Vol 19, No 2 (2020)

Full Issue

AIRCRAFT AND SPACE ROCKET ENGINEERING
Method of preliminary solution of the problem of space robot navigation by onboard astronomical measurements using the butterworth filter
Ananenko V.M., Golyakov A.D., Kalabin P.V.
Abstract

A method of preliminary solution of the problem of space robot navigation based on the results of measurements carried out using its onboard optronic equipment is presented. The initial data of the navigation problem are the directional cosines of the space robot orientation vector in the absolute geocentric equatorial coordinate system with reference to time during one revolution. Analytical expressions are obtained for determining unknown parameters of the motion of the space robot center of mass in the form of Kepler’s elements of the orbit. It is shown that to determine the right ascension of the ascending node, the inclination and the semi-major axis of the orbit of the space robot, information about the orientation of its radius vector at various times is used, and to determine the perigee argument, the moment of passing the perigee and the eccentricity of the orbit, the angular orbital speed of the space robot is used, which is determined by the results of evaluating the speed of change in the orientation of its radius vector over time. The presented results can be used in the development of software for navigation systems that allow autonomous determination of the parameters of the space robot’s orbit using onboard electro-optical sensors in the absence of a priori information about the parameters of the reference orbit or signals from satellite radio navigation systems.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2020;19(2):7-18
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Conceptual framework of designing complex bundles of aircraft on-board cable network
Koptev A.N., Myasnikov A.Y.
Abstract

The article presents mathematical formulation of the problem of synthesizing the image of complex harnesses as an integral part of the on-board complex of aircraft equipment. This problem arises in the design of the on-board cable network of each individual aircraft. The article describes the language that we use to form the basis of applied methods for synthesizing the structures of a set of objects, irrespective of their specific nature, but taking into account their relative position and their properties that are characterized by various features. The article poses the problem of synthesizing a complex bundle in a closed form and proposes an algorithm for solving it. In the work, a matrix of relations between the set of objects and the set of their attributes is compiled. As applied to simple on-board cable bundles, features are introduced and their qualitative values are described that characterize the variety and complexity of the objects under study. Using the example of ten simple cabin harnesses of an arbitrary aircraft, an example is given of compiling a matrix of relations between objects and features, ranked in a certain order. Based on algorithms for comparing the values of attributes, a conclusion is drawn on the aggregation of objects into classes, among which the combination of simple bundles into a complex one is most appropriate.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2020;19(2):19-30
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Optimal command control of flight paths of aerospace system hypersonic first stage in conditions of atmospheric disturbances
Krikunov M.M.
Abstract

The paper deals with disturbed motion of the hypersonic first stage of an aerospace system in accelerated climb. Disturbances are deviations of atmospheric density from the values of a standard model. A multistep control process is accepted. The command angle-of-attack schedule is specified at each step of control using the method of Pontryagin’s maximum principle. The nominal control program is applied at the first step. We present the results of modeling disturbed motion with command control of the angle of attack for maximum “rarified” and maximum “dense” atmosphere. The angle-of-attack constraint is violated for “rarified” and “dense” atmosphere at the end of the accelerated flight segment when a boundary value problem is solved. If command control obtained as a result of solving the boundary value problem is maintained the target terminal speed and altitude conditions are fulfilled. The finite value of the flight path inclination angle for “rarefied” atmosphere is 10% lower than the target one, while for “dense” atmosphere it is 12% higher.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2020;19(2):31-37
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Gas turbine engine dynamic model based on variable-memory LSTM architecture
Kuznetsov A.V., Makaryants G.M.
Abstract

The buildup of thermodynamic cycle parameters is the main way to increase gas turbine engine efficiency. However, the growth of engine pressure and temperature ratio leads to the increase in the turbine heat load, which reduces the engine lifetime dramatically. In terms of gas turbine engines, to avoid the engine life loss is a crucial problem especially for small engines, because the limited size of a small gas turbine engine does not allow implementing various measures for nozzle vane cooling. In light of this, the contribution of the turbine heat control is essentially increasing. It places great demands on the accuracy of control over the main engine variables (such as the rotor speed and turbine outlet temperature). The state-of-the-industry gas turbine engines use an on-board engine mathematical model to improve the quality of the control. These models deal with engine processes of short duration and considerable overshooting. For that reason, the model accuracy is the main aspect in the control process. However, the issues of accurate and at the same time resource-saving calculation of rapidly varying processes of changing the rotor speed and the turbine gas temperature remain under-investigated. In the work, neural network methods were used to model the unsteady modes of a small gas turbine engine. Using the data obtained as a result of firing tests of the JetCat P-60 engine, the engine regression neural network model was created. The main issue that arose during the creation of the model was to describe the dynamics of rapidly varying processes with pronounced overshoot. For this purpose, modification of the architecture of the classical LSTM network was carried out, the essence of which was to add a functional dependence of the exit node on the memory tensor. This allowed us to make the memory size independent of the number of model outputs, thereby increasing the modeling accuracy. The developed architecture was proposed a new name - VMLSTM network. As a result of comparison with the traditional Elman network and the classic LSTM network, the developed VMLSTM network showed the least value of the average error with a comparable number of modifiable model parameters. In addition, unlike the existing neural networks, the developed network demonstrated the ability to simulate turbine outlet gas over-temperature at the moments when the engine operating mode changes. The developed neural network architecture increases the reliability of modeling the dynamics of a small gas turbine engine as an object of control, which in the conditions of economical use of computing resources opens up possibilities of its application in on-board microcomputers.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2020;19(2):38-52
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MECHANICAL ENGINEERING
Mathematical modeling of the process of selective laser melting of Ti-6Al-4V titanium alloy powder
Agapovichev A.V., Sotov A.V., Smelov V.G.
Abstract

A digital (finite element) model has been developed for heating and melting of a layer of metal powder under conditions of its heating by a laser heat flux using a modern standard software product for assessing the geometric parameters of a molten bath brought about by the action of laser radiation on a layer of Ti-6Al-4V titanium alloy metal powder. The model takes into account latent heat released during the phase transition of the material; melting of the material in the temperature range of solidus and liquidus; radiation and convection from the surface of a layer of metal powder. It has been established that the formation of interlayer defects arising from inadequate penetration between layers or insufficient overlap between tracks is the main reason for the formation of porosity in materials synthesized by selective laser melting technology. So the depth of the molten bath should be at least 1.5 of the layer thickness for the synthesis of dense material. The results of numerical simulations made it possible to determine the range of technological scanning parameters upon application of which a melt pool with a depth of more than 75 μm is formed.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2020;19(2):53-62
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Properties of a multi-layer multi-span corrugated package
Alkeev R.I., Suslikov V.I., Eskin I.D.
Abstract

In this article we deal with the problem of cyclic compression of a multilayer multi-span corrugated package by using the finite element method (FEM) and a three-dimensional model (3-D model) of deformation in Ansys. We take into account plastic deformation of the package, as well as the complex law of its propagation and mutual elastic slippage with dry friction over tops of corrugation and in local regions at the tops of corrugation along the package tapes, valid for any geometrical shape of corrugation. This solution can be considered as the second part of the general complex nonlinear problem of cyclic compression of a multilayer multi-span corrugated package with dry friction on contact surfaces. The solution obtained makes it possible to construct any loading processes in the field of elastic-hysteresis package loops. The comparison of elastic-frictional characteristics of the package (EFCs) obtained by calculation and the experimental ones showed their good agreement. The influence of the corrugated package parameters on its EFCs was studied. A number of properties of the package were determined allowing us to draw conclusions and formulate recommendations that make it possible to define the number of package tapes, the required accuracy in the manufacture of corrugations of its tapes, and the choice of the geometric shape of corrugations in almost all cases of practical use of corrugated packages. The solution obtained can be used to determine the effectiveness of a bumper and other protective devices during crash tests of a car for frontal and side impacts and to determine the optimal parameters of these devices by calculating. Certain results and recommendations of this paper can be useful for the calculation of parameters of damping elements of a blisk, hollow wide-chord blades of aircraft GTE fans, ring dampers of rocket engine rotors, as their damping elements are made in the form of multilayer, multi-span corrugated packages.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2020;19(2):63-72
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Development and research of a gas stamping device for making hollow products from a pipe billet
Botashev A.Y., Bayramukov R.A., Bisilov N.U., Dzhumanazarov E.K., Malsugenov R.S.
Abstract

It is advisable to produce hollow thin-walled parts widely used in machine designs from tubular blanks. In existing methods cold forming of the tubular billet takes place for the production of hollow products. In this case, due to the contained plasticity of the blank, parts of complex shape are produced in several transitions. This raises the cost of their production. We have developed a new device for forming hollow products by heating a tubular billet. The device contains a combustion chamber and a working cylinder, separated by a piston. Heating and shaping of the workpiece is carried out under the pressure of the combustion products of compressed fuel mixture supplied to the cavity of the workpiece from the working cylinder. The study was conducted on the basis of well-known equations of thermodynamics and the equations of the heat balance of the process of gaseous fuel combustion. It was found that the ratio of the volumes in the combustion chamber and the working cylinder should range within 2.5...5, and the ratio of the volumes of the working cylinder and the cavity of the pipe billet within 2...2.5. This ensures an increase in gas pressure in the blank cavity by a factor of 25...32, as a result of which the gas pressure reaches 50...65 MPa, and its temperature 2300 °C. Due to this, the stamping process is carried out in the temperature range of hot processing, which makes it possible to stamp parts of complex shape in one operation.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2020;19(2):73-84
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Calculating the dynamic error in measurement of electrohydromechanical system parameters, taking into account the operating speed of sensors
Gareyev A.M., Gimadiev A.G., Stadnik D.M., Popelnyuk I.A.
Abstract

It is necessary to ensure appropriate information content of the measuring instruments used for intelligent diagnosing systems of energy and technological complexes based on the measurement of dynamic parameters. Sensors and measuring equipment should possess sufficient accuracy, reliability, speed and consistency of performance. Types of sensors for measuring dynamic parameters are selected depending on the system’s structure. They can be, for example, sensors for the electrohydromechanical systems of these complexes, pressure sensors, as well as sensors of flow and temperature of the working media, displacement of moving elements and vibration of the base members. The type of sensor intended for use in the diagnostic system is largely determined by the dynamics of the processes taking place in it. It is necessary that the sensors satisfy their performance requirements. If the sensors have lower speed than is necessary for the process dynamics in the electrohydromechanical system, it can lead to dynamic measurement error and an error in the diagnostics of technical condition. In technical literature, the requirement for the sensor speed is indicated by the fact that it should be an order of magnitude higher than the dynamics of the processes occurring in the system. This approach is not acceptable for choosing the type of sensors for diagnostic systems, taking into account the process dynamics. Firstly, sensors for measuring with this required parameter may not be available. Secondly, even if there is a sensor with a parameter close in speed to the dynamics of the system processes, it is necessary to know in advance what dynamic error it can lead to and how it will affect the accuracy of the diagnostic system. An analytically generalized dependence of the dynamic measurement error of electrohydromechanical system parameters on the relative sensor speed is obtained in this paper. This dependence allows you to choose a sensor with a dynamic error that does not exceed a given value. The calculation of the dynamic measurement error is shown using the MI-8 helicopter hydraulic system as an example.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2020;19(2):85-98
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Acoustic diagnostics of local damages of spur wheels in multi-shaft drive using neural network models
Parfiyevich A.N., Dragan A.V., Sokol V.A.
Abstract

In the course of acoustic diagnosis of multi-shaft drives on the basis of spur wheels, the diagnostician is faced with the problem of excessive saturation of the analyzed signal with various kinds of frequency components. Reducing the amount of data analyzed may result in the loss of important diagnostic information. Therefore, in order to make the diagnostician’s work easier and at the same time maintain the accuracy of the diagnosed local damage to the gear tooth it is necessary to identify the list of informative frequency components. They should respond to the occurrence of this defect in the tooth-contact zone and have a sufficiently thoroughly studied mathematical framework that will make it possible to use methods of their automatic determination. The obtained digital image will allow using artificial neural network models for its processing.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2020;19(2):99-106
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Technology of low-emission fuel combustion and conceptual structure of the combustion chamber of a gas-turbine power plant
Tsybizov Y.I., Tyulkin D.D., Vorotyntsev I.E.
Abstract

Currently, the priority for improvement of the combustion chambers of aircraft gas turbine engines and ground-based gas turbine plants is associated with a decrease in the concentration of harmful substances in the exhaust gases while ensuring fuel economy and operational efficiency. Pride of place in the design of a gas turbine power plant goes to solving the problem of organizing the combustion process, i.e. the development of a low-emission combustion system that provides high efficiency and environmental safety. Thus, ecology today determines not only the appearance of a combustion chamber, but also that of a gas turbine power plant as a whole. Below, an attempt is made to summarize the results of developing a low-emission combustion system for various types of combustion chambers of convertible gas turbine power plants and to present a unified approach to the problem  of designing a conceptual structure of a low-emission combustion chamber.

VESTNIK of Samara University. Aerospace and Mechanical Engineering. 2020;19(2):107-120
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