Vol. 8, no. 3, 2024
OMSK SCIENTIFIC BULLETIN. SERIES «AVIATION-ROCKET AND POWER ENGINEERING»
CONTENTSPOWER AND CHEMICAL ENGINEERING
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B. A. Kalashnikov, V. V. Bokhan, V. E. Smolko Experimental and theoretical study of the features of the amplitude-frequency response features of the anharmonic Duffing oscillator DOI: 10.25206/2588-0373-2024-8-3-13-20 In this paper, experimental waveforms of the bifurcation phenomena in a Duffing oscillator weakly damped by viscous friction. The bifurcation points are found by solving the numerical solution of a harmonically linearized system with respect to the square of the frequency and the square of the amplitude. Approximate dimensionless expressions for amplitudes and their corresponding frequencies at the bifurcation points are proposed. The comparison of experimental and theoretical amplitudefrequency characteristics and their values at these points is given. Keywords: Duffing oscillator, degree of nonlinearity, harmonic linearization, relative attenuation coefficient, amplitude-frequency response, amplitude and frequency of bifurcation points, jump points. |
13-20 |
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V. L. Yusha, S. S. Busarov, A. V. Nedovenchany The assessment of applicability of single-stage piston long-stroke low-speed compressors in low-temperature refrigeration machines DOI: 10.25206/2588-0373-2024-8-3-21-28 The work processes and integral characteristics of low-temperature ammonia single-stage piston longstroke low-speed compressors are considered. A method for calculating the actual working process of a stage of such a compressor is presented, taking into account such basic factors as the processes of non-stationary heat transfer between the working fluid in the cylinder and the external cooling medium; processes of flow of the working fluid through leaks in valves and in seals of the cylinder-piston group; dynamics of motion of the shut-off valve body, etc. The flow coefficient, cooling coefficient, and discharge temperature are considered as integral indicators. The following independent parameters are considered: condensation and boiling temperatures, the main dimensions and parameters of the stage, the temperature of the cooling medium and the heat transfer coefficient on the outer surface of the cylinder, as well as the diameters of the suction and discharge valve seats. A comparative analysis of the efficiency of the working process of the considered stage is performed at a condensation temperature of 303 K and boiling temperatures in the range from 243 K to 173 K. The relationship between the main dimensions and parameters of the stage, as well as the boiling point of ammonia with the integral characteristics of the compressor under consideration, has been studied. The obtained results of the theoretical analysis make it possible to evaluate the possibility of replacing multi-stage and cascade low-temperature refrigeration compressors with alternative single-stage ones based on a low-speed, long-stroke stage as promising. Keywords: piston refrigeration compressor, ammonia, low-temperature mode, low-speed long-stroke stage, operating processes, mathematical modeling, coefficient of performance. |
21–28 |
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V. L. Yusha, M. A. Sutyaginskiy, Yu. A. Potapov, G. S. Russkikh Adaptation of the performance control system of a technological piston hydrogen compressor to unstable operating conditions DOI: 10.25206/2588-0373-2024-8-3-29-35 Issues related to possible problems of the feasibility of operating the existing system for regulating the performance of a technological piston hydrogen compressor at a large chemical production and the relevance of its modernization are considered. In practice, modernization is one of the options for implementing import-substituting technologies in relation to equipment operated at large chemical, oil and gas processing enterprises. Technical and economic factors are accepted as the dominant prerequisites; as an alternative to the existing control system by squeezing the valves for part of the piston stroke, a control technology is chosen by changing the value of the dead volume in the working chamber of the cylinder. The presence of significant uncertainty factors in the implementation of known methods for calculating the productivity losses of the actual working process in the stage of a piston compressor has led to the need to perform variant calculations. The implementation of this approach ensured high convergence of the results of calculations and industrial tests and made it possible to clarify the value of the conditionally constant polytropic index of the final parameters, applicable for similar calculations of the object under consideration. Recommendations for the design of piston compressors with variable capacity are presented. Keywords: piston compressor, hydrogen, capacity control, valve pressing, dead volume change, capacity, discharge temperature. |
29–35 |
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A. D. Vanyashov, V. V. Karabanova, A. A. Nefedov Evaluation of the prospects for the use of single-stage centrifugal compressors based on high-pressure stages with an inlet guide device at linear gas compressor stations DOI: 10.25206/2588-0373-2024-8-3-36-45 The issues of evaluating the technical and economic prospects for the use of gas pumping units with single-stage centrifugal compressors with an axial suction nozzle, created on the basis of high-pressure stages with axial impellers and an adjustable inlet guide device, at linear gas compressor stations are considered. A brief description of the methodology for recalculating tests of a small compressor stage performed in air for working conditions as part of a gas compressor station is given. A comparative assessment of the competitiveness of the proposed compressor type with existing types of compressors in two-stage design has been performed. Keywords: centrifugal compressor, inlet guide device, axial radial impeller, gas dynamic characteristics, gas pumping unit, compressor station, gas transmission system. |
36–45 |
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A. A. Raykov, A. A. Isaev, A. V. Burmistrov Mathematical modeling non-contact external compression pumps with different molecular weights gases DOI: 10.25206/2588-0373-2024-8-3-46-52 A distinctive feature of Roots type vacuum pumps is the selective of pumping, which is due to the dependence of reverse flows on the type of gas. To study this phenomenon, a mathematical model of the work process is used, based on solving differential equations of a system with variable mass. Comparisons of the experimental and calculated values of pumping speed and pressure increase for helium, argon and air show a discrepancy of no more than 10 %. Calculations have shown that under viscous flow conditions, switching from pumping argon to helium reduces pumping speed by more than 10 % and pressure increase by 50 %. Keywords: selective pumping, pumping speed, conductivity, backflows, Roots vacuum pump, channels conductivity, mathematical model. |
46–52 |
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A. F. Sarmanaeva, N. V. Sokolov, O. Yu. Paranina, V. V. Kuzovov, Yu. V. Sidorova, I. S. Davletshin, I. N. Lotfullin, M. V. Korshunov Problematic issues and ways to solve them during reverse engineering of compressor design units DOI: 10.25206/2588-0373-2024-8-3-53-60 A significant part of the compressor fleet in Russia consists of foreign-made centrifugal and screw compressors, which, with operating time and depreciation, require repair according to regulations or modernization due to changed technological operating conditions. The supply of spare parts needed for repairs has become more complicated due to the rise in cost or lack of logistics. This leads to the problem of maintaining the compressor equipment in working order or its downtime. The manufacture of spare parts is problematic due to the lack of design documentation from operating organizations. The offer of reverse engineering services for spare parts and compressor assemblies by specialists of JSC «NIIturbocompressor n. a. V. B. Shnepp» makes it possible to improve and solve the problem of maintaining the effective condition of foreign equipment. At the same time, the article describes the problems that arise during reverse engineering of rotors of centrifugal and screw compressors, the spatial profile of impellers and fluid film bearings. The main points contributing to the successful completion of reverse engineering tasks are indicated, the accuracy of 3D scanning is determined, and methods for setting nominal dimensions and deviation tolerances are presented. Keywords: compressor, equipment replacement, reverse engineering, 3D-scanning accuracy, compressor rotor, impeller, journal and thrust plain bearings. |
53–60 |
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O. A. Solovyeva, I. S. Sharikov, N. I. Sadovsky The influence of reality gas calculation methods on the gasdynamic characteristics of a gas pumping unit centrifugal compressor DOI: 10.25206/2588-0373-2024-8-3-61-68 When designing compressors, it is necessary to take into account the reality of the working fluid, since when calculating the compressor using ideal gas models, strong deviations of the operating parameters from the calculated ones occur, which can lead to non-fulfillment of the technical specifications, as well as to the formation of non-stationary processes. The correct choice of the gas reality accounting methodology allows us to bring the calculated data as close as possible to the experimental ones. Thus, the choice of the most accurate method of accounting for the reality of gas makes it possible to predict the experimental characteristics of the designed compressor even before conducting physical tests. There are many methods that allow us to take into account the reality of gas, namely, to calculate the compressibility factor using empirical formulas. In this paper, a comparison of four methods is presented, and the calculation of a centrifugal compressor is performed taking into account the values of the compressibility factor obtained according to these methods. The calculated gas dynamic characteristics are compared with experimental data and discrepancies are revealed at different rotor speeds. Keywords: ideal gas, compressibility factor, methane, adiabatic coefficient, natural gas, gas reality, centrifugal compressor. |
61-68 |
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E. V. Filimonov, L. N. Marenina, A. A. Drozdov, N. I. Sadovsky Experience of applying 3D-scanning and CFD calculations to study and optimization the flow in the impeller of a multi-shaft centrifugal compressor DOI: 10.25206/2588-0373-2024-8-3-69-79 The paper presents an analysis of semi-open centrifugal impellers of a three-stage multi-shaft compressor. A 3D-scanning of the geometry of the impellers is carried out, a CFD calculation is carried out at the design operating mode of the compressor, and the results obtained are analyzed. Problems have been identified with the second stage impeller. Next, the geometry of all three impellers is optimized using Ansys CFX software, an improvement in efficiency and an improvement in the flow pattern are obtained. Keywords: centrifugal compressor, impeller, computational gas dynamics, efficiency, optimization, loss coefficient. |
69-79 |
AVIATION AND ROCKET-SPACE ENGINEERING
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I. Yu. Lesnyak Experimental investigations of opening leaks in a welded seam of a closed container under thermal and acoustic influences DOI: 10.25206/2588-0373-2024-8-3-80-89 To conduct experimental investigations of the drying process of a closed container, taking into account the opening of a leak channel in a weld, an experimental research stand, an experimental container and experimental samples with model leaks of different sizes are designed and manufactured. The scientific problem of experimental research has been formulated, a program and methods for conducting experiments have been developed. Requirements for metrological equipment have been formed and the measurement error of temperature, humidity and pressure has been determined. Preliminary experiments are carried out on wetting the experimental container and experimental samples with a model liquid and clogging the leak channels, as well as on drying the inner surface of the experimental container wall with a convective gas flow and conductive heating of the wall until the leak channels clogged with liquid are opened. The dependences of the change in temperature of the liquid, air, wall of the experimental container, experimental samples and pressure in the experimental container are obtained over the time of the experiment during wetting and drying of the experimental container and experimental samples. The parameters of thermal exposure at which the leak channels is opened within a specified time are determined. Keywords: leak channel, container drying, experiment, ultrasound, low pressure, capillary. |
80-89 |
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R. A. Peshkov, A. S. Shmetkova, O. V. Ispravnikova, Ju. L. Suskina The analysis of the influence of the turbulence model selection on the parameters of interaction of a supersonic jet with an obstacle DOI: 10.25206/2588-0373-2024-8-3-90-97 Due to the intense loading of the elements of launch structures when exposed to rocket engine jets, it is obvious that it is necessary to determine the gas-dynamic, thermal and other loads that occur during the launch of the launch vehicle. Numerical modeling using application programs is one of the widely used methods of their calculation, since physical modeling requires significant resources. The study analyzes the case of interaction of a single supersonic gas jet with a flat barrier oriented perpendicular to the direction of the jet. Differential equations describing the motion of a compressible viscous heatconducting gas (Navier-Stokes equations) are presented, and a method for averaging them by Reynolds is described. Some one- and two-parameter turbulence models based on Reynolds equations are considered. A numerical simulation of the flow of a supersonic jet of air from a Laval nozzle onto a flat aluminum barrier located perpendicular to the axis of the jet is carried out. The ANSYS Fluent software package is used to analyze the effect of choosing a turbulence model on the distribution of the Mach number and pressure on the barrier. A comparison of the results of the study with experimental data showed that the most accurate results are obtained using the k-ω SST turbulence model. Keywords: supersonic jet, gas dynamics, jet-barrier interaction, turbulence models, turbulent flow, ANSYS Fluent. |
90-97 |
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V. A. Urbansky, A. A. Petruk Theoretical and experimental studies of the influence of gas flow parameters on the entrainment of liquid droplets from an experimental vessel DOI: 10.25206/2588-0373-2024-8-3-98-106 On the basis of mathematical modeling, the values of velocities above the liquid surface in the experimental vessel are obtained to ensure the condition of droplet detachment and entrainment. The program of physical experiments on the entrainment of liquid droplets from experimental vessel is developed. Physical modeling of liquid droplets entrainment from experimental vessel is carried out, which showed that the separated mass of liquid significantly depends on the parameters of the gas flow at the inlet to experimental vessel (temperature, flow velocity). At the temperature of the inlet gas flow equal to 20 °C the percentage of separation ts 62 %, at 30 ºC — 69 %, at 35 ºC — 70 %, at 40 ºC — 78 %. Keywords: centrifugal separator, liquid droplets, gas flow velocity, similarity criteria, gas flow parameters, two-phase flow, liquid droplet entrainment, passivation. |
98-106 |
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V. V. Fedyanin, V. V. Shalay, P. S. Yachmenev, I. S. Vavilov Development of a stand for measuring thrust of micro-jet thrusters based on machine vision DOI: 10.25206/2588-0373-2024-8-3-107-115 In the presented work, the issues of measuring the thrust force of spacecraft thrusters are considered. A program for determining the thrust force based on machine vision has been developed. A mathematical model of the mechanical part of the stand has been compiled. Numerical modeling of the compiled system of equations is carried out. The simulation results are processed using the developed program. The relative error of misalignment is no more than 5 %. Field experiments are carried out and the thrust levels of the ion thruster are measured. A comparative analysis of the experimental results obtained with a mathematical model is shown. Experimental studies have been conducted to determine the thrust of a prototype arcjet thruster using a stand based on machine vision and using a stand based on a displacement sensor. The discrepancy in the results of the thrust force is 5,6 %. Keywords: ion thruster, arcjet thruster, jet thruster, thrust measurement stand, small spacecraft, machine vision. |
107-115 |
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A. B. Yakovlev Mathematical description of the processes in the pumping system for supplying fuel to the combustion chamber of a liquid rocket engine DOI: 10.25206/2588-0373-2024-8-3-116-122 The article considers a mathematical model of a pumping system for supplying fuel to a liquid rocket engine chamber consisting of active and passive parts of a hydraulic system. A differential equation describing the processes occurring in the fuel supply system is obtained. The mathematical model makes it possible to analyze and identify the main patterns of influence of the control and disturbing quantities on the controlled quantity, as well as to obtain transients. Keywords: dynamic processes, liquid rocket fuel, fuel pump, nozzle head, fuel lines, active part of the hydraulic system, passive part of the hydraulic system, transition process. |
116-122 |
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E. S. Fisenko Review of certification methods for unmanned aircraft DOI: 10.25206/2588-0373-2024-8-3-123-127 Certification of high-tech products, such as unmanned aircrafts, occupies a sufficient part of time and material resources for developers and manufacturers, which inevitably leads to the slowdown of production output. The article analyzes the methods of certification of unmanned aircrafts existing at the moment in some countries. It also reveals the existing difficulties in obtaining certification and passing tests to obtain it. In order to simplify the testing, the introduction of digital twin technology as a less resource-consuming procedure is proposed. This article can be useful both for developers and manufacturers, and certification centers. Keywords: certification, unmanned aircraft, digital twin, digital model, flight tests, airworthiness. |
123-127 |
MATERIAL SCIENCE AND PROCESSING TECHNOLOGY
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E. A. Rogachev, A. A. Kalenchuk Development of an electrically conductive polymer composite based on linear low-density polyethylene modified with high-structural carbon black DOI: 10.25206/2588-0373-2024-8-3-128-134 The developed polymer composites based on low-density linear polyethylene modified with OMCARB CH85 technical carbon have been experimentally investigated. A comprehensive analysis of the composites' properties has demonstrated that the use of this filler type results in a percolation transition at a 25 % mass fraction of filler, leading to an decrease in resistivity. Samples with lower concentrations exhibit electrical resistance values corresponding to those of semiconductors. When the filler concentration reaches 20 %, the maximum material stiffness is observed, and the character of stretching transitions from ductile to brittle. Electron microscopic examination of the samples reveals a mesh microstructure of the polymer matrix with embedded carbon black particles acting as crystallization nuclei. As a result, the mechanical properties and electrical conductivity of the composite are enhanced. Keywords: electrically conductive carbon black, linear low-density polyethylene, polymer composites, polymers composites structure, the mechanical properties of polymer composites, the manufacture of polymer composites, electron microscopy of polymers. |
128-134 |