• Fire Science and Engineering
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• v.28 no.1
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• pp.37-43
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• 2014

The high predictive performance of fire detector models is essentially needed to assure the reliability of fire and evacuation modeling in the process of Performance-Based fire safety Design (PBD). The main objective of the present study is to measure input information in order to predictive the accurate activation time of fixed temperature heat detectors adopted in Fire Dynamics Simulator (FDS) as a representative fire model. To end this, Fire Detector Evaluator (FDE) which could be measured the device properties of detector was used, and the spot-type fixed temperature heat detectors of two thermistor types and one bimetal type were considered as research objectors. Activation temperature and Response Time Index (RTI) of detectors required for the fire modeling were measured, and then the RTI was measured for ceiling jet flow and vertical jet flow in consideration of the install location of detectors. The results of fire modeling using measured device properties were compared and validated with the experimental results of full-scale compartment fires. It was confirmed that, in result, the numerically predicted activation time of detector showed reasonable agreement with the measured activation time.

• 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.

• The Journal of the Convergence on Culture Technology
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• v.7 no.4
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• pp.869-878
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• 2021

This study is a study on 11-story apartments that increase the event of fires in old apartments where building-related laws and regulations are not retroactively applied. As a result of analyzing the risk of installing fire doors in Improvement Scenario 2-4, assuming that fire doors are installed as basic scenario 1 in the existing situation where fire doors are not installed at the entrance of direct stairs. In basic scenario 1, the visible distance to the entrance of the direct staircase due to the spread of smoke was 260 seconds. Improvement scenarios 3 to 4 with fire doors installed open 300 seconds after the fire was recognized, and when the fire doors were installed at the entrance of the direct stairs, the visibility to the entrance of the statistics team was less than 600 seconds. In this case, the visibility was 600 seconds at the time of installation of the fire door, and scenarios 3 to 4 increased 56.6% compared to scenario 1, lowering the risk of evacuation by more than 50%. In order to eliminate the risk of non-installation of direct statistical groups that increase the risk of smoke spread, building-related laws such as the Fire Fighting Act shall be retroactively applied when installing a direct stairway entrance or balcony folding evacuation system. The improvement caused by the installation of fire doors has numerically proven the necessity of fire doors during evacuation, and the importance of maintaining fire doors can be grasped.

• Fire Science and Engineering
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• v.33 no.5
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• pp.37-47
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• 2019

In the present study, the influences of the fire curtain and natural vent in a theater fire were investigated through the numerical simulation of a reduced-scale model of a theater fire using the Fire Dynamics Simulator (FDS). Based on a previous experimental study using the reduced-scale model, the 1/14 reduced-scale model and its conditions were constructed according to the law of similarity with a real-scale theater. Through a series of numerical simulations, the smoke movements were visualized, and the temperatures in the stage and auditorium, mass flow rate of the outflow through natural vent, and time at which smoke started moving toward the auditorium were measured and analyzed. The general trends on the effects of the fire curtain and natural vent during the theater fire predicted by the present numerical simulation were similar to the previous experimental results. For quantitative comparison of the present numerical simulation and previous experimental results, the mean percentage errors of temperatures in the stage and auditorium, and the mass flow rate of outflow through the natural vent were calculated. The present numerical simulation results showed good agreement with previous experimental results with reasonable accuracy.

• Fire Science and Engineering
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• v.32 no.5
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• pp.34-39
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• 2018

In this study, the experiment conditions for the variation of heat release rate in compartment space were constructed to analyze the effects of fire spread and the operation time of sprinkler in accordance with the heat loss of the sprinkler's heat element. The compartment composed of fire board (width = 0.3 m, height = 0.5 m, length = 3.0 m), are manufactured to measure the temperature distributions in the inner space, the mass loss rate and heat release rate during the experiment of N-heptane pool fire test. Also, the operation time of sprinkler is analyzed with the installation of sprinkler and C-factor using Fire Dynamics Simulator Ver.6 under the experiment conditions. The results show that the operation time of sprinkler, which has RTI $100(m{\cdot}s)^{0.5}$ operating temperature $70^{\circ}C$, is 30 s~60 s for C-factor = 0 and 1, 62 s~92 s for C-factor = 3, and 120 s over for C-factor = 5, respectively.

• Fire Science and Engineering
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• v.31 no.2
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• pp.52-60
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• 2017

Numerical simulations were performed to evaluate the habitability of an operator for a cabinet fire in the main control room of a nuclear power plant presented in NUREG-1934. To this end, a Fire Dynamics Simulator (FDS), as a representative fire model, was used. As the criteria for determining the habitability of operator, toxic products, such as CO, were also considered, as well as radiative heat flux, upper layer temperature, smoke layer height, and optical density of smoke. As a result, the probabilities of exceeding the criteria for habitability were evaluated through the sensitivity analysis of the major input parameters and the uncertainty analysis of fire model for various fire scenarios, based on V&V (Verification and Validation). Sensitivity analyses of the maximum heat release rate, CO and soot yields, showed that the habitable time and the limit criterion, which determined the habitability, could be changed. The present methodology will be a realistic alternative to enhancing the reliability for a habitability evaluation in the main control room using uncertain information of cabinet fires.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2013.11a
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• pp.182-183
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• 2013

FDS(Fire Dynamics Simulator)는 국내에서 화재해석을 위해 사용되고 있는 가장 보편적인 소프트웨어 중의 하나이다. 미국의 NIST에서 25년간 지속적인 업그레이드를 통해 개발되어 오고 있으며 인터넷 상에서 무료로 배포되고 있어 전 세계의 화재관련 연구자 및 학생들이 연구 및 학습의 목적으로 사용하고 긴 기간동안 많은 전문가들에 의해 검증되어온 소프트웨어이다. 하지만 FDS가 난류해석을 위해 사용하고 있는 Smagorinsky의 LES(Large Eddy Simulation)모델은 현재까지 발표된 LES모델 중 가장 초기의 모델로서 건축물과 같이 복잡한 형상을 갖는 계산영역에서는 결과의 신뢰성이 많이 떨어지는 것으로 알려져 있다. 본 연구에서는 FDS의 대공간의 화재해석 성능을 평가하는 것을 목적으로 스페인 Murcia에서 수행된 Murcia Atrium Fire Test를 해석 대상으로 하여 FDS가 사용하고 있는 Smagorinsky의 LES모델 및 3가지의 다른 LES모델을 사용하여 대공간 내부의 연기유동을 해석하였으며 그 결과를 비교하였다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.3
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• pp.266-272
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• 2017

In this study, it was simulated and analyzed the evacuation safety to identify the cadets' evacuation time by using maritimeEXODUS which is applied IMO MSC.1/Circ.1238 theory as well as the trim and heel which are the major factor of reducing the ship evacuation speed. In addition, this study carried out a simulation through the special program for fire analysis - FDS (Fire Dynamics Simulator) in order to find the effective evacuation time, i.e. life survival time. Particularly, this study did comparative analysis of the influence on the survival of cadets based on the collected simulation data by fire size and sort. As a result of the analysis, It was analyzed the Evacuation Allowable Limit Temperature $60^{\circ}C$ and resulted that there is no influence in evacuation by temperature. As a result of the analysis on visibility evacuation limit 5 m, it was found that the only one evacuation rallying point could not meet the evacuation safety. However, it derived the perfect evacuation safety under the condition of two rallying points available on wood fire. In case of Kerosene, it was satisfied the evacuation safety if the heeling was under $10^{\circ}$. Moreover, it could not meet the evacuation safety by evacuating through upper deck although there were two evacuation rallying points. When it was set by the lifeboat descending maximum angle-$20^{\circ}heel$ and $10^{\circ}trim$ which was described in SOLAS regulation, it was simulated that the wood fire having two evacuation rallying points in the center of the ship satisfied the evacuation safety.

• Journal of the Korean Society of Safety
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• v.30 no.1
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• pp.14-20
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• 2015

A Large Eddy Simulation(LES) was performed for the prediction of unsteady dispersion behavior of hydrogen fluoride (HF). The HF leakage accident occurred at the Gumi fourth industrial complex was numerically investigated using the Fire Dynamics Simulator (FDS) based on the LES. The accident area was modeled three-dimensionally and time-varying boundary conditions for wind were adopted in the simulation for considering the realistic accident conditions. The Message Passing Interface (MPI) parallel computation technique was used to reduce the computational time. As a result, it was found that the present LES simulation could predict the unsteady dispersion features of HF near the accident area effectively. The dispersion behaviors of the leaked HF was much affected by the unsteady wind direction. The LES could predict the time variation of the HF concentration reasonably and give an useful information for the risk analysis while the prediction with the time-averaging concept of HF concentration had a limitation for the amount of HF concentration at specific location point. It was identified that the LES is very useful to predict the dispersion characteristics of hazardous chemicals.

• International Journal of Safety
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• v.2 no.1
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• pp.12-16
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• 2003

In Part 1, the flame structure of the counterflow nonpremixed flames computed by using Fire Dynamics Simulator was compared with that of OPPDIF for different concentrations of methane in the fuel stream. In this study, comparisons were made for the global strain rate that is an important parameter for diffusion flames for further evaluation of FDS. At each of the three fuel concentrations, $20% CH_4＋ 80% N_2, 50% CH_4 ＋ 50% N_2, 90% CH_4 ＋ 10% N_2$ in the fuel stream, the temperature and axial velocity profiles were investigated for the global strain rate in the range from 20 to $100s^{-1}$. Changes in flame thickness and radius were also compared with OPPDIF. There was good agreement in the temperature and axial velocity profiles between the axisymmetric simulations and the one-dimensional computations except for the regions where the flame temperature reach its peak and the axial velocity rapidly changes. The simulations of the axisymmetric flames with FDS showed that the flame thickness decreases and the flame radius increases with increasing global strain rate.