scholarly journals Calculation of Gas Flow in High-Altitude Engine Nozzle and Experience of Using Water-Cooled Nozzle Head during Tests

2018 ◽  
Vol 2018 (2) ◽  
pp. 83-93
Author(s):  
K. A. Nikitenko
Keyword(s):  
High Altitude ◽  
Gas Flow ◽  
Nozzle Head

Research on the Turbocharger Technology of Piston Aircraft Engine

2013 ◽  
Vol 457-458 ◽  
pp. 531-535
Author(s):  
Zhong Jian Pan ◽  
Qing Hua He ◽  
Yong Guo ◽  
Yu Ming Zhao ◽  
Jing Yang
Keyword(s):  
Simulation Model ◽  
High Altitude ◽  
Gas Flow ◽  
State Power ◽  
Aircraft Engine ◽  
Cylinder Pressure ◽  
Piston Engine ◽  
Ground Condition

The supercharger technology of piston aviation engine determines its flight capabilities, and then establishes a turbocharger simulation model of an aviation piston engine. After simulating the engine ground features and 5000-meter altitude characteristics, and comparing the efficiency of compressor and turbocharger in different environments, after the installation of mechanical supercharger, gas flow has been improved, the cylinder pressure decreased about 10% compared with ground condition and engine altitude state power is restored, even 20,000 feet Power restored to 80%, which can meet the needs of high-altitude flight.

Regional cerebral blood flow and tissue oxygenation during hypocarbia in geese

1992 ◽  
Vol 263 (2) ◽  
pp. R221-R225 ◽  
Author(s):  
P. E. Bickler ◽  
D. Julian
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
High Altitude ◽  
Regional Cerebral Blood Flow ◽  
Gas Flow ◽  
Regional Cerebral Blood ◽  
Local Blood Flow ◽  
Tissue Po2 ◽  
O2 Delivery ◽  
Kinetics Of

Very low arterial CO2 tension (PaCO2) experienced by birds during high-altitude flight may result in cerebral vasoconstriction and reduced cerebral O2 delivery. To examine this possibility, we measured regional cerebral blood flow (CBF) and tissue PO2 in pentobarbital-anesthetized geese (Anser domesticus). Twenty-five-micrometer Teflon-coated platinum electrodes for H2-clearance measurements of local blood flow or tissue PO2 were implanted in the cerebral cortex in 11 geese. Tissue H2 and O2 were measured by voltage clamping the electrodes at +0.30 and -0.5 V, respectively. Washout kinetics of H2 gas administered via unidirectional lung ventilation was used to calculate local blood flow for those electrodes exhibiting one- or two-compartment washout kinetics of H2 (128 of 296 washouts in 31 electrodes). PaCO2 was controlled between 8 and 55 mmHg by altering pulmonary gas flow or by adjusting inspired PCO2. CBF decreased as PaCO2 fell from 50 to 20 mmHg but did not decrease further as PaCO2 was reduced below 20 mmHg. CBF was uniformly distributed in different regions of the cortex. Despite the plateau in CBF during severe hypocapnia, tissue PO2 continued to decline as PaCO2 fell below 20 mmHg. Severe alkalosis may limit cerebral O2 delivery in birds during high-altitude flight.

scholarly journals Diatom-oxygen isotope record from high-altitude Lake Petit (2200 m a.s.l.) in the Mediterranean Alps: shedding light on a climatic pulse at 4.2 ka

2019 ◽  
Vol 15 (1) ◽  
pp. 253-263 ◽  
Author(s):  
Rosine Cartier ◽  
Florence Sylvestre ◽  
Christine Paillès ◽  
Corinne Sonzogni ◽  
Martine Couapel ◽  
...  
Keyword(s):  
High Altitude ◽  
Oxygen Isotope ◽  
Gas Flow ◽  
Isotope Composition ◽  
Mediterranean Area ◽  
Western Mediterranean ◽  
Southern Alps ◽  
Precipitation Regime ◽  
The Mediterranean ◽  
High Altitude Lake

Abstract. In the Mediterranean area, the 4.2 ka BP event is recorded with contrasting expressions between regions. In the southern Alps, the high-altitude Lake Petit (Mercantour Massif, France; 2200 m a.s.l.) offers pollen and diatom-rich sediments covering the last 4800 years. A multi-proxy analysis recently revealed a detrital pulse around 4200 cal BP due to increasing erosion in the lake catchment. The involvement of a rapid climate change leading to increasing runoff and soil erosion was proposed. Here, in order to clarify this hypothesis, we measured the oxygen isotope composition of diatom silica frustules (δ18Odiatom) from the same sedimentary core. Diatoms were analysed by laser fluorination isotope ratio mass spectrometry after an inert gas flow dehydration. We additionally enhanced the accuracy of the age–depth model using the Bacon R package. The δ18Odiatom record allows us to identify a 500-year time lapse, from 4400 to 3900 cal BP, where δ18Odiatom reached its highest values (>31 ‰). δ18Odiatom was about 3 ‰ higher than the modern values and the shifts at 4400 and 3900 cal BP were of similar amplitude as the seasonal δ18Odiatom shifts occurring today. This period of high δ18Odiatom values can be explained by the intensification of 18O-enriched Mediterranean precipitation events feeding the lake during the ice-free season. This agrees with other records from the southern Alps suggesting runoff intensification around 4200 cal BP. Possible changes in other climatic parameters may have played a concomitant role, including a decrease in the contribution of 18O-depleted Atlantic winter precipitation to the lake water due to snow deficit. Data recording the 4.2 ka BP event in the north-western Mediterranean area are still sparse. In the Lake Petit watershed, the 4.2 ka BP event translated into a change in precipitation regime from 4400 to 3900 cal BP. This record contributes to the recent efforts to characterize and investigate the geographical extent of the 4.2 ka BP event in the Mediterranean area.

scholarly journals Influence of the nozzle head geometry on the energy flux of an atmospheric pressure plasma jet

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Thorben Kewitz ◽  
Christoph Regula ◽  
Maik Fröhlich ◽  
Jörg Ihde ◽  
Holger Kersten
Keyword(s):  
Energy Flux ◽  
Atmospheric Pressure ◽  
Gas Flow ◽  
Atmospheric Pressure Plasma ◽  
Plasma Jet ◽  
Atmospheric Pressure Plasma Jet ◽  
Linear Dependency ◽  
Pressure Plasma ◽  
Flow Through ◽  
Nozzle Head

AbstractThe influence of different nozzle head geometries and, therefore, the variation of the excitation and relaxation volume on the energy flux from an atmospheric pressure plasma jet to a surface have been investigated. Measurements have been performed by passive calorimetric probes under variation of the gas flow through the nozzle. The results show that the geometry of the nozzle head has a significant impact on the resulting energy flux. The relaxation volume affects the dependence of the energy flux on the gas flow. While there is no significant influence of the working gas flow on the energy flux without a relaxation volume, utilizing a relaxation volume leads to a decrease of the energy flux with increasing working gas flow. Within the analyzed parameter range, the energy flux reveals for both nozzle heads a linear dependency on the applied primary voltage.

CFD Simulation of Steam Ejector System in High Altitude Test (HAT) Facility

2012 ◽  
Author(s):  
Pavani Sreekireddy ◽  
T. Kishen Kumar Reddy ◽  
Venugopal Dadi ◽  
P. Bhramara
Keyword(s):  
High Altitude ◽  
Flow Rate ◽  
Gas Flow ◽  
Cfd Simulation ◽  
Reverse Flow ◽  
Design Parameters ◽  
Gas Flow Rate ◽  
Steam Ejector ◽  
Ejector System ◽  
The Given

In the present work, the performance of Steam Ejector System in High Altitude Test (HAT) facility is numerically studied, in the absence of the condenser. Steam is used as secondary fluid to eject the burnt gases into atmosphere. Experimental visualization of mixing of burnt gas and steam and subsequent flow pattern is difficult, hence numerical simulation using FLUENT was done and the resulting flow stream lines, static and total pressures, shock patterns are computed along the ejector system to understand the physics of the problem. Three burnt gas flow rates of 9.17, 27.5 and 45.8 kg/s corresponding to lower, mid and upper limits of ejection from the HAT facility with the steam flow rate of 50 kg/s from Ejector I and 130 kg/s from Ejector II are studied. This corresponds to three cases of Entrainment Ratios for each of the ejector. Results show that for a burnt gas flow rate of 27.5 and 45.8 kg/s with the given dimensions of the HAT facility provided by ASL, DRDO, the gas and steam start mixing in the converging duct, pass through the mixing tube and attains atmospheric pressure at the exit of the HAT facility. For the burnt gas flow rate of 9.17 kg/s, reverse flow is observed in the Ejector II, indicating the malfunction mode of the system for the given design parameters.

Clinical experience with the Sorin Monolyth Oxygenator at high altitude

Perfusion ◽  
1999 ◽  
Vol 14 (1) ◽  
pp. 77-81 ◽  
Author(s):  
Carl Steinberg ◽  
Robert Dragan
Keyword(s):  
Pressure Drop ◽  
High Altitude ◽  
Gas Flow ◽  
Blood Gases ◽  
Barometric Pressure ◽  
Low Pressure ◽  
Gas Transfer ◽  
Pressure Drops ◽  
Priming Volume ◽  
Recorded Data

High altitude combined with low barometric pressure can present unique challenges during cardiopulmonary bypass (CPB), not only for the perfusionist, but also for the oxygenator. Manufacturers of cardiopulmonary devices have responded to the requests from the perfusion community with a variety of oxygenators which balance low priming volumes and low pressure drops against high gas transfer. This paper will feature the first author’s clinical studies using the Sorin Monolyth Oxygenator in a selected group of patients at an altitude of approximately 5200 feet and an average barometric pressure of 634 mmHg (sea level is 760 mmHg). A review of the 47 charts on patients requiring CPB and who met the selection criteria was performed retrospectively. To qualify for this study, the patient needed to weigh more than 91 kg. The data reviewed included type of surgery, age, weight, bypass time, crossclamp time, pump flows (l/min/m2), hematocrits pre- and post-CPB, and pressure drop across the membrane. The PaO2, PaCO2, FiO2 and sweep gas flow at hypothermia and normothermia were recorded. Data concerning oxygen transfer were obtained from the manufacturer’s report to the Food and Drug Administration. All patients had adequate blood gases while on CPB. We feel that the design of the Sorin Monolyth Oxygenator met our criteria for an oxygenator: low priming volume, low pressure drop, and sufficient gas transfer to provide safe oxygenation of all patients at high altitude.

Contrast of Filament Bright Rims

1994 ◽  
Vol 144 ◽  
pp. 365-367
Author(s):  
E. V. Kononovich ◽  
O. B. Smirnova ◽  
P. Heinzel ◽  
P. Kotrč
Keyword(s):  
High Altitude ◽  
Line Profile ◽  
Line Center ◽  
Magnetic Structures ◽  
The Mean

AbstractThe Hα filtergrams obtained at Tjan-Shan High Altitude Observatory near Alma-Ata (Moscow University Station) were measured in order to specify the bright rims contrast at different points along the line profile (0.0; ± 0.25; ± 0.5; ± 0.75 and ± 1.0 Å). The mean contrast value in the line center is about 25 percent. The bright rims interpretation as the bases of magnetic structures supporting the filaments is suggested.

Clean Electron Microscope Substrate Films Used for Micrometeorite Collection and Study

1967 ◽  
Vol 25 ◽  
pp. 366-367
Author(s):  
D. M. Davies ◽  
R. Kemner ◽  
E. F. Fullam
Keyword(s):  
Thin Film ◽  
Electron Microscope ◽  
High Altitude ◽  
Amyl Acetate ◽  
Temperature Variations ◽  
Film Forming ◽  
Film Specimen ◽  
Particulate Contaminants

All serious electron microscopists at one time or another have been concerned with the cleanliness and freedom from artifacts of thin film specimen support substrates. This is particularly important where there are relatively few particles of a sample to be found for study, as in the case of micrometeorite collections. For the deposition of such celestial garbage through the use of balloons, rockets, and aircraft, the thin film substrates must have not only all the attributes necessary for use in the electron microscope, but also be able to withstand rather wide temperature variations at high altitude, vibration and shock inherent in the collection vehicle's operation and occasionally an unscheduled violent landing.Nitrocellulose has been selected as a film forming material that meets these requirements yet lends itself to a relatively simple clean-up procedure to remove particulate contaminants. A 1% nitrocellulose solution is prepared by dissolving “Parlodion” in redistilled amyl acetate from which all moisture has been removed.

TEM evaluation of graded SixGe1-x heterolayers

1991 ◽  
Vol 49 ◽  
pp. 894-895
Author(s):  
N. David Theodore ◽  
Mamoru Tomozane ◽  
Ming Liaw
Keyword(s):  
Heterojunction Bipolar Transistors ◽  
Gas Flow ◽  
Field Effect Transistors ◽  
Chemical Vapor ◽  
Dark Field ◽  
Bipolar Transistors ◽  
Structural Quality ◽  
Weak Beam ◽  
Transmission Electron ◽  
And Behavior

There is extensive interest in SiGe for use in heterojunction bipolar transistors. SiGe/Si superlattices are also of interest because of their potential for use in infrared detectors and field-effect transistors. The processing required for these materials is quite compatible with existing silicon technology. However, before SiGe can be used extensively for devices, there is a need to understand and then control the origin and behavior of defects in the materials. The present study was aimed at investigating the structural quality of, and the behavior of defects in, graded SiGe layers grown by chemical vapor deposition (CVD).The structures investigated in this study consisted of Si1-xGex[x=0.16]/Si1-xGex[x= 0.14, 0.13, 0.12, 0.10, 0.09, 0.07, 0.05, 0.04, 0.005, 0]/epi-Si/substrate heterolayers grown by CVD. The Si1-xGex layers were isochronally grown [t = 0.4 minutes per layer], with gas-flow rates being adjusted to control composition. Cross-section TEM specimens were prepared in the 110 geometry. These were then analyzed using two-beam bright-field, dark-field and weak-beam images. A JEOL JEM 200CX transmission electron microscope was used, operating at 200 kV.

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