Prediction by three-dimensional mathematical modeling of the gas turbine low-emission combustion chambers thermo-acoustic characteristics

Розглянуто питання числового моделювання термо-акустичних процесів в камерах згоряння газотурбінних двигунів. Проведено аналіз пульсаційних процесів в низькоемісійній камері згоряння газотурбінного двигуна за допомогою сучасних інструментів обчислювальної гідродинаміки. Представлені результати моделювання процесів нестаціонарного горіння в низькоемісійній камері згоряння газотурбінного двигуна. За результатами тривимірних розрахунків визначено максимальні по амплітуді пульсації, що виникають у жаровій трубі і міжтрубному просторі камери згоряння газотурбінного двигуна.The use of modern tools of computational fluid dynamics for investigation the pulsation processes in the combustion chamber caused by the design features of flame tubes and aerodynamic interaction compressor, combustor and turbine is discussed. Purpose. Investigation and forecasting of non-stationary processes in gas turbine low-emission combustion chambers using mathematical modeling. Design/methodology/approach. The numerical experiment by definition of pressure pulsations level in the gas turbine combustion chamber is performed. The results of the numerical experiments using a three-dimensional mathematical models in gaseous fuels combustion chambers are adequately reflect the physical and chemical processes of unsteady combustion and can be recommended for optimizing the geometrical and operational parameters of low-emission combustion chambers. Findings. According to the results of three-dimensional calculations, the maximum amplitude fluctuation arising in the flame tube and the annulus gas turbine combustion chambers are defined. Originality/value. The application of such mathematical models for the creation new samples combustors operating at a lean air-fuel mixture as well as the modernization of the existing cameras to develop constructive measures aimed at reducing the likelihood of pulsation combustion modes, is advisable.Рассмотрены вопросы численного моделирования термо-акустических процессов в камерах сгорания газотурбинных двигателей. Проведен анализ пульсационных процессов в низкоэмиссионной камере сгорания газотурбинного двигателя с помощью современных инструментов вычислительной гидродинамики. Представлены результаты моделирования процессов нестационарного горения в низкоэмиссионной камере сгорания газотурбинного двигателя. По результатам трехмерных расчетов определены максимальные по амплитуде пульсации, возникающие в жаровой трубе и межтрубном пространстве камеры сгорания газотурбинного двигателя

Study of helium swelling in nitride ceramics at different irradiation temperatures

This paper presents the results of a systematic study of helium swelling and the subsequent process of degradation of the near-surface layer of aluminum-based nitride ceramics. The samples were irradiated with 40 keV He2+ ions at temperatures of 300 and 1000 K with a fluence of 1 × 1017-5 × 1017 ions/cm2. The choice of radiation doses and temperature conditions was due to the possibility of simulating reactor tests of structural materials. It has been established that an increase in the irradiation fluence leads to the formation of large agglomerates of clusters of helium bubbles, as well as an increase in the degree of roughness and waviness of the surface with the formation of crater-like inclusions. In the case of irradiation at high temperatures, there was a slight decrease in the average size of helium inclusions compared with irradiation at room temperature. However, the density of inclusions and surface roughness were much higher. It is established that irradiation at room temperatures leads to a sharp decrease in ceramics density, as well as deformation of the crystal structure due to an increase in the density of dislocations and macrostresses in the structure. The decrease in ceramics density due to the formation of helium inclusions led to an increase in porosity and a defective fraction in the structure of the surface layer of ceramics. © 2019 by the authors

PROPERTY RELATIONS IN THE INVESTMENT AND CONSTRUKTION COMPLEX

The problem of the relationship between the concepts of property. The historical aspects of the formation of the property category in Russia are indicated is considered. The economic and legal aspects of the concept of property are considered. The main forms of ownership and their shares in the total number of construction companies on the Russian market are described. The mechanism of profit distribution in the investment and construction complex in accordance with the share of ownership of each participant in the construction process is described. The importance of investment risks in the formation of construction projects is reflected, as well as the importance of large vertically integrated structures in the form of investment and construction companies that allow the entire investment and construction cycle to be closed within the same company

Synthesis of Cu/CuO nanostructures obtained by electrochemical deposition

Unique physical-chemical properties of nanostructured materials are explained by the crystal structure, geometry and conductive properties that can be controlled by changing the synthesis conditions of nanostructures. In turn, the process of electrochemical deposition makes it possible to control the formation of nanostructures and their physical-chemical properties with high accuracy. Electrochemical synthesis in tracks of the template was carried out in potentiostatic mode at a voltage of 0.5 to 1.5 V. The electrolyte temperature was 25, 35, 50 °C. The composition of the electrolyte solution: CuSO4·5H2O (238g/l), H2SO4 (21g/l). The yield of copper by current from the sulfuric acid solutions of electrolytes is 100%. The growth of nanostructures was monitored by the chronoamperometry method with the "Agilent 34410A" multimeter. Since the template PET matrices are dielectric, a layer of gold with a thickness of no more than 10 nm, which is further a working electrode (cathode) during electrochemical deposition, was deposited to create a conductive layer by magnetron sputtering in a vacuum. By controlling the deposition time, the difference in the applied potentials, the electrolyte temperature, we can change the geometric parameters of synthesized nanostructures. All possible reactions associated with the synthesis process are listed below

Phase transformations and photocatalytic activity of nanostructured Y2O3/TiO2-Y2TiO5 ceramic such as doped with carbon nanotubes

This work is devoted to the study of phase transition processes in nanostructured ceramics of the Y2O3/TiO2-Y2TiO5 type doped with carbon nanotubes as a result of thermal annealing, as well as to the assessment of the prospects of the effect of phase composition on photocatalytic activity. By the method of X-ray phase analysis, it was found that an increase in the annealing temperature leads to the formation of the orthorhombic phase Y2TiO5, as well as structural ordering. Based on the obtained UV spectra, the band gap was calculated, which varies from 2.9 eV (initial sample) to 2.1 eV (annealed at a temperature of 1000 ◦C). During photocatalytic tests, it was established that the synthesized nanostructured ceramics Y2O3/TiO2-Y2TiO5 doped CNTs show a fairly good photocatalytic activity in the range of 60–90% decomposition of methyl orange. © 2020 by the authors.Ministry of Education and Science of the Republic of Kazakhstan: BR05235921This study was funded by the Ministry of Education and Science of the Republic of Kazakhstan (grant BR05235921)

Induced spirals in polyethylene terephthalate films irradiated with ar ions with an energy of 70 MeV

This paper presents the results of a study of the ordering in polyethylene terephthalate (PET) film induced by Ar8+ ions with an irradiation fluence of 2 × 1012 ions/cm2, and of the temporal stability of the induced ordering in the irradiated sample, over a three month period. Immediately after irradiation, sharp new reflections not seen at lower fluences were observed in X-ray diffraction patterns, with angular positions of 2 θ = 9–10° and 19° and variable azimuthal intensities. X-ray reflections, previously observed at lower fluences, were also seen: at 2 θ = 26° and 23°, associated with PET crystallites, and at 2 θ = 5–12°, associated with induced ordering in the amorphous zone. Aging of the irradiated sample led to significant growth of the ordering region in the amorphous zone for angles up to 2 θ < 15°, as well as to dissipation and blurring of the new diffraction reflections at 2 θ = 9–10° and 2 θ = 19° and the formation of a new diffraction ring reflection in the range 2 θ = 11–16°. The azimuthal distribution of diffraction reflection intensities immediately after irradiation displays a clear oblique cross located predominantly along lines at angles of π/4 with respect to the direction of the texture of the PET film, indicating the formation of spiral structures based on the molecular strands of PET. Our experimental results lead us to conclude that the formation of coherent scattering areas in the amorphous region at 2 θ < 15° is due to intra-chain rotations of benzene-carboxyl subunits of repeat units of the PET chain molecules interacting with the residual electric field of a single latent track; whereas the formation of spiral structures is due to the inter-chain interaction of these preordered asymmetric subunits under the influence of the electric fields from overlapping latent tracks. © 2020 by the authors

Generation of Terahertz Pulsed Radiation with Photoconductive Antennas Based of Low-Temperature-Grown Gallium Arsenide and Its Applications

The design and technological conditions for manufacturing photoconductive antennas based on low-temperature-grown gallium arsenide (LT-GaAs) have been developed. An optimized photoconductive THz antenna based on LT-GaAs with flag geometry of the contacts was fabricated. LT-GaAs samples were obtained by molecular-beamepitaxy at temperatures of 230 ∘C on GaAs (100) substrates. On an optical setup with a femtosecond titanium-sapphire laser, a volt (watt)-ampere characteristics and photocurrent efficiency of the photo-conductive antenna measured by the pyroelectric sensor. The optimum annealing temperature of LT-GaAs was determined for generation of intense THz radiation. PCA have been tested in the terahertz radiation generation. The substantial effect of water vapor in the air and the environment of transparent objects is THz. The useful terahertz bandwidth extends from 0.1 to 2.7 THz and the source of terahertz wave is the most commonly used nonlinear crystal ZnTe in the biomedicine applications. However, in comparison PCA on LT-GaAs with ZnTe have better results in the intensity and the power of the THz response. Therefore, it will be possible to detect a lower concentration of biological objects. Keywords: Photoconductive antennas; low-temperature grown gallium arsenide

Investigation of the influence of irradiation on Structural properties of AlN ceramics

One of the essential tasks of modern materials science is the studying of the interaction of various types of ionizing radiation with structural materials that have a promising application in reactor engineering [1-3]. Moreover, the creation of new radiation-resistant materials must take into account the effect of ionizing radiation on the resistance to defects formation in the structure and their subsequent evolution, which can lead to deterioration in operational properties of materials. Also, the energy losses of incident ions in matter directly affect defects formation in ceramic materials. Ionizing radiation can initiate dynamic processes associated with the violation of the atomic structure of ceramics, as well as the formation of metastable phases that can lead to partial amorphization and structural failure. The appearance of new metastable phases and the subsequent amorphization of the structure are the most common effects in irradiation of ceramic materials: AlN, TiO2, Si3N4, and SrO2

AIDS - the plague of the 21st century. Distribution in the Sverdlovsk region. Problems and solutions

In work on the basis of different sources of literature deals with the relevance of the study of acquired immune deficiency syndrome, the prevalence of HIV infection in the Sverdlovsk region and solving the problem of a healthy lifestyle, facing educational institutions, society and the state as a wholeВ работе на основании различных источников литературы рассматриваются вопросы актуальности изучения синдрома приобретенного иммунного дефицита, уровня распространенности ВИЧ-инфекции в Свердловской области и проблемы решения здорового образа жизни, стоящие перед образовательными учреждениями, обществом и государством в цело

Synthesis and properties of Ferrite-based nanoparticles

The work is dedicated to the study of the structural and optical characteristics, as well as the phase transformations, of ferrite nanoparticles of CeO2-Fe2 O3 . To characterize the results obtained, the methods of scanning and transmission microscopy, X-ray diffraction (XRD) spectroscopy, and Mössbauer spectroscopy were applied. It was found that the initial nanoparticles are polycrystalline structures based on cerium oxide with the presence of X-ray amorphous inclusions in the structure, which are characteristic of iron oxide. The study determined the dynamics of phase and structural transformations, as well as the appearance of a magnetic texture depending on the annealing temperature. According to the Mossbauer spectroscopy data, it has been established that a rise in the annealing temperature gives rise to an ordering of the magnetic properties and a decrease in the concentration of cationic and vacancy defects in the structure. During the life test of synthesized nanoparticles as cathode materials for lithium-ion batteries, the dependences of the cathode lifetime on the phase composition of nanoparticles were established. It is established that the appearance of a magnetic component in the structure result in a growth in the resource lifetime and the number of operating cycles. The results show the prospects of using these nanoparticles as the basis for lithium-ion batteries, and the simplicity of synthesis and the ability to control phase transformations opens up the possibility of scalable production of these nanoparticles for cathode materials. © 2019 by the authors. Licensee MDPI, Basel, Switzerland