An experimental study of acoustically driven medium-scale pool fires

이기용,Andrew Lock,Anthony Hamins 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.8

A set of experiments has been conducted on a medium-scale propane fueled pool fire acoustically forced in order to facilitate repeatable measurements defining the flame’s transient behavior. The fuel flow was slightly perturbed at the pool fire’s natural frequency by a sine waveform driven with a loudspeaker which was installed under the burner. As a result of the perturbation, the puffing behavior of the pool fire and the fire shape were modified. As the magnitude of the sine wave was increased larger perturbations were clearly observed,based on the measurement of the radiative heat flux and image analysis. Temperature and soot volume fractions were measured along the center line and throughout a slice of the flame. The soot volume fractions in the flame region are in good agreement with the data of other researchers. The reproducibility of these measurements was established through several experiments. The acoustically driven flame provides the possibility of more repeatable measurements of the transient behavior of these pool fires.

An Experimental Study of Acoustically Driven Medium-Scale Pool Fires

이기용(Ki Yong Lee),Andrew Lock,Anthony Hamins 한국연소학회 2010 KOSCOSYMPOSIUM논문집 Vol.- No.40

Experimental investigations have been performed on a medium-scale pool fire acoustically forced in order to facilitate repeatable measurements defining the flame’s transient behavior. The fuel flow was slightly perturbed at the natural frequency of the pool fire by a sine waveform driven with a loudspeaker which was installed under the burner. As a result of the perturbation, the puffing behavior of pool fire and the fire shape were modified. As the magnitude of sine wave was increased more motion was clearly observed, based on the measurement of the radiative heat flux and image analysis. Temperature and soot volume fractions were measured along the center line and throughout a slice of the burner. The soot volume fractions in the flame region are in very good agreement with other researchers. The reproducibility of these measurements is established through several series of experiments. The acoustically driven flame provides the possibility of a more repeatable measurements of the transient behavior of these pool fires.

구획화재에서 환기조건의 변화가 화재특성에 미치는 영향 (Part I: FDS의 성능평가)

황철홍,박충화,고권현,Andrew Lock 한국화재소방학회 2010 한국화재소방학회논문지 Vol.24 No.3

Experimental and numerical studies were conducted to investigate the thermal and chemical characteristics of heptane fires in a full-scale ISO 9705 room. Representative fire conditions were considered for over-ventilated fire (OVF) and under-ventilated fire (UVF). Fuel flow rate and doorway width were changed to create OVF and UVF conditions. Detailed comparisons of temperature and species concentrations between experimental and numerical data were presented in order to validate the predictive performance of FDS (Fire Dynamic Simulator). The OVF and UVF were explicitly characterized with distributions of temperature and product formation measured in the upper layer, as well as combustion efficiency and global equivalence ratio. It was shown that the numerical results provided a quantitatively realistic prediction of the experimental results observed in the OVF conditions. For the UVF, the numerically predicted temperature showed reasonable agreement with the measured temperature. The predicted steady-state volume fractions of O2, CO2, CO and THC also agreed quantitatively with the experimental data. Although there were some limitations to predict accurately the transient behavior in terms of CO production/consumption in the UVF condition, it was concluded that the current FDS was very useful tool to predict the fire characteristics inside the compartment for the OVF and UVF. 실규모 ISO 9705 표준 화재실에서 과환기화재 및 환기부족화재에 대한 열 및 화학적 특성에 관한 실험 및 수치해석 연구가 수행되었다. 과환기화재 및 환기부족화재의 발생을 위하여 연료 유량과 출입구의폭이 변화되었다. FDS(Fire Dynamic Simulator)의 화재현상 예측성능을 검토하기 위하여 실험과 수치해석에서 얻어진 온도 및 화학종의 농도에 대한 상세한 비교가 이루어졌다. 과환기화재 및 환기부족화재의전반적인 특성은 연소효율, 총괄당량비뿐만 아니라 고온 상층부에서 측정된 온도 및 화학종의 농도분포에의해서도 명확하게 구분되었다. 과환기화재에서 FDS는 온도 및 화학종의 농도에 관한 실험결과를 정량적으로 매우 잘 예측하였다. 반면에 환기부족화재의 경우, 시간 증가에 따른 CO2의 감소 및 CO의 증가와같은 비정상적 화학적특성의 예측에는 한계가 있음을 알 수 있었다. 그럼에도 불구하고 정상상태 구간의시간 평균된 온도 및 화학종의 농도는 실험결과를 적절히 잘 예측하였다. 위 결과로 부터 FDS는 과환기화재 및 환기부족화재의 특성을 예측하는데 매우 유용하게 활용될 수 있음을 알 수 있었다.

실제 규모의 구획화재에서 총괄당량비와 화재특성의 상관관계에 관한 실험적 연구

황철홍(Cheol-Hong Hwang),박충화(Chung-Hwa Park),고권현(Gwon Hyun Ko),Andrew Lock 한국연소학회 2010 한국연소학회지 Vol.15 No.3

An experimental study was conducted to investigate the relationship between global equivalence ratio(GER) and fire characteristics in an ISO 9705 room. Heptane fuel was burned with different fuel flow rates and doorway widths in order to force the room to be placed in different GER conditions. It was observed that after the onset of under-ventilated fire conditions, temperature and unburned fuel components such as CO and soot increased with increasing heat release rate (HRR), regardless of the doorway width. From the analysis of local mixture fraction, it was reconfirmed that the inclusion of soot production in the product composition was very important to predict accurately the chemical conditions inside the compartment, particularly for the under-ventilated fire conditions. In addition, the local equivalence ratio (LER) was directly proportional to the GER with a unit gradient regardless of doorway width when the soot production was included in the chemical products. This finding provided an important potential that the GER could be used to correlate the local thermal and chemical environment measured at the upper layer of a full-scale enclosure when soot was included.

환기부족 구획화재에서 다차원 화재거동

황철홍(Hwang, Cheol-Hong),박충화(Park, Chung-Hwa),고권현(Ko, Gwon-Hyun),Lock, Andrew 한국화재소방학회 2010 한국화재소방학회 학술대회 논문집 Vol.2010 No.춘계

실제 규모 ISO 9705 표준 화재실에서 과환기(over-ventilated) 및 환기부족(under-ventilated) 화재에 대한 열 및 화학적 특성에 관한 실험이 수행되었다. 또한 FDS(Fire Dynamic Simulator)를 이용하여 수치적 예측성능에 대한 평가와 환기부족화재에서 건물 내부의 다차원 화재현상에 대한 해석이 이루어졌다. 과환기 및 환기부족화재의 특성은 연소효율, 총괄 당량비 뿐만 아니라 고온 상층부의 온도분포, 연소 생성물의 농도에 의해 명확하게 구분되었다. 실험결과와의 비교를 통해 과환기 및 환기부족화재에서 FDS는 공간내부의 온도, 열유속 및 다양한 화학종의 분포를 정량적으로 잘 예측함을 확인하였다. 과환기화재와 비교할 때, 환기부족화재에서 내부유동은 반대방향의 다차원 재순환 유동구조를 갖고 있음을 발견하였다. 동시에 공간내부의 <TEX>$O_2$</TEX> 및 CO의 분포 역시 다차원 구조를 갖기 때문에 기존화재연구에서 측정되는 고온 상층부의 열 및 화학적 특성은 환기부족화재를 이해하는데 많은 한계가 있음을 확인하였다.

실규모 구획화재에서 총괄당량비와 화재특성의 상관관계

황철홍(Cheol-Hong Hwang),박충화(Chung-Hwa Park),고권현(Gwon Hyun Ko),Andrew Lock 한국연소학회 2010 KOSCOSYMPOSIUM논문집 Vol.- No.40

An experimental study was conducted to investigate the relationship between global equivalence ratio(GER) and fire characteristics in an ISO 9705 room. Heptane fuel was burned with different fuel flow rates and doorway widths in order to force the room to be placed in different GER conditions. It was observed that after the onset of under-ventilated fire conditions, temperature and unburned fuel components such as CO and soot increased with increasing heat release rate(HRR), regardless of the doorway width. From the analysis of local mixture fraction, it was reconfirmed that the inclusion of soot production in the product composition was very important to predict accurately the chemical conditions inside the compartment, particularly for the under-ventilated fire conditions. In addition, the local equivalence ratio(LER) was directly proportional to the GER with a unit gradient regardless of doorway width when the soot production was included in the chemical products. This finding provided an important potential that the GER could be used to correlate the local thermal and chemical environment measured at the upper layer of a full-scale enclosure when soot was included.