Vol 8, No 4 (2024)
Статьи
On the variation of kinetic energy in a hydraulic inertial motion converter
Abstract
The research investigates the dynamics of a hydraulic inertial motion converter in a non-conservative system. The hydraulic inertial motion converter portion of the inertial tubes in the piston is overlapped synchronously with the change in direction of piston velocity. The cylinder piston is forced into progressive oscillating motion by a servo drive, which is mounted on a movable platform along with the cylinder.
The relative movement of the cylinder piston in a non-conservative system leads to an increase in kinetic energy, which could affect the motion of the moving platform, both in the absence of resistance forces and when the resistance is small and proportional to the platform velocity.
5-11
Consideration of hydrodynamic forces in determining the force factors acting operating elements of a scroll compressor
Abstract
Increasing the efficiency of compressor equipment is an important task, the solution of which contributes to the rational use of economic resources and improvement of the environmental situation. In this regard, the task of improving the characteristics of oil-filled scroll compressors is relevant. The purpose of this study is to clarify the degree of influence of hydrodynamic forces on the working elements of a scroll compressor during the movement of a movable scroll. When the tangential gap is filled with oil and the spiral moves during operation, we can talk about the influence of the hydrodynamic lifting force, on the basis of which the operating principle of hydrodynamic plain bearings is implemented. As a result, the hydrodynamic forces in the tangential gap of a scroll compressor and the possibilities of applying the theory of hydrodynamic lubrication for its calculation are investigated.
12-20
Evaluation of rational energy costs for liquid dispersion in piston compressors with a two-phase working fluid
Abstract
The paper considers the condition of efficient operation of a piston compressor with coolant injection, which consists in the fact that the costs of its spraying and injection should be less than the gain in indicator work obtained with intensive gas cooling and the compression process approaching isothermal.
The maximum relative gain in the supplied technical work is no more than 25 % when using a coolant injection system. Therefore, to obtain an energy effect from using a cooling system, the costs of organizing it should not exceed (10–15) %.
The greatest influence on the amount of energy gain when organizing liquid injection is exerted by the average radius of coolant droplets, then by the relative amount of injected liquid.
The efficiency of liquid injection increases with an increase in the ratio of the discharge pressure to the suction pressure and with a decrease in the number of crankshaft revolutions.
21-28
Analysis of the thermodynamic efficiency of a theoretical multi-stage compressor with the combined use of adiabatic, isothermal and subisothermal compression processes
Abstract
A thermodynamic analysis of compression processes with intensive heat removal is presented under the assumption that it can be realized with a polytropic index less than 1. A terminological classification of polytropic processes is proposed, including the concept of a subisothermal process. A method has been developed for determining the polytropic index of a subisothermal process under theoretical combined multi-stage compression, as well as methods for comparative assessment of the energy efficiency of various options for theoretical combined multi-stage compression and the thermal load on heat exchange equipment. A comparative thermodynamic analysis of various options for theoretical multi-stage compression with the combined use of adiabatic, isothermal and subisothermal stages has been performed. The results obtained suggest that, theoretically, from the point of view of thermodynamic efficiency criteria, combined multistage compression is preferable to multistage adiabatic compression. The prospects for the practical use of subisothermal stages as part of multi-stage compressor units are determined by the possibilities of their constructive implementation.
29-38
Aluminum-based material for use in hydrogen cartridges of the hydrogen fuel cell supply system
Abstract
Materials have been developed for hydrogen cartridges using the reaction of activated massive commercial aluminum alloys with water as a hydrogen source. A wide range of industrial aluminum alloys, including secondary aluminum, as well as compacted chips, can be used as starting aluminum materials. It has been shown that activated products are stable for a long time when stored in dry conditions. Prolonged exposure to water vapor leads to loss of reactivity.
39-45
Influence of the extracorporeal membrane oxygenation system centrifugal pump operation mode on blood damage
Abstract
One of the key tasks in the development of mechanical circulatory support pump is to take into account its interaction with blood components and their corresponding damage. Within the framework of this study, numerical modeling of the pump operation in different modes is carried out and an assessment of the corresponding change in the values of hemolysis and thrombosis is made. It is found that the most dangerous operating modes also change depending on the parameter under consideration: hemolysis demonstrated the greatest dependence on rotation rate, thrombosis — on flow rate. It is also noted that regardless of the damage parameter taken into account, the greatest contribution to blood damage is made by volute, but the balance between the contribution of the pump elements vary depending on the damage parameter under consideration. The obtained results demonstrate that in order to create a safe mechanical circulatory support pump, during its design and optimization process it is necessary to take into account both hemolysis and thrombosis, as well as the dynamics of system operation.
46-53
Improving the efficiency of adsorption filters with a short diffuser by improving their flow part
Abstract
The study examines short-diffuser adsorption filters designed to remove pollutants from vapor-gas mixtures. The design process of the flow path of such filters is considered, which includes the stages of determining the parameters of the adsorbent layer, modeling gas-dynamic processes using numerical methods in the ANSYS CFX program and analyzing the results. The numerical studies cover various options for backfilling the adsorbent, including layer profiling and the use of adsorbent with different porosity, which allows us to assess the impact of these factors on the aerodynamic resistance and overall efficiency of the filter. A design algorithm is also proposed that ensures optimal compliance between the adsorbent layer thickness and the local flow velocity, which helps to increase the protective action time of the filter and improve the quality of cleaning.
54-62
Overview of results in the application of flywheel hybrid transportation systems
Abstract
Among several typical energy storage methods, that flywheel energy storage has advantages such as high instantaneous power, high-performance and long service life, making it perfect secondary energy storage technology for traditional internal combustion engine vehicles. Although some progress has been made in the applied research of flywheel energy storage technology, there are no detailed studies at home and abroad that summarize its application in the vehicle applications. This paper searches the data on «flywheel energy storage», analyzes the research progress of flywheel energy storage in automotive industry, and analyzes the research progress of flywheel energy storage in vehicle applications. The search data show that flywheel energy storage technology for the vehicle applications has been studied for the last 20 years, although it is a niche research area. With respect to two typical flywheel hybrid systems, namely electric and mechanical drive, we have focused on the history of the study, research and validation of mechanical flywheel hybrid system in the automotive industry, as well as the structural characteristics of this system, the current state of research and future research trends.
63-72
Methodology of designing a small spacecraft for technological purposes
Abstract
The paper presents a methodology for designing a small spacecraft to perform the tasks of technological processes in near-Earth space. When designing such a small spacecraft, it is assumed that it will be equipped with a microgravity platform to meet the requirements for micro-accelerations. The methodology is based on the principles of individuality, attainability and controllability. They guarantee the maximum possible consideration of the features of the gravity-sensitive process being implemented, including compliance with the requirements for limiting the micro-acceleration module in the working area of technological equipment and effective control of this implementation. The developed technique can be used in the design of a small spacecraft for technological purposes.
73-79
Study of equipment deformation based on high-speed photography using a vibrating platform
Abstract
To better measure equipment deformation due to vibration in a laboratory environment the project team has introduced an improved Hough transform method for calibration and then carried out the study with the help of a vibration platform. Through experiments, the designed method is successfully used to study the effects of vibration on various types of equipment. The corresponding data and results have successfully proved the effectiveness of using the above process.
80-86
Experimental research of technological elastic deformations of the central holes of gears
Abstract
The research experimentally investigates the occurrence of technological elastic deformations of the central holes of gears of low technological rigidity (non-rigid gears) caused by their fixation in 3-cam self-centering cartridges. The authors present an experimental comparison of the attachment scheme by the involute with the scheme by the external diameter. Moreover, the graphs of distortion of the hole shape from roundness as a function of the torque applied to the wrench handle were plotted. The least squares method was used to confirm the assumed linear dependence of the graphs of hole shape distortion from roundness as a function of the tightening torque applied to the wrench handle. The authors compare the results obtained by the experiment with the obtained earlier using computer modeling, the adequacy of computer models and the reliability of the experimental results. Experimentally it was determined that at fixing by involute there is on 30,23 % less value of hole shape distortion from roundness in comparison with the scheme of fixing by external diameter. As a result, the scheme of fixing by involute with a gear of low technological rigidity is the best in terms of hole shape distortion from roundness in comparison with the scheme of fixing by external diameter.
The scientific novelty is to investigate the influence of clamping forces on the hole shape distortion of a gear of small technological rigidity when fixed by its external diameter and involute in a 3-cam self-centring chuck. The resulting data allows scientifically justifying assignment of parameters of clamping devices in the production of gears of small technological stiffness used in aeronautical vehicles.
87-99
Effect of volumetric modification with nanosized zirconium dioxide particles on structure and mechanical properties of composite material based on polytetrafluoroethylene
Abstract
The article demonstrates the influence of the concentration of nanosized particles of zirconium dioxide ZrO2 applied as a bulk modifier-filler on the structure and strength characteristics of polytetrafluoroethylene-based composite. samples with concentrations of 0 %, 4 %, 8 % and 26 % of ZrO2 nanosized zirconium dioxide particles were obtained by the sintering method in a mould in conditions of volumetric limitation of thermal expansion. The authors analyzed the structural-chemical state and elemental composition of the samples by X-ray photoelectron spectroscopy using Surface Science Center (Riber) and scanning electron microscopy with application of energy-dispersive analysis. Moreover, the hardness was determined on a Shore type A TWR-AM (durometer) with an analogue indicator. Wear tests were carried out on the UMT-2168 universal friction machine by the mode without lubricating fluid at the 5 N constant load, peripheral speed with the 0,32 m/s abrasive sheet. The results of the conducted research were confirmed under full-scale test conditions. As a result, the authors present recommendations on the percentage composition of nanosize filler in polytetrafluoroethylene for seals in friction units.
100-106