characteristics of biodiesel in accordance with equivalence ratio. The closed homogeneous reactor model used for the analysis. The analysis conditions were set to 900 K of the initial temperature, 20 atm of initial pressure and equivalence ratio was changes from 0.6 to 1.4. The results of analysis were predicted and compared in terms of combustion temperature, combustion pressure, CO and $NO_X$ emissions. The results of combustion characteristics showed that ignition delay was decreased and the combustion temperature and combustion pressure was increased in accordance with equivalence ratio. CO emission was decreased in lean condition(${\Phi}$ < 1.0), however, CO emission was increased in rich condition(${\Phi}$ > 1.0) because oxygen supply insufficient. $NO_X$ emission showed the largest amount in condition 0.8 of equivalence ratio because the oxygen concentration was sufficient.

• 한국자동차공학회논문집
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• 제12권2호
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• pp.1-8
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• 2004

A cylindrical constant volume combustion chamber was used to investigate the exhaust emission characteristics of homogeneous charge, stratified pattern and inhomogeneous charge under various conditions using gas chromatography. In the case of homogeneous charge condition, the $CO_2$ concentration is proportional to excess air ratio and overall charge pressure, the $CO_2$ concentration is proportional to excess air ratio and the UHC concentration is inversely proportional to ignition time and overall charge pressure. In the case of stratified pattern, the RI(rich injection) condition shows better exhaust emission characteristics, especially $CO_2$, than that of HI (homogeneous injection) or LI (lean injection) conditions. In inhomogeneous charge conditions, when initial charge pressure is increased, $CO_2$ and UHC concentration is reduced but $O_2$ concentration is increased. And when the excess air ratio of initial charge mixture is 3.0, UHC and $CO_2$concentration show lowest values.

• 대한기계학회논문집B
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• 제29권1호
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• pp.55-62
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• 2005

Combustion Characteristics and quenching criteria of micro combustor in various condition was exploited experimentally. Two different gases were used, and various geometric matrixes were considered to figure out quenching characteristic of micro combustor. The micro combustor studied in this study was constant volume, and has cylindrical shape. Geometric parameter of combustor was defined to be combustor height and diameter. The effect of height was exploited parametrically as 1 mm, 2mm and 3mm and the effect of diameter was parameterized to be 7.5mm and 15mm. Three different combustibles. (1) Stoichiometric mixture of methane and are, (2) Stoichiometric mixture of hydrogen and air and (3) Mixture of hydrogen and air with fuel stoichiometry of two were used. Pressure transition during combustion process was recovered. The ratio of maximum pressure to initial pressure responded favorably with the change of height of combustor and the initial pressure, the maximum pressure was also increased. The flame propagation was observed only when a specific condition was satisfied. From the experiment the condition that guarantees stable propagation of flame was tabulated. The tabulated results includes criteria of quenching according to combustor height, combustor diameter, species of fuel and initial pressure.

• 한국자동차공학회논문집
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• 제4권4호
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• pp.201-209
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• 1996

This study describes the combustion characteristics of methance-air mixture with various equivalence retio and initial conditions of mixture in constant volume combustion chamber. Combustion characteristics of methane-air mixture such as combustion pressure, combustion temperature, and heat release were investigated by the measurement of combustion pressure and temperature in the combustion chamber. The results show that maximum combustion pressure, gas temperature and rate of heat release have peaks at equivalence ratio of 1.1. Combustion duration is also the shortest at the equivalence ratio of 1.1 and it is shortened as initial mixture temperature increases.

• Journal of Advanced Research in Ocean Engineering
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• 제4권1호
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• pp.7-15
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• 2018

The submarine is an underwater weapon system which covertly attacks the enemy. Pressure hull of a submarine is a main system which has to have a capacity which can improve the survivability (e.g., protection of crews) from the high pressure and air pollution by a leakage of water, a fire caused by outside shock, explosion, and/or operational errors. In addition, pressure hull should keep the functional performance under the harsh environment. In this study, optimal design of submarine pressure hull is dealt with 7 case studies done by analytic method and then each result's adequacy is verified by numerical method such as Finite Element Analysis (FEA). For the structural analysis by FEM, material non-linearity and geometric non-linearity are considered. After FEA, the results by analytic method and numerical method are compared. Weight optimized pressure hull initial scantling methods are suggested such as a ratio with shell thickness, flange width, web height and/or relations with radius, yield strength and design pressure (DP). The suggested initial scantling formulae can reduce the pressure hull weight from 6% and 19%.

• 한국가스학회지
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• 제16권1호
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• pp.8-14
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• 2012

수소는 온실가스 배출을 저감하기 위한 미래 에너지로 고려되고 있지만, 폭발위험에 대한 문제점을 지니고 있다. 따라서 수소가 미래 에너지로 사용되기 위해서는 폭발위험에 대한 연구가 충분히 이루어져야 한다. 폭발위험은 폭발충격에 대한 이해 즉, 폭발과정에서 압력 상승속도에 대한 분석과 밀접한 관계가 있다. 본 연구에서는 폭발에 영향을 미치는 변수, 즉 연소 전후의 비열비, 화학평형상태에서 최대폭발압력, 그리고 연소속도, 이들 변수가 압력 상승속도에 미치는 영향을 살펴보았다. 화학평형상태에서 최대폭발압력과 연소속도는 압력 상승곡선에 큰 영향을 미치는 것을 알 수 있었고, 미연소 가스의 비열비는 초기압력 상승속도보다 최종압력 상승속도에 더욱 영향을 미치고, 연소가스의 비열비는 반대로 초기압력 상승속도에 더욱 큰 영향을 미치는 것을 알 수 있었다. 연소속도는 실험 데이터로부터 구하였으며 밀폐공간에서 수소가스 폭발에서는 폭연에서 폭굉으로 전이가 일어나기에는 연소속도가 매우 느림을 알 수 있었다.

• 한국연소학회지
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• 제20권3호
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• pp.21-26
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• 2015

This study was performed to provide the information of the combustion characteristics of n-butanol fuel in accordance with the n-heptane fuel mixing ratio. The closed homogeneous reactor model was used for the analysis. The analysis conditions were set to 800 K of the initial temperature, 20 atm of initial pressure and 1.0 of equivalence ratio. The results of analysis were compared in terms of combustion temperature, combustion pressure, CO, Soot and $NO_X$ emissions. The results of combustion and exhaust emission characteristics showed that ignition delay was decreased and the combustion temperature was increased as the n-heptane mixing ratio was increased. Also, the carbon monoxide(CO) was slightly decreased however, the soot and nitrogen oxides($NO_X$) increased a little in accordance with the n-heptane fuel mixing ratio. In addition, the pressure difference was almost the same in any conditions.

• 한국자동차공학회논문집
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• 제3권1호
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• pp.65-75
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• 1995

The present study was investigated combustion characteristics of methane-air mixtures at stratified charge in a constant volume combustion chamber. The results indicated that even the vety lean mixture, which is normally not flammable in single chamber type, could be burned within. a comparatively short time by using sub-chamber with stratified charge method. And the lean inflammability limit of mixture in a main chamber was about ($\phi_m$cr=O.46, when the equivalence ratio of a sub-chamber was $\phi_s$= 1.0. Initial time of pressure increase and total burning times were decreased and maximum combustion pressure. was increased as the equivalence ratio of both sub and main chamber approached unity. Specifically, initial time of pressure increase and total burning times were greatly affected rather by. the equivalence ratio of sub-chamber than that of main chamber. The maximum combustion pressure was little affected if the total equivalence ratio lies in the same range.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2003년도 제20회 춘계학술대회 논문집
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• pp.87-90
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• 2003

압축성 유동장의 주된 특징은 유동장의 형성과정에 의존한다는 것은 잘 알려져 있다. 본 연구의 목적은 비평형 응축을 수반하는 초음속 제트유동장의 발달에 미치는 제트의 시간이력을 조사하는 것이다. 특히 초음속 습공기 제트에서 마하디스크 직경과 위치의 거동이 노즐압력비와 초기 상대습도의 항으로 소개된다. 대기흡입식 풍동설비에 장착된 노즐의 출구에서 부족팽창된 습공기 제트를 얻기 위해 노즐의 압력비와 초기상대습도를 변화시켰다. 마하디스크의 직경은 동일한 압력비에서 상대습도가 증가함에 따라 증가하지만, 그 위치는 상류로 이동하는 것으로 나타났다. 또한 노즐의 작동압력비가 증가하는 경우의 마하디스크 직경과 발생위치가 감소하는 경우보다 더 크다.