卷 19, 编号 1 (2025)

Background: The paper considers numerical modeling of the transverse flow around a five-row corridor-type tube bundle with an air flow at coupled heat exchange. The studied model is typical for air-cooled heat exchangers such as air condensers, oil coolers or cooling towers. The outer surface of the pipes had a temperature higher than the temperature of the air flow. The air flow rate corresponded to the Reynolds number in the narrow section of the tube bundle, typical for heat exchangers of the abovementioned type. The results of numerical modeling are determined by the quality of the mesh. At the same time, the more the calculation cells and the smaller their size, the more computational power and time budget are required to solve the problem. However, the results obtained are closer to a field experiment.

Aim: Determination of the level of detail of the mesh, at which obtaining correct results of numerical simulation of coupled heat transfer is possible.

Results: The influence of the quantitative characteristics of six mesh variants on the value of the average heat transfer coefficient is estimated. The variants differed in the degree of detail: the number and size of cells (from large to small). In each case, the values of the average heat transfer coefficient are obtained, determined by the degree of error of the numerical experiment. The data obtained were compared with the data obtained when solving the criterion equations of convective heat transfer using three methods.

Conclusion: The error of finding the heat transfer coefficient by the considered methods is determined. It is found that the results of numerical modeling with a high degree of detail are close to the results obtained in the calculation using the Baer method. The results obtained can be useful in numerical modeling of flows in heat exchangers with transverse flow around tube bundles.

Background: Currently, industrial controllers solve numerous diversified tasks. One of the main tasks for the programmed logical controller (PLC) is data transferring to other controllers, devices and systems. The data can be stored in the controller or be obtained from external terminal devices, other controllers, sensors etc.

Aim: Increasing the abilities of an industrial controller by means of integration of additional interaction protocols.

Methods: Currently, data transfer protocols in automation, control and telemechanics systems are critical as they give an opportunity of data exchange between devices of all levels of automation. The device’s capability of sending and receiving the information allows using these solutions in the systems that require accumulation, analysis, processing and displaying the data demanded to the system.

Results: Based on the problem related to the development of the integration of interaction protocols in an industrial controller, the interaction of the controller with external devices allows implementing control on mechanisms, data analysis for further information processing, accumulation and processing of the data for transferring to the upper-level systems like the SCADA (supervisory control and data acquisition) systems.

Conclusion: As the result of the conducted study, domain analysis was conducted, main types of data transfer protocols, widely used in industrial controllers, were found, their purposes and main features were denoted. The method of integration of the interaction protocol into the controller’s programming environment obtained in this study allows for the complete implementation of the new data transfer method by following certain rules.

Background: Pumps with increased noise, vibration and harshness (NVH) requirements are in high demand in various fields of both civil and military equipment, especially underwater, due to stricter standards of sound pollution and the development of vehicle tracking systems. Disc pumps are one of the “quietest” pumps, due to their simple design and the absence of elements that cause eddy formation, but at the same time they ensure less pressure than, for example, vane pumps, which is why the former have not been studied in detail at the moment. Despite this, these machines require optimization, design innovations and deeper analysis in the field of vibrational intensity reduction.

Aim: Study of vibrational intensity of a disc pump using hydrodynamics and solid-state modeling, optimizing the geometry of the flow part to achieve continuous flow.

Methods: The calculation is a combination of computational fluid dynamics and computer-aided design, was performed in the Simcenter STAR-CCM+ software package, the simulation included unsteady conditions, the Detached Eddy Simulation (DES) turbulence model was selected for hydrodynamics, vibrational dampers were modeled. The HEEDS software is used for optimization.

Results: A 3D model of the entire pump, a vibration acceleration spectrogram, and a velocity field in the optimized flow part were obtained.

Conclusion: The practical value of the study lies in the obtained qualitative and quantitative data on the vibrational intensity of disc pumps, as well as in the correct body of mathematics for optimizing the geometry of the flow part to achieve non-cavitating flow in the flow part and maximum hydraulic efficiency, and, as a result, to achieve better noise behavior of the pump.

Background: The issue of using vibratory machines for compaction of road construction materials is that during the vibration process, the energy of the vibratory drum is spent on useful compaction work only in the half-period of oscillations when the vibratory drum moves «downward». In the second half of the period, the oscillating vibratory drum moves «upward» and does not produce useful compaction work on the material. Thus, more than half of the energy spent on excitation of vibration is wasted, which increases energy costs and reduces the share of useful work of the vibratory machine.

Aim: Increasing the efficiency of using the vibration exciter energy for useful work.

Methods: From the point of view of increasing the share of energy expended by the roller on the work of compacting the material, it is necessary to reduce the «idle» component of the work on the «upward» motion of the vibratory drum. This principle is implemented in the following design: a vibratory roller contains a frame and a working element consisting of two rollers, the main vibratory roller and the additional compensating roller, articulated by means of a double-arm lever through a support and rotary device. During the compaction process, during that half-period of oscillations, when the vibratory roller moves upward, the force is transmitted by means of a double-arm lever, through a support and rotary unit, to the compensating roller, which moves downward and has a useful effect on the compacted material and compensates for part of the lost energy of the main vibratory roller.

Results: A scheme for modeling the impact on the supporting surface has been designed. Taking into account the constructed scheme, reasonable weight-and-dimensional characteristics of the original compensating combined working body of the road roller have been determined.

Conclusion: Based on the results of the dynamic analysis conducted in the study, the design features of the original working body of the road machine were determined, allowing identification of its reasonable weight-and-dimensional characteristics. The obtained results make it possible to analyze, in the first approximation, the design parameters for the development and production of domestic high-performance road equipment for the construction of highways and other transport facilities.

Background: In recent years, much attention has been paid to brushless electric machines, which have a long service life and do not require maintenance in operation. Switched reluctance machines, in particular inductor alternators, are widely used due to their design simplicity and high reliability. This paper discusses salient pole type switched reluctance motors with a star-shaped rotor and presents the design procedure of a magnetic circuit as well. The proposed approach enhances the accuracy of modeling electromagnetic energy conversion processes and can also be applied in the design and optimization of switched reluctance generators for both transportation systems and stationary power installations.

Aim: To present design procedure of the magnetic circuit of salient pole type switched reluctance machines.

Methods: The design procedure of specific conductivities in the air gap and the groove area using the method of variable separation into a Fourier series.

Results: A review of salient pole type switched reluctance machines with various magnetic systems and design is carried out. The advantages and disadvantages of the magnetic circuit of switched reluctance machines are determined and the most optimal design of the star-shaped rotor is selected, which ensures maximum material utilization.

Conclusion: The design procedure of the magnetic field of a switched reluctance machine by means of determining the specific conductivities in air gap with the method of variable separation into a Fourier series is presented.