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Aerospace technic and technology
Number of Followers: 2 Open Access journal ISSN (Print) 1727-7337 - ISSN (Online) 2663-2217 Published by National Aerospace University [1 journal] |
- THE PROVISION OF COMPLETE SUPERIORITY OF TACTICAL MTA An-188
Authors: Александр Васильевич Лось, Владимир Федорович Шмырев, Виктор Иванович Рябков
Pages: 5 - 11
Abstract: In the "Antonov" Company, a unique medium-sized tactical military transport aircraft An-12 and An-70 have been created. Based on the Аn-12 basic version, several modifications have been developed, which operate in many countries around the world.To replace this aircraft has been created the An-70 with a higher capacity and hourly capacity, which on some key parameters outperforms the competition-analogs: American C-130J-30, West-European A400M, and Japanese C-2.However, the range with the maximum capacity is worse for Аn-77 compared to the A400M, but cruising speed and combat readiness – for C-2.For the most complete implementation of tactical tasks:– transportation of personnel, equipment, goods, and means of procurement;– delivery of military units, equipment, and cargo in the interests of peacekeeping or counter-terrorism operations;– transportation of troops, arms, military equipment and material resources of strategic direction;– delivery of units and formations of the airborne forces and ground forces in the areas of military purpose;– provision of the relocation of aviation units and formations, and provision of superiority at range with maximum load, at cruising speed and combat readiness the team of the “Antonov” Company created the An-188 – the medium-sized tactical aircraft with short takeoff and landing, which provides execution of a series of tasks, not available even for C-2.At the initial stage of designing this modification scientific principles the "Design techniques of modifications of the MTA taking into account the profound changes in the wing and the power plant" were used. The most important modification change in An-188 is the replacement of the D-27 turboprop engine for СFM LЕАР-1A turbofan engine, which increased the capacity and combat readiness of modification.Another important modification change was the use of discrete geometric twist of the wing local chord, bringing its shape in plan view to elliptical one and has brought a reduction in induced drag for a given lift force. This solution provided an increase in the range of up to 3200 km.Such profound modification changes in the power plant and the geometry of the wing have contributed to the complete superiority of the An-188 in the class of operational-tactical MTA.In combination with An-132D and An-178 modification, the An-188 can be considered as a unified system of support for the troops with military transport planes.
PubDate: 2020-08-31
DOI: 10.32620/aktt.2020.8.01
- ALGORITHM OF INTEGRATION OF THE POWER PLANT OF MEDIUM-RANGE PASSENGER
PLANES
Authors: Сергей Алексеевич Дмитриев, Александр Юрьевич Суровцев
Pages: 12 - 18
Abstract: A study on the integration of the propulsion system of medium-range passenger aircraft has been performed. The architecture of the power plant system and the system approach to power plant design are considered. The block division of the solved problems is offered – connected with a choice of schemes and the basic design parameters of aircraft with its power plant and integration of management. The influence of the power plant and elements of the glider on the choice of parameters of the working process and the scheme of the engine at the technological and structural level is considered. The model of research of the principle of the dependence of characteristics of the movement of the passenger aircraft on a level of integration of characteristics of its power plant is considered. Based on this model, an algorithm for increasing the efficiency of integration of the propulsion system of medium-range passenger aircraft is proposed. The study focuses on the consideration of the aircraft as a complex and highly efficient system that contains subsystems and components. Accordingly, the subject area of the study has a multifaceted complex nature and is presented taking into account the technological evolution of air passenger traffic, which has already reached a fairly high degree of development of the existing system architecture. The approach to the integration of the characteristics of the propulsion system of passenger aircraft is reduced to a multifaceted systematic consideration of the ICAO requirements for passenger aircraft, as well as the requirements for their certification. Aspects of modern scientific researches that are carried out in the field of modeling of synthesis of integration of characteristics of a power plant and accordingly are developed taking into account technological and design decisions concerning the improvement of the general architecture of the system in a foreshortening system are considered. Based on the calculations of the developed algorithm, the results of integration modeling are presented within the aerodynamic design of a passenger aircraft, compressors, and turbines. The diagram of efficiency of integration of power plant of medium-range passenger planes is given. The study demonstrated that at the technological and structural level, a generalized-integrated consideration of the power plant and glider elements, respectively, affects the choice of operating process parameters and engine scheme.
PubDate: 2020-08-31
DOI: 10.32620/aktt.2020.8.02
- DYNAMIC ANALYSIS OF A COMPOSITE ROCKET DOME DURING SEPARATING TAKING INTO
ACCOUNT STRUCTURE DELAMINATING
Authors: Борис Филиппович Зайцев, Татьяна Владимировна Протасова, Дмитрий Васильевич Клименко, Дмитрий Васильевич Акимов, Владимир Николаевич Сиренко
Pages: 19 - 26
Abstract: The dynamic processes in the rocket fairing when the pyrotechnic separation system is triggered are considered. The fairing construction is mixed and includes composite and metal elements. The main composite construction element is a fiberglass shell with regular and irregular winding zones. The speed acceleration required to separate the fairing occurs under the action of impulse pressure from the powder gases in the pyrotechnic system. The displacement of the fairing is made up of displacements of the movement as a rigid whole along its axis and vibrations caused by deformations. The calculation of the fairing movement is carried out according to a three-dimensional FEM model using software that uses a topologically regular discretization system. The problem solution in time is performed according to the implicit Wilson finite-difference scheme. When studying the fairing dynamics, it is allowed to break the structure of the shell in the form of lamination, which in the FEM scheme is modeled by a special method. A cut with double nodes is created on the surface of the proposed lamination along topological planes by transforming the finite element mesh. Modification of the stiffness matrix and mass matrix for the transformed mesh is performed based on the created information base of degenerate finite elements and formalized matrix operations. In numerical studies, two types of lamination from irregular zones of fiberglass winding are considered – the internal location from the flange and edge location with access to the fairing free edge. The results of calculating vibrations along the sides of lamination and data on the redistribution of dynamic stresses due to lamination are presented. Radial and axial displacements when passing through the lamination surface discontinue, the magnitude of which for internal lamination is much less, which is explained by the compression of deformation for this case, in contrast to the lamination that goes to the boundary. When estimating the relative axial displacements, the component of the displacement of a rigid whole, determined by a separate calculation, was excluded. The maximum radial displacements during lamination from the edge reach 3 mm, which is one and a half times higher than for an undamaged shell. Axial stresses are maximal from the action of inertial forces during acceleration. Its redistribution over the layers is significantly greater for the edge lamination, for which the maximum values increase almost two times concerning the undamaged shell, which determines this type of lamination as more dangerous.
PubDate: 2020-08-31
DOI: 10.32620/aktt.2020.8.03
- HEAT TRANSFER CAPACITY OF METAL MESH WICK
Authors: Геннадий Александрович Горбенко, Рустем Юсуфович Турна, Роман Сергеевич Орлов, Евгений Эдуардович Роговой
Pages: 27 - 33
Abstract: In the manufacture of wicks for capillary transport of coolant in various heat transfer devices such as heat pipes, capillary pumped loop, accumulators with thermal regulation, evaporative heat exchangers, heat sinks, etc., capillary porous structures are used. Capillary and porous structures made of compressed powders (metal or non-metal) are widely used. However, the technology of making such porous structures is complicated and time-consuming. Important requirements for wicks are high capillary pressure, low-pressure drop, low weight, and manufacturability. Capillary porous structure, which meets these requirements, can be a wick made of several layers of metal mesh, superimposed on each other, and connected by contact welding. The main advantages of such wicks are low weight and ease of fabrication. The article deals with the methods and results of determining the limit heat transfer capacity of a free wick (not in contact with solid walls) of metal meshes. The design of an experimental unit is given, which allows testing not only at positive but also at small negative angles of the wick to the horizon. Experiments on ammonia to determine the limit heat transport capacity of a flat free wick made of two-layer metal mesh 0.2×0.13 mm woven weave is conducted. By results of the spent experiments dependence of limiting the heat-transport ability of a wick from the temperature of saturation of the heat carrier and an angle of slope to the horizon is received. The performed experiments allow for a wick of the given design to calculate its maximum heat-transport capacity in earth conditions at any width, a transport length of a wick, and an angle of slope to the horizon. Formulas for calculating the thermal transport capacity of wicks made of metal mesh of different length and width under microgravity conditions and in the field of gravity of the earth at different orientations are recommended. The results of the experiments allow determining the thermal transport capacity of wicks from metal meshes and in microgravity conditions.
PubDate: 2020-08-31
DOI: 10.32620/aktt.2020.8.04
- SELECTION AND JUSTIFICATION OF THE GRID GENERATION METHOD FOR FLOW
SIMULATION IN A GAS TURBINE ENGINE FAN
Authors: Михаил Владимирович Хижняк, Екатерина Викторовна Дорошенко, Вячеслав Юрьевич Усенко
Pages: 34 - 40
Abstract: The study of flow in aircraft gas turbine engines is one of the main components for the creation of new compressors and fans with improved aerodynamic, acoustic, strength, overall weight, and other characteristics. In modern scientific research, the methods of the physical experiment are used at the final stages of flow studies in blade machines. a numerical experiment is used in the early stages. An obvious advantage of the numerical experiment is the ability to study many variants of constructions under different input and boundary conditions in a short period. However, a numerical experiment requires a preliminary selection and justification of its parameters and components. One such important component is the type of calculation mesh. The literature review shows that it is impossible to make an unambiguous conclusion about the choice of the type of method for generating the finite element mesh and the turbulence model. This work aims to compare a hybrid and structured mesh for flow modeling in an axial fan of a bypass engine with a high bypass ratio. Two impellers of a bypass engine with a high bypass ratio are selected as the object of study. Flow simulation in fans was studied at a rotor speed of 2202 rpm in the range of values of the gas-dynamic flow function at the inlet q (λ) = 0.4 ... 0.65. Based on the literature review, the system of Navier-Stokes equations was closed by the SST turbulent model. To select and substantiate the method of finite-element grid generation, a structured and hybrid mesh for two fan variants were constructed. According to the results of the calculations, the dependence of the pressure ratio of fan π on the gas-dynamic flow function at the inlet q (λ) was constructed. According to the results of the study, it can be stated that the discrepancy of the calculations for the impellers in the axial fan of a bypass engine with a high bypass ratio with structured and hybrid meshes will be up to 2 %. When choosing the method of mesh generation, the time of calculation is also an important factor. Studies have shown that the calculation with a structured mesh took place in less time by 50 ... 70% than when using a hybrid mesh for one variant of the geometry.
PubDate: 2020-08-31
DOI: 10.32620/aktt.2020.8.05
- RESEARCH OF THE INFLUENCE OF PEN FLEXIBILITY ON OPTIMUM REQUIREMENTS
LINKINGS OF SHELVES PAIRWISE SHROUDED BLADES OF TURBINES
Authors: Анатолій Павлович Зіньковський, Вячеслав Михайлович Меркулов, Іван Гордійович Токар, Олег Леонідович Деркач, Руслан Юрійович Шакало
Pages: 41 - 49
Abstract: In the article outcomes of probes by definition of influencing the flexibility of pen on optimum requirements of linking of shelves pairwise shrouded blades of turbines are considered. A design feature of such blades is that a composite shank, each half of which has a pen with a bezigless shroud platform, is freely inserted into the groove of disk. The application examples pairwise shrouded blades in turbines of a gas turbine engine (GTD), and also outcomes of the analysis of initial conditions of linking on shroud platforms of such blades are set up. It is shown that under the conditions of operation of the engine, there can be both an interference fit and a clearance on the shroud platform. A description is given of the developed methods for the experimental determination of the initial conditions for pairing the retaining shelves of pairwise shrouded blades and the study of their damping ability and vibration stress. Outcomes of the analysis of requirements of linking of bandage shelves of blading of impellors, experimental researches by definition of their influencing on vibrational stresses and a damping current capacity pairwise shrouded blades and their beam models as systems with a rigorous regular which one is characterized by the elastic-dissipative connection caused both bandages, and tool joints, taking into account flexibility of pen are introduced. It is displayed, that there is the best value of the argument of linking of bandage shelves at which one the maximum damping current capacity of twin blades and according to their minimum of vibrational stresses is reached. Thus, its meaning depends on the flexibility of the pen of a blade. By results of the conducted experimental researches of packages of pairwise shrouded blades of three turbine stages GTD AI-25 and turbine GTD D-36 first stage the relation of the best value of argument Δн, wholesale of linking of bandage shelves from the flexibility of pen which one allows to forecast its value for blades of other stages GTD is constructed. As blades of first stages of turbines GTD AI-322 and D-36 are characterized by flexibility neighbors it is possible to forecast with a high probability, that best values of the argument of linking of their shroud platforms will be one level.
PubDate: 2020-08-31
DOI: 10.32620/aktt.2020.8.06
- FREE VIBRATIONS OF GAS TURBINE ENGINE AXIAL COMPRESSOR BLADES
Authors: Михаил Романович Ткач, Сергей Александрович Моргун, Юрий Григорьевич Золотой, Аркадий Юрьевич Проскурин, Юрий Николаевич Галынкин
Pages: 50 - 60
Abstract: The required level of reliability of modern gas turbine engines cannot be achieved without ensuring the vibrational strength of the compressor blades. One of the tasks of ensuring vibrational strength is to determine the frequency spectrum of free vibrations, as well as the arising forms of vibrations. Moreover, the most reliable results are achieved by combining experimental and theoretical research methods. Experimental studies of the free vibrations of the blades were carried out by the time-dependent holographic interferometry method. A description of the experimental stand is given, the features of using optical equipment and processing units are indicated. The implemented algorithm for conducting experimental studies is described, the features of the digitization of optical signals implemented in the developed software are indicated, the mathematical equations used in the implementation of this software are presented, and some emerging experimental forms are illustrated. To verify the experimental data based on the finite element method, an updated mathematical model of the free vibrations of compressor blades has been developed. The characteristics of the finite element from which the mathematical model is formed, the basic equations used in the simulation of free vibrations are given. As an object of study, we considered a compressor blade 54 mm high and 37 mm long chord with a peripheral section twist angle of 17°, the considered blade is made of a titanium alloy. For this blade, some waveforms were obtained, the location of the nodal lines was shown, and data obtained experimentally and analytically were compared. An analysis was made of the frequency spectrum of the natural oscillations of the compressor blades, which showed that the difference between the vibration frequencies obtained by experimental and numerical methods for the same modes does not exceed 5 %.
PubDate: 2020-08-31
DOI: 10.32620/aktt.2020.8.07
- THE EXPERIMENTAL-RATED METHOD OF STYDYING OF WIDE-CHORD FAN OF THE
AIRCRAFT ENGINE FOR THE ABSENCE OF FLUTTER
Authors: Вячеслав Владимирович Донченко, Игорь Федорович Кравченко
Pages: 61 - 66
Abstract: The main gas-dynamic parameters are considered for studying of the absence of flutter wide-chord fan of aircraft engine. The experimental-rated method is proposed to confirm the absence of flutter on the fan in the entire operating range of the aircraft engine. The method is based on experience in the design and development of aircraft engine fans. The method proposes the limitations of the study area of operation of a wide-chord of the aircraft engine fan. The method shows the boundaries of the possible operation of a wide-chord of the aircraft engine fan, taking into account the limitations of the studied range for the research and development of the testing. The aircraft flight parameters were processed with the control of the absence of flutter using pressure pulsation gauges. The results of processing the studied flight parameters are generalized and systematized. A technique for graphically depicting of the main controlled parameters of the method in a two-dimensional and three-dimensional setting is shown, indicating the boundaries of the possible range of operation, the wide-chord fan of the aircraft engine under study, taking into account the reserves of pressure and temperature. To verify the method, the test points of the fan are graphically showed in a thermal vacuum chamber of a similar sized fan of an aircraft engine, which, as the figures show, lie near the boundaries proposed in the method. It is proposed to use the studied points with a proven absence of flutter for verification of computational models using software systems and methods, for calculating the absence of flutter, taking into account the limits of possible operation defined in the method. The proposed boundaries of the studied ranges will significantly reduce the list of tests at the flying laboratory and the number of design points, which will allow us to make the best option for checking the absence of self-oscillations of the aircraft engine fan by the experimental-rated method in Ukraine without using a thermal pressure vacuum chamber and flying in hot and cold conditions.
PubDate: 2020-08-31
DOI: 10.32620/aktt.2020.8.08
- RESEARCH METHOD OF THE AIRCRAFT ENGINE HOUSING VIBRATION WHEN THE FAN
BLADE ABRUPTION
Authors: Сергей Владимирович Филипковский, Валентин Семёнович Чигрин, Николай Саввович Топал, Лариса Алексеевна Филипковская
Pages: 67 - 72
Abstract: Following the Certification Specifications, at the design stage, the structural strength of the aircraft is calculated when the blades abruption and the engine bearing is destroyed, which cause large vibrations. At the finalization stage, these calculations should be confirmed by tests. The most effective way of dynamic test operation now is a numerical simulation because it makes it possible to study the influence of a large number of different factors, to analyze structural vibrations in those modes that are impossible or dangerous to reproduce in full-scale tests, significantly saving time and material resources.Studies of transient vibrational processes for a simplified calculation model of linear deformation of bearing assembly were performed. The most dangerous case of damage to the fan blade abruption is considered.The engine is attached to the pylon at five points. Two attachment points to the front traverse and two attachment points to the rear traverse are hinges with axes parallel to the axis of the engine. The fifth point is a hinge with an axis perpendicular to the vertical plane. At this point, the engine is attached to the pull rod. In the first approximation, we assume that the body is solid, and its center of mass is located on the axis of rotation of the rotor. We consider traverses as elastic beams working in bending, and the rod for lifting the thrust as an elastic rod working in tension. We simulate the rotor with a solid body on bearings, since the deformations of the rotor parts are small in comparison with the deformations of the bearings and the lowest natural frequency of the oscillations of the rotor as an elastic body is an order of magnitude higher than the frequencies of the rotors on the bearings.The frequency response of the rotor, the dependence on the time of movement of the support sections, and the orbits of the centers of the support sections of the rotor relative to the stator are obtained. The frequency response of the engine with the rotor, the dependence on the time of the generalized stator coordinates is constructed. An analysis of the applicability of the developed model and calculation method for different cases of damage to the rotor and its bearings is carried out. The importance and prospects of continuing research with nonlinear calculation models are shown.
PubDate: 2020-08-31
DOI: 10.32620/aktt.2020.8.09
- PECULIARITIES OF EXPERIMENTAL DATA PROCESSING IN DETERMINING THE HEAT
TRANSFER COEFFICIENT IN THE BEARING CHAMBER OF GTE
Authors: Илья Иванович Петухов, Тарас Петрович Михайленко, Андрей Александрович Брунак, Сергей Валерьевич Епифанов, Артём Викторович Ковалёв, Олег Владимирович Шевчук, Василий Викторович Тихомиров
Pages: 73 - 81
Abstract: The development of gas turbine technology is accompanied by an increase in temperatures, pressures, and airflow velocity in the gas path. Increasing operating cycle parameters for gas turbine engine complicates the tasks of ensuring the permissible temperature state of engine parts, requires improving the methods of their calculation and design. This fact fully applies bearing assemblies, especially those operating in a hot environment, and causes interest in the study of thermohydraulic processes in the bearing chamber, which determines the temperature state of the rotor parts. The necessity of pressurizing the seals leads to the presence of the oil-air mixture in the bearing chamber. A wide range of operating parameters, flow inhomogeneity, phase disequilibrium, and phase separation significantly complicate the mathematical description of processes in the bearing chamber, including the use of CFD-modeling. Therefore, considerable attention is paid to experimental research. The experimental results are used not only to verify mathematical models but also to obtain generalizing dependencies. Most often, the desired value is the heat transfer coefficient in the oil cavity of the support. The article deals with the heat transfer features in the near-wall zone of the gas-turbine engine bearing chamber which were associated with the presence of oil-air flow. Also, approaches to the experimental determination of the heat transfer coefficient were analyzed and an appropriate system for measuring the local temperatures of the media was formed. The values of the error of the experimental heat transfer coefficient and the degree of influence of the determining factors were estimated. The contribution of the non-uniformity of the temperature field in the walls of the chamber and the uncertainty in the value of the temperature of the flow core was determined. The advantages of using the averaged heat transfer coefficient for engineering calculations and the significant influence of the averaging method on its value were also shown. Averaging over the heat flux density corresponds most accurately to the tasks of such calculations, at which the total heat flux through the chamber walls does not change.
PubDate: 2020-08-31
DOI: 10.32620/aktt.2020.8.10
- THE DEVELOPMENT OF THE BIRD-IMPACTOR MODEL FOR MATHEMATICAL MODELING OF
TURBOFAN ENGINE PARTS DAMAGE PROCESSES
Authors: Дмитрий Владимирович Ивченко, Вячеслав Михайлович Меркулов, Наталья Владимировна Сметанкина
Pages: 82 - 90
Abstract: This study aims to develop of the bird-impactor model for mathematical modeling of turbofan engine parts damage processes in case of a bird ingestion into the its air-gas channel. The bird-impactor model was justified for simulation of bird with mass of 0,70…3,65 kg for certification requirements on aircraft engines according to aviation regulations CS-E, FAR-33, AP-33. It was implemented in numerical SPH model for explicit LS-DYNA Solver of ANSYS LS-DYNA software package. The pre - and postprocessor LS-PrePost program also was used for numerical SPH model generating, preparing input data and processing the results from calculations. The bird-impactor model was had a hemispherical-ended cylinder geometry form. Material of the bird-impactor model was defined as a mixture of water (90-percent of volume) and air (10-percent of volume). The Null material model with low strength and the linear polynomial equation of state were used for the bird modeling. It was considered impacts bird to the rigid plate at striking velocities of 100...300 m/s and impact angle of 45°, 90° for the bird- impactor model verification. The rigid plate was modeled as a fixed thick steel plate. Volume of rigid plate was meshed with finite elements. The transducer was installed in center of the rigid plate. It was modeled by one finite element. The pressure of impact bird was obtained by dividing the contact force for finite element - transducer to its area. Thus the pressure curves were calculated for each impact bird to rigid plate. The Hugoniot pressure (shock pressure) was defined as maximum of pressure curve. The stagnation pressure was defined for phase of curve with approximately constant low pressure level by Simpson's rule. Verification of the developed bird-impactor model was performed by comparing the calculating results of Hugoniot and stagnation pressures used the developed bird-impactor, the one-dimensional hydrodynamic theory and calculation results of other authors. Verification of developed the bird-impactor model was shown good agreement with the one-dimensional hydrodynamic theory and with results of other authors.
PubDate: 2020-08-31
DOI: 10.32620/aktt.2020.8.11
- PARAMETRIC IDENTIFICATION AND OPTIMIZATION OF HIGH-TEMPERATURE
TENSORESISTORS
Authors: Юрий Алексеевич Гусев
Pages: 91 - 99
Abstract: The development of gas turbine engines (GTE) is inextricably linked with an increase in their main characteristics. In this case, the parameters of the working fluid (in particular, the temperature of the gas flow) and the intensity of loads on the structural elements increase. The strength reliability of highly heated GTE elements is a factor that determines the life of the engine as a whole. The most common cases of damage to GTE elements are caused by static and vibration stresses and mainly relate to the blades of gas turbines operating at temperatures up to 1200оС. Vibration stresses of individual GTE parts can be determined only experimentally during GTE testing and fine-tuning. Their values are determined at individual points of the surfaces of parts by the values of directly measured deformations. At present, the main means for determining the vibration deformations of GTE elements are resistance strain gauges. In the process of testing, the information generated by the strain gages makes it possible to determine not only the dynamic deformation but also the static and dynamic temperature of the blade at the place where the strain gauge is installed. A technique is proposed for the parametric identification of a high-temperature tensoresistor (HTTR), based on the representation of the analyzed HTTR and affecting its state, as some, in the general case, non-linear measuring system. The structural and mathematical models of HTTR are considered, in which both temperature and strain are simultaneously measured using a single sensor element. An original technique is proposed for studying the reliability of the results of HTTR parametric identification. It is proved that the ellipsoidal character of the level lines of residual function, as well as the absence of an extremum region together with the point nature of the minimum, indicate the practical identifiability of the tensometric system. The proposed technique allows a quantitative and qualitative analysis of the effect of shunting on the accuracy of HTTR readings. This technique can also be used to create new types of insulating materials intended for HTTR insulator substrates. This method presents a possibility of the measurement deformation and temperature of element thermal using single platinum-based tensometer sensor.
PubDate: 2020-08-31
DOI: 10.32620/aktt.2020.8.12
- INFLUENCE MASS OF THE RINGS, RESILIENTLY SET ON DISK, ON DYNAMIC
DESCRIPTIONS OF HYDROSTATODYNAMIC BEARING OF THE DOUBLED TYPE
Authors: Владимир Иосифович Назин
Pages: 100 - 105
Abstract: The task is to develop recommendations for the design of dual-type hydrostatodynamic plain bearings based on the existing experience in designing this type of plain bearings, as well as based on many theoretical and experimental studies performed by the author of this work. The number of the most necessary parameters for the design of dual-type hydrostatodynamic bearings is determined. Particular attention was paid to the development of recommendations for additional parameters specific to the design of double type plain bearings. Attention is paid to the selection of double-type bearing materials and it is shown that the problem of selecting materials for hydrostatic dynamic bearings is not so relevant, however, sometimes in start-up and shutdown modes, as well as in emergencies, to ensure high reliability of the designed machine, it is necessary to pay attention to the choice of bearing materials. The influence of various forms of chambers on the static and dynamic characteristics of hydrostatodynamic bearings is analyzed and it is shown that the greatest distribution in practice, they got rectangular cameras. It is shown that the flow regime of the working fluid also significantly affects both the static and dynamic characteristics of the bearing. It is noted that even with a non-rotating rotor in a hydrostatodynamic bearing, the most turbulent mode of flow of the working fluid is most often observed. The influence of the thickness of the working fluid layer on increasing the rigidity of the supports and expanding the range of stable operation is considered. It is shown that with a decrease in the clearance in the bearing, its bearing capacity increases and the range of stable operation expands, however, this increases the friction power loss, increases the likelihood of clogging of the slit bearing path, and also increases the requirements for the quality of manufacture of the bearing working surfaces. It is recommended that in the double hydrostatodynamic bearing in the outer and inner parts to assign the same clearances. It is shown that in a dual hydrostatodinamic bearing, the existing recommendation on the number of chambers can lead in some cases to large working fluid flow.
PubDate: 2020-08-31
DOI: 10.32620/aktt.2020.8.13
- EQUATIONS OF SPATIAL MOTION OF A SOLID BODY WITH MOLDABLE FASTENING TO THE
FOUNDATION (THE TASK OF DEPRECIATION IN SPACE)
Authors: Андрей Александрович Тарасенко, Александр Иванович Тарасенко
Pages: 106 - 110
Abstract: The task of fastening equipment, especially ship equipment, is considered important in conditions of vibration and shock. Equipment can be mounted on shock absorbers. These shock absorbers solve the problems of vibration isolation and shock protection. The classic case is the use of rubber-metal shock absorbers. The equipment can be attached to the foundation with bolts and dowels. In this case, the bolts mustn't collapse and the joints do not open during shock. An interesting case is an attachment, the fastening of which should not be destroyed. Attachments are usually attached by bolts, the destruction of which is not permissible. In the case of plastic deformation of the bolts they can be tightened, and then replacing the collapsed shock absorber is not easy. The condition of the fastening devices can be investigated by modeling, using computer technology, the movement of the unit. The use of computer technology is justified by the cumbersomeness of the task, the nonlinear characteristics of rubber-metal shock absorbers, and bolts in the case of plastic deformations. Typically, when modeling the movement of shock-absorbing equipment, they are limited to a flat task or a case of hard keys. To solve the spatial problem, we introduce three coordinate systems. One system is non-mobile and connected to the foundation. Two other coordinate systems have a beginning at the center of gravity of the unit. The axes of one of these systems are parallel to the axes of the system associated with the foundation. And the other of these systems are rigidly connected to the unit. At the initial moment, in case of rest, all three systems coincide. For the general case of motion, Euler angles can be used, but due to the small movements of the equipment, accuracy is lost. Indeed, the intersection line of the planes determining the Euler angles is determined with an error (the case of almost parallel planes). To solve this problem, the authors used the angles between the axes associated with the equipment and the foundation plane. Then, through these angles, Euler angles were expressed and expressions were obtained that allow the use of numerical methods to solve the equations of motion.
PubDate: 2020-08-31
DOI: 10.32620/aktt.2020.8.14
- CURRENT STATE OF THE PROBLEM OF THE DEVELOPMENT OF ACOUSTIC LINERS FOR
GAS-TURBINE ENGINES
Authors: Євген Олександрович Римаренко
Pages: 111 - 120
Abstract: A review of current international aviation noise requirements is provided. It is shown that international requirements for aircraft noise levels are constantly increasing. The rapid growth of the international fleet leads to an increase in the number of take-offs and landings of aircraft at airports, and as a result, the problem of aircraft noise still relevant. To reduce noise levels at airports, various methods are used, one of which is the operational limitations of aircraft concerning the levels of noise they create. In European Union countries there are operational restrictions for aircraft meeting the requirements of Chapter 3 with a noise margin of less than 10 EPNdB. For already established aircraft that have passed certification, again it is necessary to look for methods to reduce noise. The main type of aircraft in operation in the world is an aircraft with turbofan engines. For such an aircraft, the main sources of noise during take-off will be the noise of the fan and jet, while landing, the noise of the landing gear, flaps, slats, and fan noise. When choosing a method of reducing aircraft noise, it should determine the source that most affects the overall noise level. It has been determined that fan noise is one of the main sources of noise. Acoustic liners constructions are widely used to reduce the noise level created by the fan. They are one of the most priority areas for reducing fan noise. Achievements in the use of acoustic liners to decrease the noise of domestic aircraft An-124-100, An-148-100 are considered. It is noted that due to the increasing requirements for aircraft noise, it is necessary to use new acoustic liners with improved sound-absorbing properties. It was determined that it is possible to improve the sound-absorbing properties of the acoustic liners by expanding the frequency range of sound absorption of such structures.Modern methods for improving the acoustic properties of the acoustic liners are presented: the use of multilayer resonant acoustic liners makes it possible to customize the design for an increased number of calculation parameters; the use of modified variants of the acoustic liners core such as corrugated core, oversized perforated core; the use of porous and porous fiber materials in the design of the acoustic liners to provide additional sound-absorbing ability, the use of low-frequency acoustic liners to reduce the noise of promising turbofan engines with a high and ultra-high bypass ratio.
PubDate: 2020-08-31
DOI: 10.32620/aktt.2020.8.15
- NUMERICAL DETERMINATION OF EFFECTIVE ELASTIC CHARACTERISTICS OF
THREE-DIMENSIONAL FIBER COMPOSITE MATERIAL
Authors: Андрій Володимирович Морозов
Pages: 121 - 129
Abstract: The processes occurring in composite materials are determined by differential equations in partial derivatives with variable coefficients. Most composite materials have a periodic structure, so the coefficients in the equations are rapidly oscillatory periodic functions. The most effective method for studying the stress and deformation field in structures made of composite materials is the method of finite elements, where a nonhomogeneous composite material is replaced by an equivalent homogeneous anisotropic material. To determine averaged characteristics of a composite material with a periodic structure requires a verified methodology allowing to do this. Therefore, the fundamental goal of the mechanics of composite materials is to calculate the effective elastic characteristics of the material. The paper considers the urgent issue of determining effective elastic characteristics of three-dimensional reinforced composite materials based on known elastic properties of fibers and matrix and distribution of reinforcing fibers by volume of composite material.The paper presents the mathematical modeling of the minimum three-dimensional representative volume element based on the specified reinforcement scheme and geometrical dimensions of components. Numerical experiments are performed with the ANSYS software package. A series of numerical experiments simulate six deformation cases: uniaxial tension in the X, Y, Z directions, and shear in the XY, YZ, and XZ planes. Numerical studies of the stress and strain state of the representative volume element of composite material determine the effective elastic constants of equivalent homogeneous material. Two series of calculations are performed with specifying appropriate symmetry and periodicity conditions.The results of the experimental study allow for the verification of the proposed methodology for determining the effective elastic characteristics of three-dimensional reinforced fiber composite materials. The developed numerical methodology enables us to solve the issues of the mechanics of composite materials with the help of modern software packages in the mathematical framework of which the finite element method is used.
PubDate: 2020-08-31
DOI: 10.32620/aktt.2020.8.16
- INOCULATION OF ML5 MAGNESIUM ALLOY WITH CARBON NANOPOWDER
Authors: Спартак Геннадьевич Маковский, Владимир Васильевич Лукинов, Владимир Валерьевич Клочихин, Вадим Анатольевич Шаломеев, Сергей Петрович Шейко
Pages: 130 - 135
Abstract: The development of contemporary aerospace engineering requires consistent improvement of operating characteristics, therefore, the use of advanced light materials becomes more and more urgent. As magnesium alloys are one of the lightest structural materials, their utilization in power plants allows for enhancement of performance characteristics, such as specific power and fuel efficiency. Especially topical is the improvement of the physical and mechanical properties of the magnesium alloys (Mg-Al-Zn system) by controlling their structural characteristics through inoculation. An efficient low-cost grain refinement technique for ML5 magnesium alloy with micro additions of commercially pure carbon nanopowder has been suggested. A comparative metallographic examination of the specimens material with incremental additions of the carbon nanopowder (0.001 %, 0.005 %, 0.01 % 0.05 %, 0.1 % wt.). It has been shown that an optimum addition of the nanopowder in the quantity of 0.005 % wt. contributes to the refinement of the macro- and microstructure and increases a full set of mechanical properties. The addition of the carbon nanosized grain refining agent has also contributed to the refinement of the eutectoid. [δ+γ] phase and the macro grain size have decreased approximately by a factor of 1.5. It has been found that the inoculation of the metal structure is effective within a narrow range of the inoculant concentration in the melt. In particular, the addition of the carbon nanopowder in the quantity of 0.1 % wt. and above led to the formation of internal flaws in the metal – microporosity and film inclusions. The additions of the carbon nanopowder in ML5 alloy have also contributed to the improvement of the ductility properties. In so doing, the addition of 0.005…0.01 % wt. provided for the maximum (approximately two times) increase of the ductility properties and to was some extent beneficial for the tensile strength of the alloy. Further increase of the inoculating agent concentration led to some deterioration of the mechanical properties of the alloy. Thus, the inoculation of the magnesium alloys of Mg-Al-Zn system with micro additions of the carbon nanoparticles is a promising method of improvement of the physical and mechanical properties of cast parts for critical aerospace applications.
PubDate: 2020-08-31
DOI: 10.32620/aktt.2020.8.17
- THERMOPHYSICAL CHARACTERISTICS AND THERMOEROSION RESISTANCE OF CERAMIC
MATERIAL BASED ON BORON CARBIDE
Authors: Юрий Игоревич Евдокименко, Ирина Александровна Гусарова, Геннадий Александрович Фролов, Вячеслав Михайлович Кисель, Сергей Васильевич Бучаков
Pages: 136 - 145
Abstract: A study of the thermophysical characteristics, heat resistance, and thermal erosion resistance of high-temperature structural ceramics (SC), which was developed at NTUU "I. Sikorsky Kyiv Polytechnic Institute" under the supervision of Corresponding Member of the National Academy of Sciences of Ukraine, Professor P. I. Loboda was made. This high-temperature structural ceramics is intended for use in aerospace engineering, in particular - for the manufacture of aerodynamic surfaces of reusable hypersonic aircraft and heat-stressed elements of the gas-dynamic paths of their engines. The samples of B4C-SiC-B6Si ceramics of two compositions (No. 1 and No. 2) were studied, which differ in the mass content of the initial components. Temperature dependences of the specific heat and thermal conductivity of the spacecraft, radiation coefficient, heat resistance in an oxidizing environment, and the thermal erosion resistance in supersonic flow of combustion products of an air-kerosene fuel mixture were determined. The temperature dependence of the specific heat was determined using an IT-c-400 instrument (in the range of 40 °C - 440 °C) and by the calculation of the temperature dependences of the specific heat capacity of the system components following the Reno rule (up to 2100 °C). The temperature dependence of the thermal conductivity coefficient of the SC of composition No. 1 was determined by solving the inverse heat conduction problem on a computer model based on experimental data. Temperature fields and heat fluxes were obtained under conditions of one-sided heat-ing with a reducing flame of a propane-oxygen welding burner. The thermal conductivity coefficient of SC composition No. 1 increases from 11 W/(m×K) at 20 °С to 25 W/(m×K) at 1400 °С. Its radiation coefficient in the temperature range 1000 °С - 1400 °С is ε = 0.96 ± 0.02. Heat resistance of SC of both compositions in the oxidizing flame of an oxygen welding burner at a surface temperature of 1400 °C has demonstrated that after two hours of heating, the average values of mass ablation for the two tested samples of compositions №1 and № 2 respectively 2.1% and 1.4% (a sample thickness of 4 mm). Tests in the supersonic flow of combustion products at the same surface temperature confirm the high resistance of the material to thermoerosion in the oxidizing medium. The change in the morphology of the heated surface of the sample after six five-minute heating cycles was manifested only by an increase in its roughness without visible oxidation. High thermal conductivity, heat and thermoerosion resistance, radiation coefficient of the studied SC at a temperature of 1400 °C in combination with low density (2.7 g / cm3) make this high-temperature structural material of aerospace technology promising for use.
PubDate: 2020-08-31
DOI: 10.32620/aktt.2020.8.18
- MATION OF FORM OF SPATIAL SHELLS BY METHOD OF EXPLOSIVE STAMPING
Authors: Володимир Васильович Третяк
Pages: 146 - 152
Abstract: A target of work is verification of the adequacy of the theoretical model of correction by the dynamic fold and verification of capacity of principle technological charts of the explosive stamping of flat purveyances. Of researches, exposure is a task of technological dependences, the receipt of which is possible only by the experimental path. The article presented results of experimental verification of the technological process of formation of form for the spatial shells on the typical models. Of the conducted work verification was a target of the rightness of theoretical positions, results of mathematical design and conclusions, and also approbation of methods of computations of technical parameters and charts of punching. The experiments are conducted on the flat models of edging, spherical and parabolic edging of large flexibility, and also curvilinear baskets models, models, and model standards. In the article, a process is explored of slanting collision, remaining tensions, deformations, and form of edging after deformation. Influencing of size, forms, and distances of charge on deviation from the matrix. The approbation was conducted on the party of the spherical model edging. Purveyances are approved on the model fragment.Formulated conclusions and prospects of development and introduction of technology in thermonuclear researches, building, mining industry, rocket, and air production. Experimentally it is set, that the reduction of distance below recommended results in exceeding of deformation of punching of the middle part (curvature more than matrix) and reduction of deformation of punching of the periphery (curvature is a less than matrix). Most rejections are details noticeable in the angular areas. This it is possible to explain by the regional effect from the waves of unloading, and by some asymmetry of installation of charge. The greater part of the surface has a rejection of about 1 mm, which is exceeded by exactness on 8 degrees on the base of 1200 mm. Application of technological admittances by the size of about 50 mm with subsequent their deleting, allows to decrease the mean deviation twice (0,5 mm), and promote exactness of the prepared edging. The experimental working off of technology of correction of declivous petals of double curvature showed a rightness of outputs of the theoretical part.
PubDate: 2020-08-31
DOI: 10.32620/aktt.2020.8.19
- SIMULATION OF TWO-PHASE FLOW IN COLD GAS-DYNAMIC SPRAYING
Authors: Андрій Олегович Волков, Олександр Володимирович Шорінов, Анатолій Іванович Долматов, Сергій Євгенійович Маркович
Pages: 153 - 159
Abstract: The one-dimensional gas-dynamic model for calculation of acceleration and heating of particles which takes into account space from the nozzle outlet to the substrate has been improved. One cycle of particle acceleration by a gas flow can be divided into three parts: mixing a gas flow with powder; particle movement and acceleration in the divergent part of the nozzle; the movement of gas-powder flow from nozzle outlet to substrate. It is known that cold spray coating formation depends on the normal component of particle velocity towards the surface to be sprayed. Each material obtains its value of the critical velocity when the coating formation process starts. At particle velocities above critical, they adhere to the substrate and form coating due to plastic deformation of particles, and at velocities below critical value surface erosion or spraying with low efficiency is observed. One of the features of the process of cold gas-dynamic spraying is a relatively small distance between the nozzle outlet and the deposited surface, which leads to the occurrence of the reverse flow of the gas stream (bow shock) reflected from the substrate. The reflected flow significantly inhibits the trajectory of particles of sprayed powder which need to be investigated. Impact temperature and velocity of aluminum and nickel particles with size 25 microns with a substrate for SK-20 supersonic nozzle of DIMET-405 low-pressure cold spraying machine has been calculated. Although the one-dimensional isentropic gas-dynamic model, which is usually used to calculate flow parameters, describes flow only along the axis of the nozzle, excluding heat transfer with nozzle and friction loss on the inner walls, which leads to overestimated results of calculations, its utilization allows to optimize the geometry of the nozzle channel and develop a technological process of the spraying process. Mathematical modeling of two-phase flow dynamics of the cold spraying process was performed using the MATLAB software. Comparison of simulation results with experimental data to determine the flow velocity and temperature showed that the theoretical calculations differ from the experimental ones by no more than 10 %.
PubDate: 2020-08-31
DOI: 10.32620/aktt.2020.8.20
- BASIC MODEL OF THE AIRCRAFT ENGINE REGULATOR AND ITS MODIFICATIONS
Authors: Геннадий Степанович Ранченко, Анна Григорьевна Буряченко, Вячеслав Михайлович Грудинкин, Всеволод Владимирович Данилов
Pages: 160 - 165
Abstract: It is shown that the creation of a unified electronic control and control equipment for aircraft gas turbine engines is one of the determining trends in the experimental design work of enterprises developing components of aircraft equipment. The results of the creation of some helicopter and aircraft engine controllers (turboshaft and turboprops) in JSC Element are presented. The basic model for them was the regulator RDC-450М (category A component product according to AP-21 classification), which was developed for the AI-450M family of turboshaft engines of Мi-2M and Mi-2MSB and in 2014 received the APPLIANCE DESIGN APPROVAL. There is given information concerning the mass-produced regulator RDTs-450M rework to meet the new requirements specified by the engine designer as the results of certification tests of the AI-450M engine and state tests of the Mi-2M and Mi-2MSB helicopters. It is shown that the rework was carried out taking into account the maximum possible “modifiability” of the regulator, which is the maximum ease of its adaptation in the future to new requirements, including requirements for working with other types of engines, including turboprops. The modular principle of constructing the functional structure and design of the regulator is described; its structural scheme is given. Data are given on the results of equivalent cyclic tests of the regulator RDTs-450M, which was modified to meet the new requirements, and on subsequent work on its adaptation to monitor and regulate the modes of turboprop aircraft engines AI-450C (including its modifications) and MS-500V-02S. Information is given on the newly developed regulators RDTs-450M-S, RDTs-450M-S-1, RDTs-450M-S-T-P, RDTs-450S-500, among which there is an engine regulator designed for an unmanned aerial vehicle. It is noted that the modular design assumes the presence of a significant number of board-to-board connections, and the prospects of increasing the reliability of regulator having a modular design by using the technology of flexible-rigid boards are described.
PubDate: 2020-08-31
DOI: 10.32620/aktt.2020.8.21
- STUDY OF INDICATORS OF EFFICIENCY OF OPERATION OF MEANS OF MEASUREMENTS BY
THE METHOD OF COMPUTER SIMULATION
Authors: Олександр Володимирович Томашевський, Геннадій Валентинович Сніжной
Pages: 166 - 169
Abstract: The operational efficiency of measuring equipment (ME) is important in determining the cost of maintaining ME. To characterize the operational efficiency of the ME, an efficiency indicator has been introduced, an increase of which will reduce costs caused by the release of defective products due to the use of ME with unreliable indications. Over time, the ME parameters change under the influence of external factors and the ME aging processes inevitably occur, as a result of which the parameters of the ME metrological service system change. Therefore, in the general case, the parameters of the metrological maintenance system of ME should be considered as random variables. Accordingly, the efficiency indicator of measuring instruments is also a random variable, for the determination of which it is advisable to apply the methods of mathematical statistics and computer simulation. The performance indicator depends on the parameters of the metrological maintenance ME system, such as the calibration interval, the time spent by the ME on metrological maintenance, and the likelihood of ME failure-free operation. As a random variable, the efficiency indicator has a certain distribution function. To determine the distribution function of the efficiency indicator and the corresponding statistical characteristics, a computer simulation method was used. A study was made of the influence on the indicator of the effectiveness of the parameters of the metrological maintenance system ME (interesting interval, the failure rate of ME). The value of the verification interval and the failure rate of MEs varied over a wide range typical of real production. The time spent by ME on metrological services is considered as a random variable with a normal distribution law. To obtain random numbers with a normal distribution law, the Box-Muller method is used. After modeling, the statistical processing of the obtained results was done. It is shown that in real production, the efficiency indicator has a normal distribution law and the value of the efficiency indicator with an increase in the calibration interval does not practically change.
PubDate: 2020-08-31
DOI: 10.32620/aktt.2020.8.22