• 화약ㆍ발파
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• 제30권2호
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• pp.52-58
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• 2012

싱가포르 DTL2 C915 건설공사 중 TBM 발진을 위한 개착구간의 암발파 공사를 위해 당초 전기뇌관과 ANFO로 발파시공이 계획되었으나 1회 발파공수 제한 및 가시설에 대한 엄격한 진동관리 규정 등으로 인해 작업공정이 많이 지연되어 TBM 발진을 위한 예정된 공기를 준수하지 못하는 것으로 검토되었다. 따라서 암발파 공법의 효율을 개선하고 1회 발파공수 및 파쇄면적의 최대화를 위해 다단장약이 검토되었으며, 다단장약의 효율성을 높이기 위해 정밀성이 장점인 전자뇌관이 선정되었다. 다단장약 적용으로 천공장이 길어짐에 따라 커지는 암반 구속력에 대응하기 위해 폭약의 위력을 증대시키는 방안으로 Emulsion Cartridge 폭약을 적용하였다. 그 결과 발파효율과 시공성을 개선함과 동시에 가시설의 안정성을 확보할 수 있었다.

• 한국전산유체공학회지
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• 제9권1호
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• pp.25-33
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• 2004

Flame onset and propagation within hydrogen premixed gas mixture are numerically investigated in an rectangular enclosure. A detailed chemistry for hydrogen reaction is applied to anticipate the thermochemical behavior of intermediate species appropriately. To facilitate computation, 10 species and 16 elementary reaction steps for hydrogen combustion are taken into account. On the basis of 30％ of hydrogen concentration in hydrogen-air mixture, the effects of position and quantity of ignition sources on the flame evolution are analyzed. From the simulation results, the methods to decrease the potential hazard caused by the flame propagation are suggested.

• 한국자동차공학회논문집
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• 제11권6호
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• pp.73-79
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• 2003

The characteristics of NOx emission in multi fuel/air staged combustor have been experimentally studied. The design concept of multi fuel/air staged combustor is creation of two separate flame, a primary flame is act as a pilot flame for the secondary combustion stage combustion zone, where most of fuel burns. Experiments were performed on a semi-industrial scale (thermal input 0.233 ㎿) in a laboratory furnace and Liquefied Petroleum Gas(LPG) was used as primary and secondary fuels. The study included parametric study to identify the optimum operating conditions which are primary/secondary fuel ratio, primary/secondary air ratio, primary swirl intensity and secondary swirl intensity for reducing NOx emission. The test demonstrated that NOx emission can be reduced by >70% in accordance with operating conditions.

• 대한기계학회논문집B
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• 제28권4호
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• pp.389-394
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• 2004

An experimental study on the NOx formation of LNG flame in fuel staged combustor has been studied. The design concept of multi fuel/air staged combustor is creation of two separate flame, a primary flame is a act as a pilot flame for the secondary combustion stage combustion zone, where most of fuel bums. Experiments were performed on a semi-industrial scale (thermal input 0.233 MW) in a laboratory furnace and Liquefied Natural Gas(LNG) was used as a primary and secondary fuels. This study included parametric study to identify the optimum operating conditions which are primary/secondary fuel ratio, and primary/secondary air ratio for reducing NOx emission with two types of nozzle. The test demonstrated that NOx emission can be reduced by >70% in accordance with operating conditions.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2001년도 제22회 KOSCI SYMPOSIUM 논문집
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• pp.163-171
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• 2001

The characteristics of NOx emission in multi fuel/air staged combustor have been experimentally studied. The design concept of multi fuel/air staged combustor is creation of two separate flame, a primary flame is act as a pilot Dame for the secondary combustion stage combustion zone, where most of fuel bums. Experiments were performed on a semi-industrial scale (thermal input 0.233 MW) in a laboratory furnace and Liquefied Petroleum Gas(LPG) was used as primary and secondary fuels. The study included parametric study to identify the optimum operating conditions which are primary/secondary fuel ratio, primary/secondary air ratio, primary swirl intensity and secondary swirl intensity for reducing NOx emission. The test demonstrated that NOx emission can be reduced by ${>}$70% in accordance with operating conditions.

• 대한기계학회논문집
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• 제19권2호
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• pp.591-596
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• 1995

In order to investigate the reduction of NO emissions, natural gas was fueled for two-stage combustion apparatus. NO and CO emissions were described by five variables: total air ratio, primary air ratio, secondary air injection position, secondary air injection velocity, and swirl ratio. It was mainly observed that, as the primary air ratios of 0 and 0.4 NO emission decreased with increasing the secondary air injection position and secondary air injection velocity. The effect of weak swirl on NO emission was found to be insignificant.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.161-166
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• 2001

An Experimental study on the NOx formation of LNG flame in fuel staged combustor has been studied. The design concept of multi fuel/air staged combustor is creation of two separate flame, a primary flame is act as a pilot flame for the secondary combustion stage combustion zone, where most of fuel burns. Experiments were performed on a semi-industrial scale (thermal input 0.233 MW) in a laboratory furnace and Liquefied Natural Gas(LNG) was used as primary and secondary fuels. The study included parametric study to identify the optimum operating conditions which are primary/secondary fuel ratio, and primary/secondary air ratio for reducing NOx emission with two types of nozzle. The test demonstrated that NOx emission can be reduced by >70% in accordance with operating conditions.

• 대한기계학회논문집B
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• 제27권2호
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• pp.215-226
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• 2003

Experimental and numerical studies have been done to examine the effects of excess air ratio and tertiary air swirl number on the formation characteristics of NOx in a pilot scale combustor adopting a multi-air staged burner. In numerical calculation the mathematical models for turbulence, radiation and nitric oxide chemistry were taken into account. The radiative transfer equation was solved using the discrete ordinates method with the weighted sum of gray gases model. In the NOx chemistry model, the chemical reaction rates for thermal and prompt NOx were statistically averaged using a probability density function. The results were validated by comparison with measurements. For the experiment, a 0.2 MW pilot multi-staged air burner has been designed and fabricated. Using the numerical simulation developed here, a variation of thermal and prompt NOx formation was predicted by changing the excess air ratio and tertiary air swirl number. As the excess air ratio increased up to 1.9, the formation of the total as well as thermal NOx at exit increased while the prompt NOx decreased. The formation of thermal NOx was more affected by concentration of $O_2$ and $N_2$ than gas temperature. When the tertiary air swirl number increased, the formation of the total as well as the prompt NOx slightly decreased.

• 한국가스학회지
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• 제24권1호
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• pp.49-55
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• 2020

산업용 혹은 발전용 가스터빈에 사용되는 이중 콘형 예혼합 연소기의 다단 연소 특성을 이해하기 위하여 실험적연구를 수행하였다. 이를 위하여 기존에 모두 경사면에 공급되는 연료를 콘부분으로 일부 할애하는 방식으로 다단연소 방식을 구성하였으며 콘에서 분사되는 연료공급은 축방향과 콘 경사면 방향으로 하였다. 다단연소 연소특성을 이해하기 위하여 콘에서의 연료 분사 방향과 연료 분배율 변화에 대한 NOx와 CO의 배출 농도 그리고 벽면 온도분포를 측정하였다. 그 결과 총 연료에 대한 콘으로의 분배율이 3%인 경우 콘에서의 연료 분사방향에 관계없이 노즐내의 예혼합 영역에서 연료가 공기와 균일하게 혼합됨으로서 연소영역의 고온점 감소에 의하여 NOx 배출 농도가 감소된다. 그러나 콘에서 축방향으로 분사되는 연료분배율이 8%로 증가하는 경우 노즐 내부 예혼합 영역으로의 화염 역화로 인하여 NOx의 배출농도가 오히려 증가하게 된다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 제33회 추계학술대회논문집
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• pp.378-381
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• 2009

압축기에 불안정한 특성인 선회실속(Rotating stall)이 발생하면 압력 및 효율이 저하되고, 기계적인 손상도 야기한다. 이러한 불안정성을 개선하고 안정 운전영역을 넓히기 위해 4단 저속 축류압축기에 공기 분사(Air injection) 방법을 적용하여 안정성 개선 실험을 실시하였다. 동익 팁에 축방향으로 공기를 분사할 수 있도록 하기 위해 코안다 효과를 적용한 노즐을 사용하였고, 8개의 인젝터를 1단 동익 상단에 등간격으로 설치하였다. 축류 압축기 80% speed로 운전하면서 선회실속이 발생하기 전에 공기 분사를 실시하였고, 모드(Mode) 발생 유량의 5.4%에 해당하는 공기를 분사하여 약 4%의 안정성 개선 효과를 얻었다.