scholarly journals MATHEMATICAL MODELING OF DESTRUCTION OF FIBERGLASS-BASED THERMAL-PROTECTION MATERIAL

2020 ◽  
pp. 71-78
Author(s):  
D.Ya. Barinov ◽  
◽  
P.S. Marakhovskij ◽  
A.V. Zuev ◽  
◽  
...  
Keyword(s):  
Thermal Protection ◽  
Experimental Studies ◽  
Thermophysical Characteristics ◽  
Capsule Type ◽  
Typical Trajectory ◽  
Material Sample ◽  
Heat Shielding ◽  
Physical And Mathematical Models ◽  
The Mathematical Model ◽  
Shielding Material

The paper proposes physical and mathematical models of heat and mass transfer in fiberglass used as a destructive heat-shielding material for capsule type descent vehicles. To provide the mathematical model with the initial data, experimental studies of the thermophysical characteristics of the material and the kinetic parameters of destruction have been carried out. There has been made a simulation of the destruction of a material sample during descent in the Earth's atmosphere along a typical trajectory for various areas of the heat shield; as a result, the dependences of temperatures on the flight time and the depth of the coked layer have been determined.

scholarly journals Оптические свойства отечественного сетчатого стеклоуглерода и его основы

2020 ◽  
Vol 128 (4) ◽  
pp. 548
Author(s):  
В.В. Черепанов ◽  
А.Г. Щурик ◽  
Р.А. Миронов
Keyword(s):  
Optical Properties ◽  
Glassy Carbon ◽  
Experimental Studies ◽  
Carbon Foam ◽  
Statistical Simulation ◽  
Scattering Phase ◽  
Scattering Phase Function ◽  
Heat Shielding ◽  
The Mathematical Model ◽  
Shielding Material

The paper presents the results of experimental studies and mathematical modeling of the optical properties of glassy carbon and domestic reticulated foam materials based on it. Since the optical properties of the surface are studied on dense samples, dense samples were previously created, identical in physical properties to glassy carbon - the basis of highly porous cellular carbon materials. From the experimentally measured the spectral hemispherical reflectivity of the surface of the samples under its normal illumination and by the Kramers-Kronig relations the spectra of optical constants of glassy carbon - the refractive indices and absorption, as well as a number of their derivative characteristics were determined. For them, simple approximating relations are given in the paper. The obtained spectral data was incorporated into the previously developed optical statistical simulation model of ultra-porous reticulated foam materials, which is based on a rigorous electromagnetic theory and allows you to take into account both the features of their microstructure and physical processes that occur in such systems at different spa-tial and temporal scales. The results of the calculation of local spectra, the scattering phase function, and radiation thermal conductivity are presented for the reticulated glassy carbon foam, which has wide prospects for use as a structural and heat-shielding material. Some additional features of the mathematical model are demonstrated also.

scholarly journals ТЕРМІЧНИЙ ОПІР ХУТРЯНОГО ОДЯГУ

2021 ◽  
pp. 41-47
Author(s):  
С. І. Мойсеєнко ◽  
С. В. Донченко ◽  
А. І. Кулішова
Keyword(s):  
Thermal Resistance ◽  
Red Fox ◽  
Thermal Protection ◽  
Experimental Studies ◽  
Information Support ◽  
Total Thermal Resistance ◽  
Information Base ◽  
Heat Shielding ◽  
Fur Animals ◽  
Available Information

Improving the process of forecasting thermal protection of clothing by expanding the information base of thermophysical indicators of fur, namely its thermal resistance. Methodology. To achieve this goal, an experimental method has been applied to study the thermal resistance of clothes by indirectly measuring and simulating heat transfer of the human body with the environment at various temperatures without using a climate chamber.Results. The paper analyzes the existing information base for the thermophysical parameters of the fur of diff erent animals, as a result of which it was found that the available information is not suffi cient to predict the thermal protection of clothing. The subject of the study was selected fur animals that are in greatest demand among consumers in Ukraine. Experimental studies of the thermal conductivity of fur vests were carried out as a result of which their thermal resistance was determined. It has been established experimentally that the thermal resistance of the fur of a long-haired rabbit is 0,1 °C m 2 /W more than that of a red fox. As a result of experimental studies, it was found that the total thermal resistance of red fox fur and long-haired rabbit is in the range of 0,471 to 0,559 °C m 2  / W.  For the fi rst time, the thermal resistance of vests made of long-haired rabbit and red fox fur was determined taking into account the anatomical reliefs of the human torso. The existing methodology for determining the thermal resistance of garments on the simulated thermal stand of a human torso (ITSHB) to determine the thermal resistance of fur products has been adapted. Practical signifi cance. Extension of information support for the process of forecasting the heat-shielding properties of fur clothing. Reducing material costs for researching the thermal resistance of fur products.

scholarly journals Heat Engineering Heterogeneity Of The Outer Walls Of Earthquake-Resistant Buildings

2020 ◽  
Vol 02 (12) ◽  
pp. 1-8
Author(s):  
Shipacheva E.V. ◽  
◽  
Pirmatov R. Kh. ◽  
Turdalieva M.K. ◽  
◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Thermal Protection ◽  
Experimental Studies ◽  
Heat Fluxes ◽  
Heat Engineering ◽  
Earthquake Resistant ◽  
Aerated Concrete ◽  
Shielding Properties ◽  
Heat Shielding ◽  
Concrete Elements

When assessing the level of energy efficiency of civilian buildings, a special place is given to establishing the level of thermal protection of their external enclosing structures. Significant discrepancies in the results of theoretical and experimental studies of heat fluxes through the outer walls of buildings erected in seismic areas are associated with the design features of fences - the presence of reinforced concrete elements in them: anti-seismic belts at the level of floors, cores at intersections of walls and along the edges of large window openings ... In addition, in recent years, external walls have become widespread, which are filling of bricks or aerated concrete blocks between the main structural elements of the frame - monolithic reinforced concrete columns and crossbars. The introduction of reinforced concrete elements into the structure of the external wall fencing provides strength, rigidity and stability of buildings, guarantees its seismic resistance. At the same time, reinforced concrete inclusions are significant “cold bridges” in warmer brick or aerated concrete masonry. Such heat engineering heterogeneity of earthquake-resistant outer walls significantly complicates the process of determining their heat-shielding properties. This, in turn, leads to errors in the design of heating systems, which inevitably affects the thermal comfort of the premises, the formation of condensation and mold zones in the cold zones of the inner surface of the fences. The article presents the results of theoretical and experimental studies to determine the heat-shielding properties of external heat-engineering heterogeneous walls of earthquake-resistant buildings. The most reliable method for calculating the reduced resistance to heat transfer of an inhomogeneous external structure and the coefficient of its thermal inhomogeneity have been established.

scholarly journals INVESTIGATION OF THE INFLUENCE OF THERMAL AND CLIMATE EFFECTS ON THE PERFORMANCE OF TILED THERMAL PROTECTION OF SPACECRAFT

2019 ◽  
Vol 16 (33) ◽  
pp. 657-667
Author(s):  
L. N. RABINSKIY ◽  
O. V. TUSHAVINA
Keyword(s):  
Mathematical Model ◽  
Thermal Protection ◽  
Experimental Studies ◽  
Climatic Conditions ◽  
Shear Stresses ◽  
Shear Forces ◽  
Sufficient Degree ◽  
And Performance ◽  
Heat Shielding ◽  
The Impact

The article discusses the thermal protection of spacecraft under various types of thermal and climatic influences. During the pre-launch preparation, several types of icing are possible on the surface of the tiled structure, consisting of quartz heat-shielding tiles. It is very important in the process of operation, to determine normal and shear stresses during icing and the impact of ice formed in the tile gaps. It is necessary to calculate the strength and performance of the tiled thermal protection in active stages of flight of spacecraft. A mathematical model was constructed that allows, with a sufficient degree of accuracy, to research the tiled structure for strength, shear and tearing of the tile when exposed to ice. Calculations for strength, shear, and tearing of tiles under the influence of ice were performed. Theoretical and experimental studies were compared. The performed calculations made it possible to show that the tile will not collapse under the considered load. The strength of the substrate withstands the emerging shear forces. The values of the adhesion strength of ice appearing on the surface of quartz fiber heat-protective coating were obtained. It was demonstrated that the proportion of tangents in the stressed state of the tile does not exceed 10%. The proposed mathematical model for studying the characteristics of the tiled thermal protection of a spacecraft adequately describes the processes under study. Experimental studies have shown satisfactory agreement with theoretical results. The calculations performed to determine the ultimate shear stresses in the substrate showed that the strength of the substrate withstands the emerging shear forces. Consideration of climatic conditions can significantly reduce risks in the design of thermal protection of modern aircraft. The results of this study can be used in further studies, and they can also be taken into account in the construction of aircraft.

Experimental Evaluation of Thermophysical Characteristics of High-Temperature Thermal Insulation Materials

2020 ◽  
pp. 99-116
Author(s):  
V.I. Tomak ◽  
A.S. Burkov ◽  
A.M. Rytsarev ◽  
V.A. Tovstonog
Keyword(s):  
High Temperature ◽  
Power Plants ◽  
Materials Science ◽  
Thermal Protection ◽  
Experimental Studies ◽  
Characteristic Size ◽  
Whole Body ◽  
Thermophysical Characteristics ◽  
Insulating Materials ◽  
Highly Porous

One of the most important problems in the development of advanced products of aerospace engineering and highly efficient power plants is to make high-temperature structural, heat-shielding and heat-insulating materials with extremely high operating temperatures of 2000--2500 °C. Even for prototype models, it is necessary to make a qualitative breakthrough in the field of materials science and the production of new high-temperature composite and heat-insulating materials which provide thermal protection and the permissible temperature conditions of structural elements at high temperatures. The practical application of the developed materials requires an evaluation of the whole body of their physicomechanical, optical, and thermophysical characteristics, which can only be done in experimental studies. We developed the design of the experimental setup and the methodology for the approximate evaluation of the thermophysical characteristics of highly porous heat-insulating materials at temperatures up to 2000 °C. A propane / oxygen or acetylene / oxygen multi-nozzle torch serves as a heating source for samples with a characteristic size of up to 50 × 50 mm. The paper substantiates the methodology for processing the measurement results in order to determine the thermophysical characteristics, and gives the results of a study of the thermal conductivity of highly porous zirconium oxide-based material

EXPERIMENTAL STUDIES OF CAR PROPERTIES ON A PHYSICAL MODEL

2019 ◽  
pp. 10-16
Author(s):  
Oleksii Timkov ◽  
Dmytro Yashchenko ◽  
Volodymyr Bosenko
Keyword(s):  
Mathematical Model ◽  
Remote Control ◽  
Physical Model ◽  
Model Experiment ◽  
Experimental Studies ◽  
Electrical Energy ◽  
Short Term ◽  
Motor Current ◽  
Memory Card ◽  
The Mathematical Model

The article deals with the development of a physical model of a car equipped with measuring, recording and remote control equipment for experimental study of car properties. A detailed description of the design of the physical model and of the electronic modules used is given, links to application libraries and the code of the first part of the program for remote control of the model are given. Atmega microcontroller on the Arduino Uno platform was used to manage the model and register the parameters. When moving the car on the memory card saved such parameters as speed, voltage on the motor, current on the motor, the angle of the steered wheel, acceleration along three coordinate axes are recorded. Use of more powerful microcontrollers will allow to expand the list of the registered parameters of movement of the car. It is possible to measure the forces acting on the elements of the car and other parameters. In the future, it is planned to develop a mathematical model of motion of the car and check its adequacy in conducting experimental studies on maneuverability on the physical model. In addition, it is possible to conduct studies of stability and consumption of electrical energy. The physical model allows to quickly change geometric dimensions and mass parameters. In the study of highway trains, this approach will allow to investigate the various layout schemes of highway trains in the short term. It is possible to make two-axle road trains and saddle towed trains, three-way hitched trains of different layout. The results obtained will allow us to improve not only the mathematical model, but also the experimental physical model, and move on to further study the properties of hybrid road trains with an active trailer link. This approach allows to reduce material and time costs when researching the properties of cars and road trains. Keywords: car, physical model, experiment, road trains, sensor, remote control, maneuverability, stability.

The mathematical modelling of corrosion in hot dip galvanized steel reinforced concrete

2011 ◽  
Vol 2 (1) ◽  
pp. 1-12
Author(s):  
A. Hegyi ◽  
H. Vermeşan ◽  
V. Rus
Keyword(s):  
Mathematical Model ◽  
Reinforced Concrete ◽  
Numerical Model ◽  
Equation System ◽  
Galvanized Steel ◽  
Steel Reinforced Concrete ◽  
Numeric Model ◽  
Physical And Mathematical Models ◽  
Physical Phenomena ◽  
The Mathematical Model

Abstract In this paper we wish to present the numerical model elaborated in order to simulate some physical phenomena that influence the general deterioration of steel, whether hot dip galvanized or not, in reinforced concrete. We describe the physical and mathematical models, establishing the corresponding equation system, the initial and boundary conditions. We have also presented the numeric model associated to the mathematical model and the numeric methods of discretization and solution of the differential equations system that describes the mathematical model.

Self-preservation Effect of Gas Hydrates

2021 ◽  
Vol 23 ◽  
pp. 346-355
Author(s):  
Anatoliy Pavlenko
Keyword(s):  
Gas Hydrates ◽  
Gas Hydrate ◽  
Experimental Studies ◽  
Interphase Surface ◽  
Quantitative Characteristics ◽  
Nonequilibrium Conditions ◽  
Water Simulation ◽  
Gas Loss ◽  
Physical And Mathematical Models ◽  
And Storage

This work was performed to improve the storage and transportation technology of gas hydrates in nonequilibrium conditions. At atmospheric pressure and positive ambient temperature, they gradually dissociate into gas and water. Simulation of the gas hydrate dissociation will determine optimal conditions for their transportation and storage, as well as minimize gas loss. Thermodynamic parameters of adiabatic processes of forced preservation of pre-cooled gas hydrate blocks with ice layer were determined theoretically and experimentally. Physical and mathematical models of these processes were proposed. The scientific novelty is in establishing quantitative characteristics that describe the gas hydrates thermophysical parameters thermophysical characteristics influence on the heat transfer processes intensity on the interphase surface under conditions of gas hydrates dissociation. Based on the results of experimental studies, approximation dependences for determining the temperature in the depths of a dissociating gas hydrate array have been obtained. Gas hydrates dissociation mathematical model is presented.

scholarly journals THEORETICAL RESEARCH OF THE EXTERNAL TEMPERATURE INFLUENCE ON THE TRACTION AND SPEED PROPERTIES AND THE FUEL ECONOMY OF CARGO-CARRYING VEHICLES

2020 ◽  
pp. 1-9
Author(s):  
Zhasur Kulmukhamedov ◽  
Ravshan Khikmatov ◽  
Alisher Saidumarov ◽  
Yulduz Kulmukhamedova
Keyword(s):  
Experimental Data ◽  
Fuel Economy ◽  
Experimental Studies ◽  
Statistical Processing ◽  
Research Data ◽  
Theoretical Research ◽  
Temperature Influence ◽  
External Temperature ◽  
Average Speed ◽  
The Mathematical Model

The manuscript proposes analytical methods for calculating fuel economy and traction-speed properties when modeling the movement of cargo-carrying vehicles on real routes, based on theoretical and experimental studies in a hot and dry climate, which allows for determining the efficiency of cargo-carrying vehicles objectively in terms of traction and speed, fuel and economic indicators. Using the statistical processing of experimental, theoretical research data, the authors calculate the coefficient X2, which allows for evaluating the adequacy of the mathematical model and experimental data. As an example, the manuscript provides for an assessment of fuel economy and traction and speed properties. The authors presented the results in graphs for the ease of evaluating the effect of external temperature on fuel consumption and the average speed of a road train. The authors’ methodology allows for determining the efficiency of cargo-carrying vehicles in a hot and dry climate.

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