• 에너지공학
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• 제4권1호
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• pp.85-94
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• 1995

본 연구에서는 최근 차량용 대체연료로서 주목받고 있는 천연가스의 연소특성을 규명하기 위해 밀폐된 정적연소실을 이용, 당량비, 초기압력 및 점화위치 변화에 따른 연소실험을 행하였으며, 그 결과 다음과 같은 결론을 얻었다. 메탄-공기 예혼합기의 화염전파과정은 이론혼합기 부근에서 구면형으로 진행되는데 반해, 과농 또는 과박 혼합기 그리고 점화위치가 연소실 벽면에 가까울수록 타원형으로 진행되며, 초기압력이 증가함에 따라 화염전파는 느려진다. 화염전파속도와 연소 속도는 초기압력이 낮고 점화위치가 연소실 중심에 가까울수록 빠르며, 당량비 1.0∼1.1 사이에서 최대치를 보인다.

• 대한기계학회논문집B
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• 제34권4호
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• pp.365-373
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• 2010

제트 혼합 반응기(JSR) 내의 NOx와 같은 배출물질을 예측하기 위해서 화학반응기 모델을 개발했다. 본 연구에서는 JSR에 대한 화학반응기 모델로서 two-PSR 모델이 채택되었다. CHEMKIN 코드와 4가지 NO 생성 메커니즘을 포함한 GRI 3.0 메탄-공기 연소 메커니즘을 이용해서 JSR내의 희박 예혼합 메탄-공기 연소의 NO 생성예측을 실시하였다. 모델의 검증을 위해서 계산된 결과를 Rutar의 실험 데이터와 비교하였다. NO 생성의 중요 파라미터와 4 가지 NO 경로의 기여도를 조사하였다. 화염 영역에서는 prompt 메커니즘이 주된 경로이고, 화염후영역에서는 Zeldovich 메커니즘이 주된 경로이다. 희박 예혼합 조건에서는 N2O 메카니즘이가 화염 및 화염후 영역 모두에서 중요한 경로이다.

• 한국자동차공학회논문집
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• 제4권3호
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• pp.156-167
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• 1996

The present work is a continuation of our previous study to investigate the effects of parameters such as equivalence ratio, hydrogen supplement rate and initial pressure on combustion characteristics in a disk-shaped constant volume combustion chamber. The main results obtained from the study can be summarized as follows. The flames in near stoichiometric mixture of methane-air are propagated with a spherical shape, but in excess rich or lean mixtures are propagated with a elliptical shape. And, they are changed to an unstable elliptical shape flame with very regular cells by increasing the hydrogen supplement rate. Also, flame is sluggishly propagated at increased initial pressure in combustion chamber. Volume fraction of burned gas and flame radius as the combustion characteristics are increased by increasing the hydrogen supplement rate, especially at the combustion middle period, but then are slowly increased by increasing the initial pressure.

• 한국자동차공학회논문집
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• 제11권3호
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• pp.48-57
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• 2003

A cylindrical constant volume combustion chamber was used to investigate the flow characteristics at spark plug and the combustion characteristics of homogeneous charge methane-air mixture under various initial pressure, excess air ratio and ignition times in quiescent mixture. The flow characteristics such as mean velocity and turbulence intensity was analyzed by hot wire anemometer. Combustion pressure development measured by piezoelectric pressure transducer and flame propagation acquired by ICCD camera were used to investigate the effect of initial pressure, excess air ratio and ignition times on pressure, combustion duration, flame speed and burning velocity. Mean velocity and turbulence intensity had the maximum value at 200 or 300ms and then decreased to near 0 value gradually after 3 seconds. Combustion duration, flame speed and burning velocity were observed to be promoted with excess air ratio of 1.1, lower initial pressure and ignition time of 300ms.

• 한국자동차공학회논문집
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• 제11권4호
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• pp.29-36
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• 2003

A cylindrical constant volume combustion chamber was used to investigate the flow characteristics at spark plug and the combustion characteristics of inhomogeneous charge methane-air mixture under several parameters. The flow characteristics such as mean velocity and turbulence intensity was analyzed by hot wire anemometer. Combustion pressure development measured by piezoelectric pressure transducer was used to investigate the effect of initial charge pressure, excess air ratio and ignition times on combustion pressure and combustion duration. Mean velocity and turbulence intensity had the maximum value at 200 or 300ms and then decreased to beneath 0.05m/s gradually at 3 seconds. Second mixture is accompanied by an increase in the combustion rate, and that the higher the mass which is added in the second stage injection, the faster the burn rate.

• 한국자동차공학회논문집
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• 제17권5호
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• pp.46-52
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• 2009

In this study the predictions of NOx in methane-air lean premixed combustion in PSR were carried out with GRI 3.0 methane-air combustion mechanism and Zeldovich, nitrous oxide, prompt, and NNH NO formation mechanism by using CHEMKIN code. The results are compared to the JSR experimental data of Rutar for the validation of the model. This study concerns about the importance of the chemical pathways. The chemical pathway most likely to form the NO in methane-air lean-premixed combustion was investigated. The results obtained with the 4 different NO mechanisms for residence time(0.5-1.6ms) and pressure(3, 4.7, 6.5 atm) are compared and discussed.

• 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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• 제36권2호
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• pp.225-232
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• 2012

희박 예혼합 가스터빈 연소기에서 배출되는 NOx, CO 와 같은 오염물질을 예측하기 위해서 화학반응기 네트워크 모델을 개발했다. 본 연구에서는 CHEMKIN 코드와 4 가지 NO 생성 메커니즘을 포함한 GRI 3.0 메탄-공기 연소 메커니즘을 이용해서 가스터빈의 부하조건을 변화시키며 NOx 및 CO 배출의 예측을 수행하였다. 모델의 검증을 위해서 계산된 결과를 모사연소기의 실험 데이터와 비교하였다. 여러부하조건에 따른 4 가지 NO 경로의 기여도를 조사하였다. 또한 인젝터의 질량유동 및 당량비의 불균일성이 NOx 배출이 끼치는 영향을 고찰하고 10ppm 이하의 저 NOx 연소기 개발을 위한 저감 방법을 제안했다.

• 한국산업융합학회 논문집
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• 제11권1호
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• pp.5-10
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• 2008

A flame speed of methane mixture of water vapor and air have been measured to study the process of flame propagation using schlieren photographs. The quantity of water vapor contained were changed 5% and 10% of total mixture, and equivalence ratio of mixture between 0.8 and 1.2 were tested under the ambient temperature 323K and 373K. The results showed that the burning velocity was decreased by increasing the water vapor contents due to the interruption of flame development. And, the reduction rate of burning velocity was smaller by increasing the water contents under the same ambient temperature. The effects of ambient temperature on burning velocity was decreased by increasing the water vapor contents.

• 한국산업융합학회 논문집
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• 제12권3호
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• pp.137-142
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• 2009

Burning velocity of methane-air mixtures with water vapor have been measured to study the process of flame propagation using schlieren photographs and computation. The computations were carried out for the burning velocity using premix code of Chemkin program to compare the experimental results. The quantity of water vapor contained were changed 5% and 10% of total mixtures, and equivalence ratio of mixtures between 0.8 and 1.2 were tested under the ambient temperature 323K and 373K. The results showed little difference between these two methods, the burning velocity was decreased by increasing the water vapor contents due to the interruption of flame development. And, the effect of ambient temperature was less significant by increasing the water contents on the burning velocity.