• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.501-504
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• 2010

In this study, fire behavior for subway coach fire in the 1/10 reduced scale model is analyzed using numerical analysis method (FDS). The size of the reduced model coach is 1.9 m long, 0.290 m high and 0.235 m. The simulation is carried out only one-sided four doors of the coach are opened. A fire source is the n-heptane pool fire with a mean heat release rate 2.33 kW. Smoke temperature, heat release rate and mass loss rate for the model are calculated.

• Journal of ILASS-Korea
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• v.13 no.3
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• pp.156-161
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• 2008

The present article reports a numerical study on the fire characteristic change by water-mist in under-ventilated compartments. The natural gas and heptane pool fires are used as fire sources, which are located in the bottom center of the 2/5 reduced-scaled model of the ISO 9705 standard room. The fire modeling using the FDS (Fire Dynamics Simulator) is validated by comparison with previously published experimental results. For temperature and combustion gas concentrations at two positions located in the upper layer of compartment, the predicted results with and without water-mist are compared each other. The results show that under the water-mist operation, the predicted temperature and carbon monoxide concentration reduce as $300{\sim}400^{\circ}C$ and about 20%, respectively, compared to those without water-mist.

• Fire Science and Engineering
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• v.27 no.2
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• pp.62-69
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• 2013

In this study, a full scale experiment was carried out to analyze the heat and smoke movement. The experiment was conducted a kindergarten that is scheduled to reconstruction. The kindergarten is a two-story building and the area of each floor is 252 $m^2$. 36 l heptane was used as a fuel and heptane was burned in a 0.8 m square steel pool. Maximum heat release rate was 1.7 MW at natural condition. Smoke movement and temperature variation were measured during the experiment. In the first floor corridor, smoke was moved downward about 1.4 m at 1 minute after a fire. Corridor was filled with smoke at 4 minutes after a fire. In the second floor, temperature was maintained at $70^{\circ}C$ or less. But, second floor rooms were filled with smoke.

• Fire Science and Engineering
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• v.32 no.2
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• pp.7-16
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• 2018

In this study, the previous design fire curve for fire simulation was modified and re-suggested. Numerical simulations with the FDS and CFAST were performed for the n-heptane and n-octane pool fires in the ISO 9705 compartment to evaluate the prediction performances of the previous 1-stage and modified 2-stage design fire curves. The numerical results were compared with the experimental temperature and concentrations of $O_2$ and $CO_2$. The FDS and CFAST simulations with the 2-stage design fire curve showed better prediction performance for the variation of temperature and major species concentration than the simulations with 1-stage design fire curve. Especially, the simulations with the 2-stage design fire curve agreed with the experimental temperature more reasonably than the results with the 1-stage design fire curve. The FDS and CFAST simulations showed good prediction performance for the temperature in the upper layer of compartment and the results with the FDS and CFAST were similar to each other. However, the FDS and CFAST showed poor and different prediction performance for the temperature in the lower layer of compartment.

• Fire Science and Engineering
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• v.33 no.5
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• pp.28-36
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• 2019

In the present study, the effects of supply gas and water mist on the heptane pool fire extinguishing performance were investigated using the full cone and hollow cone twin-fluid atomizers. Air or nitrogen of 30 lpm (Liter per minute; L/min) was used as the supply gas, and the experiments were conducted under the water flow rate conditions of 0 lpm (i.e., discharge of air or nitrogen only) and 0.085 lpm (i.e., discharge of water mist with supply gas). Experimental results confirmed that the use of water mist discharge with the supply gas and full cone spray pattern reduced the fire extinguishing time as compared to that of only supply gas discharge and hollow cone spray pattern. In addition, for the discharge of water mist using the full cone twin-fluid atomizer, water mist significantly affected fire extinguishing performance, whereas the effect of the supply gas was less pronounced. On the other hand, for the discharge of water mist using the hollow cone twin-fluid atomizer, the fire extinguishing time was remarkably reduced by the supply of nitrogen, as compared with that of air, indicating that the supply gas as well as water mist can significantly affect fire extinguishing performance.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.1
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• pp.41-48
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• 2009

The present study has been performed to investigate the thermal characteristics of under-ventilated compartment fire which is a typical fire condition in structures. A series of fire experiments was conducted to characterize the thermally driven flow in a 2/5 scale ISO 9705 fire compartment. Three different fuels were used in this test series, methane gas, heptane pool, and polystyrene pellets fire. In order to measure accurate temperature, double shield aspirated thermocouples reducing the effect of radiative energy exchange on temperature measurement were used in addition to bare bead thermocouples. The upper layer temperature for well ventilated fire was increased with increasing heat release rate, but it was slightly decreased for under-ventilated fire. The measured temperatures in the upper layer at the front sampling location were higher than at the rear. Thermal characteristics through the doorway were also analysed for a wide range of heat release rates. This study provides a comprehensive and quantitative assessment of fire behavior for under-ventilation condition of fire.

• 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.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.2130-2138
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• 2008

The present study investigates the ventilation effects on smoke spreading characteristics in railway tunnels with the rescue stations. Experiments were carried out for n-heptane pool fires with a square length 4 cm at different fire locations, and the heat release rates (HRR) were obtained by the measurement of burning rates. In addition, using the commercial code (FLUENT), the present article presents numerical results for smoke behavior in railway tunnels with rescue station, and it uses the MVHS (Modified Volumetric Heat Source) model for estimation of combustion products resulting from the fire source determined from the HRR measurement. As a result, it is found that smoke propagation is prevented successfully by the fire doors located inside the cross-passages and especially, the smoke behavior in the accident tunnel can be controlled through the ventilation system because of substantial change in smoke flow direction in the cross-passages.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2010.10a
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• pp.171-174
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• 2010

도로터널에서의 미분무수 소화시스템의 적용 가능성을 검토하기 위해 실물 화재 실험을 수행하였다. 적용된 화원은 실물 승용차 화재와 유류화재를 모사한 화원면적 $1.4m^2$의 heptane pool 화재이며, 기존 도로터널에 설치된 저압 물분무 시스템과 고압 미분부수 소화시스템과의 냉각효과 비교실험을 수행하였다. 도로터널 내의 환기조건을 구현하기 위해 실물모형 터널의 한 편에 터널 유속(0.9~3.8 m/sec 범위) 발생장치를 설치하였으며, 화원에서 하류 방향으로 터널 내 온도분포를 측정하였다. 실험 결과 1/5의 유량을 사용하는 고압 미분무수 소화시스템은 저압 물분무 시스템과 동등한 수준의 냉각효과를 보였다.

• Fire Science and Engineering
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• v.32 no.3
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• pp.42-50
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• 2018

The effect of sub-grid turbulence and combustion models on the mean flame height in a heptane pool fire according to the Fire Dynamics Simulator (FDS) version (5 and 6) based on Large Eddy Simulation (LES) was examined. The heat release rate for the fire simulation was provided through experiments performed under identical conditions and the predictive performance of the mean flame height according to FDS version was evaluated by a comparison with the existing correlation. As a result, the Smagorinsky and Deardorff turbulence models applied to FDS 5 and 6, respectively, had no significant effects on the mean flow field, flame shape and flame height. On the other hand, the difference in pool fire characteristics including the mean flame height was due mainly to the difference in the mixture fraction and Eddy Dissipation Concept (EDC) combustion models applied to FDS 5 and 6, respectively. Finally, compared to FDS 6, FDS 5 provided the predictive result of a significantly longer flame height and more consistent mean flame height than the existing correlation.