Vol. 7, no. 1, 2023
OMSK SCIENTIFIC BULLETIN. SERIES «AVIATION-ROCKET AND POWER ENGINEERING»
CONTENTS
POWER AND CHEMICAL ENGINEERING
|
V. A. Pronin, A. V. Kovanov, V. A. Tsvetkov, E. N. Mikhailova, E. A. Kalashnikova Assessment of the influence of gap wall mobility factor at calculation of leakage in working section of a scroll compressor. Part 1 DOI: 10.25206/2588-0373-2023-7-1-9-17 The scroll type compressor is widely used in the medium capacity segment of refrigeration and air conditioning technology including heat pumps. Today there is an active process of changing from hydrofluorocarbons to natural refrigerants with low global warming potential. CO2, with its low critical point and correspondingly high operating pressures, is gaining in importance. For operation with new refrigerants, the scroll compressor has to be adapted to take account of all its design features, the most important of which are the clearances in the machine's flow area. It has to be considered that the thermodynamic properties of carbon dioxide, different from hydrofluorocarbons, have a significant influence on the volume and energy values of the compressor. In this case relevance consists in increase of accuracy of compressor losses calculation and prediction of refrigeration machine characteristics. As the basic volumetric losses in the scroll compressor are leakages of working substance in its working part, and the process of flow of medium is unsteady, their quantitative component causes interest. The purpose of this work is to clarify the physical basis of the leakage process in the radial clearance and the degree of influence of various factors on it. Such analysis gives further opportunity to refine the methodology of calculation of leakages of compressed medium, taking into account the mobility factor of gap walls. It will raise accuracy of the received results which can serve as a base to prognosis of optimum characteristics of the compressor, due to their approximation and will allow to optimize designing of refrigerating machines at the chosen modes of work. Keywords: scroll compressor, working medium leakage, unsteady flow, working gap, gap wall mobility, leakage dynamics. |
9-17 |
|
V. L. Yusha, A. Yu. Gromov, P. V. Ushakov The analysis of influence of temperature conditions of piston long-stroke compressor stage on thermodynamic efficiency of a heat pump DOI: 10.25206/2588-0373-2023-7-1-18-25 A brief overview analysis of the applicability of heat pumps in various branches of engineering and production as one of the most energy-saving technologies is presented. The theoretical cycle of a heat pump based on a piston long-stroke low-speed compressor stage is considered, which allows to realize the compression process in a wide range of the polytrope index. The analysis of the relationship of the integral characteristics and energy efficiency of the heat pump with the temperature regime of the compressor stage when using water vapor as a working fluid is performed. The presented results of the theoretical analysis reflect the nature of the dependence of the thermal power and the transformation coefficient of the heat pump on the polytropy index of the compression process, boiling temperature, steam overheating at suction, the difference in condensation and boiling temperatures. Keywords: heat pump, theoretical cycle, reciprocating compressor, water vapor, compression process, polytrope index, boiling temperature, suction overheating, condensation temperature. |
18–25 |
|
S. S. Busarov, R. E. Kobylsky, A. Yu. Gromov The method of calculating the lobe wall thickness of cuff cylinder piston seal DOI: 10.25206/2588-0373-2023-7-1-26-31 The presented article describes a method for calculating the wall thickness of the lip seal lobe in the ANSYS Workbench Mechanical software package. The main problem that designers face when choosing the wall thickness of the lobe of cuff seals for reciprocating compressor units operating without lubrication is described. As a result of the work, the maximum and minimum wall thickness are calculated for the materials most common in oil-free compressor units. Antifriction materials of the Flubon and Fluvis groups containing up to 20 % carbon fibers have the smallest wall thickness in all pressure ranges considered. At the same time, the results obtained allow us to speak about the low efficiency of cuff seals with a maximum wall thickness at pressures below 1 MPa. Keywords: cuff seals, sealing, antifriction material, piston compressor, contact pressure, wall thickness. |
26–31 |
|
E. A. Dorofeev, A. S. Tegzhanov, V. E. Shcherba The analysis of pumpless cooling systems reciprocating compressors DOI: 10.25206/2588-0373-2023-7-1-32-39 The article discusses the existing methods of cooling reciprocating compressors, where special attention is paid to liquid systems in which the motion of the coolant is carried out not from an external pump, but due to fluctuations in gas pressure or rarefaction. An analysis of the designs of pumpless cooling systems is carried out, advantages and disadvantages are identified, directions for their further improvement are identified. Keywords: piston compressor, compressor cooling, pumpless cooling, underpressure, pressure fluctuations, hybrid power machine. |
32–39 |
|
E. A. Pavlyuchenko, A. S. Tegzhanov, V. E. Shcherba, E. A. Lysenko, A. K. Kuzhbanov The analysis of methods for calculating seals of hybrid power machines DOI: 10.25206/2588-0373-2023-7-1-40-46 The article discusses the main methods for calculating seals of hybrid power machines. The analysis of works on the designs of hybrid power machines is carried out. The main types of piston seals of pumps, compressors and hybrid power machines are considered, with an emphasis on the main advantages and disadvantages of each type of seal, as well as recommendations on the choice of seals for hybrid power machines. Based on the analysis of the work on the research of piston seals, the main methods for calculating the seals of hybrid power machines are considered and the most suitable one is determined. Keywords: seals, hybrid machines, power machines, step seals, slot seals, seal in the form of a hydrodiode. |
40–46 |
|
M. Omran, A. A. Zharkovskiy, V. A. Schur, D. G. Svoboda Technique for designing and optimization of the Francis turbine blade system DOI: 10.25206/2588-0373-2023-7-1-47-54 A technique for designing the blade systems of Francis turbine is proposed. Starting with the determination the main parameters of the turbine components, where it is compatible with the operation of a hydraulic turbine at a given head. Also, the diameter of the impeller required to generate the nominal power. Then, using the realizing of the quasi-three-dimensional approach, the shape of the blade is obtained as a first approximation for a given blade, a series of calculations of three-dimensional single-phase and two-phase viscous flow is performed to determine the efficiency of the turbine at different operating modes, the cavitation properties of the turbine, respectively. The critical cavitation coefficient is determined for three operating points of hydraulic turbines. Using Multi-objective Genetic Algorithm (MOGA), the optimization of energy and cavitation properties is carried out for three operations pointes. The mathematical model is based on the Latin hypercube method. As a result of the optimization, a significant improvement in the efficiency of the hydraulic turbine has been obtained, especially at partial loads. Keywords: Francis turbine, blade system, multi-objective genetic algorithm, mathematical model, cavitation. |
47–54 |
AVIATION AND ROCKET-SPACE ENGINEERING
|
V. N. Blinov, V. V. Kositsin, A. I. Lukyanchik Studies of the design layout of resistojet with porous structure for propulsion systems of small spacecraft DOI: 10.25206/2588-0373-2023-7-1-55-60 The results of experimental studies on nitrogen with an overpressure of 0,02 MPa resistojet propulsion system of a small spacecraft with a porous structure weighing 45 g and an autonomous heating element with a radius of 3 mm with a power consumption of up to 60 watts for a warm-up time of up to 300 s are presented. The possibility of using a porous structure as a volumetric fuel gas pipeline with an increase in heat transfer intensity has been experimentally proved and the actual specific heat capacity of the porous structure has been determined. Taking into account the actual specific heat capacity, theoretical studies of the mass and geometry of the porous structure in the resistojet composition are carried out, optimal with respect to the autonomous heating element used by the power and the amount of fuel heating in the range (573–1273) K. Taking into account the radius of the heating element, the fuel temperature range (573–973) K corresponding to the optimal masses and radii of the porous structure for the formation of the resistojet design layout is determined. Keywords: autonomous heating element, propulsion system, small spacecraft, porous structure, design layout, specific heat capacity, resistojet. |
55-60 |
|
M. S. Korytov, V. S. Shcherbakov, I. E. Kashapova Investigation of vibration protection system of a seat with quasi-zero stiffness under stochastic effects on the elements of running equipment of a motor grader DOI: 10.25206/2588-0373-2023-7-1-61-69 With the help of a complex simulation mathematical model of a motor grader developed in the Matlab environment, including subsystems of vibration-protective cab supports, a vibration-protective mechanism of the operator's seat, setting stochastic effects on the elements of running equipment when moving along a microrelief, a computational experiment is carried out, when processing the results of which, the influence of a number of system parameters on the root-mean-square seat acceleration deviation in the vertical direction. The variable parameters are the root mean square deviation of the vertical coordinates of the microprofile of the supporting surface, the speed of motion of the motor grader, the size of the zone of quasi-zero stiffness of the vibration protection mechanism of the operator's seat, the value of the increase in the spring stiffness coefficient of the vibration protection mechanism, which sets the slope of the average section of the static power characteristic of the vibration protection mechanism. An increase in the size of the zone of quasi-zero stiffness allows several times to reduce the average value of the root-mean-square deviation of the seat acceleration for a set of movements at various profile heights and speeds. Giving the middle part of the static characteristic a small slope also allows a slight decrease in the average value of the standard deviation of the seat. Keywords: vibration protection, vibration, seat, quasi-zero stiffness, modeling. |
61–69 |