Experimental study of large-scale fire behavior under low pressure at high altitude

Airplane as one of the important transport vehicles in our life, its safety problem related to in-flight fire has attracted a wide-spread attention. The combustion behavior of the cabin fire in flight shows some special characteristics because of the high-altitude environment with low-pressure and low oxygen concentration. A low-pressure chamber of size 2 m×3 m×2 m has been built to simulate high-altitude environments, where multiple static pressures for pool fire tests can be configured in the range between standard atmospheric pressure 101.3KPa and 30KPa. Two different sizes of pool fires were tested. Then corresponding modeling were conducted by a LES code FDS V5.5 to examine the mechanism of pressure effect on the n-Heptane pool fire behavior. The burning of liquid fuel was modeled by a Clausius-Clapeyron relation based liquid pyrolysis model. The modeling data was validated against the experimental measurements. The mass burning rate of free-burning pool fire decreases with the decreasing of pressure, which was observed from the modeling to be due to the reduction of flame heat feedback to the fuel surface. Under low pressure, the fire plume temperature increases for the same burning rate. The mechanism of pressure effect on fire behavior was analyzed based on the modeling data.

Download Full-text

N-Heptane Pool Fire Behavior in a Controlled Oxygen and Low-Pressure Environment

Volume 7: Fluids Engineering Systems and Technologies ◽

10.1115/imece2014-37389 ◽

2014 ◽

Author(s):

Quanyi Liu ◽

Kewei Chen ◽

Nan Wu ◽

Jiusheng Yin ◽

Rui Yang ◽

...

Keyword(s):

High Altitude ◽

Radiative Heat ◽

Flame Temperature ◽

Fire Behavior ◽

Low Pressure ◽

Pool Fire ◽

Fire Tests ◽

Mass Burning Rate ◽

Low Oxygen ◽

Lower Temperature

Fires at high altitude airports have attracted a lot of attention. Such fires show some special characteristics because of the coupling impact of low pressure and low oxygen levels. Some experiments, which were conducted recently at high altitude locations, such as Lhasa and in some low pressure chambers, were usually extinguished due to the limited supply of oxygen. In order to reveal the dependence of fire behavior on pressure comprehensively, a low-pressure chamber with ventilation control of 2×3×4.65m3 in volume has been developed and built, which can allow larger scale fire tests to be conducted and simulate more realistic high-altitude environment. In this study, pool fire tests using 20-cm and 30-cm-diameter pans are configured under five different static pressures, e.g. 101kPa, 75kPa, 64kPa, 38kPa and 24kPa. Each test has been repeated three times. The parameters measured include flame temperature, radiative heat flux, and mass loss etc. It is concluded that under lower pressure, mass burning rate is lower, temperature is higher, and height of the flame is higher, which demonstrated that low pressure fire is more dangerous to the buildings at high altitude airports.

Download Full-text

Vertical structure of Antarctic tropospheric ozone depletion events: characteristics and broader implications

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-8189-2010 ◽

2010 ◽

Vol 10 (3) ◽

pp. 8189-8246 ◽

Cited By ~ 2

Author(s):

A. E. Jones ◽

P. S. Anderson ◽

E. W. Wolff ◽

H. K. Roscoe ◽

G. J. Marshall ◽

...

Keyword(s):

High Altitude ◽

Ozone Depletion ◽

Tropospheric Ozone ◽

Large Scale ◽

Field Experiments ◽

Strong Association ◽

Vertical Component ◽

Low Pressure ◽

The Arctic ◽

Low Pressure Systems

Abstract. The majority of tropospheric ozone depletion event (ODE) studies have focussed on time-series measurements, with comparatively few studies of the vertical component. Those that exist have almost exclusively used free-flying balloon-borne ozonesondes and almost all have been conducted in the Arctic. Here we use measurements from two separate Antarctic field experiments to examine the vertical profile of ozone during Antarctic ODEs. We use tethersonde data to probe details in the lowest few hundred meters and find considerable structure in the profiles associated with complex atmospheric layering. The profiles were all measured at wind speeds less than 7 ms−1, and on each occasion the lowest inversion height lay between 10 m and 40 m. We also use data from a free-flying ozonesonde study to select events where ozone depletion was recorded at altitudes >1 km above ground level. Using ERA-40 meteorological charts, we find that on every occasion the high altitude depletion was preceded by an atmospheric low pressure system. An examination of limited published ozonesonde data from other Antarctic stations shows this to be a consistent feature. Given the link between BrO and ODEs, we also examine ground-based and satellite BrO measurements, and find a strong association between enhanced BrO and atmospheric low pressure systems. The results suggest that, in Antarctica, such depressions are responsible for driving high altitude ODEs and for generating the large-scale BrO clouds observed from satellites. In the Arctic, the prevailing meteorology differs from that in Antarctica, but we show that major low pressure systems in the Arctic, when they occur, can also generate BrO clouds. Such depressions thus appear to be fundamental when considering the broader influence of ODEs, particularly in Antarctica, such as halogen export and the radiative influence of ozone-depleted air masses.

Download Full-text

Experimental Study on Occurrence Limit Heat Release Rate of Flashover in a Building Fire

Korean Society of Hazard Mitigation ◽

10.9798/kosham.2021.21.2.65 ◽

2021 ◽

Vol 21 (2) ◽

pp. 65-71

Author(s):

Seunggoo Kang ◽

Yi Chul Shin

Keyword(s):

Experimental Study ◽

Heat Release ◽

Heat Release Rate ◽

Release Rate ◽

Large Scale ◽

Fire Behavior ◽

Design Calculation ◽

Building Fire ◽

Fire Source ◽

Combustion Tests

In this study, to allow the flashover to occur, combustion tests were conducted by setting the conditions of a fire source using a large-scale compartment and changing the opening condition. As a result, the inside temperature of the compartment was measured under the fire source conditions. Moreover, according to the “Handbook on Design Calculation Methods of Fire Behavior” by the Architectural Institute of Japan, the validity of the heat release rate required for the flashover to occur was verified through the correlation between <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>Q</mi><mrow><mi>F</mi><mi>O</mi></mrow></msub><mo>/</mo><msub><mi>Q</mi><mrow><mi>v</mi><mi>m</mi><mi>a</mi><mi>x</mi></mrow></msub></math> and <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>A</mi><mi>T</mi></msub><msup><mrow><mo>(</mo><mi>k</mi><mi>p</mi><mi>c</mi><mo>)</mo></mrow><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msup><mo>/</mo><msub><mi>c</mi><mrow><mi>P</mi></mrow></msub><mn>0</mn><mo>.</mo><mn>5</mn><mi>A</mi><msup><mi>H</mi><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msup></math>.

Download Full-text

An experimental study on fire behavior of an inclined ceiling jet in a low-pressure environment

International Journal of Thermal Sciences ◽

10.1016/j.ijthermalsci.2019.01.023 ◽

2019 ◽

Vol 138 ◽

pp. 487-495 ◽

Cited By ~ 4

Author(s):

Zhenxiang Tao ◽

Rui Yang ◽

Cong Li ◽

Yina Yao ◽

Ping Zhang ◽

...

Keyword(s):

Experimental Study ◽

Fire Behavior ◽

Low Pressure

Download Full-text

Vertical structure of Antarctic tropospheric ozone depletion events: characteristics and broader implications

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-7775-2010 ◽

2010 ◽

Vol 10 (16) ◽

pp. 7775-7794 ◽

Cited By ~ 56

Author(s):

A. E. Jones ◽

P. S. Anderson ◽

E. W. Wolff ◽

H. K. Roscoe ◽

G. J. Marshall ◽

...

Keyword(s):

High Altitude ◽

Ozone Depletion ◽

Tropospheric Ozone ◽

Large Scale ◽

Field Experiments ◽

Strong Association ◽

Vertical Component ◽

Low Pressure ◽

The Arctic ◽

Low Pressure Systems

Abstract. The majority of tropospheric ozone depletion event (ODE) studies have focussed on time-series measurements, with comparatively few studies of the vertical component. Those that exist have almost exclusively used free-flying balloon-borne ozonesondes and almost all have been conducted in the Arctic. Here we use measurements from two separate Antarctic field experiments to examine the vertical profile of ozone during Antarctic ODEs. We use tethersonde data to probe details in the lowest few hundred meters and find considerable structure in the profiles associated with complex atmospheric layering. The profiles were all measured at wind speeds less than 7 ms−1, and on each occasion the lowest inversion height lay between 10 m and 40 m. We also use data from a free-flying ozonesonde study to select events where ozone depletion was recorded at altitudes >1 km above ground level. Using ERA-40 meteorological charts, we find that on every occasion the high altitude depletion was preceded by an atmospheric low pressure system. An examination of limited published ozonesonde data from other Antarctic stations shows this to be a consistent feature. Given the link between BrO and ODEs, we also examine ground-based and satellite BrO measurements and find a strong association between atmospheric low pressure systems and enhanced BrO that must arise in the troposphere. The results suggest that, in Antarctica, such depressions are responsible for driving high altitude ODEs and for generating the large-scale BrO clouds observed from satellites. In the Arctic, the prevailing meteorology differs from that in Antarctica, but, while a less common effect, major low pressure systems in the Arctic can also generate BrO clouds. Such depressions thus appear to be fundamental when considering the broader influence of ODEs, certainly in Antarctica, such as halogen export and the radiative influence of ozone-depleted air masses.

Download Full-text