A Review and Analysis of the Thermal Exposure in Large Compartment Fire Experiments

Gupta, Vinny,Hidalgo, Juan P.,Lange, David,Cowlard, Adam,Abecassis-Empis, Cecilia,Torero, Jose L. Council on Tall Building and Urban Habitat Korea 2021 International journal of high-rise buildings Vol.10 No.4

Developments in the understanding of fire behaviour for large open-plan spaces typical of tall buildings have been greatly outpaced by the rate at which these buildings are being constructed and their characteristics changed. Numerous high-profile fire-induced failures have highlighted the inadequacy of existing tools and standards for fire engineering when applied to highly-optimised modern tall buildings. With the continued increase in height and complexity of tall buildings, the risk to the occupants from fire-induced structural collapse increases, thus understanding the performance of complex structural systems under fire exposure is imperative. Therefore, an accurate representation of the design fire for open-plan compartments is required for the purposes of design. This will allow for knowledge-driven, quantifiable factors of safety to be used in the design of highly optimised modern tall buildings. In this paper, we review the state-of-the-art experimental research on large open-plan compartment fires from the past three decades. We have assimilated results collected from 37 large-scale compartment fire experiments of the open-plan type conducted from 1993 to 2019, covering a range of compartment and fuel characteristics. Spatial and temporal distributions of the heat fluxes imposed on compartment ceilings are estimated from the data. The complexity of the compartment fire dynamics is highlighted by the large differences in the data collected, which currently complicates the development of engineering tools based on physical models. Despite the large variability, this analysis shows that the orders of magnitude of the thermal exposure are defined by the ratio of flame spread and burnout front velocities (V_S / V_BO), which enables the grouping of open-plan compartment fires into three distinct modes of fire spread. Each mode is found to exhibit a characteristic order of magnitude and temporal distribution of thermal exposure. The results show that the magnitude of the thermal exposure for each mode are not consistent with existing performance-based design models, nevertheless, our analysis offers a new pathway for defining thermal exposure from realistic fire scenarios in large open-plan compartments.

구획화재에서 환기조건의 변화가 화재특성에 미치는 영향 (Part II: 다차원 화재거동)

김종현,고권현,박충화,황철홍 한국화재소방학회 2010 한국화재소방학회논문지 Vol.24 No.5

Multi-dimensional fire dynamics were studied numerically with the change in ventilation conditions in a full-scale ISO 9705 room. Fire Dynamic Simulator (FDS) was used for the identical conditions conducted in previous experiments. Flow rate and doorway width were changed to create over-ventilated fire (OVF) and under-ventilated fire (UVF). From the numerical simulation, it was found that the internal flow pattern rotated in the opposite direction for the UVF relative to the OVF so that a portion of products recirculated to the inside of compartment. Significant change in flow pattern with ventilation conditions may affect changes in the complex process of CO and soot formation inside the compartment due to increase in the residence time of high-temperature products. The fire behavior in the UVF created complex 3D characteristics of species distribution as well as thermal and flow structures. In particular, additional burning near the side wall inside the compartment significantly affected the flow pattern and CO production. The distribution of CO inside the compartment was explained with 3D O2 distribution and flow patterns. It was observed that gas sampling at local positions in the upper layer were insufficient to completely characterize the internal structure of the compartment fire. 실규모 ISO 9705 표준 화재실에서 환기조건 변화에 따른 다차원 화재거동에 관한 수치해석적 연구가수행되었다. 선행된 실험과 동일한 조건에 대하여 FDS(Fire Dynamic Simulator)가 사용되었다. 과환기화재 및 환기부족화재의 발생을 위하여 연료 유량과 출입구의 폭이 변화되었다. 주요 결과로서, 환기부족화재의 내부 유동패턴은 과환기화재와 비교할 때 반대방향을 갖으며, 그 결과 다량의 고온 생성물이 구획내부에서 재순환되는 매우 중요한 특징을 확인하였다. 환기조건에 따른 유동패턴의 변화는 구획 내부에서고온 생성물의 체류시간을 크게 변화시키며, CO 및 그을음의 복잡한 생성과정에 큰 영향을 미칠 수 있다. 환기부족화재는 구획 내부의 열 및 유동구조 뿐만 아니라 화학종의 분포에 관하여 매우 복잡한 3차원 구조를 생성하였다. 특히, 구획 내부의 측면에서 추가적인 반응은 유동패턴 및 CO 생성에 매우 큰 영향을주고 있다. 복잡한 CO의 분포는 3차원 산소 농도의 분포 및 유동 패턴을 통해 체계적으로 분석되었다. 위 결과로 부터 고온 상층부에서 측정된 국부 화학종 농도는 구획 내부의 화재특성을 규명하는데 많은한계가 있음을 확인할 수 있었다.

Simulating the Response of a 10-Storey Steel-Framed Building under Spreading Multi-Compartment Fires

Jiang, Jian,Zhang, Chao Council on Tall Building and Urban Habitat Korea 2018 International journal of high-rise buildings Vol.7 No.4

This paper presents a numerical investigation on the structural response of a multi-story building subjected to spreading multi-compartment fires. A recently proposed simple fire model has been used to simulate two spreading multi-compartment fire scenarios in a 10-story steel-framed office building. By assuming simple temperature rising and distribution profiles in the fire exposed structural components (steel beams, steel column and concrete slabs), finite element simulations using a three-dimensional structural model has been carried out to study the failure behavior of the whole structure in two multi-compartment fire conditions and also in a standard fire condition. The structure survived the standard fire but failed in the multi-compartment fire. Whilst more accurate fire models and heat transfer models are needed to better predict the behaviors of structures in realistic fires, the current study based on very simple models has demonstrated the importance and necessity of considering spreadingmulti-compartment fires in fire resistance design of multi-story buildings.

Analysis of Air Flow inside the Compartment under Backdraft Conditions using Solid Combustibles

Jaeseong An(Jaeseong An),Taehoon Kim(Taehoon Kim) 한국화재소방학회 2022 International Journal of Fire Science and Engineer Vol.36 No.2

Backdraft is a phenomenon of explosive combustion that occurs when fire in a state of smoldering due to the lack of oxygen grows as the air is admitted after opening the entrance door or window. In this study, a reduced compartment was produced to simulate a backdraft. In an actual site, the fire was generated by solid combustibles, and hence, wood pieces were used to generate the backdraft in this study. Twenty-seven thermocouples were installed inside the compartment. One side of a wall consists of polycarbonate and the interior of the compartment was monitored using a camera. An additional fire simulation was performed using a fire dynamics simulator for in-depth analysis of the phenomena inside the compartment. In the experiment, the air flown into the compartment through the vent opening turned the smoldering fire of solid combustibles into the flaming fire, which led to the ignition of flammable gas inside the compartment. Next, the propagation of the flame was first directed upwards to the combustibles, then towards the center, and ultimately to the exterior. This phenomenon was observed in the analysis of the compartment holding a homogeneous flammable mixture. The results of the analysis showed that the flammable mixture on the interior was released to the exterior because of the rise in the internal pressure caused by flame propagation. Consequently, as the internal flame was propagated to the exterior, the mixture was ignited. Thus, the phenomenon of backdraft in the case of compartment fire was shown to occur as follows. First, the air flown in via the vent opening was elevated to the upper part of the compartment by the smoldering heat on the interior. Next, the flame led to the ignition of the flammable mixture formed on the upper part.

국내 방화규정에 따른 건축물 방화구획 성능 및 개선방안에 관한 연구

천우영(Chun, Woo-Young),이광원(Lee, Kwang-Won),이지희(Lee, Ji-Hee),김화중(Kim, Wha-Jung) 한국화재소방학회 2008 한국화재소방학회 학술대회 논문집 Vol.2008 No.춘계

Recently, the buildings have gradually become higher, more massive and more complex with high growth of economy and varieties of the patterns of people's living. Therefore we study a performance and Improving Methods of the fire compartment as a measure to minimize the damage of the people and property from the fire. Currently, under the economic crisis situation, we do not consider about prevention of disaster safety enough; safety investment evasion, safety carelessness, and management relaxation etc. Also in the aspect of regulation system, industrial technology and plan engineering, Korean techniques of preventing fire disasters are far behind of other advanced nations. At this point, we are in need of improving about it. When considering like this situation, we need more studies on the practical improvement in order to assure fire prevention for buildings. The fire compartment prevent from magnifying the fire to the wide area by compartment into specific area. From this, it is possible to minimize fire damage and property and secure emergency exit for life safety. This fire compartment has primary function to extinguish fire easily, and the openings and penetrations are important passage which makes the smoke and fire go away from the fire area to the contiguous space. This study suggests improving methods of domestic fire compartment efficiency standard through comparative analysis of overseas advanced provision and domestic provision about base element of the building fire prevention.

축소 구획실에서 화원과 측벽의 거리에 따른 화재특성 변화

윤홍석,황철홍 한국화재소방학회 2019 한국화재소방학회논문지 Vol.33 No.1

Experimental and numerical studies on the fire characteristics according to the distance between the fire source andsidewall under the over-ventilated fire conditions. A 1/3 reduced ISO 9705 room was constructed and spruce wood cribswere used as fuel. Fire Dynamics Simulator (FDS) was used for fire simulations to understand the phenomenon inside thecompartment. As a result, the mass loss rate and heat release rate were increased due to the thermal feedback effect ofthe wall in the compartment fire compared to the open fire. As the distance between the fire source and sidewall wasreduced, the major fire characteristics, such as maximum mass loss rate, heat release rate, fire growth rate, temperature, andheat flux, were increased despite the limitations of air entrainment into the flame. In particular, a significant change in thesephysical quantities was observed for the case of a fire source against the sidewall. In addition, the vertical distribution oftemperature was changed considerably due to a change in the flow structure inside the compartment according to thedistance between the fire source and sidewall. 과환기 화재조건에서 화원과 측벽의 거리에 따른 화재특성에 관한 실험 및 수치해석 연구가 수행되었다. 1/3 축소된 ISO 9705 화재실이 제작되었으며, Spruce wood crib이 연료로 사용되었다. 구획 내부의 현상 이해를 위하여 FireDynamics Simulator (FDS)를 활용한 시뮬레이션이 수행되었다. 개방된 공간 화재에 비해 구획실 화재는 벽면의 열피드백 효과로 인하여 질량 감소율과 열발생률이 증가됨이 확인되었다. 측벽과 화원의 거리가 감소됨에 따라 화염으로의 공기 유입 제한에도 불구하고 주요 화재특성인 최대 질량 감소율, 열발생률, 화재 성장률, 온도 및 열유속이증가되었다. 특히 측벽과 화원이 접촉되었을 때 이들 물리량의 가장 큰 변화가 확인되었다. 추가로 화원과 측벽의거리에 따른 구획 내부의 유동구조의 변화로 인하여 온도의 수직분포에 상당한 변화가 발생됨이 확인되었다.

방화구획 내 스틸창호의 내화성능에 관한 실험적 연구

이재승,양승조,임현창 한국방재학회 2016 한국방재학회논문집 Vol.16 No.4

본 연구는 방화구획 내에서 방화문을 대체하여 사용할 수 있는 새롭게 개발된 방화창호의 내화성능을 평가하기 위하여 수행되었다. 내화실험은 KS F 2845에 따라 이중 PVC 창호, 이중창호, 단판유리 창호를 대상으로 실험하였다. 실험 결과, 이중 PVC 창호 및 이중 창호는 3분, 단판유리 창호는 22분의 비차열 성능을 기록하였다. 분석 결과, 스틸창호의 경우 실런트 팽창 및 프레임의 이격거리에 의해 시험체가 파괴되었으며, 이를 보완하면 30분 이상의 차열 성능을 확보할 수 있을 것으로 판단된다. This study was performed to evaluate the fire resistance performance of newly developed fire windows, which can be used instead of fire doors in a fire compartment. To evaluate fire resistance performance, fire resistance tests were conducted by KS F 2845. The experiments were PVC windows, double steel windows and single steel windows. As results of tests, PVC windows and double steel windows were 3mins on the fire resistance time respectively. On the other hand, single steel windows was 22 mins on the fire resistance time. In the case of the steel windows, the fire insulation performance can be secured over 30 min by consideration on the expansion of the silent and the separation distance between the window frame and glass.

Similarity of energy balance in mechanically ventilated compartment fires: An insight into the conditions for reduced-scale fire experiments

Suto Hitoshi,Matsuyama Ken,Hattori Yasuo 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.8

When evaluating energy balance and temperature in reduced-scale fire experiments, which are conducted as an alternative to full-scale fire experiments, it is important to consider the similarity in the scale among these experiments. In this paper, a method considering the similarity of energy balance is proposed for setting the conditions for reduced-scale experiments of mechanically ventilated compartment fires. A small-scale fire experiment consisting of various cases with different compartment geometries (aspect ratios between 0.2 and 4.7) and heights of vents and fire sources was conducted under mechanical ventilation, and the energy balance in the quasi-steady state was evaluated. The results indicate the following: (1) although the compartment geometry varies the energy balance in a mechanically ventilated compartment, the variation in the energy balance can be evaluated irrespective of the compartment size and geometry by considering scaling factor F (∝heffAwRT, where heff is the effective heat transfer coefficient, Aw is the total wall area, and RT is the ratio of the spatial mean gas temperature to the exhaust temperature); (2) the value of RT, which is a part of F, reflects the effects of the compartment geometry and corresponds to the distributions of the gas temperature and wall heat loss

반밀폐된 ISO 9705 화재실에서 비정상 화재특성 예측을 위한FDS의 성능평가

문선여,황철홍 한국화재소방학회 2012 한국화재소방학회논문지 Vol.26 No.3

The objective of this study is to evaluate the prediction accuracy of FDS(Fire Dynamic Simulator) for the thermal and chemical characteristics of under-ventilated fire with unsteady fire growth in a semi-closed compartment. To this end, a standard doorway width of the full-scale ISO 9705 room was modified to 0.1 m and the flow rate of heptane fuel was increased linearly with time (until maximum 2.0 MW based on ideal heat release rate) using a spray nozzle located at the center of enclosure. To verify the capability of FDS, the predicted results were compared with a previous experimental data under the identical fire conditions. It was observed that with an appropriate grid system, the numerically predicted temperature and heat flux inside the compartment showed reasonable agreement with the experimental data. On the other hand, there were considerable limitations to predict accurately the unsteady behaviors of CO and CO2 concentration under the condition of continuous fire growth. These results leaded to a discrepancy between the present evaluation of FDS and the previous evaluation conducted for steady-state under-ventilated fires. It was important to note that the prediction of transient CO production characteristics using FDS was approached carefully for the under-ventilated fire in a semi-closed compartment. 비정상(unsteady) 화재성장이 발생되는 반밀폐된 구획에서 환기부족화재의 열 및 화학적 특성에 관한 FDS(Fire Dynamics Simulator)의 예측성능 평가가 수행되었다. 이를 위해 실규모 ISO 9705 표준 화재실의 출입구 폭이 0.1 m로축소되었으며, spray 노즐을 통해 Heptane 연료유량은 선형적으로 증가되었다. 수치계산에 대한 신뢰도 확보를 위하여동일 조건에서 수행된 실험결과와의 상세한 비교가 이루어졌다. 적절한 격자계를 이용한 FDS의 결과는 구획 내부의 온도 및 열유속(heat flux)은 비교적 잘 예측하지만, 비정상 CO 및 CO2 생성특성은 적절히 예측하지 못함을 확인하였다. 이러한 결과는 최근 수행된 유사조건의 정상상태 환기부족 구획화재에 대한 FDS 예측결과와 상반된 것으로서, 반밀폐된구획화재 모델링에서 FDS를 이용한 비정상 CO 생성특성 예측에 상당한 주위가 요구됨을 확인하였다

인텔리전트빌딩 단위가연물의 구획화재실험을 통한 화재특성 연구

채승언,권오상,김흥열 한국방재학회 2015 한국방재학회논문집 Vol.15 No.6

In this study, real fire tests have been performed for the fire behavior and temperature analysis of the compartment. The size of Mockup experiments were 3 m length, 3.2 m wide, 2.5 m height m. The BFD curve method of C.R. Barnett is adopted to study a empirical model for fire compartment temperatures. The fire load was 35.375 kg/m 2 with office combustible supplies including access floors. The temperatures in the Mock-up compartment were measured using two different locations of thermocouple trees. These conclusions and experiment data obtained in this paper could be helpful in reference for the fire simulation, fire hazard assessment and fire protection design (including PBD). Based on experimental data, BFD curve and mathematical models need to be discussed to predict temperature curve in flashover and fire spread in the compartment. Also, this empirical model study needs more test to verify and optimize. 본 연구에서는 오픈 공간의 인텔리전트 빌딩을 대상으로 구획공간에서의 화재 성상 및 온도 변화 분석을 하였다. 화재실험은 3(L)×3.2(W)×2.5(H) m 크기의 사무실 공간을 Mock-up 제작하여 실제 사무실 화재하중을 배치하여 수행하였다. 사무실 구획공간 내부의 가연물들은 사무용 가구 및 컴퓨터와 바닥에는 악세스 플로어(Access floor)를 설치하였으며 화재실험의 화재하중은 35.375 kg/㎡이 적용되었다. Mock-up 실험체에는 두 개의 열전대 트리가 각각 설치되었으며 구획공간 내의 온도를 측정하였다. 본 실험의 데이터는 화재 시뮬레이션, 화재 위험 평가 및 화재방지설계 등에 활용될 수 있다. 본 실물화재실험에서의 온도변화 곡선은 실험 시작 후 약 13분경에 구획공간 바닥재로 화재가 확대되었다. 구획공간 내의 화재확산과 플래시오버 등의 예측을 위한 BFD 곡선, 실험 온도 곡선 등의 입증을 위한 추가 연구가 필요하다.