Modeling on n-Heptane Pool Fire Behavior in an Altitude Chamber

2013 ◽  
Author(s):  
Quanyi Liu ◽  
Wei Yao ◽  
Jiusheng Yin ◽  
Rui Yang ◽  
Hui Zhang
Keyword(s):  
High Altitude ◽  
Burning Rate ◽  
Pressure Effect ◽  
Fire Behavior ◽  
Low Pressure ◽  
Pool Fire ◽  
Low Oxygen ◽  
Fire Plume ◽  
Plume Temperature ◽  
Modeling Data

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.

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.

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

2013 ◽  
Vol 31 (6) ◽  
pp. 481-494 ◽  
Author(s):  
Wei Yao ◽  
Xiaokang Hu ◽  
Jianzhong Rong ◽  
Jian Wang ◽  
Hui Zhang
Keyword(s):  
Experimental Study ◽  
High Altitude ◽  
Large Scale ◽  
Fire Behavior ◽  
Low Pressure

The Mass Burning Rate of n-Heptane Pool Fire Under Dynamic Pressure

2016 ◽  
Author(s):  
Qiuju Ma ◽  
Quanyi Liu ◽  
Runhe Tian ◽  
Junjian Ye ◽  
Rui Yang ◽  
...  
Keyword(s):  
Burning Rate ◽  
Cold Water ◽  
Dynamic Pressure ◽  
Pressure Rise ◽  
Low Pressure ◽  
Pool Fire ◽  
Chamber Pressure ◽  
Pure Liquid ◽  
Mass Burning Rate ◽  
The Impact

Fire safety is critical for safety of airplane operation. During an emergency landing, airplane goes through dramatic external pressure change from cruise altitude to sea level, considering the impact caused by low pressure atmosphere. The objective of this work is to examine the effect of dynamic pressure on the behavior of a horizontally burning diffusion flame over a pool fuel surface based on experimental approach. The experiments were conducted in a large-scale altitude chamber of size 2 m × 3 m × 4.65 m. The pressure rise process was examined under different dynamic pressures from respectively 38 kPa, 64 kPa and 75 kPa to 90 kPa with various pressure rise rates of 100 Pa/s, 150 Pa/s, 200 Pa/s, 250 Pa/s and 300 Pa/s, which is to simulate the airplane landing process from different altitudes. The whole system of the altitude chamber is of unique capability that the pressure in the chamber can be exactly controlled by a powerful pressure controlling system, and the oxygen concentration can maintain at the level about 20%, which are achieved through controlling inlet air flow for oxygen level and outlet gas flow for pressure (static or dynamic) level. A round steel fuel pans of 34 cm in diameter and 15 cm in height were chosen for the pool fire tests. The fuel pan was filled with 99% pure liquid n-Heptane. Cold water is added beneath the fuel layer to cool the pan and minimize the temperature rise in the fuel. Parameters such as mass, mass burning rate, chamber pressure were measured. The results of those tests demonstrated the significant impact to fire behaviors caused by high altitude or low pressure atmosphere.

Solid Fuel Fire Behavior Under Fixed Pressure in a Low-Pressure Chamber

2015 ◽  
Author(s):  
Rui Feng ◽  
Quanyi Liu ◽  
Runhe Tian ◽  
Kewei Chen ◽  
Rui Yang ◽  
...  
Keyword(s):  
Burning Rate ◽  
Solid Fuel ◽  
Fire Behavior ◽  
Low Pressure ◽  
Pressure Chamber ◽  
Fire Tests ◽  
Mass Burning Rate ◽  
Base Dimension ◽  
The Difference ◽  
Fire Characteristics

To comprehensively reveal the difference of solid fuel fire characteristics at different altitudes, fire experiments of cardboard boxes at multiple static pressures with two configurations filled with shredded office paper were conducted in a low-pressure chamber. The measured parameters are mass burning rate, radiative heat flux, oxygen concentration and heat release rate (HRR) etc. The mass burning rate divided by fire base dimension ṁ/D is correlated against the production of pressure-squared times length-cubed (P2L3) to the power of 0.29 based on current cardboard boxes fire test data. HRR of two boxes fire tests are higher than that of one box fire tests under fixed pressures. However, there are a higher peak of HRR under a fixed higher pressure for one-box fire tests while a lower peak of HRR under a higher pressure for two-box fire tests. The HRR would decrease sharply after reaching the peak.

scholarly journals Analysis for Fire Plume Temperature in Developing Area and Radiation Heat Flux Distribution in Small-scale Pool Fire

2018 ◽  
Vol 211 ◽  
pp. 606-613 ◽  
Author(s):  
Gan-su Shen ◽  
Jun-cheng Jiang ◽  
Kui-bin Zhou ◽  
Shao-jie Zhang ◽  
Fan Wu ◽  
...  
Keyword(s):  
Heat Flux ◽  
Flux Distribution ◽  
Pool Fire ◽  
Small Scale ◽  
Heat Flux Distribution ◽  
Radiation Heat ◽  
Radiation Heat Flux ◽  
Fire Plume ◽  
Plume Temperature ◽  
Developing Area

scholarly journals Oxygen regulation of macrophage migration inhibitory factor in human placenta

2007 ◽  
Vol 292 (1) ◽  
pp. E272-E280 ◽  
Author(s):  
Francesca Ietta ◽  
Yuanhong Wu ◽  
Roberta Romagnoli ◽  
Nima Soleymanlou ◽  
Barbara Orsini ◽  
...  
Keyword(s):  
High Altitude ◽  
Migration Inhibitory Factor ◽  
Macrophage Migration Inhibitory Factor ◽  
Inhibitory Factor ◽  
Extravillous Trophoblast ◽  
Macrophage Migration ◽  
Low Oxygen ◽  
Placental Development

Macrophage migration inhibitory factor (MIF) is an important proinflammatory cytokine involved in regulation of macrophage function. In addition, MIF may also play a role in murine and human reproduction. Although both first trimester trophoblast and decidua express MIF, the regulation and functional significance of this cytokine during human placental development remains unclear. We assessed MIF expression throughout normal human placental development, as well as in in vitro (chorionic villous explants) and in vivo (high altitude placentae) models of human placental hypoxia. Dimethyloxalylglycine (DMOG), which stabilizes hypoxia inducible factor-1 under normoxic conditions, was also used to mimic the effects of hypoxia on MIF expression. Quantitative real-time PCR and Western blot analysis showed high MIF protein and mRNA expression at 7–10 wk and lower levels at 11–12 wk until term. Exposure of villous explants to 3% O2 resulted in increased MIF expression and secretion relative to standard conditions (20% O2). DMOG treatment under 20% O2 increased MIF expression. In situ hybridization and immunohistochemistry showed elevated MIF expression in low oxygen-induced extravillous trophoblast cells. Finally, a significant increase in MIF transcript was observed in placental tissues from high-altitude pregnancies. Hence, three experimental models of placental hypoxia (early gestation, DMOG treatment, and high altitude) converge in stimulating increased MIF, supporting the conclusion that placental-derived MIF is an oxygen-responsive cytokine highly expressed in physiological in vivo and in in vitro low oxygen conditions.

scholarly journals The Expression Regulatory Network in the Lung Tissue of Tibetan Pigs Provides Insight Into Hypoxia-Sensitive Pathways in High-Altitude Hypoxia

2021 ◽  
Vol 12 ◽  
Author(s):  
Yanan Yang ◽  
Haonan Yuan ◽  
Tianliang Yang ◽  
Yongqing Li ◽  
Caixia Gao ◽  
...  
Keyword(s):  
High Altitude ◽  
Regulatory Networks ◽  
Alveolar Wall ◽  
Potential Candidate ◽  
Low Oxygen ◽  
Structure Damage ◽  
High Altitude Adaptation ◽  
Tibetan Pigs ◽  
Altitude Adaptation ◽  
Insight Into

To adapt to a low-oxygen environment, Tibetan pigs have developed a series of unique characteristics and can transport oxygen more effectively; however, the regulation of the associated processes in high-altitude animals remains elusive. We performed mRNA-seq and miRNA-seq, and we constructed coexpression regulatory networks of the lung tissues of Tibetan and Landrace pigs. HBB, AGT, COL1A2, and EPHX1 were identified as major regulators of hypoxia-induced genes that regulate blood pressure and circulation, and they were enriched in pathways related to signal transduction and angiogenesis, such as HIF-1, PI3K-Akt, mTOR, and AMPK. HBB may promote the combination of hemoglobin and oxygen as well as angiogenesis for high-altitude adaptation in Tibetan pigs. The expression of MMP2 showed a similar tendency of alveolar septum thickness among the four groups. These results indicated that MMP2 activity may lead to widening of the alveolar wall and septum, alveolar structure damage, and collapse of alveolar space with remarkable fibrosis. These findings provide a perspective on hypoxia-adaptive genes in the lungs in addition to insights into potential candidate genes in Tibetan pigs for further research in the field of high-altitude adaptation.

scholarly journals High-altitude Pulmonary Hypertension: an Update on Disease Pathogenesis and Management

2016 ◽  
Vol 10 (1) ◽  
pp. 19-27 ◽  
Author(s):  
Aibek E. Mirrakhimov ◽  
Kingman P. Strohl
Keyword(s):  
Pulmonary Hypertension ◽  
High Altitude ◽  
Indoor Air Pollution ◽  
Screening Tools ◽  
Heart Catheterization ◽  
Low Oxygen ◽  
Lower Altitude ◽  
Individualized Approach ◽  
Chest X Ray ◽  
Low Oxygen Concentration

High-altitude pulmonary hypertension (HAPH) affects individuals residing at altitudes of 2,500 meters and higher. Numerous pathogenic variables play a role in disease inception and progression and include low oxygen concentration in inspired air, vasculopathy, and metabolic abnormalities. Since HAPH affects only some people living at high altitude genetic factors play a significant role in its pathogenesis. The clinical presentation of HAPH is nonspecific and includes fatigue, shortness of breath, cognitive deficits, cough, and in advanced cases hepatosplenomegaly and overt right-sided heart failure. A thorough history is important and should include a search for additional risk factors for lung disease and pulmonary hypertension (PH) such as smoking, indoor air pollution, left-sided cardiac disease and sleep disordered breathing. Twelve-lead electrocardiogram, chest X-ray and echocardiography can be used as screening tools. A definitive diagnosis should be made with right-sided heart catheterization using a modified mean pulmonary artery pressure of at least 30 mm Hg, differing from the 25 mm Hg used for other types of PH. Treatment of HAPH includes descent to a lower altitude whenever possible, oxygen therapy and the use of medications such as endothelin receptor antagonists, phosphodiesterase 5 blockers, fasudil and acetazolamide. Some recent evidence suggests that iron supplementation may also be beneficial. However, it is important to note that the scientific literature lacks long-term randomized controlled data on the pharmacologic treatment of HAPH. Thus, an individualized approach to treatment and informing the patients regarding the benefits and risks of the selected treatment regimen are essential.

scholarly journals Experimental study on Jet-A pool fire at high altitude

2014 ◽  
Vol 11 ◽  
pp. 510-516 ◽  
Author(s):  
Z. Zhou ◽  
W. Yao ◽  
Haihang Li ◽  
C. Lin ◽  
J. Yin ◽  
...  
Keyword(s):  
Experimental Study ◽  
High Altitude ◽  
Pool Fire
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