• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2012.04a
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• pp.258-261
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• 2012

풀화재에서 화염화염진동은 주위공기와의 밀도차에 의한 부력효과에 기인하여 주로 발생한다. 본 연구는 풀화재의 화염불안정성에 대해 산화제 유속 및 농도 변화에 따른 효과를 검토하기 위하여 컵버너 실험을 수행하였다. 실험결과는 산화제의 농도를 변화시켰을 경우에는 산화제의 불활성기체의 농도가 증가할수록 청염의 길이가 길어지고 컵버너 끝단으로부터 부상되는 것이 관찰된다. 한편, 산화제의 유속이 증가함에 따른 진동주파수가 감소함을 보인다. 이는 무차원 변수로 표현되는 주파수와 부력의 관계로 도시하였을 때 다양한 속도스케일을 사용할 수 있었지만, 연료와 산화제의 유속차로 정의되는 특성속도인 경우에 정지되어 있는 공기중에서의 풀화재 진동과 일치하는 관계식을 얻을 수 있었다. 그리고 진동주파수는 산화제 희석율과는 특정한 관계를 보이지 않는데 이는 국부적 화염구조와 연관성을 가지기 때문으로 판단된다.

• Fire Science and Engineering
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• v.31 no.5
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• pp.12-18
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• 2017

The present study has been conducted to predict the mass burning flux of methanol pool fire using liquid vaporization model in FDS and examine the effect of thermal properties of liquid fuel such as radiative fraction and mean absorption coefficient. A series of calculation for the pool diameter of 5 cm to 200 cm were performed and the size of computational domain was determined by the scale of the pool diameter. The reference grid size was determined by the grid sensitivity analysis and the computational grids consisted of approximately 750,000 cells. For the methanol pool fire, the mass burning flux predicted by liquid vaporization model of FDS followed the trend of transient characteristics as a function of pool diameter and showed good agreement within measurement uncertainty range of previous studies. The mass burning flux increased with increasing the radiative fraction and the mean absorption coefficient greatly affected on relatively small pool diameter.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2010.04a
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• pp.96-101
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• 2010

본 연구에서는 터널 내부에서의 화재 사고 시 화재를 자동으로 조기 발견 경보하여 화재 초기에 대응력을 확보시킬 수 있게 하는 화재 감지기의 성능 평가를 위해 터널 내부에서의 실물 화재 실험을 실시하였다. 실물화재실험은 일반적으로 도로 터널에 적용 중인 공기관식, 반도체식 감지기를 대상으로 "도로터널 방재시설 설치지침(2004, 건설교통부)"의 터널 내부의 화재 감지기 성능 실험 기준에 따라 메탄올을 이용한 풀버너와 소형 승용차를 이용하였다. 실험결과 메탄을 풀화재(단면적 $4m^2$)의 경우 약 36초 안에 모두 화재를 감지하였으며, 실물자동차화재실험의 경우는 1분 이내에 모두 화재를 감지하는 결과를 나타내었다.

• Fire Science and Engineering
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• v.19 no.3 s.59
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• pp.58-63
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• 2005

Experimental measurements of flames and the product properties were performed for small kerosene pool fires. which is widely used as a fire source of laboratory scale experiments with scaling modeling. The flame length and flickering frequency were investigated for the flame structures, and compared with the theory. Three measurement methods were introduced to clarify the smoke characteristics, i.e. various gas concentrations, smoke density and thermophoretic sampling with transmission electron microscopy (TEM). The yield of carbon dioxide and the consumption of oxygen were proportional to the heat release rate of pool fires, but there is no trend on carbon monoxide emission. Smoke density of turbulent flames was exponentially increased with the heat release rate. The morphology of the soot particle was investigated to address the degree of soot maturing. The results show that the similar smoke morphology between an inverse jet flame and a pool fire exists despite of different combustion controlling mechanisms.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2004.06a
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• pp.75-81
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• 2004

• Journal of the Korean Institute of Gas
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• v.22 no.5
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• pp.38-45
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• 2018

Jet fire, pool fire, and vapor cloud explosion are major accident scenarios in LPG filling station. The protection wall would mitigate radiation effect in a jet fire. In case of a pool fire, the protection wall would restrict expanding the pool area. The protection wall might both obstruct the dispersion of released vapor and protect blast overpressure in a vapor cloud explosion scenario. In this paper, An availability assessment method of the protection wall how much reduce damage to receptors is proposed. Additionally application cases are presented for the effectiveness of protection wall in the LPG filling station. The study shows that the protection wall can effectively reduce the death probabilities of receptors located behind the wall in cases of the jet fires and the vapor cloud explosions.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2002.05a
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• pp.35-41
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• 2002

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.3
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• pp.309-314
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• 2012

Flame flickering occurs mainly because of the buoyancy force for pool fires under ambient air. The cup-burner flame was used for experimental investigation of the effect of the oxidizer velocity on the gravitational instability. The results showed that the flickering frequency decreased with increasing oxidizer velocity. The frequency-buoyancy relation with nondimensional variables coincided with that of the buoyant flume and pool fires when the characteristic velocity was defined as the difference between the fuel and oxidizer velocities, which implies that the origin of the gravitational instability is the Kelvin-Helmholtz instability in the shear layer. The effect of the oxidizer composition on the instability was also examined through nitrogen dilution in the oxidizer stream. As the concentration of inert gas increased, the length of the blue flame increased and lift-off behavior was observed. The oscillation frequency was independent of the dilution ratio, but was related to the local flame structure.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2013.11a
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• pp.180-181
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• 2013

• Fire Science and Engineering
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• v.16 no.3
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• pp.71-76
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• 2002

The real scale tunnel fire tests are carried out for the first time in domestic range to assess the extent of risk in the tunnel fire. The tunnel dimension is 465 m in length, 9.2 m in width and 6.5 m in height. Gasoline pools with 0.25 MW∼2.5 MW size and a 1500CC passenger car are used as fire sources. Six jet fans are used to change the flow velocity inside the tunnel. Temperatures at total 86 points in the tunnel are measured to find the temperature distribution and smoke behavior in the real tunnel fire. In the experiment, it is examined that the important parameters to assess the extent of risk in tunnel fire such as back layering of smoke front, descending of smoke layer and the fire size of a real passenger car.