Авиационная и ракетно-космическая техника. Рубрика в журнале - Сибирский аэрокосмический журнал
Development of three-point aviation fuel quantity gauge
Статья научная
In response to the well-developed digital technologies, modern methods can be worked out for the spheres where radical changes seemed hardly possible. This paper describes the development of a new method of fuel quantity meas- urement that has not been applied before. To measure the level of fuel in the fuel tank of an aircraft, it is proposed to use three fuel level gauges and a special electronic calculation unit; they model the fuel level surface inside the given volume, and then the actual amount of fuel can also be calculated. This can considerably reduce the evaluation errors allowed with the application of the existing fuel quantity gauges. The main advantage of the system offered is the elimi- nation of the errors arising with the aircraft evolutions and irregular motions. The article gives the analysis of the fuel level assessment methods used in the aviation sphere at present, the types of fuel quantity gauges used in aviation, and the specific conditions of measuring the fuel level in the aircraft fuel tanks. The proposed method has a number of advantages, in comparison with the traditional ways of measuring the fuel level; a basic mathematical model of the aircraft tank fuel level calculation has also been worked out.
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Статья научная
Transport operations that ensure the change of the orbit of a spacecraft or its transfer to the departure trajectory are an integral part of almost all space missions. Increasing requirements for the efficiency of transporting spacecraft form the need to search for possible ways to increase this efficiency and assess the characteristics associated with the proposed methods. Current boosters and interorbital tugs, as a rule, use a chemically powered cruise engine, although solutions with the use of an electric jet engine are becoming more common. Due to the high rate of the outflow of working fluid which is much higher than that of combustion products in a chemical engine, the efficiency of use of the substance mass by an electric jet engine significantly exceeds this indicator for a chemical engine. However, the low thrust provided by the electric jet engine leads to high duration of the transport operation and, as a result, to considerable time of exposure to the outer space factors, in particular, radiation. Therefore, the use of the electric jet engine only does not always meet the requirements for the mission. One of the promising ways to increase the efficiency of transport operations is the combination of the traditional chemical and electric jet engines in the propulsion system. Various aspects of the use of such an integrated propulsion system (IPS) consisting of a solar electric jet system and “Fregat” booster were considered, for example, in the frame- work of “Dvina TM” research project. Unlike a chemical engine, in which energy is released from chemical bonds, the energy for accelerating the working fluid by an electric jet engine is supplied from outside. Solar batteries are the most widespread energy source in near- earth orbits, where the amount of solar radiation is sufficient to meet the energy needs of a spacecraft. Solar batteries are sensitive to radiation, damage accumulates in their internal structure and their characteristics degrade. Therefore, there is a need to account for the radiation dose accumulated during the execution of the transport operation and to evaluate the reduction in the efficiency of solar batteries. Uneven irradiation intensity in the radiation belts formed by the Earth’s magnetic field (Van Allen belts) can be taken into account if the assessment of the radiation intensity at the trajectory points of the maneuver is made using the Earth radiation belt model. The paper proposes a method that allows taking into account the effect of ionizing radiation on the degradation of solar batteries when performing a transport operation using an integrated propulsion system based on a liquid- propellant rocket engine and an electric jet engine, taking into account the chosen trajectory and the model of the Earth’s radiation belt.
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GIS and satellite remote sensing for archeology: exploring polar history
Статья научная
The development of archeology in the second half of the twentieth century has received new impetus thanks to the emergence of a new tool - remote sensing, which began its development with the help of satellite technology. Images from space have allowed detecting archaeological sites, the location of which has not been possible to establish other ways. Initially, the new technology was advancing in the framework of state programs in different countries (USA, France, India, Russia and others.). Subsequently, a number of private geo-information services, such as Google Earth, Wikimapia, which significantly simplified access to the technology by all comers. Both small research teams and enthusiasts had the opportunity to use the services of satellite technology in their investigations. The downside of this technology can be used by looters and pseudoarcheologists. Modern geographic information systems have global reach, but different regions are of a different capacity. The northern territories of the Krasnoiarskii krai are reflected in open-access satellite imagery the resolution of which is not always sufficient enough to contribute to research. This results in the need for high-precision satellite imagery. Likewise, it is still necessary to perform field investigation to establish the concrete position of a historical site. This article discusses the use of open-access satellite imagery in studying a number of historical sites and objects (shipwrecks) related to the history of polar exploration on the lower Yenisei and the delta of this river.
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Geo satellite attitude and orbit control: fixed orbit control thrasters
Статья научная
The paper describes the enhanced application ofhigh-economical electro-jet orbit control thrusters for geostationary satellites; in particular, generation of controlling moments to the benefit of satellite attitude determination and control subsystems in the course of orbit control maneuvers ongoing. The scheme with thrusters fixed on a satellite body is analyzed. Possible orbit control session procedures are proposed on the basis of controlling moments generation. Advantages and disadvantages of the proposed approach are analyzed.
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Hardware implementation of the unit of the GNSS consumer
Статья научная
Navigational equipment is currently used to solve a variety of tasks, such as providing civil and special aviation, navigating, surveying and mapping, Internet devices and unmanned vehicles perfomance. The level of technological development of digital signal processing devices at first glance removes the need for deep study of computational algorithms, but this is only at first glance. As a result of expanding the scope of navigation tools, there is a need to increase the working channels, increase the dynamic range of the processed signals, and also improve the reconfiguration capabilities of signal processing devices. Any synthesized computational algorithm that can be described in hardware description languages, such as VHDL and Verilog, consists of summation operations and a shift operation of the register. There are several basic architectures of adders, each of which has the advantage of either speed of operation or simplicity of implementation. The development of computational architectures working at frequencies of 100 - 200 MHz requires pipeline calculations. Despite the fact that the pipeline architecture has large overheads for equalizing the delays of the computational blocks, its use is justified when processing and converting signals while solving the navigation task. The architecture of hardware computational blocks for constructing navigation equipment for the GLONASS / GPS consumer is considered in the article. The possible ways of increasing the efficiency of some architectures when implementing them on the basis of programmable gate arrays (FPGA) are given.
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Impact of the reinforcement technique on characteristics of composite tubular structures
Статья научная
Different composite elements including tubular structures are used as support structures in spacecraft optical systems. The compliance with the specified dimensional stability over a wide temperature range, in particular from -269 up to 100 °C, is important for the design of tubular structures. The promising method of manufacturing tubular structures of CM - radial braiding combined with RTM molding method is discussed in this paper. In addition, the paper describes the method of determining the optimal reinforcement technique for a braided perform which allows to reduce geometrical deflections occurring during a molding process. The impact of the reinforcement technique on the dimensional stability of tubular structures is illustrated in this paper by the example of several reinforcement techniques and manufacturing methods. The paper also contains the analysis of these techniques and the determination of the optimal one to comply with the specified characteristics.
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Implementation of Russian sattelite communication system "Gonets" in aircraft monitoring
Статья научная
One of the main problems of air transportation is the problem of continuous aircraft monitoring, which allows to control every specified flight plan, record deviations from the route, and, in case of a crash or an accident, immediately perform the aircraft search, location and rescue. This problem can be effectively solved by means of satellite navigation systems, satellite communication systems and automatic vehicle monitoring systems. The onboard aircraft satellite telemetric terminal “ Gonets D1-M ” is a good option for solving the problem, as it was specially designed for installation in vehicles to record their location, speed and direction. Additionally, it can register a number of other parameters, such as analog / digital input data and sensor readings; that allows to transfer to the control center not only the data on aircraft attitude and speed, but also on the status of its operation. At present, the policy of import substitution is widely implemented on the territory of the Russian Federation, and it has an influence on all spheres of economic activity. This paper gives a presentation of the home-produced satellite navigation system “ Gonets ”, which has a number of advantages in comparison with foreign analogues. The proposed system is being used in the field of sea transportation and has already established itself as practical; so there is a prospect of introducing such a system to the aviation sphere.
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Increase of data transmisson efficiency in aircraft satellite monitoring
Статья научная
Satellite systems are one of the most common methods of tracking various objects around the world. There are vari- ous types of satellite systems for different purposes, but their common feature is data transmission by radio signal. The atmosphere of our planet is nonuniform and its every layer has some characteristics which impede data transmission. In case of insufficient power supply the transmission is practically impossible. That is why there should be worked out special methods and algorithms able to mitigate the atmospheric effect on the signals of the aircraft monitoring devices. The ionosphere, in particular, is the main cause of errors in determining the object’s location. For “Iridium” satellites that receive signals from “Iridium 9602” module at frequency of 1616-1625.5 MHz the ionosphere influence induces the alteration of the signal power due to the inhomogeneity of charged particles. The article presents the calculation of attitude data transmission loss in space as they are transmitted by “Iridium 9602” transceiver up to heights of 450, 500 and 600 km. The proposed method is based on modeling the current map of the total electronic content of the ionosphere. On the basis of this model, a correction of determining the monitored object’s location can be made. Today there are several centers performing calculation of total electronic content of the ionosphere. The calculation results are in free access. Thus, having the initial data obtained from the maps of the total electronic content of the ionosphere and the algorithm for making corrections, it is possible to correct the data while solving navigation problems. In particular, the GEMTEC model can be used, as its source of data is a map of total electronic content of the atmosphere.
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Статья научная
In the process of launching a liquid rocket engine (LRE) and on the modes of its deep throttling of thrust, the prob- lem of balance of axial forces in the turbo-pump assembly (TPA) is the most important. The reason is the pumps and turbine work of the engine in non-nominal modes, and, consequently, the appearance of unbalanced excess of axial forces acting on the bearings of TPA. To reduce the axial loads in the TPA, an automatic discharge device (ADD) is used, the task of which is to reduce the axial impact on the bearings due to the action of hydrodynamic forces. In the process of working in the ADD, friction of the surfaces, which forms a hydraulic gap, is not allowed, otherwise it can lead to the local combustion. The object of influence is LRE RD-120 developed by “NPO Energomash named after academician V. P. Glushko” [1], working on liquid oxygen-kerosene components, with afterburning of the oxidizing gas-generating gas scheme. The pneumatic-hydraulic scheme of the engine, the TPA design, the working principle of automatic discharge device are presented. Using the example of the LRE RD-120, the effect of axial forces acting on the angular contact ball bear- ing located on the side of the turbine TPA is considered. When the engine was developed, it was established that under some launch conditions it is possible to contact sur- faces in the discharge device. In the article authors identify the conditions of contact in ADD and try to study the effect of the launch parameters of the LRE on the gap size of the working surfaces in the discharge device. For the theoretical analysis of the problem, a dynamic mathematical model of a liquid rocket engine is used. Mathematical modeling of engine start-up with nominal and early entry into operation of the combustion chamber was studied. The results show that with early starts of combustion chamber, there is a significant temperature rise in the gas generator, which can lead to the ignition of the nozzle or blades of the TPA turbine. Modeling the launch of the LRE with a change in the closing pressure of the oxidant supply valve to the pre-pump turbine booster, shows that this provides a longer operation of the oxidizer pump with a reduced hydraulic head, and allows changing the balance of axial forces during the engine launch and, as a result, prevent the full closure of the working gap in the ADD.
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Influence of plasma jets of electric jet engines on spacecraft functional characteristics
Статья научная
The issues of compatibility of correcting electric jet engines (EJE) and large-size transformable antennas (LTA) used in high-orbit communication satellites are considered. The paper deals with the erosive and polluting effect of EJE jets interacting with knitted mesh material (grid mesh), which is used for manufacturing LTA reflectors. The erosive effect of the EJE jets on the LTA mesh is characterized by the fact that the angles of ions incidence on the surface of the threads in the mesh are in the range from 0 to 90°, i. e. such effect takes place at practically any angle of ions incidence on the mesh surface. The research includes both mathematical description of physical processes and conducting a wide series of experiments, which makes it possible to achieve the necessary reliability of the results. It has been established that the effect of plasma jets of correcting engines can lead to significant sputtering of the reflecting coating from the surface of a large-size antenna reflector. The authors obtained experimental data on the degradation of the reflection coefficient of electromagnetic radiation from the mesh, depending on the degree of plasma jet influence. It was found that the sputtering of reflecting coating from the surface of threads does not significantly affect the reflection coefficient. The sputtering of the coating at the points of threads contact is much more significant. Strong dependence of the reflection coefficient on the type of mesh weaving was also found. The mechanism of sputtering products deposition on reflecting coatings of the thermal control system radiators was investigated. The results of calculations of the sputtering coefficient and the sputtering indicatrix of the reflecting coating applied to the mesh threads were obtained. The degradation of the functional characteristics of thermoregulatory coatings (TRC) during the deposition of thin films of gold, which is one of the possible materials for a reflecting coating, was experimentally determined. Estimates of the maximum permissible level of TRC contamination were obtained. It is shown that, subject to the relevant design rules, it is possible to use EJE and LTA together in high-orbit communication satellites.
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Inter-satellite optical communication link
Статья научная
A two-level system of data transmission in the optical range is considered between a low-orbit spacecraft located in a sun-synchronous orbit and a repeater satellite located in a geostationary orbit. This topic is rather relevant due to the fact that the rapid development of remote sensing satellites resulted in the increase of the amount of transmitted infor- mation, which in consequence introduced new requirements for communication systems. The increase of data transmission rate and severization of requirements for communication systems contributed to the development of one of the most promising areas of space communications, based on the information transmission via a laser channel, due to a high energy concentration and a much higher carrier frequency. The prospects for the application of optical communication systems are designated by lower power consumption, dimensional specifications and the mass of the transceiver equipment of the optical range (compared to radiofrequency range systems). The article describes the solution of application of optical communication link between a low-orbit spacecraft and a repeater satellite. The main factors that contribute to the attenuation in the process of signal propagation along the route are presented and analyzed. A model of a communication channel between a low-orbit spacecraft and a repeater satellite is provided for a visual image. Two different approaches of mutual guidance and tracking of laser terminals are described for using beacons and without ones. EDRS foreign system is considered as an analogue. The estimation of the main parameters of the communication link is given. The communication system considered in the article will allow for greater carrier capacity of the data transmission in the optical range between the low-orbit spacecraft and repeater satellite. The application of this system will allow solving problems, including in the interests of any departments and structures of the Ministry of Defense of the Russian Federation, for which the rate of obtaining information is one of the basic requirements for a satellite communication system. The tasks of precise targeting of receiving and transmitting devices arising as a result of narrow beam patterns can be solved with current technical means.
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Investigation of charge-discharge processes in the spacecraft detachable connector
Статья научная
Modern spacecraft consists of structural materials with different electro-physical characteristics, and it causes the occurrence of charge-discharge processes on the spacecraft during interaction with the magnetospheric plasma. The study of this phenomena arising during the natural spacecraft charging and its influence on the onboard systems func- tioning is of great interest in the field of ensuring the stability of spacecraft under the space factors influence. The paper presents the experimental results of charge-discharge processes occurring in detachable connectors dur- ing in-space exploitation after undocking the separating device and placing the spacecraft onto the orbital slot. For the determination of impact factors characteristics of electrostatic discharge and its potential effect on spacecraft board equipment the charge-discharge processes research methods with account of spacecraft equipment interfaces were de- signed. For modeling of electrostatic discharge in detachable connectors and its effects in technological circuits of spacecraft equipment the imitation loads were applied. These loads include input interface elements of spacecraft power convectors and onboard control complex. The results show that the dielectric material of connector contact field can accumulate a charge to the value limited by the discharge on it. Discharge processes on the dielectric material induce interfering pulses in onboard cable har- ness and can have a significant impact on the work of onboard equipment. The obtained results are useful in spacecraft equipment designing in the sphere of interference immunity.
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Статья научная
High-precision and reliable inspection of thermal deformations is necessary in terms of simulating the effects of space in the ground-based experimental processing of antennas and mirror systems of spacecrafts. Inspection of objects up to 1.5 m in size is considered in the paper. In practice, it can reach sizes up to 10 m. Requirements for thermal deformation are in range of 10-200 micrometers. The deformable surface is rough (Ra » λoptic). The measurement error, however, should not exceed ± 1 micron. The electronic speckle pattern interferometry (ESPI) method is the most suitable for solving this problem. The method allows to inspection objects with a randomly inhomogeneous surface. The method assumes that it is necessary to calculate the wave phase values from the recorded picture by the digital matrix. It is the phase that contains information about the deformation, and the spatial phase shift method is used to calculate it. One of the measuring systems based on this method is the measuring system PulsESPI (Carl Zeiss Optotechnik GmbH production, Germany). It has a high sensitivity which is about 50 nm. However, this measuring system is designed for single measurements. In this regard, an additional software module for processing and visualization the result of a series of several hundred measurements has been developed. The experimental test bench with a test object has been developed to research the metrological characteristics of the PulsESPI system in accordance with thermal deformations measurements (multiple determinations). The PulsESPI system and the Renishaw XL-80 interferometer introduced into register of measuring instrumentation of Russian Federation were located on different sides of the object 1.5 m in size. As a result of measuring the surface displacement measured by the Renishaw XL-80 interferometer and its corresponding point from the PulsESPI system deformation map are compared. Three types of tests were carried out at the developed bench. The root-mean-square deviation of single measurements was no more than ± 0.2 μm. Error was no more than ± 1 μm when the series of measurements was conducted in which a total strain of 200 μm was obtained. The results obtained suggest the possibility of using this system for high-precision inspection of thermal deformations of large objects.
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Issues of reliability in smart antennas
Статья научная
Adaptive digital antenna arrays, also known as smart antennas, are a perspective direction in the development of ground-based command and measurement antenna stations. Smart antennas can significantly improve the efficiency of controlling data exchange between the satellite and ground-based earth station. This benefits the productivity of the technological operations and reduces the time intervals forperforming the technological control cycle. Depending on the requirements, smart antennas containfrom a hundred to several thousand active modules. In this case, the probabil- ity of failure of the active module increases. This article discusses the issues of ensuring reliability ofsmart antennas : their ability to maintainin timethe values of their technical parameters within the established limits, which are deter- mined by failures of the equipment included in the antenna, mainly by module failures.
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Mathematical model for geostationary spacecraft disturbing torques determination
Статья научная
Modern requirements to increase spacecraft active existence lead to the efficiency of all its resources use improve- ment. And one of the main spacecraft resources, which determines the period of active existence, is the orientation en- gines fuel. The fuel consumption of the orientation engines depends on the external disturbance torques affecting the spacecraft. The work is devoted to the development of a mathematical model that allows to determine external distur- bance torques continuously affecting the spacecraft. The mathematical model is based on the assumption that the ki- netic moment of the spacecraft remains unchanged in the inertial coordinate system. The use of an active flywheel ori- entation system makes it possible to measure a spacecraft kinetic and disturbance moments. A special feature of this measurement is the rigid connection of flywheels with the spacecraft body that rotates at an orbital speed. This feature makes it necessary to take into account the kinematic relationship of the flywheel kinetic moment with the kinetic and disturbance moments in the inertial space. Thus, according to the kinetic moment variation law, it was possible to ob- tain a mathematical model for the interrelation between the flywheel kinetic moment and external disturbance torques. To test the model, two of the most common methods of mean-square filter readings were examined: the Gaussian filter and the Kalman filter. Modeling systems of equations and coefficients of error matrices were determined for modeling. The model was tested in the GNU Octave mathematical computing environment using telemetry information received in 2017, from medium-sized spacecraft (based on the Express-1000H platform) and heavy (Express-2000) class. To com- pare the results, the graphs for calculating the kinetic moment from the model and the measured kinetic moment from the flywheels are given. The mean-square deviation of the compared values did not exceed 0.1 Nm for the Gaussian filter and 0.03 Nms for the Kalman filter. The graphs of disturbing torques estimation by a mathematical model are given. The mean-square deviation of the estimate of the disturbing torquess for the Gaussian filter did not exceed 0.9 % and for the Kalman filter it was 2 %. The convergence of the disturbing torques estimates shows the adequacy of the developed mathematical model.
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Measurement of temperature distribution using a three-wire system of sensors based on thermistors
Статья научная
Improving the reliability and increasing the avionics resource is associated with possibility of continuous control of temperature fields of printed circuit boards. This problem can be solved only with the use of a large number of temperature sensors. It raises the problem of connecting the measuring elements and recording equipment. Several methods with their own advantages and disadvantages are proposed. One of the implemented and patented methods is using a set of resistive diode sensors installed in series on a threewire line. The temperature sensors are pairs of counter - connected diodes with a sequential survey when applying sawtooth voltage. The system is simple and easy to implement, but its main drawback is the method of determining the temperature by measuring the amplitude of the total reverse currents of diode pairs. It determines the large measurement errors, especially in the temperature range less than 20°C. The article deals with a similar design of a three-wire circuit, but with a fundamentally different approach to temperature measurement. The temperature sensor here is not diode pairs, but thermistors with a well-known dependence of resistance on temperature and high accuracy, and diode pairs record only the moment of coincidence of the sawtooth voltage with the voltage on the thermistors. This approach allows using mathematical methods of signal processing to accurately determine the voltage drop on the thermistor, and this ensures the accuracy of the resistance/temperature and the expansion of the temperature range. Given the fact that thermistors are increasingly used to measure temperature, simplifying their inclusion in a large number will allow to register the temperature field of electronic units, which is extremely important for spacecraft. The proposed version of a three-wire circuit for connecting temperature sensors at several points was tested experimentally, including at negative temperatures.
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Статья научная
One of the main tasks arising in power supply systems (PSS) of spacecraft (SC) design is the determination of ra- tional structure in terms of providing consumers with electricity of the required quality. At the same time, a reasonable consumption of power generated by solar batteries (SB) and accumulator batteries (AB) should be realized in PSS. The choice of the PSS structure is based on the calculation and comparative analysis of PSS options, taking into account the adopted system performance criteria, the main ones being the energy and weight-dimension characteristics. For this purpose, the process of energy flows distribution in the PSS by forming a mathematical description of the PSS operating modes is carried out. In order to obtain the graphs of the SB generated power and to calculate SB parameters during the service life, a mathematical model of the SB based on the use of initial and experimental parameters of its photo- voltaic elements of any area was developed. The SB model provides the required accuracy of I-V and V-W characteris- tics calculation for any given values of illumination and temperature. In the article the method for calculating the energy characteristics of PSS and SB parameters taking into account the possibility of its limitation at the maximum or minimum level was described. It is shown that the method allows to determine the ways of rational redistribution of energy flows in the systems being designed to improve its weight- dimension characteristics by reducing the maximum design power of energy-converting equipment (ECE), which is achieved by forming a rational logic for applying the SB maximum power point tracking mode, in particular, when the spacecraft leaves the Earth's shadow. Energy balance in PSS is provided by applying correction coefficients. The calcu- lation results obtained by the method are the basis for requirements for ECE and SB design in PSS and can be used by developers and manufacturers of onboard and ground PSS.
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Статья научная
This paper deals with the research methods of wing-in-ground effect vehicle (WIG vehicle) longitudinal static stability. The methods are focused on the use of the algorithm of preliminary WIG aerodynamics and control system design. The algorithm is based on the iteration process of stability criteria calculations, the subsequent factor analysis of these criteria with respect to their value-determining parameters and variations of WIG vehicle configuration parameters. The methods include preliminary determination of WIG vehicle aerodynamic characteristics. The best results can be obtained when different methods of determining these aerodynamic characteristics (experimental and by means of computational aerodynamics) are combined. In this paper the calculation of aerodynamic characteristics is performed by applying ANSYS software packet. To assess the reliability of the aerodynamic characteristics obtained with the ANSYS program, experimental studies in a wind tunnel and a vertical hydrodynamic pipe were carried out. Certain aerodynamic characteristics are determined by means of originally made computer programs using the method of discrete vortices. A special database is formed of the obtained aerodynamic characteristics. The database essentially is a mathematical model of a WIG vehicle which supplies the characteristics (aerodynamic coefficients and their derivatives) with an estimated degree of reliability within a given range of determining parameters. On the basis of the widely used criterial approach to static stability assessment of various WIG vehicle modifications, a mathematical algorithm for parameter calculation and a computer program were developed. They permit the calculation-based analysis of the factors determining stability or non-stability of a WIG vehicle. The mathematical model of WIG vehicle stability analysis is implemented in the form of a software packet based on MatLab. The results worked out by the program are in the form of data suitable for operational analysis. Using these data, one can assess the WIG vehicle static stability and determine the stability range for the given structural and configurational factors. The results of the analysis make a foundation for subsequent modifications of WIG vehicle's aerodynamic configuration or for working out requirements for automatic control and stabilizing systems' upgrade. The methods demonstrating the analysis of original load-carrying systems design are also presented. For the example analysis, an original WIG- tandem load- carrying system was chosen. The methods are applicable for the analysis of various aircraft modes' stability, for all vehicles built on aerodynamic principles of flight maintenance.
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Modeling components of bioregenerative life support system intended for space purposes
Статья научная
We have developed a linear model for compiling and optimizing food components in a bioregenerative life-support system (BLSS) intended for space purposes in the Excel environment using OpenSolver public add-in with COIN-OR- CBC solver. The independent variables in the model are the masses of ingredients used in dishes. The objective functions of modeling are to minimize the total mass of the daily diet and maximize its antioxidant potential. The daily intakes of nutrients in the menu are limited to NASA standards. The upper and lower limits are also imposed on independent variables and the masses of dishes. We have found the content of nutrients in ingredients in open databases. The menu includes the first course, the second course, snacks, desserts, drinks, bread and water. We have presented an example of a concrete calculation of the daily menu consisting of 12 dishes: fresh-soup, chicken with rice, the roast, sausages, tofu, chickpeas, candied nuts, bread, goat milk, soy milk, cocktail and water. These dishes are prepared using 24 ingre- dients: table salt, water, wheat grains, rice, quinoa, millet, sweet potato, white potato, carrots, safflower oil, soybeans, chickpeas, lentils, cowpeas, strawberries, tomatoes, onions, garlic, chili pepper, quail, pork, tilapia, goat’s milk and sugar. The ingredients being used represent edible biomass of plants and animals that are candidates for inclusion in BLSS. Caloric content of a daily diet is assumed to be equal to 2800 kcal. It is shown that food imbalances in the esti- mated daily menu are caused by a shortage of estimated daily intake of pantothenic acid, and also by an excess of iron, phosphorus and saturated fats. Excess intake of iron and phosphorus may not be critical for the health of the users of BLSS. The minimum weight of the daily menu is 2641 g, and its antioxidant potential can reach 14 mmol Ttrolox- equivalent.
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Статья научная
One of the promising areas for improving the methods of manufacturing structural elements of rocket and space technology is the use of selective laser melting technology which represents a unique opportunity to manufacture metal products by melting powder and producing a one-piece solid phase structure. However, pores and other structural defects can appear in the formed element during laser sintering which causes a decrease in the strength characteristics of the parts produced. An important step in the additive technologies introduction is the development of methodology for the preliminary prediction of the strength characteristics of manufactured structural elements under the influence of mechanical loads with the help of mathematical modeling. The methodology for estimating the material strength reduction of a rocket-space technology element obtained using additive technologies by simulating a porous structure and calculating the characteristics of the stress-strain state is presented. The proposed mathematical model and the methodology for calculating the specimen loading on the basis of the distortion energy theory allow calculating the stress-strain state in the process of numerical simulation for different values of the pore diameter. The reduction in yield strength due to the material porosity of the part is estimated using a coeffi- cient equal to the ratio of equivalent stresses arising when a load is applied to a specimen manufactured using traditional and additive technologies. The value of the introduced coefficient characterizes the structure of the grown product and is considered as a function of the random arrangement of pores in the specimen under study. The appearance of pores is the result of a combination of factors: the composition and dispersion of the original metal powder, feed rate, removal distance and laser power during sintering, part orientation and sintering direction, the height of the level of powder deposited on a special base before sintering, etc. The paper evaluates the reduction in strength for the working part of a series of tensile test specimens grown from metal powder of different dispersity. The non-linear nature of the dependence of the yield strength on the particle diameter of the original metal powder is established. The maximum value of the yield strength corresponds to the specimen with the minimum value of the total surface area of the pores.
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