Статьи журнала - Siberian Aerospace Journal
Все статьи: 330
Статья научная
Internal network security is an important aspect of a successful enterprise. There are various means to prevent cyber threats and analyze visited Internet resources, but their speed and the possibility of applica-tion strongly depend on the volume of input data. This article discusses the existing methods for determin-ing network threats by analyzing proxy server logs, and proposes a method for clustering Internet re-sources aimed at reducing the volume of input data by excluding groups of secure Internet resources or selecting only suspicious Internet resources. The proposed method consists of 3 stages: data preprocessing, data analysis and interpretation of the results obtained. The initial data for the method are the proxy server log entries. At the first stage, data useful for analysis is selected from the source data, after which the con-tinuous data stream is divided into small sessions using the nuclear density estimation method. At the sec-ond stage, soft clustering of visited Internet resources is performed by applying the thematic modeling method. The result of the second stage are unmarked groups of Internet resources. At the third stage, with the help of an expert, the results are interpreted by analyzing the most popular Internet resources in each group. The method has many settings at each stage, which allows to configure it for any format and specif-ics of the input data. The scope of the method is not limited in any way. The resulting method can be used as an additional preprocessing step in order to reduce the amount of input data.
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Applied classification problems using ridge regression
Статья научная
The rapid development of technical devices and technology allows monitoring the properties of different physical nature objects with very small discreteness of the data. As a result, one can accumulate large amounts of data that can be used with advantage to manage an object, a multiply connected system, and a technological enterprise. However, regardless of the field of activity, the tasks associated with small amounts of data remains. In this case the dynamics of data accumulation depends on the objective limitations of the external world and the environment. The conducted research concerns high-dimensional data with small sample sizes. In this connection, the task of selecting informative features arises, which will allow both to improve the quality of problem solving by eliminating “junk” features, and to increase the speed of decision making, since algorithms are usually dependent on the dimension of the feature space, and simplify the data collection procedure (do not collect uninformative data). As the number of features can be large, it is impossible to use a complete search of all features spaces. Instead of it, for the selection of informative features, we propose a two-step random search algorithm based on the genetic algorithm uses: at the first stage, the search with limiting the number of features in the subset to reduce the feature space by eliminating “junk” features, at the second stage - without limitation, but on a reduced set features. The original problem formulation is the task of supervised classification when the object class is determined by an expert. The object attributes values vary depending on its state, which makes it belong to one or another class, that is, statistics has an offset in class. Without breaking the generality, for carrying out simulation modeling, a two-alternative formulation of the supervised classification task was used. Data from the field of medical diagnostics of the disease severity were used to generate training samples.
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Applying software-mathematical models of onboard equipment to develop onboard software
Статья научная
This paper deals with the testing of the functioning logic of spacecraft subsystems at the stage of developing system onboard software. The increasing complexity of the structure and operation logic of spacecraft due to the increased requirements in terms of providing consumers with information services (navigation, satellite monitoring of transport, geodesy, communications etc.) demands maintaining the reliability of uninterrupted operation, the implementation of automated parrying of emergency situations during the operation of spacecraft onboard equipment. In order to meet these requirements, it is necessary to test the interaction of onboard equipment and onboard integrated computing complex software that implements the target-oriented operation of spacecraft onboard systems. In such a case, meeting the requirements for reliability increase of onboard software should not lead to the increase of the manufacturing period of spacecraft. In this work we propose the approach for testing information and logical interaction between onboard equipment and software of a spacecraft onboard integrated computing complex with the use of a laboratory testing sample unit and a software-mathematical model. We described the basic concepts of conducting two-stage testing of onboard software, involving autonomous and system testing on the ground testing complex. The proposed approach is applied as part of the onboard software development cycle in accordance with the standards of the JSC “Academician M.F. Reshetnev “Information Satellite Systems”. The approach proposed in this work helps reduce the number of errors during onboard software development and testing of information and logical interaction between onboard equipment and a spacecraft as a whole in every operation mode.
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Approach to optimization of the magnetic circuit of a three-phase induction plant
Статья научная
The article describes an approach to optimization of the electromagnetic regimes of an induction metallurgical plant, designed to mix liquid aluminum under the influence of a running magnetic field. To improve the properties of the molten metal in the furnace, short pole linear magnetohydrodynamic machines with copper windings and a steel core are used. The open configuration of the magnetic circuit and the magnetic coupling between the windings of the inductor lead to asymmetry of the magnetic field. As a rule, a low-frequency transistor inverter is used in the power supply system of metallurgical machines intended to affect non-ferrous metals. Asymmetrical currents in the phases create specific modes of the frequency converter, close to emergency, and a two-phase, three-phase or multi-phase power supply system may become unbalanced. To calculate the integral magnetic fluxes in the toothed zone of an induction installation, it is convenient to apply a multiphase nonlinear model of a magnetic circuit. As a result of the iterative calculation, vector magnetic flux diagrams are obtained and the tractive forces in the melt are estimated. The best conditions for the impact on the melt are obtained with a given objective function when searching for options during optimization of the magnetizing forces of the windings.
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Approximation of beam support coefficient val-ues at vibrations and buckling
Статья научная
The problem of calculating the first natural frequency of vibration and the first critical force for a beam with elastic supports is considered. An analytical review of the literature on solving such problems showed that in the theory of vibrations and the theory of stability of beams, consideration of the support conditions is based on the use of support coefficients, the values of which were obtained after solving the corresponding differential equation. The reviewed literature contains only a limited set of values of these coefficients, mainly for ideal supports of simple types: hinges, embedding, etc. Consideration of the stiffness of supports can only be found in individual editions and only for a limited number of values. In this work, the calculation of the support coefficients depending on the stiffness of the beam supports for the first natural frequency of vibrations and the first critical force is made. The obtained values were divided into three zones and approximated within each zone by quadratic functions. The use of quadratic approximation made it possible to obtain simple analytical dependencies suitable for engineering applied calculations, and the division of stiffness into zones provided an acceptable error of the obtained values. Also, quadratic dependencies made it possible to solve inverse problems for determining the stiffness of supports for a given value of the first natural frequency of vibrations or the first critical force. A detailed study of the error of the obtained approximating functions over the entire considered range of stiffness was carried out, which showed that the error in determining the coefficient of supports during fluctuations is not more than 2 %, and in case of loss of stability – 6 %. The error depends on the combination of stiffness of the supports, and can increase if the stiffnesses differ by more than an order of magnitude. The high sensitivity of the solution of the inverse problem to the input data was also established, which is the result of the high nonlinearity of the dependence of the coefficients of the supports on the stiffness. The obtained results can be used in engineering calculations of the first natural frequency of vibrations and the first critical force of a beam with elastic supports.
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Asymptotic behavior of the average recovery cost in models of recovery processes
Статья научная
Failures can occur during the operation of rocket and space technology, electronic computing systems, power supply systems, heat supply systems, transport systems and many others; there are threats of attacks, security threats and many other impacts that are random in nature and have got a negative role in their operation. Such impacts lead to recovery processes where the operating time of the recovered elements before their failure, the number of failures, the time and cost of recoveries are random variables. In the theory of probability and in the mathematical theory of reliability, when studying recovery processes, the recovery function (the average value of the number of random failures) plays a special role. We especially note its importance in optimization problems when choosing a strategy for carrying out recovery processes. So one of the most important optimality criteria is the average number of failures, the average cost of recovery, cost intensity, availability factor. We also outline the problem of the need and timing of preventive recoveries. Within the framework of the mathematical theory of reliability, models of recovery processes are considered taking into account the cost of recoveries with varying distribution functions of the time to failure of the recovered elements and the costs of recoveries. For the models under consideration, a formula for the cost function (average recovery cost) through the recovery functions of two general recovery processes is obtained, which allows to prove theorems on the asymptotic behavior of the cost function, well known for the asymptotic behavior of the recovery function of the general recovery process, where the recovery time is not taken into consideration. The obtained asymptotic theorems for the average cost of recoveries are generalized to the introduced alternating (when the random time of recoveries is also considered) recovery process, taking into account the cost of recoveries with changing distribution functions of the time to failure of the recovered elements and the costs of their recoveries.
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Attribute features application in specification of regression model of apartments cost
Статья научная
In the study of statistical data with a pronounced endogenous variable, it is necessary to identify factors (explanatory variables) that have a strong impact on the result. In this, factors can be both quantitative and attributive. To assess influence of numerical features, regression analysis methods can be used. Influence of attributive features is not taken into account. However, often these are they who make the decisive contribution to variation of the result. It is necessary to develop methods for analyzing influence of attributive features and accounting for these features in regression models. On the example of sets of apartments proposed for sale in the city of Krasnoyarsk, a new method is used to assess influence of attributive features on the quantitative using ranking them in accordance with their influence on the endogenous variable. Method of fictitious variables is used to analyze the attribute features. Each attribute with m values is assigned (m-1) dummy variables and a regression model is constructed. Influence of exogenous variables can be expressed using standardized regression coefficients. In this case, influence of attributes can be estimated by cumulative correlation coefficient calculated on the basis of a regression model with fictitious variables. For further research, set is proposed to rank, assigning each element a "rank" – value of a standardized coefficient which reflects closeness of the relationship with the endogenous variable. Thus, all features have a numerical value. A standardized regression model is constructed. Proposed approach can be used in the analysis of statistical aggregates, units of which are characterized by quantitative and attributive features.
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Статья научная
Recent decades have been characterized by increased activity in the use of polymer and composite materials in transport engineering. In this paper, the authors give a generalizing analysis of previously created systems of scientific research and analyze the principles of building automated systems of scientific research (ASSR) that allow solving the problems of determining the parameters of heat exchange, electrophysical parameters and phase transformations in polymer and composite materials when exposed to the HF field. The authors continue the research of the ASSR HF developed by the Irgups team, a number of other scientific schools working in the same direction.therefore, within the framework of the hardware created by these teams, both similar and original developments and solutions are viewed. The analysis of the software parts of the ASSR HF presented by a number of mathematical models and software complexes is given. Thus, the analysis of the structure of the developed systems of scientific research allows us to speak about its dynamic development. The developed and presented flowcharts of automated experiment and automated research systems allow the author to assert that the systems of automated experiment for studying the properties of polymer materials in RF electrothermia created for cer-tain tasks, despite the fact that they were conducted independently and separately, have a single construction methodology. Comparing the results of the research, the author concludes that the construction of a complex system of ASSR HF polar thermoplastic polymers is generally complete
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Статья научная
For successful technological process in automated control systems it is necessary to maintain technological parameters constantly at the required level, which is ensured by the use of automated process control systems (APCS). The classical solution of this problem is the application of control devices of various types, the choice of which directly depends on the system under consideration and the requirements to it. The leading position among the automatic control system regulators for the last decades belongs to the proportional-integral-differentiating (PID) regulator, which efficiency of application in the technological process is defined by the speed and accuracy of its work. These qualities directly depend on the correct setting of the regulator parameters. The synthesis of regulators requires using of modern computer-aided design systems. The article presents the method of automatic setting of PID-regulator of the dynamic system of high order with negative feedback on the example of automatic room temperature control system. The modern Russian environment of dynamic simulation of technical systems SimInTech applied at a number of nuclear, oil refining and aerospace enterprises is used as the environment for system model development, as well as the process of its analysis and optimization. The main components of the system and transfer functions of its elements are presented. The stepby- step description of the process of project construction from standard software blocks and submodels, interacting through a single database with the use of built-in programming language, is described. The use of the built-in block of SimInTech visual simulation environment optimization for automated search of PID-regulator parameters is described in details and illustrated. The advantages and disadvantages of this adjustment method revealed during the project implementation are listed.
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Статья научная
Lithium-ion batteries (LIB) are widely used as energy accumulators in the electrical power systems (EPS) of spacecraft. The article considers the automated bench SIA 12/24 for electrical tests and diagnostics of the resource characteristics of lithium-ion cells (LIC), on the basis of which the EPS LIB of spacecraft is developed and manufactured. LIC resource tests are the most time-consuming and lengthy, they are carried out in ground conditions for several months with repeated cycling of charge/discharge and cell temperatures until the conditions for completion of the tests are reached with periodic monitoring, measurement and registration of LIC parameters. The use of the automated bench, which makes it possible to carry out resource testing of LIC based on dynamic stress testing (DST), makes it possible to shorten the resource testing of LIC and thereby significantly accelerate the design and development of EPS LIB of spacecraft. The structure, the description of the component parts and the technical characteristics of the bench SIA 12/24 allowing to perform electrical tests simultaneously of twelve LIC are given. The principle of operation and technical characteristics of the original charging-discharge device with a load converter (CDD-LC) forming the basis of the bench are considered. The proposed original CDD-LC and load converter (LC) topologies with two-stage power conversion and stabilized bridge transformer converter (BTC) input voltage make it possible to automate the process of lithium-ion cells electric testing by automatically reproducing functionally necessary test modes and by ensuring energy saving in cells charging-discharge modes. For a two-stage power conversion CDD-LC, it is shown that the use of BTC input voltage stabilization gives the following benefits: – extension of the LIC attribute control ranges: current, voltage, power; – low dependency of static error of stabilization of LIC attributes and transition quality indicators on the type of LC load.
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Automated system for cleaning liquid waste products for closed ecosystems for space purposes
Статья научная
Ensuring human life activity for several years in isolated conditions of future Martian and lunar bases is possible with the organization of a circular process of converting organic waste, including human exometabolites (feces . urine), into the products he needs: water, oxygen and food. A promising way to organize such a circular process is to create a three–link closed ecosystem (CES): a person, a link for obtaining fertilizers from organic waste and plants - where plants synthesize the products necessary for a person. The paper considers the original scheme of a complex installation for the purification of liquid products of processing of human exometabolites from pollutants in the process of obtaining nutrient solutions for growing plants in a CES. The processing of human exometabolites was carried out in a device for physicochemical oxidation of hydrogen peroxide in an aqueous medium under the action of alternating electric current – in a “wet” combustion reactor. Peripheral equipment was selected for the organization of the automatic control system of the cleaning plant, problems were identified and approaches were developed in the automation of technological processes and the creation of software for human interaction with the proposed installation. Experiments on the cultivation of lettuce plants have been carried out, confirming the effectiveness of the proposed processes of purification of liquid products of processing of human exometabolites. It is concluded that the created integrated cleaning plant, equipped with the proposed software, can be used for scientific research in relation to the subject of CES, including space purposes.
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Automated system for detecting anomalies of periodic electrical signals
Статья научная
The aim of the work is to develop an automated system for detecting anomalies of periodic electrical signals with improved characteristics of the speed and efficiency of search. To solve this goal, the analysis of the problem of detecting anomalies of periodic electrical signals measured from electronic equipment was carried out and its relevance was substantiated. A hardware and software system for detecting anoma-lies of periodic electrical signals has been developed, which makes it possible to automate the testing pro-cess and increase the efficiency of detecting malfunctions of electronic equipment for various purposes. The improvement of the aforementioned characteristics was achieved due to a new test method underlying the implementation of the proposed system and protected by the patent of the Russian Federation for an inven-tion, as well as due to the high-quality implementation of software and hardware. When solving the set tasks, the methods of algebra-logic, mathematical statistics and object-oriented programming were used. The results of developing hardware, software and test algorithms are presented. A program for an electronic computer that implements control of the proposed hardware-software system is described.
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Automatic Joint Guidance and Beam Focusing Device for electron-beam welding
Статья научная
Physical, technological and power characteristics of the Electron Beam Welding (EBW) support its application in those circumstances that require greater focus on features and quality of the welding joints and improved weight and robustness aspects for individual joints of an object and products as a whole. At the same time, those characteristics of the EBW establish it as a complicated process that results from multiple factors interacting with one another. The quality of a welding joint depends on the precision of the beam alignment with the joint plane and the positioning of the minimum section (focus) of the electron beam in the penetration channel. These factors have a significant impact on the welding depth, the shape of the seam and presence of defects in it. The challenge of providing precise positioning of the beam along the joint of the welded parts is especially critical during the welding of long joints of large construction parts. This level of precision requires reliance on equipment for automatic beam alignment with the seam. Dispersion and re-reflection of the electrons in the beam leads to the loss of focus for the beam at a stable current of the focusing system. To obtain the data for the beam’s position at the seam and the position of the beam’s focus at the welding surface, we use phenomena closely associated with the EBW, such as the secondary electron emission and the X-ray radiation in the welding area. We are presenting a functional diagram of a device for the automatic positioning and focusing of the electron beam.
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Статья научная
The paper contains the results of research on the automation of controlling the geometric characteristics of gears. The use of coordinate measuring machines can significantly increase the productivity and accuracy of measurements. However, their use for controlling gears requires the application of special programs for carrying out and processing measurement results of products with complex surface shapes. The use of software for metrological control of the geometric characteristics of worm and bevel gears makes it possible to achieve high accuracy of control and measurement work. To automate the control of geometric characteristics of worm and bevel gears, an additional module has been created for the standard program. With its help, all points of the measured curved surface of gears, obtained by contact method according to a standard measurement program, are structured into a single data array with a measurement protocol. On the basis of these data, the module generates a profile of the measured surface of a wheel tooth and builds a geometric contour of the measured tooth profile. The result of the module's operation is the formation of a general profile of the entire gear and its comparison with the original (theoretical) profile of the gear as a whole. The control process itself is carried out in a short time interval, which makes it possible to use the proposed approach to automating the control of gear profiles in small-scale production.
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Beam support stiffness analytic solution for the first eigenfrequency and critical force
Статья научная
The problem of providing the required first natural frequency of bending vibrations of the beam under the action of a longitudinal force by introducing the necessary stiffness of the supports is discussed in the article. Considering and combining the equations of free vibrations of the beam and the equations describing the loss of its stability helped to obtain the operability condition based on providing a minimum given value of the first natural frequency of vibrations considering the action of the axial force. In this case, the achievement of the zero frequency of natural vibration corresponds to the loss of stability, which allows solving both problems. This task is mathematically complicated, and in the known scientific literature its solution is usually given only in graphical or tabular forms. The problem is in the nonlinear dependence of the coefficients of supports on the stiffness during vibrations and loss of stability. To solve this problem, the approximation of the nonlinear coefficients of the supports by the least squares method and the obtaining of quadratic approximating functions was used. As a result, the problem of determining the required stiffness of the supports brought to a fourth-degree resolving algebraic equation, for which an analytic solution exists. The obtained solution allows the stiffness of the beam supports, which provides the required value of the first natural frequency of vibrations of the beam and its first critical load in the form of external compressive force or temperature effects. Replacing the nonlinear dependencies of the support coefficients with the stiffness of the supports with simpler quadratic functions led to relatively simple analytic dependencies that allow the resolution equation to be transformed according to the particular problem being solved. At the same time, quadratic functions influenced the calculation error, to reduce which, the range of the support stiffness under consideration was limited and divided into three zones. The results of calculations using the proposed analytical solution were compared with numerical calculations using finite element method. The comparison of the calculation results showed an error of not more than 5 % for the considered range of stiffness of the supports, which is quite enough for engineering calculations of beam structures. To limit the error of the result, it is recommended that the stiffnesses of both supports be equal or of the same order.
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Статья научная
Technologies and production widely use composite materials now. “Mechanics of deformable solids” was formed as a science based on the study of materials used in the 19th and 20th centuries. Modern composite materials require new theoretical and experimental studies. Determining the stresses and deformations that occur at the points of contact of the matrix with the fibers is a special problem. Composites with a plastic matrix play an important role in modern technology. These materials successfully cope with cracking and significantly slow down the growth of cracks. In this article, the problem of the stress state of a composite beam with an elastic-plastic matrix and elastic fibers located along the axis of the beam is solved. It is assumed that in the zone of contact of the matrix with the fibers, according to the model of Yu. N. Rabotnov, a constant tangential stress is realized, less than the yield strength of the fiber. One end of the beam is fixed, and a constant force applied to the center of gravity coinciding with the origin of coordinates acts on the second. It is assumed that at the free boundary of the beam and at the points of contact of the beam with the fibers, the stresses reach the plasticity limit. The problem is solved with the help of conservation laws. This makes it possible to find the stress state at an arbitrary point of the section as a calculation of integrals along the outer boundary of the beam and the boundaries of the matrix and fibers.
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CFD methods for cavitation modeling in centrifugal and axial pumps of LRE
Статья научная
Currently, design and manufacture of liquid-propellant rocket engines (LRE) are imposed with ever greater reliability requirements. Accordingly, the standards for the design and manufacture of rocket engine units are raising. One of these units is a turbopump unit (TNA), which provides continuous supply of liquid components from combustion reaction to the combustion chamber of a rocket engine to create traction or other engine units. TNA is also the main source of pressure increase for these liquid components in front of the LRE combustion chamber. Important requirements are imposed on a turbopump unit (TNA): ensuring work performance and basic parameters for a given resource with the necessary possible pauses of a specified duration; providing all engine operating modes, supplying the fuel components of the required flow rate and pressure, guarantying a high degree of reliability with acceptable entire unit efficiency; providing high anti-cavitation characteristics of the pump in all modes. In the article, the authors summarize the latest results of the study on cavitation in turbopump units of liquid propellant rocket engines alongside with the relevant research in the field of hydraulics. The problems of cavitation in cryogenic liquids, simulation of stall characteristics, and usability of various models to simulate cavitation flow are observed. A solution to the problems of flow modeling was considered with respect to applicability to the following structural elements of LRE units: interscapular space of the screw centrifugal main and booster pumps, axial pre-pump. Particular attention is paid to the implementation of various numerical methods based on the use of various cavitation models, computational fluid dynamics in various CFD packages, and also comparison of results with the model. In summary, the authors draw conclusions about the possibility of applying these methods to solve the problems of the cavitation phenomenon research in LRE.
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Статья
The article presents a computational and experimental study of the dynamic characteristics of a spacecraft telescope frame mock-up. The main attention is paid to the methodology of vibrodynamic tests using a three-component laser vibrometer and the creation of a finite element model of the mock-up under study. To analyze the dynamics of the structure, the main criteria such as modal parameters, model validation and harmonic analysis are defined. Particular attention is paid to the effect of experimental data transformation on the accuracy of calculating the modal assurance criterion. The research investigates telescope frame mock-up, which is a truss structure fixed on springs. The tests were carried out by applying a random impact of the “white noise” type. The dynamic characteristics of the structure were obtained, including the natural frequency of oscillations, which was 93.7 Hz. The experimental data were compared with the results of finite element modeling, which showed a significant discrepancy between them, especially in the area of natural frequencies. This indicates the need to adjust the finite element model. Various criteria for assessing the compliance of calculated and experimental models are considered, such as the coordinate modal assurance criterion (COMAC), the modal assurance criterion (MAC), the cross signature assurance criterion (CSAC) and the cross signature scale factor (CSF). These criteria help to assess the degree of coincidence of vibration modes and frequency characteristics. An analysis of the effect of transforming experimental data into different units of measurement on the results of calculating these criteria is carried out. It is concluded that the current calculation model requires revision and clarification of parameters to achieve better compliance with reality.
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Статья научная
The thermal control system (TCS) is one of the most important systems, which largely determines the design of the spacecraft. At the present stage of development of methods and tools for spacecraft design, a promising direction is the creation of thermal mathematical models of the TCS, calculation algorithms, which allow to create effective design solutions at various design stages. The purpose of this work is to bring the system of equations of heat balances of the liquid circuit (LC) of TCS to a form that allows programmatic numerical integration in the solution search algorithm along the length of the middle line of the heat and mass exchange fluid circuit taking into account certain complex thermal resistances. In fact, this means that the terms of the temperature of the contour and the linear coordinate, the integration variable, should remain as variables in the equation record, everything else should be numerically determined from the properties of the real object. For the boundary conditions of the LC TCS of the spacecraft, the coefficients of complex heat transfer were calculated taking into account the actual topology of the circuit and the thermal properties of the coolant. Using these values, the system of thermal balances of the spacecraft of the spacecraft on the characteristic surfaces of constant temperatures was reduced to a form that allows a numerical solution: the number of equations corresponds to the number of detected temperatures along the north and south panels and is closed through the temperature of the liquid circuit refrigerant. The resulting system of equations allows us to investigate the thermal state of nonhermetic formation spacecraft at the stage of preliminary design with varying operational and design parameters in order to determine the area of efficiency and the area of optimal operation under certain performance criteria.
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Calculation of heat transfer characteristics of a finned wall
Статья научная
The reliability and resource of the radio-electronic equipment of the spacecraft is increased by ensuring op-timal temperature conditions. Thermal control systems maintain the set temperature mode and heat removal from the onboard equipment to the surrounding space. Finned heat exchangers are an important element of the de-sign of thermal control systems, which allows intensifying the heat transfer process. The calculation of the char-acteristics of finned heat exchangers must be carried out taking into account their parameters and the physical properties of the heat transfer agent. The organic liquid LZ-TK-2, which has a very low freezing point and other useful performance characteristics, is considered as a heat transfer agent. The dependences of the local heat transfer coefficient of the LZ-TK-2 heat transfer agent on the wall temperature are calculated using criteria equations. Based on the numerical solution of the two-dimensional problem of thermal conductivity, the tempera-ture fields in finned walls of various configurations are determined. Calculations of the heat transfer coefficient of the finned wall of the heat exchanger were made in two model approximations, the error of using a simplified approximation that does not take into account the temperature dependence of the local heat transfer coefficient was determined.
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