Статьи журнала - Siberian Aerospace Journal
Все статьи: 330
Calculation of the parameters and characteristics of a rotating lunar jet penetrator
Статья научная
The purpose of the work is to determine the parameters of the internal ballistics of a solid propellant jet engine mounted on a jet penetrator entering the ground at a high rotation speed around its own axis. Research methods: to determine the pressure in the chamber of a rotating engine, the known equations for the balance of gas inflow and consumption are usually used, as in the case of a non-rotating solid propellant jet engine. The difference between the internal ballistics of a rotating solid propellant jet engine is that the effect of rotation on the operating process is taken into account by the coefficient of gas flow from the chamber of the rotating engine; a change in the rate of erosive combustion of solid propellant during rotation of a solid propellant jet engine; heat loss coefficient. Results: it was found that the parameters of the internal ballistics of rotating jet engines of solid propellant are mainly influenced by the coefficient of gas flow from the chamber of the rotating engine; effect of erosive combustion of solid propellant and change in heat loss coefficient. The main calculated dependencies for determining the pressure in the combustion chamber of a rotating solid propellant engine are presented for periods when the pressure reaches a stationary mode of operation of the engine, operation of the engine in a stationary mode and during the period of free flow of gases from the chamber of a solid propellant jet engine. A method for selecting the linear and angular dimensions of a rotating engine nozzle is presented. An estimate of the thrust force for a single nozzle rotating solid propellant jet engine is given. It has been established that the magnitude of the thrust force of rotating engines (under other identical conditions in the combustion chamber) is 1.1–1.36 times less than that of non-rotating solid propellant jet engines. The experiments carried out showed a decrease in the degree of swirl of the gas flow of rotating solid propellant engines with an increase in the number of propellant pellets in the engine charge. Conclusion: the results presented in the article can be useful for scientists, graduate students and engineers involved in the creation and operation of aviation and rocket and space technology, and can also be useful for students of technical universities studying in relevant specialties.
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Статья научная
Modern and promising dynamic systems of aviation weapon systems of the Aerospace Forces (hereinaf-ter for brevity in the text – the system) are characterized by a more complex structure and increased re-quirements for reliability and efficiency of functioning. Moreover, systems of generation 4 ++ and 5 are quite unique and (or) small-scale, and their constituent elements are basically miniature and expensive, therefore, a prerequisite for fulfilling the requirements for traceability to systems and constituent elements is the maximum possible preservation of the quality of the initial basis with the inevitable new interpreta-tion of additional information. Further introduction of artificial intelligence technologies into the practice of solving problems of technical diagnostics makes it possible to obtain adequate results with almost any accuracy. The reliability of the results will be determined solely by the punctuality of the data assignment and the completeness of the mathematical description of systems, processes and events in the subject area under consideration. Therefore, it should be expected that the further development of the theory and prac-tice of technical diagnostics will follow the path of a deeper study of the physical processes occurring in systems, and a more accurate mathematical specification of procedures for finding the place of failure of systems. The aim of the work is to establish the development of an interconnected set of mathematical and logical block diagrams for obtaining and applying diagnostic knowledge in the software and mathematical support of modern and advanced onboard means of monitoring the technical state of systems. The priority direction in such studies is the differentiated selection of approved methods of technical diagnostics with the choice of the appropriate mathematical and algorithmic apparatus for direct probabilistic modeling of systems. A block diagram is presented and a variant of the practical application of the developed algorithm for sequential recognition of system failures (hereinafter referred to as an algorithm, if it is clear from the context of the presentation of the material that it is the developed algorithm) is considered. By using the algorithm, there is no need for decomposition of systems, and the potential for multiple repetitions of the results of a random process of changing the technical states of systems predetermines the possibility of ob-taining large samples with high accuracy of software compilation.
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Change in magnetoresistance in manganese chalcogenides MnSe1-XTeX from bulk to thin-film samples
Статья научная
The electrical and optical properties of anion-substituted antiferromagnetic semiconductors MnSe1-ХTeХ (0.1 ≤ X ≤ 0.4) in the temperature range 77-300 K and magnetic fields up to 13 kOe in bulk samples and in poly-crystalline thin films are investigated. Negative magnetoresistance was found in the MnSe1-XTeX solution in the neighbourhood with a Néel temperature for X = 0.1 and for a composition with X = 0.2 in the paramagnetic re-gion up to 270 K. A correlation was established between the spin-glass state and magnetoresistance for X = 0, 1 and 0.2. The opti-cal absorption spectra were measured in the frequency range 2000 cm-1 < ω < 12000 cm-1. A decrease in the gap in the spectrum of electronic excitations and a several of absorption peaks near the bottom of the conduc-tion band were found. Coexistence of two crystalline phases was found in polycrystalline films of the MnSe1-XTeX system by X-ray diffraction analysis. Resistance maxima were established in the region of polymorphic and magnetic transitions. A model of localized spin-polarized electrons with a localization radius varying in a magnetic field as a result of competition between ferromagnetic and antiferromagnetic interactions is proposed. In the paramagnetic region, negative magnetoresistance is caused by tunneling of spin-polarized electrons during orbital ordering.
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Characteristics of low thrust liquid-propellant rocket engines testing process
Статья научная
Low thrust liquid-propellant rocket engines (LTLPRE) are the main type of rocket engines for control systems of space aircrafts. The thrusters are able to work either in continuous or impulse regime, which is one of their main characteristics. The suggestion about engines` reliability should come from the results of tests which create real or greatly approximated to the real conditions. The development process of thrusters takes into a great account the problems of bench testing methodic, technical equipment of test benches for creating the closest possible to space conditions and the use of diagnostic methods and instruments for various types of physical research and dimensions. The ground test effectiveness depends on the level of real conditions imitation and the level of attention to all operational factors that influence the credibility of reliability parameter estimation during the development. One of the most important questions in terms of testing effectiveness is the question of testing result accuracy and credibility. The testing process of thrusters mainly goes under the requested conditions of vacuum, created in pressure chambers. To increase the effectiveness of space conditions imitation the paper suggests using the pressure chamber, equipped with the tube shield with the circulating liquid nitrogen under required mass flow rate. The impulse working regime creates instability of propellant moving in pipelines. The paper considers the methods of providing dynamically similar characteristics of supply systems in propulsion systems as well as conformity of hydraulic, inert and wave characteristics of supply pipelines.
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Characteristics research of a low thrust rocket engine manufactured using additive SLM technology
Статья научная
The development and improvement of rocket and space technology are largely determined by the application of manufacturing technologies that enable the production of high-reliability products with energy efficiency, while simultaneously reducing material intensity and shortening the production cycle. Among these progressive technologies, additive technologies should be mentioned. The essence of these technologies lies in obtaining parts through layer-by-layer melting of material based on a computer 3D model of the product in a chamber of a specialized 3D printer equipped with a laser device. The application of additive technologies in rocket engine construction requires extensive scientific research and experimental work to confirm compliance with industry standards, rules, and mandatory certification at the state level. In accordance with the program of priority research at SibSU, in collaboration with the industrial partner “Polychrome” LLC a complex of experimental work is being carried out to test and refine the 3D printing modes of a demonstrator model of a low thrust rocket engine (LTRE). The design of the LTRE, operating on environmentally friendly gaseous fuel components, has been developed and adapted for 3D printing on the ASTRA 420 printer. The parameters and characteristics of the printer are considered, and the sequence of experimental work on selecting printing modes for the engine chamber housing and mixing head is outlined. The fundamental possibility of adjusting the modes of laser material melting and forming of the part has been established. The main technological stages of post-printing processing of LTRE chamber parts are presented. A description of the equipment for heat treatment and electrochemical polishing of parts is provided. The sequence of material structure research is outlined, and the results of metallographic and X-ray analysis of the internal state of the metal are presented. The importance of stand tests of rocket engines in the development of innovative design solutions and the implementation of innovative production technologies is demonstrated. A description and composition of the testing stand system at SibSU are presented. The results of stand firing tests indicate the fundamental possibility of manufacturing LTRE using selective laser melting of heat-resistant alloy.
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Статья научная
A turbopump unit (TPU) is one of the main units of a liquid propellant rocket engine. Ensuring the op-erability and the possibility of continuous supply of fuel and oxidizer components with a given flow rate and pressure throughout the entire operation cycle of a liquid-propellant rocket engine is one of the main tasks in the design of a heat pump. A negative effect that manifests itself in the case of a local decrease in pressure to the pressure of saturated steam is cavitation. Currently, in connection with the growth of the computing power of modern computer systems, the methods of computational fluid dynamics (Сomputational Fluid Dynamics, CFD) are increasingly being used to test the anti-cavitation parameters of the pump in various areas of general mechanical engineering. For the rocket and space industry, which has special requirements for reliability, more statistical data is needed. At the moment, there is no cavitation model capable of fully simulating the entire process of nucle-ation, growth and collapse of a cavitation bubble. However, there are a number of simplified models of this process, among which we can single out the numerical model Zwart – Gerber – Belamri, designed to simu-late the cavitation flow in pumps. The mentioned model is the most suitable and is applied in all the works discussed below. This paper analyzes the experimental data and the results of numerical simulation of pumps with vari-ous parameters of flow, pressure and geometry. In the course of work with the model, calculations were performed in the ANSYS environment. In the final part, a conclusion was made about the relationship be-tween the characteristics and applicability of the Zwart – Gerber – Belamri model to the design of the cavi-tation flow in the TPU of an LRE taking into account the peculiarities of the pump operation.
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Статья научная
One of the main systems of a spacecraft (SC) is a power supply system (PSS). The basis of a PSS are secondary power sources (SPSs), which use various methods of controlling and converting electricity, which leads to significant differences in their dynamic properties. On the onboard consumer side, the dynamics of the PSS is determined by the total internal resistance (impedance) of the SPSs. When conducting ground electrical tests of spacecraft EES (electrical engineering systems), due to the complexity of using power supply systems, test complexes are used, the basis of which is simulators of electrical characteristics of the PSS (PSSS). Modern PSSSs use a modular configuration principle, which makes it possible to produce PSSSs of different powers, but energy modules have fixed or adjustable impedance frequency response over a narrow frequency range, which leads to the limitation of the types of PSS being simulated. Equipping the PSSS with the property of regulating frequency response in a wide frequency range expands the functionality of the PSSS, as it allows simulating the dynamic properties of the PSS containing different types of SPSs. The purpose of the work is to study and carry out the comparative analysis of three methods for regulating the impedance frequency response (IFR) of the PSSS module. The methods for regulating the frequency response of a PSSS are being considered on the basis of its generalized functional diagram containing mathematical models: adder amplifier (AA), feedforward compensator (FC), power amplifier (PA), voltage divider (VD) and load (L). The article analyzes options for regulating the impedance frequency response of PSSS, and considers three methods for regulating the IFR: two with a passive FC and one with an active FC. The paper presents a simulation model in the MicroCap package of the electrical circuit of the PSSS module, and computational experiments have been carried out on each method of regulating the IFR of the PSSS. Based on the results of the study, a method for correcting and regulating the IFR of the PSSS is recommended, which makes it possible to separately regulate the low-frequency and mid-frequency regions of the IFR, which allows us to significantly simplify the configuration and provision of the IFR of the PSSS in accordance with the specified requirements.
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Статья научная
The paper proposes the use of clustering methods to determine the most appropriate number of fuzzy terms when building a genetic fuzzy system. At the same time, a fuzzy logic system is used to solve data classification problems and is automatically generated by a genetic algorithm. We used a genetic algorithm with the encoding of terms and classes in a binary string, while each individual encoded a rule base. To build a rule base, it is necessary to set such a parameter as the number of fuzzy terms, since it significantly affects the quality of the generated classifiers. A comparison of the most well-known algorithms such as DBSCAN, k-means and the mean shift algorithm was carried out to identify the best data clustering meth-od. Computational experiments were carried out on several data sets to evaluate the effectiveness of the selected number of fuzzy terms. According to the results, it was determined that the mean shift algorithm selects such a number of terms that allows building more accurate classifiers in comparison with two other methods involved in testing. A comparison was also made with alternative classification methods such as k nearest neighbors, support vector machines and neural networks, as a result of which the proposed method showed comparable classification quality. The developed approach to automating the determination of the number of terms makes it possible to exclude manual selection of granulation for various data, reducing the cost of creating an effective fuzzy system for the classification problem.
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Comparison of methods for initializing starting points on the optimization genetic algorithm
Статья научная
The way to initialize the starting points for optimization algorithms is one of the main parameters. Currently used methods of initializing starting points are based on stochastic algorithms of spreading points. In a genetic algorithm, points are Boolean sets. These lines are formed in different ways. They are formed directly, using random sequences (with uniform distribution law) or formed using random sequences (with uniform distribution law) in the space of real numbers, and then converted to boolean numbers. Six algorithms for constructing multidimensional points for global optimization algorithms of boolean sets based on both stochastic and non-random point spreading algorithms are designed. The first four methods of initialization of Boolean lines used a random distribution law, and the fifth and sixth methods of initialization used a non-random method of forming starting points-LP sequence. A large number of optimization algorithms were restarted. Calculations of high accuracy were used. The research was carried out on the genetic algorithm of global optimization. The work is based on Acly function, Rastrigin function, Shekel function, Griewank function and Rosenbrock function. The research was based on three algorithms of srarting points spreading: LP sequence, UDC sequence, regular random spreading. The best parameters of the genetic algorithm of global optimization were used in the work. As a result, we obtained arrays of mathematical expectations and standard deviations of the solution quality for different functions and optimization algorithms. The purpose of the analysis of ways to initialize the starting points for the genetic optimization algorithm was to find the extremum quickly, accurately, cheaply and reliably simultaneously. Methods of initialization were compared with each other by expectation and standard deviation. The quality of the solution is understood as the average error of finding the extremum. The best way of initialization of starting points for genetic optimization algorithm on these test functions is revealed.
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Compound bending of an orthotropic plate
Статья научная
The problem of longitudinal-transverse deformation and strength of an orthotropic plate on the action of a local transverse force and stretching along the contour of the membrane forces is studied. The direction of laying the fiber of a unidirectional composite that provides the lowest level of stress and deflection is determined. In the zone of application of concentrated force in thin-walled structures, significant bending moments and shear forces occur, which are a source of stress concentration. To reduce stresses, the method of plate tension by membrane forces applied along the contour is chosen. The maximum possible order of membrane tension forces is selected, which provides conditions for the strength and rigidity of the solar panel plate structure, which has a hinge-fixed support along the contour. Pre-tensioning the plate web allows to reduce the stress by 50 times. The problem of compound bending of isotropic and anisotropic plates when applying transverse and selection of longitudinal loads, with restrictions on strength and stiffness, can be called a problem of rational design of the structure. The resulting equations and calculation program can be used in the design of plate structures, as well as in the educational process.
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Concentration of carbon dioxide in products of combustion of GTE NK-16ST and NK-16-18ST
Статья научная
This paper considers the design of two combustion chambers of a gas turbine engine running on natural gas. One combustion chamber has 32 burners, and the other has 136 nozzles located in two rows in the flame tube head. A major contributor to global warming is considered to be the significant emissions of greenhouse gases, primarily CO2, including those emitted by gas turbine engines and power plants. The reduction of carbon dioxide levels by developing a set of structural measures in the combustion chamber is one of the urgent tasks of engine construction which requires a solution in order to meet modern environmental requirements for gas turbine engines serving as blower drives for gas compressor units. The presented research is dedicated to the analysis of influence of changes in combustion chamber design on reduction of CO2 level in exhaust gases of gas turbine engine NK-16ST. Two modifications of the combustion chamber are considered. The first one was a serial combustion chamber with diffusion combustion; the second one was a modernized combustion chamber with a modified front device. Each of the chambers considered was tested as part of the engine. During the study, combustion products were sampled directly in the exhaust tower and their concentrations, including the CO2 content, were determined. As a result of this work, it was confirmed that there is a possibility to reduce the concentration of CO2 in the engine combustion products up to 20 % without affecting the engine parameters. This reduction in carbon dioxide content was made possible by reducing the completeness of fuel combustion in the combustion chamber. The obtained data on changes in CO2 concentration can be useful in selecting the most suitable mode of engine operation, and the presented approaches to combustion processes organization can be used by developers in designing combustion chambers of natural gas-fired gas turbine engines.
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Статья научная
If a system of differential equations admits a group of continuous transformations, then the system can be represented as a set of two systems of differential equations. As a rule, these systems have a smaller or-der than the original system. The first system is automorphic, characterized by the fact that all its solutions are obtained from a single solution using transformations of this group. The second system is permissive, its solutions, under the action of the group, pass into themselves. The resolving system carries basic infor-mation about the source system. Automorphic and resolving systems, two-dimensional stationary elasticity equations are studied in this work. They are systems of the first-order differential equations. Infinite series of conservation laws for a resolving system of equations and an automorphic system are constructed for the first time in this work. Since the two-dimensional system of elasticity equations is linear, there are infinitely many such laws. In this paper, an infinite series of linear conservation laws with respect to the first derivatives is constructed. It is these laws that made it possible to solve the first boundary value problem for the equations of elasticity theory in the two-dimensional case. These solutions are constructed in the form of quadratures, these quadratures are calculated along the contour of the studied area.
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Constraint handling genetic algorithm for feature engineering in solving classification problems
Статья научная
Feature engineering in machine learning is a promising but still insufficiently studied direction. Creating new feature space from an original set allows to increase accuracy of the machine learning algorithm chosen to solve complex data mining problems. Some existing selection methods are capable of simultaneously increasing accuracy and reducing feature space. The reduction is an urgent task for big data problems. The paper considers a new machine learning approach for solving classification problems based on feature engineering methods. The design of informative features is carried out using extraction and selection methods. Based on the initial data, new sets of characteristics have been created, which include the original characteristics and characteristics obtained by the method of principal components. The choice of an effective subset of informative features is implemented using a genetic algorithm. In order to avoid overfitting and the creation of trivial classifiers, restrictions are imposed on the fitness function of the genetic algorithm, requiring a certain number of features of the original sample, as well as a certain number of features obtained by the principal component method. A comparative analysis of efficiency of the following classification algorithms is carried out: k-nearest neighbors, support vector machine, and a random forest. Efficiency research experiments are carried out by solving applied binary classification problems from the UCI Machine Learning repository of machine learning problems. The macro F1-score was chosen as an efficiency criterion. The results of numerical experiments show that the proposed approach outperforms the solutions obtained using the original data set and the performance of random feature selection (the low bound for the results). Moreover, the accuracy enhancement is obtained for all types of problems (data sets that have more features than values). All results are proved to be statistically significant.
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Construction of high-precision low-dimensional MgFE using local approximations and generating FE
Статья научная
Composite structures (bodies), in particular, plates, beams, shells, are widely used in aviation and rocket and space technology. To analyze the stress state of elastic composite bodies (CB), the method of multigrid finite elements (MMFE) is effectively used, which is implemented on the basis of the Lagrange functional (in displacements). When constructing a multigrid finite element (MgFE), briefly a standard MgFE, using known procedures, a small base grid is used, which can be arbitrarily small, and large ones nested in a small one. The fine grid is generated by the partition of the MgFE, which takes into account its inhomogeneous, micro-inhomogeneous structure within the framework of the micro-passage. Large grids are used to reduce the dimension of the MgFE. The following is typical for a standard MgFE. Any large grid of a standard MgFE and corresponding approximations of displacements are determined on its entire region. This leads to an increase in the dimension of the standard MgFE with an increase in its order of accuracy, since in this case approximations of high-order displacements are determined on large grids. To reduce the error of solutions, high-precision MgFE are used, i. e., of a high order of accuracy, which have a large dimension. However, the use of high-precision MgFE is difficult, since they form discrete models of high-dimensional bodies. In this paper, we propose a method of local approximations (MLA) for constructing high-current MgFE of small dimension (short - small-sized MgFE), which are used to calculate elastic homogeneous and CB by MgFE. Two types of small-sized MgFE are considered. Small-sized MgFE of the 1st type are designed on the basis of standard ones with the use of local approximations of displacements, which are determined on the subdomains of standard MgFE, of the 2nd type - with the use of finite element generators (FE). The brief essence of the construction of small-sized MgFE of the 1st type is as follows. According to the MLA, we define a smaller Н grid on the V0 region of the standard MgFE than its base one. The V0 region is represented by the boundary and inner regions. The boundary (inner) regions have a common boundary, which does not degenerate into a point (do not have a common boundary), with the V0 region. On the boundary (inner) regions, we define large grids that are embedded in a small Н grid and generate local approximations of small (high) order displacements. On the V0 region, using local approximations of the displacements of the boundary and inner regions, we construct the MgFE. Then, using the condensation method, we express the movements of the internal nodes of the MgFE through the movements of the nodes lying on its boundary, i.e. on the boundary of the V0 region. As a result, we obtain a high-precision Vp MgFE of small dimension, i.e. a small-sized MgFE of the 1st type, the dimension of which is equal to the dimension of the standard one. It is important to note that with an increase in the order of accuracy of the Vp MgFE, its dimension does not change, i.e. it does not increase, and therefore it is called a highprecision MgFE of small dimension, i.e. small-sized. The procedure for constructing small-sized MgFE of the 1st type is described in detail. As is known, the calculation of the static strength of structures is reduced to determining the maximum equivalent stresses for them, the determination of which with a small error for CB is an urgent problem. Calculations show that small-sized MgFE of the 1st type generate maximum equivalent stresses in CB, the errors of which are 25 50 smaller than the errors of analogous stresses obtained using standard ones, on the basis of which small-sized, i.e. small-sized MgFE of the 1st type are more effective than standard ones. The use of small-sized MgFE of the 1st type in MMFE calculations makes it possible to determine the maximum equivalent stresses with a small error for large CB partitions. The construction of small-sized MgFE of the 2nd type is shown, which are designed on the basis of standard high-precision MgFE with the use of generating FE. A small-sized MgFE of the 2nd type has the same order of accuracy as the standard one, but its dimension is smaller than the dimension of the standard one. The advantage of small-sized MgFE of the 2nd type is that they give rise to discrete CB models of smaller dimension than standard ones.
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Contact algorithm measurement method for current crystals area grown by Czokhralski method
Статья научная
For crystals grown from the liquid melt according to the Czochralski method when monitoring and controlling the current crystal area based on the contact measurement method, the requirements for improving the accuracy of measuring the crystal area on the cylindrical part of the growth are determined. To eliminate errors due to the accuracy of stabilization of the melt level in the crucible, an algorithm for the operation of the crystal growing unit is proposed which is performed by the programm using the control system. The evaluation time of the control signal on the growing crystal cylindrical part is taken as the sampling time of a given number of crucible movement pulses. The calculation of the control signal starts at the time of the melt level sensor closure, the calculation of the control signal ends at the time of the melt level sensor closure as well, provided that a given number of crucible movement pulses is sampled. The control signal evaluation time in the previous control cycle is used in the current cycle to calculate the melt level sensor closing and opening pause. In the control system at the moment of the contact sensor closure a pause of the closed and the same subsequent pause of the open state of the level sensor is held. During pauses, the status of the contact sensor is not analyzed by the control system and the control of the crucible ascent occurs at a slowed down and accelerated rate of the crucible ascent during “conditionally” closed and “conditionally” open states of the level sensor. The control system is permanently reset at the end of each control cycle. The program control system provides the above algorithm for controlling the process of growing crystals from the liquid melt according to the Czohralski method, at the same time the accuracy of determining the current area of the grown crystal is about 1 %.
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Control and regulation equipment of electric power system for a prospective piloted transport system
Статья научная
The aim of this work is to consider solving complex of tasks focused on fulfilling the complicated tactical and technical requirements for regulation and monitoring equipment (RME) of electric power supply system (EPS) for a prospective spacecraft. These requirements are imposed due to the need to ensure high reliability of the equipment during operation under the influence of external factors (vacuum, vibro-impact loads, radiation, absence of convective cooling), as well as to achieve high mass-dimensional parameters of the equipment and its high functionality The complexity of problem solving lies in the need to ensure conflicting requirements – high levels of energy density, weight and size characteristics, reliability and durability. These problems fully apply to the RME of the EPS for a prospective piloted transport system (PPTS) which design example shows ways of solving abovementioned problems. The most rational way of solving these contradictions is to increase the specific energy indicators of the main components of the RME devices – power converters, which can be achieved by using modern power electronic elements, using new materials and semi-finished products, for example, printed circuit boards with a metal heat sink, as well as increasing the layout density design. Determining solution is to select an optimal structure of the power converter, which provides the best efficiency. An additional way to reduce the mass-dimensional indicators of the RME is the use of a digital control method, the collection of telemetric information, and the receiving and processing of commands. At the same time, on the contrary, to ensure the specified reliability of the equipment, it is necessary to use excess reservation at the element level – for power components, and the principles of majority reservation at the functional block level – for control and telemetry schemes. Using the example of RME, developed by CJSC “Orbita”, the main EPS parameters of a new generation spacecraft are shown and most important power supply subsystems are considered in the article: the solar energy control subsystem and the power storage subsystem, ways to build them for meeting specified requirements, taking into account the proposed solutions. As a result of this work, the optimal structures of power converters – the current regulator of the solar battery and the current regulator of the battery – were selected, the basic principles of power components reservation ensuring the operability of the equipment in case of a single failure of any component without loss of performance and deterioration of RME parameters as a whole are shown. Block-modular construction method is used for optimal layout and high reliability of the RME, it ensures uniform heat removal from electronic components, which is especially important in vacuum conditions, minimum dimensions and mass optimization of the RME, as well as high mechanical strength of the structure. The implemented principles of building the RME for PPTS using this approach will allow to increase the active lifetime (ALT) and reliability of the spacecraft with a simultaneous decrease in mass and dimension parameters.
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Статья научная
In this paper, we consider the concept of using methods for calculating and designing rocket engine power plants for conversion modeling of local energy in the Arctic and northern regions of the Kras-noyarsk Territory, with an obvious generalization to neighboring administrative formations with similar climatic and structural and logistical conditions. The proposed structure contains power generation units linked to both industrial woodworking waste and natural and industrial thermal tails, identified as sources of low-potential heat, as well as modern low-power reactor plants of block maintenance-free design. The unifying element of power plants is a turbo generator, designed with the use of unconventional, often waste and natural low-grade heat.
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Статья научная
The known methods of treatment of wastewater generated in rocket and space technology production using electroplating technologies do not allow to ensure the maximum permissible concentration of metal ions in treated water, or are expensive or difficult to operate. The general toxic, embryotropic and muta-genic effect of metals is well studied. These metals, getting together with water to food products in living organisms, are able to accumulate in them, causing the pathogenesis of heart diseases, brain, liver, and cancerous tumors in people. Iron ions are part of wastewater of most industries, which requires increased control and development of effective methods of wastewater treatment. The article presents a technique for conducting experiments, a method of combined water purification, including electrochemical action and adsorption, is considered. The results of studies of this method of wa-ter purification from iron ions are presented. The dependence of the degree of purification on the specific amount of electricity passing through the purified water, the strength of the electric field and the settling time is revealed. With Qav = 4.7 Kl/l, E = 1058 V/m, using quartz sand as an adsorbent and settling time for 24 hours, the concentration of iron ions decreased from 1.65 to 0, 82 mg/l. The proposed combined cleaning method requires inexpensive and affordable materials and is easy to operate.
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Design of a flexible spoke for a spacecraft umbrella antenna
Статья научная
Umbrella type antennas are often used in modern spacecraft. Their advantage is the possibility of compact placement during orbital insertion. At the same time, they must provide the necessary stability when deployed in space. Antenna stiffness mainly depends on the stiffness of the spokes, the design of which is a complex task of scientific research. Spacecraft antennas must provide functional performance and, at the same time, have a minimum mass. The cardinal direction of improvement of space antennas consists in application of new structural materials. Composites are characterized by high specific mechanical properties, which allow to create structures with a high degree of weight perfection. The problem is related to the presence of a large number of design parameters that affect the performance of composite structures in a complex way. Determining the optimal combination of these parameters for each structure and a particular design case leads to the need for a complex numerical experiment based on specialized algorithms, methods and programs. The aim of the study is to design a composite spoke for the umbrella antenna of a spacecraft, providing the required load-bearing capacity and maximum stiffness at a given mass limit of the structure. It involves the development of finite element models of the composite spoke of various designs, which would include the possibility of optimizing the design parameters by the criteria of strength, load-bearing capacity and stiffness. As a result of numerical experiment, the ways of increasing the bearing capacity and stiffness of the deployed spacecraft antenna are determined.
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Design of a multifunctional electric propulsion subsystem of the spacecraft
Статья научная
A common way to form an electric propulsion subsystem of the spacecraft is to create specialized equipment or to select the most suitable one from the ready-made ones. However, there are cases when the use of existing equipment is not optimal enough and leads to an unjustified increase of the subsystem mass. Therefore, the ques-tion of creating a minimum equipment set possibility from which it would be possible to form propulsion subsys-tems in optimal way is of interest. The set of tasks, variants of use and possible schemes of placing orbital cor-recting propulsion on the spacecraft are presented. The list of necessary propulsion subsystem elements is pre-sented as follows: a thruster block, a tank, a xenon feed unit, a power processing unit consisting of a power unit and switching units, the complete set of cables and pipelines, the software and mechanical devices for control of the thrust vector (as an option). The necessary capacity of propellant tanks for the tasks of correction and rais-ing of the satellite to GEO with a high-pulse Hall thruster is defined: for orbit correction tasks – up to100 kg, for orbit correction and raising to GEO tasks – up to200 kg. Necessary angle rates of mechanical devices for con-trol of the thrust vector are defined taking into account possible schemes of placing thrusters on the spacecraft. It is shown that in cases when it is required to apply two or more thrusters to increase overall thrust, it is more preferable in the weight aspect to apply a combination of power and switching units instead of monoblock type of power processing units, and advantage can reach tens of kilograms. Provided the listed set of functional units is created, the offered concept will make it easy to form propulsion subsystems of the spacecraft for solving a wide range of tasks. It will reduce the time and money spent on creation of propulsion subsystem for new space-crafts.
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