Inflammability and Electrical Studies of Foams Which may Occur at Altitude by De-Aeration of Aviation Turbine Fuels

Air dissolves in aircraft fuels to an extent directly proportional to the ambient pressure, so that when fuel which has been stored at sea-level atmospheric pressure is taken up to a high altitude, there is a tendency for air to come out of solution. In certain circumstances, which are later described in detail, air bubbles can be liberated very violently from fuels in aircraft tanks at high altitude and a thick foam can form on the surface for a short time.The production of fuel foams by degassing has posed a certain problem; foams, being intimate mixtures of air and fuel, may well be inflammable; furthermore, the rising of air bubbles through fuel can result in the accumulation of electrical charge in the foam giving rise to the possibility of a source of ignition.

Download Full-text

Problems related to the tests of resistance and strength of military equipment in reduced atmospheric pressure conditions

WUT Journal of Transportation Engineering ◽

10.5604/01.3001.0013.7185 ◽

2019 ◽

Vol 124 ◽

pp. 151-159

Author(s):

Patryk Płochocki ◽

Mateusz Makarewicz ◽

Przemysław Simiński

Keyword(s):

High Altitude ◽

Working Conditions ◽

Atmospheric Pressure ◽

Ambient Pressure ◽

Air Transport ◽

Normative Documents ◽

Military Equipment ◽

The Subject

This article is about military equipment research in conditions of reduced atmospheric pressure. Reported cases of equipment damage during work at high altitude or air transport show the need to perform research on phenomena occurring during storage, transport and operation of equipment at a reduced ambient pressure. One of the fragments of the article is devoted to the records contained in normative documents regarding the subject of the study. In addition, an exemplary experiment was made, the purpose of which was to illustrate some of the effects associated with the use of the equipment in the above-mentioned working conditions.

Download Full-text

THE RELATION OF EXERCISE TO BUBBLE FORMATION IN ANIMALS DECOMPRESSED TO SEA LEVEL FROM HIGH BAROMETRIC PRESSURES

The Journal of General Physiology ◽

10.1085/jgp.28.3.241 ◽

1945 ◽

Vol 28 (3) ◽

pp. 241-251 ◽

Cited By ~ 8

Author(s):

Morgan Harris ◽

W. E. Berg ◽

D. M. Whitaker ◽

V. C. Twitty

Keyword(s):

High Altitude ◽

Sea Level ◽

Atmospheric Pressure ◽

Bubble Formation ◽

Muscular Activity ◽

Pressure Treatment ◽

Factors Associated ◽

High Supersaturation ◽

Mechanical Factors ◽

Very High

1. Bullfrogs (Rana catesbiana) and rats have been subjected to high barometric pressures and studied for bubble formation on subsequent decompression to sea level. Pressures varying from 3 to 60 pounds per square inch, in excess of atmospheric pressure, were used. 2. Muscular activity after decompression is necessary for bubble formation in bullfrogs after pressure treatment throughout the above range. Anesthetized frogs remained bubble-free following decompression. Rats compressed at 15 to 45 pounds per square inch likewise did not contain bubbles unless exercised on return to sea level. 3. Bubbles form without voluntary muscular activity in anesthetized rats previously subjected to pressure of 60 pounds per square inch. Small movements involved in breathing and other vital activities are believed sufficient to initiate bubbles in the presence of very high supersaturations of N2. 4. Bubbles appear (with exercise) in rats previously compressed at 15 pounds per square inch, and in bullfrogs subjected to pressure at levels as low as 3 pounds per square inch above atmospheric pressure. The percentage drop in pressure necessary for bubble formation is less in compressed animals than in those decompressed from sea level to simulated altitudes. 5. The action of exercise on bubble formation in compressed frogs and rats is attributed to mechanical factors associated with muscular activity, combined with the high supersaturation of N2. CO2 probably is not greatly involved, since its concentration does not reach supersatuation, as it does at high altitude. 6. Anoxia following decompression from high barometric pressures has no observable facilitating effect on bubble formation.

Download Full-text

The maximum excess temperature of fire-induced smoke flow beneath an unconfined ceiling at high altitude

Thermal Science ◽

10.2298/tsci170926075l ◽

2019 ◽

Vol 23 (5 Part B) ◽

pp. 2961-2970

Author(s):

Jiahao Liu ◽

Zhihui Zhou ◽

Jian Wang ◽

Qimiao Xie ◽

Jinhui Wang ◽

...

Keyword(s):

High Altitude ◽

Atmospheric Pressure ◽

Ambient Pressure ◽

Maximum Temperature ◽

Excess Temperature ◽

Smoke Flow ◽

Different Dimensions ◽

Predicted Values ◽

S Model ◽

The Ideal

Conventional correlations for the maximum temperature under a ceiling were mainly developed based on the experimental results at atmospheric pressure. For high-altitude environment with lower ambient pressure, their feasibility needs to be reexamined. In this paper, a sequence of pool fires with different dimensions and fuel types was performed under a horizontal unconfined ceiling to measure the maximum excess temperature in a high-altitude city, Lhasa (3650 m / 64.3 kPa). The results show that the maximum smoke temperatures beneath the ceiling at high altitude are significant higher than the predicted values by Alpert?s model. Considering the effects of ambient pressure and entrainment coefficient, a new theoretical model for predicting the maximum excess temperature was proposed based on the ideal plume assumption. The current results together with the data in the literature which conform with Alpert?s model successfully converge by employing the proposed correlation.

Download Full-text

Plasma catecholamines at high altitudes

Journal of Applied Physiology ◽

10.1152/jappl.1965.20.6.1329 ◽

1965 ◽

Vol 20 (6) ◽

pp. 1329-1331 ◽

Cited By ~ 9

Author(s):

Federico Moncloa ◽

María Gómez ◽

Alberto Hurtado

Keyword(s):

High Altitude ◽

Sea Level ◽

Intravenous Injection ◽

Plasma Levels ◽

Ambient Pressure ◽

Plasma Catecholamines ◽

High Altitudes ◽

Insulin Hypoglycemia ◽

Fasting Condition ◽

Lower Glucose

High altitude native residents and newcomers to a low ambient pressure (36 hr after arrival) have normal plasma levels of adrenaline and noradrenaline in the fasting condition. Thirty minutes after the intravenous injection of insulin the high-altitude residents show increase of epinephrine greater than in men living at sea level. These results are interpreted as a consequence of the lower glucose values observed at high altitudes. high-altitude physiology; catecholamines and insulin; hypoglycemia in hypoxia Submitted on February 12, 1965

Download Full-text

Critical water temperature during water immersion at various atmospheric pressures

Journal of Applied Physiology ◽

10.1152/jappl.1988.64.6.2444 ◽

1988 ◽

Vol 64 (6) ◽

pp. 2444-2448 ◽

Cited By ~ 2

Author(s):

J. Iwamoto ◽

S. Sagawa ◽

F. Tajima ◽

K. Miki ◽

K. Shiraki

Keyword(s):

Water Temperature ◽

High Altitude ◽

Sea Level ◽

Heat Loss ◽

Heat Production ◽

Atmospheric Pressure ◽

Water Immersion ◽

Loss Ratio ◽

Metabolic Heat ◽

Healthy Males

The present work was undertaken to determine the effect of atmospheric pressure [ranging from a high altitude of 4,300 m above sea level or 0.6 atmospheres absolute (ATA) to depths of 10 m deep or 2 ATA] on the critical water temperature (Tcw), defined as the lowest water temperature a subject can tolerate at rest for 2 h without shivering, of the unprotected subject during water immersion. Nine healthy males wearing only shorts were subjected to immersion to the neck in water at 0.6, 1, and 2 ATA while resting for 2 h. Continuous measurements included esophageal (Tes) and skin (Tsk) temperatures, direct heat loss from the skin (Htissue), and insulation of the tissue (Itissue). The Tcw was significantly higher at 0.6 ATA than 1 and 2 ATA: however, Tcw at 1 ATA was identical to that at 2 ATA. The metabolic heat production remained unchanged among the pressures. During the 2-h immersion in Tcw, Tes was identical among all atmospheric pressures: however, Tsk was significantly higher (P less than 0.05) at 0.6 ATA and was identical between 1 and 2 ATA. The overall mean Itissue was near maximal during immersion in Tcw in each pressure, and no difference was detected among the pressures. However, Itissue at the acral extremities (arm, hand, and foot) decreased significantly at 0.6 ATA, and subsequently heat loss from these parts was increased, which elevated an extremity-to-trunk heat loss ratio to 1.4 at 0.6 ATA from 1.1 at 1 and 2 ATA.

Download Full-text

Short-Time Flare Events of EV Lac

International Astronomical Union Colloquium ◽

10.1017/s0252921100034655 ◽

1995 ◽

Vol 151 ◽

pp. 80-81 ◽

Cited By ~ 1

Author(s):

B.E. Zhilyaev ◽

I.A. Verlyuk

Keyword(s):

High Altitude ◽

Sea Level ◽

Time Resolution ◽

Flare Star ◽

Flare Activity ◽

Flare Stars ◽

Ev Lac ◽

Short Time

Moffett (1972) pointed out the existence of short-time outbursts in flare stars as long ago as 1972. Gershberg & Petrov (1986) had registered a flare in EV Lac with a duration of 28.4 and an amplitude of 38.4 in 1984 with ASTRON. In recent years, a few reports appeared about observations of short-time outbursts in EV Lac with a duration in the range from 08.1 to several seconds. These results were summarized briefly by Zhilyaev (1993). Our observations confirm the existence of short-time flare activity on EV Lac.The observations reported here were obtained at the 60 cm telescope at the Peak Terskol high-altitude Observatory (3 100 m above sea level) with a highspeed two-channel photometer (Zhilyaev et al. 1992) in B as well as simultaneously in both, U and V bands, with a time resolution down to 08.1. A new prefiltering technique (Zhilyaev 1995) has been used for the detection of smallscale activity of the flare star EV Lac.

Download Full-text

Forensic Engineering Analysis of Unvented Gas Appliances in High Altitudes

Journal of the National Academy of Forensic Engineers ◽

10.51501/jotnafe.v33i1.23 ◽

2016 ◽

Vol 33 (1) ◽

Author(s):

James A. Petersen

Keyword(s):

Carbon Monoxide ◽

High Altitude ◽

Sea Level ◽

Engineering Analysis ◽

High Altitudes ◽

Engineering Study ◽

Forensic Engineering ◽

Short Time

A family moves into a house about 4,000 feet above sea level. They use a refrigerator powered by LP gas. A short time after the refrigerator was installed, they notice and complain about smells and soot. They take their 9-month-old to a hospital in response to persistent crying. A short time later, they notify the refrigerator manufacturer, which examines and tests the refrigerator. They find the refrigerator’s burner venturi blocked, generating high levels of carbon monoxide. Twelve years later, the parents bring a lawsuit against the installers of the refrigerator. At that time, the appliance is not available, and the house has been remodeled. A forensic engineering study is assigned to determine the effect high altitude has on this particular appliance design.

Download Full-text

Interactive Effects in Two-Droplets Combustion of RP-3 Kerosene under Sub-Atmospheric Pressure

Processes ◽

10.3390/pr9071229 ◽

2021 ◽

Vol 9 (7) ◽

pp. 1229

Author(s):

Hongtao Zhang ◽

Zhihua Wang ◽

Yong He ◽

Jie Huang ◽

Kefa Cen

Keyword(s):

Burning Rate ◽

Atmospheric Pressure ◽

High Speed ◽

Ambient Pressure ◽

Interactive Effects ◽

Propagation Time ◽

High Speed Camera ◽

Single Droplet ◽

Fuel Droplets ◽

Spacing Distance

To improve our understanding of the interactive effects in combustion of binary multicomponent fuel droplets at sub-atmospheric pressure, combustion experiments were conducted on two fibre-supported RP-3 kerosene droplets at pressures from 0.2 to 1.0 bar. The burning life of the interactive droplets was recorded by a high-speed camera and a mirrorless camera. The results showed that the flame propagation time from burning droplet to unburned droplet was proportional to the normalised spacing distance between droplets and the ambient pressure. Meanwhile, the maximum normalised spacing distance from which the left droplet can be ignited has been investigated under different ambient pressure. The burning rate was evaluated and found to have the same trend as the single droplet combustion, which decreased with the reduction in the pressure. For every experiment, the interactive coefficient was less than one owing to the oxygen competition, except for the experiment at L/D0 = 2.5 and P = 1.0 bar. During the interactive combustion, puffing and microexplosion were found to have a significant impact on secondary atomization, ignition and extinction.

Download Full-text

Effect of high altitude on human placental amino acid transport

Journal of Applied Physiology ◽

10.1152/japplphysiol.00691.2019 ◽

2020 ◽

Vol 128 (1) ◽

pp. 127-133 ◽

Cited By ~ 2

Author(s):

Owen. R. Vaughan ◽

Fredrick Thompson ◽

Ramón. A. Lorca ◽

Colleen G. Julian ◽

Theresa L. Powell ◽

...

Keyword(s):

Birth Weight ◽

Amino Acid ◽

High Altitude ◽

Sea Level ◽

Amino Acid Transport ◽

Acid Uptake ◽

Acid Transport ◽

Transport Capacity ◽

System A ◽

Low Altitude

Women residing at high altitudes deliver infants of lower birth weight than at sea level. Birth weight correlates with placental system A-mediated amino acid transport capacity, and severe environmental hypoxia reduces system A activity in isolated trophoblast and the mouse placenta. However, the effect of high altitude on human placental amino acid transport remains unknown. We hypothesized that microvillous membrane (MVM) system A and system L amino acid transporter activity is lower in placentas of women living at high altitude compared with low-altitude controls. Placentas were collected at term from healthy pregnant women residing at high altitude (HA; >2,500 m; n = 14) or low altitude (LA; <1,700 m; n = 14) following planned, unlabored cesarean section. Birth weight, but not placenta weight, was 13% lower in HA pregnancies (2.88 ± 0.11 kg) compared with LA (3.30 ± 0.07 kg, P < 0.01). MVM erythropoietin receptor abundance, determined by immunoblot, was greater in HA than in LA placentas, consistent with lower placental oxygen levels at HA. However, there was no effect of altitude on MVM system A or L activity, determined by Na+-dependent [14C]methylaminoisobutyric acid uptake and [3H]leucine uptake, respectively. MVM abundance of glucose transporters (GLUTs) 1 and 4 and basal membrane GLUT4 were also similar in LA and HA placentas. Low birth weights in the neonates of women residing at high altitude are not a consequence of reduced placental amino acid transport capacity. These observations are in general agreement with studies of IUGR babies at low altitude, in which MVM system A activity is downregulated only in growth-restricted babies with significant compromise. NEW & NOTEWORTHY Babies born at high altitude are smaller than at sea level. Birth weight is dependent on growth in utero and, in turn, placental nutrient transport. We determined amino acid transport capacity in placentas collected from women resident at low and high altitude. Altitude did not affect system A amino acid transport across the syncytiotrophoblast microvillous membrane, suggesting that impaired placental amino acid transport does not contribute to reduced birth weight in this high-altitude population.

Download Full-text