Founded in: 1993 Field of science and issues in focus: Journal reflects the problems of the development of theory, design practices and technologies of aviation-space technology; control systems; electronic systems; computer systems and information technologies in the management of enterprises, programs and projects. The edition is included in the List of Scientific Professional Publications of Ukraine (Category "Б") by the Ministry of Education and Science of Ukraine № 975 of 11.07.2019. Specialties (ISCED-F 2013): 0413(073, 275) Management and administration 0541 (113) Mathematics 0612 (126) Database and network design and administration 0613 (121, 122) Software and applications development and analysis 0688(124) Inter-disciplinary programmes and qualifications involving Information and Communication Technologies 0713 (141, 142) Electricity and energy 0714 (173, 174, 175, 176) Electronics and automation 0715 (131, 142) Mechanics and metal trades 0716 (134, 142, 173) Motor vehicles, ships and aircraft 0788 (132) Inter-disciplinary programmes and qualifications involving engineering, manufacturing and construction 1041 (272) Air Transport ISSN: 1727-7337 (Print), 2663-2217 (Online) Media identifier No. R30-01717 (Decision dated 10/26/2023 No. 1146). Indexing: Vernadsky National Library of Ukraine; NRAT; Ulrichsweb Global Serials Directory; OCLC WorldCat; DOAJ; Index Copernicus; CiteFactor; AcademicKeys; Infobase Index; WorldCat; Google Scholar; Scillit; OUCI; Sherpa Issues and articles from 2017 have a DOI from CrossRef Founder: National Aerospace University «Kharkiv Aviation Institute» Periodicity: 6 issues per year (+ special issues). Editor-in-Chief: Yepifanov Sergiy Executive secretary: Leshchenko Oleksandr Editorial office address: 61070, Kharkiv, 17 V. Manka Str., chair 302. Tel.: +38(057)7884381, +38(067)1205222 E-mail: ntrio@khai.edu Archives of issues are HERE & HERE This journal provides immediate open access to its content on the principle that making research freely available to the public supports a greater global exchange of knowledge This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License
Національний аерокосмічний університет "Харківський авіаційний інститут"
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Development of universal mathematical model and computer program for online modeling of valved and valveless pulse jet engines
In connection with the appearance of new projects of unmanned aerial vehicles (UAVs) with a pulse jet engine, modeling their parameters and characteristics becomes relevant. However, despite a large number of research works and developed theoretical models of the working process, no calculation programs suitable for wide practical use and modeling of a pulse jet engine have been created for many years. Therefore, the subject of this work was valved and valveless pulse jet engines, and the goal of the work is to create a mathematical model and a real online program for modeling the working cycle of a pulse jet engine, available to a wide range of users. Therefore, it was necessary to solve the following problems: develop a mathematical model of processes in the combustion chamber, intake system, and resonance tube of a pulse jet engine, develop and debug an engine modeling program, place it on a special website, and model known engines to verify the model. Research methods. The model is based on the thermodynamic model of the process of volumetric combustion and gas exchange in the combustion chamber, on the method of "piston" analogy for non-stationary gas and air flow in the resonance pipe of the pulse jet engine and in the valveless engine’s intake pipe. The model includes a mathematical description of the dynamics of the valve petal movement and the non-stationary process of heat exchange with the walls. Results. The first developed special online program Pulsejet-Sim, built on a special data structure with division into server and client parts, provides the implementation of the model. The program is implemented as a web-oriented software service that does not require downloading to the user’s computer compared to traditional desktop packages and programs. This allows instant calculations using server resources and secure data storage in the cloud. Conclusions. With the help of the developed program, preliminary mathematical modeling of known pulse jet engines has been performed, which has shown satisfactory qualitative and quantitative agreement between the modeling results (error less than 10%) and the available experimental data on the main parameters. Previously unknown characteristics of pulse jet engines, including the indicator diagram, were obtained.
Copyright (c) 2025 Olexander Khrulev, Valeriy Muntyan
Validation and verification of the turbulence model and the calculation grid topology in flow simulation in a tandem compressor cascade
The study substantiates the turbulence model and the topology of the computational grid when modeling the flow in a tandem compressor cascade. The research object is a tandem compressor cascade. This study aims to verify and validate the turbulence model and the computational grid topology when simulating the flow around a tandem compressor cascade. To achieve the goal, the following tasks were solved: a three-dimensional model of the working medium was built when simulating the flow around the tandem compressor blades; the flow around the tandem compressor blades was modeled using four models of turbulent viscosity SST, SST Gamma-Theta, LRR, k-ω was carried out; modeling of the flow around the tandem compressor blades was modeled using three topological calculation grids; and the obtained results were evaluated by comparing the results of a numerical and physical experiment. A 3D model of the stand was built to conduct a numerical experiment of flow simulation, on which 5 blades of the first row and 13 blades of the second row are placed. To create a calculation grid, a structured grid using so-called O-grid blocks is built around smooth aerodynamic profiles. Three calculation grid versions were built to carry out the research: calculation grid 1–138340, grid 2–224546, and grid 3–270633 elements. Four turbulence models were tested in the work – SST, SST Gamma-Theta, LRR, k-ω. Results: The obtained calculation results allow us to state that Ansys CFX models gas-dynamic processes occurring in a compressor with tandem blades with sufficient accuracy. In addition, the SST turbulence model gives the greatest convergence of the modeling results with the calculation results. Grid 3, which corresponds to 50 calculation cells along the blade chord, gives the greatest convergence when determining the grid’s pressure losses. Consequently, the SST turbulence model and grid size with at least 50 calculation cells along the chord are selected for further research. The scientific novelty and practical significance of the conducted research are based on the data obtained for the verification and validation of the turbulence model and the topology of the calculation grid in the simulation of the flow around a tandem compressor cascade.
Copyright (c) 2025 Roman Lapii, Yuriy Tereshchenko
Modeling and investigation of the efficiency of a centrifugal fan with backward-curved
Particular attention is paid to improving the efficiency of ventilation systems in mechanical engineering, especially in the design of power equipment and aircraft. One of the promising directions in this area is optimizing the aerodynamic characteristics of centrifugal fans equipped with backward-curved blades, which provide high efficiency over a wide range of operating conditions. The fan design, specifically the shape and type of impeller, significantly affects the total pressure losses in air supply channels and the overall aerodynamic performance of the system. This study presents the results of a numerical investigation of the characteristics of a centrifugal fan with backward-curved blades, comparing two design configurations: one with an open impeller and the other with a closed impeller. Combining CFD modeling with geometric optimization enhances the accuracy of calculations and contributes to the overall effectiveness of the design solutions. The influence of the impeller type on airflow rate, total pressure, and efficiency is given particular attention. Numerical simulations were conducted to evaluate the flow characteristics inside the impeller and at the fan outlet using Ansys CFX. The BladeGen module was used to create the impeller geometry, which allowed for the precise shaping of the blades and enabled further analysis in the CFD environment. Additional aerodynamic evaluations of the fan were conducted using various simulation tools within Ansys, providing a more comprehensive understanding of performance under different design conditions. The numerical modeling results enabled a detailed analysis of how the aerodynamic performance of the fan depends on the type of impeller used. The efficiency of two types of impellers under identical boundary conditions is a distinctive feature of this study. The closed impeller provides superior performance and greater stability of operational parameters, particularly under high-load conditions. This improvement is attributed to more efficient airflow control, reduced vortex formation, and decreased losses caused by air leakage through the system’s gaps. The numerical approach developed in this research allows for the formulation of general recommendations regarding the selection of the impeller type depending on the ventilation system’s specific operating conditions. The combination of CFD simulation and geometry optimization not only ensures more accurate predictions of fan behavior but also supports the development of more energy-efficient and reliable ventilation equipment. Thus, the findings of this study have practical implications for the engineering design process, particularly in sectors where ventilation performance is critical to system efficiency and operational reliability.
Copyright (c) 2025 Kostіantyn Kapitanchuk, Serhii Yakymchuk
Assessment of the thrust force of UAV slotted propellers
The thrust characteristics of slotted propellers of an unmanned aerial vehicle are the subject of the study. The study object is a slotted propeller of an unmanned aerial vehicle. This study aims to increase the thrust of the propeller of an unmanned aerial vehicle by using special slots on the blade surface. The following tasks were solved to achieve the stated goals: development of propeller models with special slots; numerical simulation of the flow past propellers with special slots in the rotation frequency range from 3990 to 6705 rpm in the ground operating mode; analysis of the thrust characteristics of the studied propellers in a given rotation frequency range in the ground operating mode. The study was conducted for propellers with special slots, the width of which was 2 mm and the blade length was 30%.8 models of slotted propellers were developed. A numerical experiment was used to calculate the thrust of the studied propellers. Results: The thrust generation is affected by the presence of a slot on the propeller blade. Notably, not only the presence of a gap but also its location has an effect. In the presence of a gap on the propeller blades in the middle part of the blade, an effect of improving the thrust efficiency is observed for all location options, but not in the entire range of considered propeller rotation frequencies. The results of the conducted study of the thrust efficiency of air slot propellers of unmanned aerial vehicles showed that such a propeller can generate a thrust force up to 21% higher than the basic propeller without gaps with rationally selected gap parameters. A further direction of this study is the analysis of the normal characteristics of a propeller with slots. Scientific novelty and practical significance of the work: the thrust characteristics of air slot propellers for unmanned aerial vehicles were studied for the first time. The obtained results can be used to develop promising propellers with increased thrust efficiency.
Copyright (c) 2025 Liubov Markovska, Kateryna Balalaieva, Anton Balalaiev
The influence of blade temperature on the aerodynamic characteristics of the profile
The subject of the study is the aerodynamic characteristics of the compressor blade concerning the effect of its surface thermal heating. The object of this study is the compressor grid of an axial compressor impeller. This study aims to evaluate the influence of blade surface temperature on the aerodynamic characteristics of the profile. The following tasks were set and solved in the study: flow modelling in the compressor impeller considering uniform heating of the blade to temperatures in the range of Tb/Ta = 1...3 with a step of 1 at various values of the axial inlet flow velocity from 70 m/s to 140 m/s with a step of 10 m/s; calculation of the flow deflection angles for each case and construction of corresponding dependencies; and assessment of the blade heating impact of the compressor impeller on the aerodynamic characteristics of the profile. The study was carried out using the numerical experiment method in the Ansys Workbench Student software environment. Results: The influence of the uniform heating of the blade surface on the aerodynamic characteristics of the profile was evaluated. The flow deflection angles were calculated at different ratios of blade surface temperature to ambient temperature, Tb/Ta = 1...3, and axial flow velocities from 70 m/s to 140 m/s with a step of 10 m/s. A decrease in the flow deflection angle was observed with increasing temperature, which leads to reduced air compression efficiency. At the same time, at an angle of attack of 5° and a blade temperature of Tb/Ta = 2, the flow turning angle is significantly lower than other values. With the increasing temperature ratio of the blade surface to ambient air, the flow deflection angle decreases. Blade surface heating leads to the formation of flow stagnation zones. Sudden jumps in the graphs of dependencies are difficult to interpret clearly and unambiguously.The scientific novelty and practical significance: New data on the influence of blade surface temperature on the aerodynamic characteristics of the profile have been obtained. The obtained results can be used to optimize the turbofan stage of gas turbine engines and in the development of advanced three-stream gas turbine engines. Sudden value jumps on the resulting dependency graphs are difficult for clear and correct interpretation.
Copyright (c) 2025 Volodymyr Otroshchenko, Maryna Pikul
Determination of thermal-physical characteristics of thermal materials at high temperatures
This study presents an experimental–numerical method for determining the thermal conductivity and heat capacity of thermal insulation materials (TIM) at elevated temperatures. The derived thermophysical characteristics were compared with the known properties of the analogous materials. Two TIMs ZYF-150 and NAB (manufacturer: ZIRCAR Ceramics, Inc., USA), were investigated in this study. Both materials exhibit a fibrous, highly porous structure reminiscent of felt, allowing them to easily conform to a given volume and shape. In ZYF-150, the fibers are composed of zirconium dioxide (ZrO₂) stabilized with yttrium oxide (Y₂O₃), whereas NAB consists of aluminum oxide (Al₂O₃) fibers containing silicon dioxide (SiO₂) impurities. In the experiments, the samples were heated using a propane–oxygen torch operating in a reducing flame mode, with the use of a carbon–carbon composite interlayer. This prevented any direct mechanical impact of the flame on the sample surface while ensuring efficient conductive heat transfer. Finite element simulations of the heating process were performed using COMSOL Multiphysics®. The experimentally obtained surface temperature measurements were applied as boundary conditions to solve the inverse heat conduction problem. Consequently, the temperature dependencies of the thermal conductivity coefficients for the ZYF-150 and NAB materials were established. For the NAB material (λNAB5), the root-mean-square deviation was 15.5% with a maximum relative error of 23.6%, whereas these values were 21.5% and 44% for ZYF-150. The comparative analysis of the thermophysical properties of the investigated materials with those of similar materials confirms the validity of the developed methodology. The obtained results are expected to be useful for material scientists working on thermal protection materials and for the design of thermal protection systems based on them.
Copyright (c) 2025 Dmytro Borovyk, Yuriy Evdokimenko, Gennady Frolov, Oleksandr Kolotylo, Alexander Potapov, Nataliya Suetova
Estimation of the service life of aircraft panel structures under random crack growth rates
The stochastic nature of fatigue crack growth rates must be considered when predicting the cyclic service life of aircraft fuselage skin structures. This study proposes a modelling approach based on the Paris power-law relationship. Analysis of empirical data from various literature sources demonstrates that a linear inverse correlation exists between the Paris law coefficients C and m for a wide range of structural aluminium alloys, wherein log C decreases as m increases. Based on this dependence, we propose a modified fatigue crack growth model that uses only one governing parameter: the exponent m. This contrasts with the conventional Paris equation, which uses two governing parameters. The crack propagation behavior is represented as random by treating m as a random variable. Numerical simulations were performed for crack growth in sheet structures under the assumption of a uniformly distributed random exponent m, and the operating stress range was calculated using actual fuselage geometry. The resulting predictions define the structural life until the critical crack length is reached, corresponding to the material’s fracture toughness. The minimum service life across all random realizations of m within the specified range provides a conservative and practical prediction metric. A parametric numerical study was carried out for multiple stress ranges to account for variable loading conditions. The shortest predicted life to critical crack growth was determined for each case, assuming a constant initial half-crack length of 0.003 m. The relationship between the minimum residual life and applied stress range exhibits a linear trend in semi-logarithmic coordinates, with a correlation coefficient equal to one.
Copyright (c) 2025 Sergey Ignatovich, Iryna Dzhavadova
Method of integrated design of truss composite tail beam of the fuselage of a multipurpose light helicopter
The object of the study is a truss composite tail beam of the fuselage a multipurpose light helicopter. The subject of this study is the integration of CAD/CAM/CAE/PLM methods in the design of a truss composite tail beam of the fuselage multipurpose light helicopter. This study aims to scientifically substantiate the integrated design method of a composite truss tail beam of the fuselage of a multi-purpose light helicopter. Task: to develop an integrated design method for a truss composite tail beam of the fuselage of a multipurpose light helicopter, and to formulate the topological optimization problem of a composite tail beam of the fuselage of a multipurpose light helicopter. This study proposes an integrated design method for a truss composite tail beam of the fuselage of a multipurpose light helicopter and presents its scientific justification. The proposed method for the integrated design of a truss composite tail beam of the fuselage of a light helicopter is based on the use of an integrated CAD/CAE/CAM/PLM information environment for designing and maintaining the life cycle of helicopters. This environment integrates various software tools that encompass the full cycle of helicopter development, production, operation, and maintenance. This approach significantly increases work efficiency, reduces costs, and ensures the high quality of the final product. The proposed method uses topological optimization and creates a parametric master geometry of the tail beam of the truss structure, a composite material is designed, and the strength and mass characteristics of the tail beam are studied using CAD/CAE methods. The purpose of the topological optimization of the tail truss beam is to minimize the tail beam mass when applying strength constraints. Further research should test the proposed method of integrated design of the truss composite tail beam of the fuselage of a multipurpose light helicopter. Scientific novelty and practical significance of the obtained results: for the first time, a method of integrated design of the truss composite tail beam of the fuselage of a multipurpose light helicopter is proposed based on the use of topological optimization and creation of parametric master geometry of the truss structure’s tail beam.
Development and testing of the solid fuel power plant axisymmetric model applied to regimes of combustion chamber dynamic instability
Innovative use of energy resources in deep space planets is a technology that allows a significant increase in space exploration based on the design of rocket power plants, particularly for lunar landing modules using (Lunar Regolith) propellants. Simultaneously, for using such local propellants, effects were found based on the fire test of the developed physical model of the landing module power plant. These effects are characterized by combustion product vortices, thrust oscillations, incomplete combustion or extinction during propellant combustion, as well as the possible development of unstable dynamic processes during combustion product flow in the chamber of a solid-propellant rocket power plant. Unacceptable pressure rise and a sharp increase in the local temperature of combustion products can lead to the strength failure and destruction of the combustion chamber structure of rocket power plants, and transition to a critical operation mode of the rocket power plant. Based on the theoretical determination of the non-stationary process parameters in the test propellant combustion chamber during the combustion product flow, the possibility of implementing this type of working process instability (self-oscillations) in a power plant is shown. The thermodynamic characteristics of a power plant using such a metallized propellant have been numerically determined, and a preliminary analysis of the experimental and calculated acoustic oscillation parameters (thrust, dynamic pressure components, and axial velocity) was performed. The main possible directions of modern research on working process instability in a power plant with propellant obtained from lunar regolith have been determined. The study aims to identify the mechanism of pressure oscillation development in the combustion chamber, analyze and model phenomena associated with propellant ignition (including ignition delay), combustion, and heat transfer, analyze resonant damping in a power plant, develop methods for optimizing the chamber design to reduce the level of pressure oscillation amplitudes, and study the role of aluminum droplets combustion in aluminized propellant in the realization of power plant working process instability.
Copyright (c) 2025 Olexiy Nikolayev, Inna Bashliy
Mathematical modeling of the dynamic processes during check valve operation in the branched reconfigurable feed system of a liquid rocket engine
The dynamic processes in the branched reconfigurable propellant feed system of a liquid rocket engine (LRE), where check valves are used to ensure engine start-up, are the subject of this study. This study aims to develop a mathematical model of the dynamic processes during the operation of a check valve using computational fluid dynamics (CFD) and perform mathematical modeling of the transient processes in the branched reconfigurable feed system during LRE start-up. The objectives of this research are: to conduct a series of CFD calculations of the pressure distribution on the poppet of the check valve, to obtain the dependence of the flow force acting on the poppet on the poppet stroke and pressure drop across the valve, and to simulate the transient processes in the branched reconfigurable feed system of the LRE during start-up. Methods used: CFD, computational mathematics, vibration theory, and impedance methods. The following results were obtained. We developed a mathematical model of the dynamic processes in the branched reconfigurable feed system of an LRE, which includes check valves. The impedance method was used to match the frequency characteristics of different branches of the hydraulic system, derived from systems with distributed and lumped parameters, in constructing the mathematical model of hydraulic line dynamics. CFD modeling was used to construct the mathematical model of check valve dynamics. The pressure distribution of the fluid on the poppet from the inlet side was determined as a function of the poppet stroke and the pressure drop across the valve based on the simulation results. This made it possible to calculate the flow force acting on the poppet under different conditions. The dynamic processes in the branched reconfigurable hydraulic system were mathematically modeled. During the joint valve operation period, the propellant is supplied from two sources: the start tank and the fuel pump. During the motion of the poppets, their longitudinal oscillations are possible due to a drop in static pressure when the flow through the valves begins. Conclusions. Switching to steady-state propellant feed from the pump occurred smoothly, without noticeable dynamic surges or drops in propellant flow to the gas generator.
Copyright (c) 2025 Oleksandr Cherniavskyi, Serhii Shevchenko, Sergey Dolgopolov
Development and modal analysis of a discrete model of a wing with engine
The object of this study is the vibrations of a wing with an engine. This study aims to develop a model with the smallest possible number of degrees of freedom (DOF) for solving the influence of imbalance and engine axis tilt on aeroelastic oscillations of the wing console. Current economic constraints and environmental regulations require the development of more efficient aircraft configurations. The observed trend in aircraft design to reduce aerodynamic drag and fuel consumption and emissions is to increase the wing aspect ratio. However, under the same operating conditions, a thin wing is more flexible and subject to higher deflections. This effect can lead to changes in the dynamic behavior and aeroelastic response, potentially leading to instability. Following the requirements of AC 25.629-1B, the absence of aeroelastic instability must be demonstrated for all speed and altitude combinations. In this case, all possible engine operating conditions and combinations of conditions must be considered to consider the influence of gyroscopic loads and thrust on aeroelastic stability. A review of publications showed that models with a maximum of three DOF are used to study the aeroelasticity of a high aspect ratio powered wing. A discrete wing model with an engine has been developed. This model has 23 DOF. This model significantly expands the capabilities of the numerical analysis of aeroelastic oscillations compared with the generally accepted model with three DOF, which reduces wing oscillations to oscillations of an average profile. This number of DOF is sufficient to approximate the shapes of the wing’s bending and torsional oscillations in the frequency range up to the engine speed. A rotating imbalance force can be applied to the concentrated mass, which models the engine at the pylon end. The effect of imbalance in any given plane on the dynamics of the model can be investigated to meet the requirements of AC 25.629-1B. Modal analysis of the discrete model was performed. The obtained frequencies and modes of oscillations were similar to those of the high aspect ratio wing of a transport aircraft. In the future, this model will be used to investigate the effect of engine imbalance and tilt on aeroelastic oscillations, flutter, and the transition to limit wing oscillation cycles.
Copyright (c) 2025 Sergey Filipkovskij, Evgen Polyakov
Influence of stiffener parameters on the vibrational characteristics of 3D-printed honeycomb beams made of PLA
Additive manufacturing has provided a universal tool that enables the fabrication of three-dimensional objects of any complexity with minimal material consumption. Fused Filament Fabrication (FFF)-based 3D printing holds a dominant position in prototype and small-batch production of components. At the design stage, depending on the anticipated operating conditions, ensuring dynamic stability and strength under resonant vibrational excitation is crucial. A theoretical method for determining the frequency and modal spectrum of a component and an experimental verification of the obtained results have been developed for this purpose. This study investigates the vibration characteristics of honeycomb-structured PLA beams with dimensions (mm) 192.63×29.7×5.0 and an internal rib pitch of 5.0 mm, which were produced via 3D printing. The shell and rib thicknesses were set to be equal. The frequencies and mode shapes of five beam samples with 0.8 mm thick shell were experimentally determined using real-time electronic speckle pattern interferometry. The boundary conditions of the beam were free. The numerical vibration characteristics obtained by the finite element method were experimentally validated. The root-mean-square error of the calculated frequency values ranged from 0.6% for bending modes to 2.7% for torsional modes. Theoretically, the influence of shell and rib thicknesses in the range of 0.8 mm to 2.0mm on the vibrational behavior of the beam was studied. Reducing the rib (shell) thickness increases the natural frequencies of the honeycomb-structured beam. This dependence is more significant for torsional frequencies than for bending frequencies. Compared to a solid beam of the same external dimensions and material, the bending frequencies of the honeycomb beam increased by 5%–15%, while the torsional frequencies increase by 1.3 to 1.8 times, depending on rib thickness.
Copyright (c) 2025 Mykhailo Tkach, Yurii Halinkin, Yurii Zolotoy, Iryna Zhuk, Andrii Shynkarenko, Oleksandr Kostrikov
Errors in relative deformation transmission in a strain gage device at elevated temperature
The subject of study in this article is the distribution of relative deformations in the system of the strain gauge used in the study. This study aims to identify factors and study their influence on the accuracy of measuring relative deformations. Task: to conduct a simulation of the distribution of deformations to assess the distortions caused by the ineffective transfer of stresses through the bonding layer, and to study the influence of design factors on the measurement error. Obtaining reliable data and making adjustments from a strain gauge of increased thickness operating in high-temperature conditions. Method for solving the problem: computational and analytical. Thus, the results of the computational experiment demonstrate the high efficiency of the developed strain gauge device, particularly under significant temperature gradients. The key factor ensuring this efficiency is not only a stable strain transfer coefficient, which minimizes the influence of external factors on the accuracy of measurements, but also effective leveling of the thermally caused additive error. This process is achieved by the mutual arrangement of strain gauges and the use of a high-temperature insulator-connector material. The obtained data emphasize the potential of using the device in environments with unstable thermal conditions, where accurate deformation measurements are critical for ensuring reliable operation and monitoring the condition of the parts under study. Conclusions. The deformation characteristics of the strain gauge device installed on the part model were investigated using computational experiment methods when heat flow was applied and loaded. The sensitive elements perceive the deformation from the part at the level of 96%. The research results have theoretical and practical significance for increasing the accuracy of research at elevated temperatures and the possibility of making corrections to the measurement results if necessary. Further research and improvement of the strain gauge device are proposed, and the advantages of the used technical solution are analyzed.
Copyright (c) 2025 Serhiy Kryhin, Yuriy Husyev, Yuriy Torba, Oleksandr Bilohub
Study on the influence of scanning strategy parameters on the integrity of the finished product made of Inconel 718 heat-resistant alloy
Selective laser melting technology, which is an additive manufacturing process, uses a laser beam to fuse metal particles by scanning, following a trajectory according to a given three-dimensional shape based on a CAD model, on the surface of a powder layer. The purpose of the work: the study of the influence of the parameters of the scanning strategy (checkerboard scanning) on the integrity of the finished product made of the heat-resistant Inconel 718 alloy. The task of the research: the development of CAD models and manufacture test samples with dimensions of 10x10x10 mm with manufacturing parameters: power - 80...130 W with a step of 10 W, scanning speed - 850 mm/s, layer thickness - 30 μm; with variable scanning strategy parameters (distance between tracks 0.04...0.09 mm with a step of 0.01 mm); determination of the integrity of test samples was carried out by the metallographic method of research; providing recommendations on scanning strategy parameters to ensure high density finished products. Research methods. Computer modeling, 3D printing using an Alfa-150 printer with Inconel 718 heat-resistant alloy powder, and microscopic studies using an AxioVert 200M Mat optical microscope. Scientific novelty. The influence of manufacturing parameters, namely, power and distance between tracks, on the integrity of the finished product is established. Practical significance. Recommendations for scanning parameters in the manufacture of parts by the method of selective laser melting from heat-resistant alloy Inconel 718 have been developed. Results. The samples have structural defects (pores). Based on the results of the calculations of the specific energy density, it was established that the formation of this defect is connected with the high specific energy at which the manufacturing was carried out. The defects have periodicity and are related to the overlap between the tracks. According to the results of the experiment on the influence of manufacturing parameters in checkerboard order with a layer thickness of 30 microns, it was established that the test samples were printed with the following parameters: speed (850 mm/s), power (80-130 W), distance between tracks (0.04-0, 09 mm) - cannot meet the "satisfactory" rating, and the modes cannot be recommended for the further manufacture of finished products.
Copyright (c) 2025 Sergey Adjamskiy, Ganna Kononenko, Rostyslav Podolskyi, Sergey Baduk
Calculation of parameters of profiling technology with longitudinal tension of thin-walled parts of heat exchangers
Plate heat exchangers are produced at specialized enterprises using powerful press equipment and special stamping equipment. Heat exchangers are heat transfer elements that transfer heat between two media. The shape and dimensions of the heat exchangers are selected based on the physical properties of the coolants and their movement. Traditional technologies for profiling heat transfer elements by stamping are energy-intensive and, in some cases, cannot ensure the quality of heat exchangers made of high-strength alloy steels, aluminum, and copper alloys. In modern conditions, it may be rational to produce heat-transfer thin-walled profile elements based on the technology of profiling by local force with longitudinal tension, which allows the production of a variety of thin-walled profiles with the necessary accuracy and dimensional stability. This study aims to develop an engineering methodology for calculating force parameters for adjusting profiling equipment and determining the geometric parameters of technological equipment. It is possible to obtain the necessary dependencies when solving the rigid-plastic bending problem of a staff under the action of a longitudinal tensile load. In the theoretical analysis of the process of staff deformation, hypotheses and assumptions were used that are used in the study of rigid-plastic bending and are based on the deformation theory of plasticity. The hypothesis of the plane sections is used. This problem was considered for an ideal rigid-plastic material with linear reinforcement. The results obtained: the stress-strain state of a staff made of a material with linear reinforcement during its rigid-plastic bending with longitudinal elastic tension was analyzed. The position of the neutral stress layer in the cross-section was determined. Dependencies were obtained to determine the relative bending moment required for bending the staff with longitudinal tension. Analytical dependencies that allow determining elastic springback and residual curvaturewere obtained. Software was developed for practical calculations of geometric parameters of technological equipment and power parameters of profiling equipment.
Copyright (c) 2025 Anton Novoshytskyi, Svitlana Bodu, Dmytro Fabritsyiev, Aleksandr Shumilov, Aleksandr Nikolaiev
Nozzle optimization for cold gas dynamic spraying
This study investigates the influence of nozzle geometry on the characteristics of the cold gas dynamic spraying (CGDS) process under low-pressure conditions (up to 1.0 MPa). This study aims to develop a methodology for the multicriteria optimization of nozzle geometric parameters to achieve the required particle velocity for the formation of high-quality coatings using CGDS at low pressure. The research objectives are as follows: to identify the key geometric parameters of the nozzle (critical and exit diameters, and the length of the divergent section) that have the most significant impact on particle velocity; to develop an analytical model based on isentropic gas-dynamic modeling; and to perform statistical analysis using the experimental design method. Methods. An interdisciplinary approach was used, combining isentropic flow modeling, response surface methodology (RSM), second-order regression analysis, and analysis of variance (ANOVA) to achieve high-accuracy modeling of complex interactions. A total of 47 computational-analytical experiments were conducted to build a mathematical model describing particle velocity as a function of five factors related to nozzle geometry, gas temperature, and inlet pressure. Results. A precise regression model (R² > 0.95) was developed to predict the velocity of aluminum particles with a diameter of 25 µm at the nozzle exit with high reliability. The optimal parameter combination achieving a velocity exceeding 499 m/s was determined, ensuring high-quality coating. It was proven that the proper selection of nozzle geometry and gas parameters allows effective energy transfer to powder particles even under limited pressure (1 MPa). Conclusions. The proposed nozzle design optimization method improves the efficiency of the CGDS process by increasing particle velocity without increasing gas pressure, which is especially important for energy-efficient technologies for applying protective and restorative coatings under modern engineering challenges. The practical application of the obtained results can enhance industrial spraying technologies, reduce energy consumption, and extend the service life of refurbished components.
Copyright (c) 2025 Oleksandr Shorinov, Nina Savchenko, Olha Shypul, Dmytro Bilan
Devising a method for determining the strength reserves of design elements of bandage assemblies of turbogenerators
The complexity of assessing the safety margins of design elements and assemblies of high-power turbogenerators under the influence of temperature and force loads is due to the need to solve a set of problems: gas-dynamic, temperature, and thermoelastic problems. When designing a turbogenerator rotor bandage assembly, the solution to this set of problems associated with determining the thermally stressed state of structures is complicated by the presence of pre-tensions, the influence of temperature fields that depend on the parameters of the ventilation systems, and many other factors. The use of high-alloy steels with high hardness and tensile strength as the main material of the band rings also requires an increase in tension, which can cause cracks to appear in the most stressed structural elements. Solving the problem of determining the stress-strain state of the bandage assembly elements with the required accuracy when using exclusively classical engineering methods is not advisable, since they do not allow for effective consideration of the entire set of factors due to the presence of their mutual complex influence. The proposed method allows for more accurate computation of safety margins and determination of necessary stresses by solving a set of thermoelasticity and thermal conductivity problems in a three-dimensional setting using the finite element method with the transfer of initial and boundary conditions between problems. The refined safety margin coefficients of the elements of the bandage assembly in a state of rest, at nominal speed, and overspeed were determined when conducting a study using the developed method. For the main design elements of the bandage assembly of a 200 MW turbogenerator, the minimum safety factor at the overspeed and maximum tension was 1.3. The maximum contact stresses (approximately 550 MPa) that arise in the centering ring at zero rotation speed are local and concentrated in the area of the stress concentrator– the hole. All stress modes do not exceed the permissible values. At the same time, the tensions cannot be changed to a smaller side because the minimum permissible safety factor for the design elements of the bandage assembly of a 200 MW turbogenerator is from 1.5 to 1.05 at the overspeed.
Copyright (c) 2025 Oleksii Tretiak, Stanislav Kravchenko, Pavlo Gakal, Bogdan Shestak, Serhii Serhiienko, Viacheslav Nazarenko
Experience of using LDRA Tool Suite during “Element” JSC products certification
The introductory part of the article provides brief information about the main direction of the JSC Element activity: development and production of electronic control systems for aircraft engines. To ensure the safety of the hardware and software of such systems, their development must be carried out in strict compliance with the DO-178C/ED-12C and DO-254. The development must be traceable, verified, high-quality, and properly documented. The volume of work and documents for product certification is so large that traditional paper technologies do not guarantee a proper result. Therefore, special software tools are used to automate some processes. This article considers tools that automate the requirements tracking, verification, and testing processes. The following section provides an overview of software lifecycle management tools for embedded systems. The limiting factors are support for the selected programming system considering the type of target microcontroller, availability of requirements management tools, coverage and code quality analysis, tracing, and various types of testing (module, integration, etc.). The review includes the most significant tools (V/sure Requirements, Enterprise Architect, DOORS, VectorCAST, Polarion, and others) that support DO-178C certification. These tools have different price categories, feature sets, integration capabilities with other systems, development difficulty, and specific after-sales service. Element JSC chose is LDRA Tool Suite – a flexible platform for creating safe, secure, and mission-critical software in an accelerated, cost-effective, and requirements-driven process. The following sections describe the main functions and composition of LDRA Tool Suite applications. The main principles and features of using the tool are given. The disadvantages of the tool include the lack of the ability to track specific changes in the structure of requirements or other project artifacts and the high complexity of development. The authors share their experience in developing with LDRA Tool Suite, noting that the costs do not end with the purchase of a license and that staff training investments are required.
Copyright (c) 2025 Vadym Nerubaskyi, Timofii Kozaryk
Definition of requirements and stepwise development of a diagnostic model algorithm for the TV3-117V gas turbine engine
This study presents an approach to the formalized construction of a diagnostic model for the TV3-117V gas turbine engine, aimed at post-flight analysis of operational data. The model is designed to detect potentially hazardous deviations in engine performance based on the comparison of actual parameters with reference values, considering the operating mode. The relevance of developing a dedicated post-flight diagnostic tool is substantiated by considering the specific features of the TV3-117V engine and limitations of existing approaches, which are mostly empirical or statistical and lack structured mode-dependent logic. A set of diagnostically significant parameters (exhaust gas temperature, compressor shaft speed, torque, fuel consumption, and logical signals) is defined and divided into three functional groups: mode-identifying, diagnostic, and auxiliary. A modular structure of the diagnostic model, comprising blocks for preprocessing, mode identification, parameter normalization, reference characteristics, normative comparison, and logical inference generation, is proposed. The mode identification algorithm is based on a combination of logical indicators and key parameter threshold values to detect engine operation in one of five defined modes: ground idle, cruise, takeoff, 2.5-minute power, and preservation/depreservation. Formulating criteria for identifying potentially dangerous deviations is given special attention. Accounting for not only absolute deviations but also inter-parameter relationships and dynamic trends enhances diagnostic reliability. Using the "ground idle" mode as an example, a set of criteria is implemented to detect temperature, torque, and rotor speed instability. The justification for using dedicated templates of reference behavior for each operational mode to enable context-sensitive comparison is provided. The proposed diagnostic model structure lays the groundwork for the further development of an automated expert system for analyzing post-flight engine data.
Modeling of critical start-up and shutdown scenarios of a gas turbine engine for testing regulator protections
This study presents a methodology for simulation-based modeling of critical start-up and shutdown scenarios of the TV3-117 gas turbine engine to test the electronic controller’s protection algorithms. The proposed approach uses a hardware-in-the-loop simulation test bench with an integrated mathematical engine model, enabling real-time emulation of engine dynamics without the need for actual equipment. Based on this model, an automated test utility was developed, allowing the construction of start-up, shutdown, and emergency impact scenarios using logical block diagrams. The utility’s algorithms offer flexible configuration of action sequences, parameter values, fault injection, and control system response evaluation under various conditions. Simulations were conducted for both nominal and critical modes, including temperature and overspeed limit violations, delayed ignition, sensor channel faults, communication failures, and emergency engine shutdowns. The protection logic of the controller was tested for various scenarios, such as overspeed protection, temperature limiting, emergency power mode switching in case of engine failure, power loss, and inter-module communication disruptions. System responses were recorded for each case, enabling the assessment of algorithm effectiveness. The utility also supports real-time signal and parameter logging with time stamps to facilitate detailed analysis. The modeling results demonstrated a high level of correspondence with expected controller behavior, including the system’s ability to stabilize parameters under fault conditions and overloads, as well as flexible adaptation of protection logic. The developed methodology reduces testing time and cost, minimizes risks at early development stages, and ensures high simulation credibility. The proposed solution is applicable throughout the entire life cycle of engine control system development – from design to certification testing. Moreover, the test utility can be adapted to other engine types, highlighting its universality and scalability in the field of aerospace propulsion system development.
Estimation of parameters of the periodic component of the time series of data of bench tests and technical operation of complex energy facilities by the method of singular spectral analysis
This study proposes an approach to determine the cyclic component of the time series of technical condition registration during the long-term operation of complex energy facilities and their bench tests by real-time means. The relevance of solving the specified scientific and applied problem is due to the need for current analysis of the technical condition of the specified facilities to establish the possibility of their operation according to the established resource, taking into account the cyclic (periodic, seasonal) component, the influence of which is an important factor in establishing the actual technical condition of the studied facilities. An analysis and comparison of methods for assessing the cyclic component of time series in terms of the possibility of their implementation by real-time means was performed using analytical justification and solving a test case, and analyzing real data during bench tests of a complex energy facility built based on a gas turbine engine. The hypothesis is proposed and confirmed that the dimension of the analysis window corresponds to the period of the specified component if the eigenvalues of the autocorrelation matrix of a time series are equal, which corresponds to the presence of a periodic component in its orthogonal distribution.The known method of estimating the cyclic component of measurement data, namely, the method of singular spectral analysis, provides the theoretically smallest mean square error of estimation, but has a significant computational complexity. We propose a method for estimating the cyclic component of real-time measurement data by non-recursive digital filtering based on a quadrature filter with weighted coefficients according to a certain dependence. A new modification of the method of singular spectral analysis of time series for estimating the cyclic component is proposed for the first time, allowing the development of high-precision real-time algorithms.
Copyright (c) 2025 Volodymyr Myrhorod, Iryna Hvozdeva