Controlling Effect of Oxygen Concentration on Fire Behavior in Low Air Pressure Cargo Compartment

2017 ◽  
Author(s):  
Wei Wang ◽  
Hui Zhang ◽  
Rui Yang ◽  
Qiuju Ma ◽  
Xiaodong Liu ◽  
...  
Keyword(s):  
Oxygen Concentration ◽  
Atmospheric Pressure ◽  
Flame Temperature ◽  
Fire Behavior ◽  
Air Pressure ◽  
Gas Composition ◽  
Compartment Fire ◽  
Mass Burning Rate ◽  
Air Intake ◽  
Low Atmospheric Pressure

Cargo compartment fire has become the major security threat for cruising aircraft, the depressurization measurement could effectively suppress the cargo compartment fire through the reduction of the air pressure and oxygen concentration. The objective of this work is to study fire behavior characteristics in half confined chamber and high altitude laboratory at identical low atmospheric pressure, and explore the controlling effects of air exhaust condition, oxygen concentration. N-heptane pool fire experiments were conducted separately in Langfang low pressure chamber (altitude 50m) and Kangding airport laboratory (altitude 4290m) at 60 kPa air pressure, both assembled ISO-9705, but their gas supplying condition is different. Mass burning rate, gas composition, flame temperature, and radiant heat flux had been measured as the principal characteristic parameters for analysis. This paper reveals the variation characteristics of the fire behavior under different oxygen concentration but identical low atmospheric pressure. The gas composition of the chamber is controlled by the liquid fire and air intake quantity, the oxygen concentration of the chamber decreases with decreasing gas intake quantity. The mass burning rate increases and the mass burning time decreases with the increase of the oxygen concentration. The higher air intake quantity or the higher oxygen concentration could increase cargo compartment fire radiation intensity, and exacerbate the fire further propagation. However, under the low oxygen concentration condition, the liquid fire still have a higher flame temperature above a certain height. The depressurization measurement could increase the flame height and flame temperature may be caused the cabin fire-resistant liners layer is easier to burn through. The more reasonable adjustment of the cargo compartment air exhaust quantity and air pressure is very meaningful for the comprehensive fire suppression of cruising commercial airplanes.

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

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.

Effect of Low Atmospheric Pressure on Air Content of Fresh Concrete

2014 ◽  
Vol 1079-1080 ◽  
pp. 202-206
Author(s):  
Xue Feng Li ◽  
Zhi Fu ◽  
Ying Xin Hui
Keyword(s):  
Atmospheric Pressure ◽  
Fresh Concrete ◽  
Test Chamber ◽  
Air Pressure ◽  
Air Content ◽  
Normal Atmospheric Pressure ◽  
Design Requirements ◽  
Low Atmospheric Pressure ◽  
Pressure Changes ◽  
Air Entraining Agents

The effects of atmospheric pressure changes on the air entraining capability of air-entraining admixtures was studied using a low-pressure test chamber to simulate plateau environments with thin air and low atmospheric pressure. Results indicate that the atmospheric pressure of the environment significantly affects the performance of air-entraining admixtures. The air content of fresh concrete decreases by approximately 20%–49% when the atmospheric pressure is 50 KPa with respect to the normal atmospheric pressure (101 KPa). The air content of fresh concrete decrease linearly as atmospheric pressure dropped. The higher the air content of fresh concrete mixed in ordinary pressure, the faster the air content of fresh concrete decreases with the drop of air pressure. The concrete with high slump shows more resistance to drop of air-content due to low air pressure than the concrete with low slump. Therefore, in order to meet the design requirements of air content of air-entrained concrete for different constructions in the plateau regions, it is necessary to increase the dosages of air entraining agents to according to different pressure conditions and types of air-entraining agent.

Experiment Study of Cardboard Box Fire Behavior Under Dynamic Pressure in an Altitude Chamber

2015 ◽  
Author(s):  
Runhe Tian ◽  
Quanyi Liu ◽  
Rui Feng ◽  
Kewei Chen ◽  
Rui Yang ◽  
...  
Keyword(s):  
Radiative Heat ◽  
Dynamic Pressure ◽  
Ambient Pressure ◽  
Flame Temperature ◽  
Fire Behavior ◽  
Measurement Data ◽  
Safety Engineering ◽  
Mass Burning Rate ◽  
Experiment Study ◽  
Controlling System

Fires recently at low ambient pressure such as cruising airplane and high altitude airport have attracted great attention. Understanding fire behavior under low pressure is one of important fundamental problems for fire safety engineering design in forementioned environment. Observation of cardboard fires under dynamic pressure is of significant meaning to study continuous variation of fire behaviors of solid fuel during depressurization. An altitude chamber of 2×3×4.65 m3 with a powerful pressure controlling system was designed to observe fire behavior of cardboard fires under dynamic pressure. In the chamber, two configurations of cardboard boxes filled with shredded office paper were tested under dynamic pressures at descent rates: 5.46kPa/min, 10.92kPa/min, and 19.68kPa/min for both configurations. Measured parameters in this study include flame temperature, radiative heat flux, and mass burning rate. The measurement data were analyzed to reveal depressurization effect on fire behavior.

Effects of different wind directions on ventilation of surrounding areas of two generic building configurations in Hong Kong

2021 ◽  
pp. 1420326X2110160
Author(s):  
Kai Yip Lee ◽  
Cheuk Ming Mak
Keyword(s):  
Wind Velocity ◽  
Natural Ventilation ◽  
Urban Environments ◽  
Air Pressure ◽  
Pressure Distributions ◽  
Air Intake ◽  
Dynamics Simulations ◽  
Surrounding Areas ◽  
Effective Use ◽  
Velocity Zone

This study investigated effects of incident wind angles on wind velocity distributions in wakes of two generic building configurations, namely, ‘T’- and ‘+’-shaped, and the air pressure distributions along their leeward walls by using computational fluid dynamics simulations. Results show that when the wind approaches laterally (90°) (vs. when the wind is direct (0°)), the downwind length and maximum bilateral width of the low-wind velocity zone in the wake of ‘T’-shaped building decrease by 11.5% and 37.9%, respectively. When the incident wind is oblique (45°) (vs. when it is direct), the length and width of this low-wind velocity zone in the wake of ‘+’-shaped building decrease by 15.0% and 30.9%, respectively. Furthermore, results show that the air pressure on the leeward walls of the ‘T’- and ‘+’-shaped buildings gradually decreases along with the building height. The resulting low-wind conditions on upper floors of buildings reduce the fresh air intake of their leeward units utilizing natural ventilation. It is particularly apparent in the case of direct approaching wind. Thus, the appropriate selection of building configurations and their orientations allows for the most effective use of wind to enhance ventilation in indoor and urban environments.

Adaptation to Low Atmospheric Pressure

BMJ ◽  
1970 ◽  
Vol 2 (5700) ◽  
pp. 39-39
Author(s):  
S. Miles
Keyword(s):  
Atmospheric Pressure ◽  
Low Atmospheric Pressure

scholarly journals Adaptations and responses of the common dandelion to low atmospheric pressure in high altitude environments

2021 ◽  
Author(s):  
Carla C. M. Arce ◽  
Zoe Bont ◽  
Ricardo A. R. Machado ◽  
Paulo F. Cristaldo ◽  
Matthias Erb
Keyword(s):  
High Altitude ◽  
Atmospheric Pressure ◽  
The Common ◽  
Low Atmospheric Pressure ◽  
Common Dandelion
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