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Abstract: An Erratum to this paper has been published: https://doi.org/10.3103/S1068799823010269 PubDate: 2023-01-01 DOI: 10.3103/S1068799823010269
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Abstract: An Erratum to this paper has been published: https://doi.org/10.3103/S1068799823010270 PubDate: 2023-01-01 DOI: 10.3103/S1068799823010270
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Abstract: A new method for improving the thrust efficiency of a pulse air-jet engine, which is based on the control of the pulsed combustion process, is described. It is based on simultaneous implementation of two mechanisms, namely, the partial fuel conversion and shifting the combustion zone. The significant effect of shifting the combustion zone is shown, which is expressed not only in the growth of the thrust force pulsation amplitude, but also in giving the process cyclic stability. PubDate: 2023-01-01 DOI: 10.3103/S1068799823010130
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Abstract: Based on the statistical analysis of test results of production elastic multilayer beams, the variation range was determined, the expectation and variance of random values of the compliance of the hingeless hub of the helicopter main rotor, were obtained. The mechanical characteristics of the materials (fiberglass and rubber) that make up the elastic element were selected by the Nelder–Mead simplex method and the range of their spread at mass production was determined. The convergence of the applied method is shown. PubDate: 2023-01-01 DOI: 10.3103/S106879982301004X
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Abstract: The possibility of regulating the damping in hydrodynamic dampers of rotor supports, is shown. The control laws, types of actions and programs for the formation of a control signal by the parameters of elastic-damper supports are considered. A classification of controlled elastic-damper rotor supports is proposed. PubDate: 2023-01-01 DOI: 10.3103/S1068799823010105
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Abstract: The paper presents an approach for calculating the noise of an open rotor. This approach combines reasonable accuracy of noise calculations with an acceptable speed of calculations. In order to solve the aerodynamic problem, the vortex (panel) method is used. To solve the acoustic problem, the Ffowcs Williams–Hawkins method is used, in particular, the explicit Farassat formulas. This approach made it possible to use the panel method for solving aeroacoustics problems. Test calculations are carried out to determine the noise generated by the system of point monopoles. The comparison of experimental and calculated data for predicting the noise of an open rotor is carried out. PubDate: 2023-01-01 DOI: 10.3103/S1068799823010075
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Abstract: The analysis of automatic control of the temperature of coolants of propulsion systems using various control algorithms, taking into account the theory of heat transfer and hydrodynamics, is presented. An assessment of energy consumption during the pumping of coolants using various control algorithms, was carried out. PubDate: 2023-01-01 DOI: 10.3103/S1068799823010038
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Abstract: The paper considers the issues of forming the CNC-structured control programs in a problem-oriented language of the CNC system programs for processing at optimal cutting modes established using a unified methodology for solving the problems of parametric optimization of machining processes on variable cutting modes. PubDate: 2023-01-01 DOI: 10.3103/S1068799823010191
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Abstract: The results of experimental study of the average velocity of the flame propagation in the first and main phases of combustion using methane-air and methane-hydrogen-air mixtures are presented. Relations for various crankshaft rotational speeds with a change in the proportion of hydrogen added to the fuel are found. Results were obtained on the effect of hydrogen addition on increase of the propagation velocity of the flame front of the methane-air mixture during the mixture leaning and enrichment. The most effective modes of using hydrogen additives in the fuel mixture are determined. PubDate: 2023-01-01 DOI: 10.3103/S1068799823010154
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Abstract: The possibility of improving the efficiency of non-contact extraction of electric power from the wires of operating three-phase high-voltage overhead power transmission lines with the help of flat single-layer coils is investigated. PubDate: 2023-01-01 DOI: 10.3103/S1068799823010233
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Abstract: A technique for research of conducted interferences from power devices of the aircraft at the stage of modernization is proposed. The technique makes it possible to identify the ways of propagation and reduction of interference, to evaluate the effectiveness of measures taken to improve the electromagnetic compatibility. PubDate: 2023-01-01 DOI: 10.3103/S106879982301021X
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Abstract: A method of processing the edges of compressor blades by volumetric planing on a CNC machine is proposed. The techniques of creating a control program for planing processing on a five-coordinate machine are described, as well as the technological conditions for performing the planing operation on various milling multi-coordinate machining centers are considered. Experimental values of cutting modes are given. A theoretical comparison of the planing and milling processing performance was carried out while ensuring similar surface quality. PubDate: 2023-01-01 DOI: 10.3103/S106879982301018X
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Abstract: The importance of reliable information is substantiated in terms of aerodynamic angles and air speed for piloting, control, and ensuring the flight safety of airplanes and other types of aerial vehicles in the surface layer of the atmosphere. Analytical models are developed and results of calculating the methodological aerodynamic errors of measuring the true air speed, indicated speed, Mach number, and aerodynamic angles of attack and slip for the panoramic sensor of the air speed vector parameters, are presented. The ways are considered of reducing the systematic and random components of aerodynamic methodological errors by introducing the corrections to calculation algorithms, implementing the principles of interconnecting and optimal filtration. PubDate: 2023-01-01 DOI: 10.3103/S1068799823010178
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Abstract: An approximate expression of the power, which depends on the characteristics of the pilot–aircraft system, is given. It is shown that the power values for different dynamic configurations correlate with the level of flying qualities, making it possible to use it as a criterion for assessing the flying qualities. PubDate: 2023-01-01 DOI: 10.3103/S1068799823010051
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Abstract: The paper presents the methods of using the cognitive-information converters of pilot activity algorithms in the training process, which allow forming the skill of determining the laws of interaction of the instrumental and other information parameters without losing the ability to determine the current situation. PubDate: 2023-01-01 DOI: 10.3103/S1068799823010063
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Abstract: Flutter of a cylindrical shell of finite length is under consideration. In this paper, the advanced algorithm without saturation is given and specific calculations that demonstrate its high performance are presented. PubDate: 2023-01-01 DOI: 10.3103/S1068799823010026
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Abstract: Characteristics and special features of jet pumps with a curvilinear initial section of the mixing chamber are considered. The advantages of this type of pumps are noted in comparison with straight-jet pumps. The influence of the radius of curvature of the initial section of the mixing chamber on the jet pump characteristics is shown. PubDate: 2023-01-01 DOI: 10.3103/S1068799823010142
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Abstract: The problem of adjusting the shape of a radio-reflecting net of a large-sized transformable space-based reflector using a cable-stayed structure is considered. A mathematical model of the motor is presented, which makes it possible to obtain the relationship between the armature voltage and the angle of rotation of the motor shaft. A solution to the problem of controlling a DC motor based on the maximal principle using the Newton and Krylov–Chernousko methods is given. In view of the difficulties in the convergence of these methods, an algorithm for optimal correction of the parameters of the control structure was developed. PubDate: 2023-01-01 DOI: 10.3103/S1068799823010221
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Abstract: A small-sized turbofan jet engine demonstrator with a thrust up to 2000 N was developed. The project was implemented using a concept of development of gas turbine engine family based on a unified core engine. PubDate: 2023-01-01 DOI: 10.3103/S1068799823010117
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Abstract: The supersonic flow of a reactive gas mixture with Mach reflection of emerging shocks and pulsed energy supply at the main shock is considered within the framework of the Zel’dovich–Neumann–Döring model. An approximate analytical model is proposed that allows one to quickly determine the shape and size of the resulting gas-dynamic discontinuities as well as the flow parameters in various flow regions. As an example of the application of the proposed analytical model, the initial “first barrel” of a highly overexpanded jet of an air-methane mixture with a high supersonic velocity is studied. The height of the triple point of the Mach reflection is determined in the presence of a change in the chemical composition of the mixture and an isobaric pulsed energy supply at the main shock. PubDate: 2023-01-01 DOI: 10.3103/S1068799823010087