scholarly journals New approach to injection of pressurizing gas into fuel tanks of power units

2021 ◽  
pp. 90-95
Author(s):  
I Kravchenko ◽  
Yu Mitikov ◽  
Yu Torba ◽  
O Zhyrkov
Keyword(s):  
Buoyancy Force ◽  
New Method ◽  
Gas Jet ◽  
Maximum Temperature ◽  
Initial Moment ◽  
Dynamic Component ◽  
Hot Gas ◽  
Fuel Tanks ◽  
Archimedes Force ◽  
Tank Bottom

Purpose. Determination a rational way to injection of high-temperature pressurizing gas into fuel tanks of large elongation. Determination of longitudinal overload effect on the Archimedes force during the gas jet penetration in the tank. Reducing the need for pressurizing gas, the mass of the storage system. Methodology. A retrospective design analysis of devices for injecting the gas into tanks and taxonomy basics are used. With their help, it is possible to determine the causes of a wide variety of device designs for injecting gas into tanks and the common fundamental disadvantages of all known devices. Findings. As a result of the research carried out, a new method for supplying hot gas to the tanks has been found and substantiated. It is suitable for most conditions and provides a reduction in the need for pressurizing gas, does not reduce the operating fuel reserves, shows the trends for further research. Originality. The main reason for the differences between the results of ground tests and flight tests in terms of the gas parameters in the tank and the temperature of its upper bottom has been determined. This is overload effect on the increase in the buoyancy force on hot pressurizing gas jet, which is injected traditionally from the upper tank bottom to the side of the lower tank bottom. In this case, the buoyancy force acts against the dynamic component, reduces the jet range and presses the hot gas to the upper bottom. A new method for injecting the hot pressurizing gas, devoid of the indicated drawback, has been proposed and developed by using a theory of similarity. This makes it possible to mix the gas in the free volume of the tank as much as possible due to the action of the Archimedes force, to equalize gas temperature, reducing the maximum temperature at the upper bottom, and noticeable mass transfer processes in the tank are excluded. Practical value. The application of the proposed method permits defining correctly and accurately the gas flow rate for tank pressurization, using it with a temperature of up to ~1800 K. The drop in gas pressure disappears in the tank at the initial moment of operation of the pressurization system, caused by the injection of a hot gas jet into the fuel surface. Depending on the conditions, the pressurizing gas requirement can be reduced by up to 50%. In this case, the main fuel reserves in the tank are not reduced.

Airbag deployment: Infrared thermography and evaluation of thermal damage

2019 ◽  
Vol 233 (4) ◽  
pp. 424-431 ◽  
Author(s):  
Ehsan Shakouri ◽  
Alimohammad Mobini
Keyword(s):  
Infrared Thermography ◽  
Chemical Reaction ◽  
Direct Contact ◽  
Thermal Damage ◽  
Maximum Temperature ◽  
Time Intervals ◽  
Hot Gas ◽  
Exothermic Chemical Reaction ◽  
Zero Moment ◽  
Airbag Deployment

The performance of airbag and its deployment are based on a fast exothermic-chemical reaction. The hot gas resulting from the chemical reaction which results in airbag deployment can cause thermal damage and skin burning for the car passenger. The thermal burns due to airbags are of two types: burns due to direct contact with the airbag surface and burns resulting from exposure to the hot gas leaving the deflation vents of the airbag. In this research, for experimental study of the burns resulting from exposure of the skin to airbag, using infrared thermography, the extent of temperature rise of the airbag surface was detected and measured from the zero moment of its inflation. Next, using Henriques equation, the extent of thermal damage caused by airbag deployment and its resulting burn degree was calculated. The results indicated that during the inflation of airbag, the maximum temperature of its surface can be 92 °C ± 2 °C. Furthermore, if the vehicle’s safety system functions within the predicted time intervals, the risk of thermal damage is virtually zero. However, if even a slight delay occurs in detachment of the passenger’s head and face off the airbag, second- and third-degree burns could develop.

Validation of Surface Temperature Measurements on a Combustor Liner Under Full-Load Conditions Using a Novel Thermal History Paint

2016 ◽  
Author(s):  
Robert Krewinkel ◽  
Jens Färber ◽  
Martin Lauer ◽  
Dirk Frank ◽  
Ulrich Orth ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Thermal History ◽  
Measurement Techniques ◽  
Combustion Process ◽  
Lanthanide Ions ◽  
Maximum Temperature ◽  
Oxide Ceramic ◽  
Ambient Conditions ◽  
Hot Gas ◽  
Wide Range

The ever-increasing requirements on gas turbine efficiency, which are at least partially met by increasing firing temperatures, and the simultaneous demand for reduced emissions, necessitate much more accurate calculations of the combustion process and combustor wall temperatures. Thermocouples give locally very accurate measurements of these temperatures, but there is a practical limit to the amount of measurement points. Thermal paints are another established measurement technique, but are toxic and at the same time require dedicated, short-duration tests. Thermal History Paints (THPs) provide an innovative alternative to the aforementioned techniques, but so far only a limited number of tests has been conducted under real engine conditions. THPs are similar in their chemical and physical make-up to conventional thermographic phosphors which have been successfully used in gas turbine applications for on-line temperature detection before. A typical THP comprises of oxide ceramic pigments and a water based binder. The ceramic is synthesized to be amorphous and when heated it crystallizes, permanently changing the microstructure. The ceramic is doped with lanthanide ions to make it phosphorescent. The lanthanide ions act as atomic level sensors and as the structure of the material changes, so do the phosphorescent properties of the material. By measuring the phosphorescence the maximum temperature of exposure can be determined through calibration, enabling post operation measurements at ambient conditions. This paper describes a test in which THP was applied to an impingement-cooled front panel from a combustor of an industrial gas turbine. Since this component sees a wide range of temperatures, it is ideally suited for the testing of the measurement techniques under real engine conditions. The panel was instrumented with a thermocouple and thermal paint was applied to the cold side of the impingement plate. THP was applied to the hot-gas side of this plate for validation against the other measurement techniques and to evaluate its resilience against the reacting hot gas environment. The durability and temperature results of the three different measurement techniques are discussed. The results demonstrate the benefits of THPs as a new temperature profiling technique. It is shown that the THP exhibited greater durability compared to the conventional thermal paint. Furthermore, the new technology provided detailed measurements down to millimeters indicating local temperature variations and global variations over the complete component.

Advanced Diagnostics and Modeling of Spray Processes

MRS Bulletin ◽  
2000 ◽  
Vol 25 (7) ◽  
pp. 26-31 ◽  
Author(s):  
James R. Fincke ◽  
Richard A. Neiser
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Kinetic Energy ◽  
Particle Temperature ◽  
Surface Characteristics ◽  
Gas Jet ◽  
Hot Gas ◽  
Residual Stress State ◽  
Fraction Size ◽  
Thermally Sprayed

The microstructure and properties of thermally sprayed deposits depend critically on the thermal- and kinetic-energy histories of the particles entrained in the hot-gas jet. At impact, the particle temperature, molten fraction, size, velocity, and chemistry, along with substrate temperature and surface characteristics, control the morphology of individual particle splats. These factors control the adhesion, strength, microstructure, and porosity of a coating and influence the residual-stress state. In order to produce higher-quality coatings and expand the use of this versatile family of technologies, the ability to model and measure particle behavior is essential.

The influence of gas jet velocity in laser heating—a moving workpiece case

2000 ◽  
Vol 214 (8) ◽  
pp. 1059-1078 ◽  
Author(s):  
S Z Shuja ◽  
B S Yilbas
Keyword(s):  
Laser Heating ◽  
Control Volume ◽  
Steel Substrate ◽  
Finite Thickness ◽  
Three Dimensional ◽  
Gas Jet ◽  
Maximum Temperature ◽  
Heating Process ◽  
Jet Velocity ◽  
Energy Equations

In the present study, gas jet-assisted laser heating of a moving steel substrate with finite thickness is considered. Three-dimensional flow and energy equations with variable properties of the gas are introduced in modelling the heating process. The low Reynolds number k-ε model is employed to account for the turbulence. A numerical scheme using a control volume approach is introduced to discretize the governing equations. The simulation is repeated for three assisting gas jet velocities (100, 10, 1 m/s) and a constant workpiece speed (0.3 m/s). It is found that the effect of assisting gas jet velocity on the surface temperature is more pronounced in the cooling cycle than in the heating cycle of the laser heating process. The workpiece movement affects the location of the maximum temperature at the surface, which moves away from the initially irradiated spot centre in the direction of motion of the workpiece.

A New Method for Temperature Measurement to Determine the Temperature Variation in Cylindrical Grinding Contact Arc

2010 ◽  
Vol 139-141 ◽  
pp. 762-767
Author(s):  
Bei Zhi Li ◽  
Da Hu Zhu ◽  
Jing Zhu Pang ◽  
Zhen Xin Zhou ◽  
Jian Guo Yang
Keyword(s):  
Temperature Measurement ◽  
Temperature Variation ◽  
High Speed ◽  
New Method ◽  
Maximum Temperature ◽  
Depth Of Cut ◽  
Measured Temperature ◽  
Plunge Grinding ◽  
Temperature Signal ◽  
Contact Arc

Due to the difficulty in arrangement of thermocouples, temperature measurement in grinding presents a number of challenges, particularly in high speed cylindrical-plunge grinding. Based on existing literature, only single thermocouple is considered for measuring the maximum temperature in the grinding contact arc, without considering the overall temperature variation. In this paper, a new method for temperature measurement, named four K-type thermocouples, is proposed aslant along the direction of the width of workpiece which is developed for measuring the overall contact arc in high speed cylindrical-plunge grinding. It is shown that the temperature increases to the maximum with a sharp gradient, then decreases due to the strengthening of cooling effect and the decrease of depth of cut, which is consistent with previous study. The measured temperature signal reveals the generation rule and dissipation rule of grinding heat.

Gas-Jet-Assisted Keyhole Laser Welding of Q235 Mild Steel

2012 ◽  
Vol 629 ◽  
pp. 180-186 ◽  
Author(s):  
Xian Feng Shen ◽  
Wen Hua Teng ◽  
Wen Rong Huang ◽  
Chao Xu
Keyword(s):  
Laser Welding ◽  
Penetration Depth ◽  
Gas Jet ◽  
Maximum Temperature ◽  
Maximum Increase ◽  
Ship Building ◽  
Key Factor ◽  
Columnar Grains ◽  
Series Of Experiments ◽  
Conventional Laser

Increases in the penetration depth of laser welding has gained undoubted interest, especially in the aerospace, power station, ship building, and other heavy industries. Gas-jet-assisted keyhole laser welding is a prospective method for improving the penetration of conventional laser welding. A series of experiments using this method were conducted with different parameters of the assisted gas jet and the welding speed. The microstructures of weld joints were observed using optical microscopy, and microhardness was also measured. The investigation results showed that the penetration depth of this laser welding increased by more than 20%, with a maximum increase of approximately 26%, at different welding speeds, while the weld width was significantly reduced compared with that of conventional laser welding. The key factor affecting the penetration increase is the interaction between the assisted gas jet and the plasma. The penetration increase was determined by the distribution and amplitude of the assisted gas jet at the position of the keyhole orifice. The grain in the heat-affected zone (HAZ) and weld seam of gas-jet-assisted keyhole laser welding was finer, and the number of columnar grains was also significantly reduced. The microhardness of the HAZ for the assisted gas jet was much lower, and more pearlite and less martensite were observed this zone. This was caused by the reduced maximum temperature of the molten pool, reduced high-temperature residence time, increased cooling rate, and diminished temperature gradient with the introduction of the assisted gas jet.

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