Aerospace technic and technology最新文献

{"title":"Моделювання процесу парашутування літака на злітно-посадкову смугу при його посадці","authors":"Liudmyla Kapitanova, Viktor Riabkov, Danylo Kirnoson","doi":"10.32620/aktt.2024.1.02","DOIUrl":"https://doi.org/10.32620/aktt.2024.1.02","url":null,"abstract":"The landing of an aircraft is an unknown part of its flight, and at this stage, the highest number of accidents and even disasters are observed. It should be noted that the movement of the aircraft in its airspace, when it is under the influence of aerodynamic forces, gravity, and engine thrust, is quite accurately modeled by various authors and presented in printed sources. The peculiarities of the aircraft’s movement during air-to-ground landing, i.e., at the moment of parachuting directly onto the runway, are insufficiently studied. The influence of parachuting conditions on post-landing stability has barely been studied. The subject of study in this article is the modeling of the parachuting process under conditions of aircraft landing. The goal of this study is to develop and test mathematical and simulation models of the aircraft’s movement during its parachuting from the alignment zone to the runway and to ensure the stability of longitudinal movement at the moment of the first landing impact and subsequent movement. Tasks: analyze the characteristics of the landing distances of transport category aircraft; establish the features of the parasailing stage of the aircraft during landing; develop a parametric model of the aircraft in its parachute configuration; establish conditions for modeling shock-absorbing landing gear; and, based on general and simulation models, establish zones of longitudinal movement stability of the aircraft after the first landing. Based on the results of experimental studies, the proposed mathematical model of the aircraft in landing configuration and the simulation model of participation in the landing of shock-absorbing landing gear systems quite reliably (compared to experimental data) estimate the aircraft’s movement at the moment of its touchdown and subsequent roll. This means that mathematical modeling can avoid repeated bounces during landing, ensure stability of longitudinal aircraft movement, reduce the length of the unbraked roll, and decrease the required runway length during aircraft landing. Conclusions: By analyzing normalized landings, the six most characteristic stages in the landing distance of transport category aircraft have been identified. A method of mathematical modeling of aircraft movement during parachuting onto the runway, considering not only the glider’s characteristics but also the features of the landing gear shock-absorbing systems, allows evaluating the parameters of parachuting that ensure stability of longitudinal aircraft movement after the first impact on the landing gear. Using the example of the An-140 aircraft, it is demonstrated how the values of brake wheel stability parameters are ensured and how the parachuting speed affects the length of its landing distance.","PeriodicalId":418062,"journal":{"name":"Aerospace technic and technology","volume":"274 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140427899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unsteady flow of droplet liquid in hydraulic systems of aircrafts and helicopters: models and analytical solutions","authors":"Pavlo Lukianov, Kateryna Pavlova","doi":"10.32620/aktt.2024.1.03","DOIUrl":"https://doi.org/10.32620/aktt.2024.1.03","url":null,"abstract":"The subject of this study is the unsteady flow of liquid in pipelines, which are part of the design of airplanes and helicopters. This name means, first of all, the phenomenon of a sharp increase in pressure in the pipeline, which is known as a hydraulic shock. Although we have already learned to deal with this phenomenon in some parts of the systems, in many structural elements (flexible pipelines), inside which the working pressure reaches several hundred atmospheres, this phenomenon is still quite dangerous. As you know, the best way to deal with an unwanted phenomenon is through theoretical study. To date, there has been a huge amount of work in the direction of hydraulic shock research. This article does not fully cover these studies. It is limited to references to reviews and relevant works. Because the phenomenon of hydraulic shock has a significantly nonlinear character, analytical solutions of systems of equations corresponding to the simplest models were unknown until recently. This work presents, as an overview, already known analytical solutions describing the process of shock wave propagation. Most importantly, new achievements are given, both for the inviscid approximation and for considering internal viscous friction. It is shown that the internal friction within the considered model is negligible almost everywhere, except for the thin shock layer. The asymptotic is proportional to the tangent function and inversely proportional to the square root of the product of the Reynolds number and the dimensionless parameter characterizing the convection effect. Convection of the velocity field significantly affects the distribution of characteristics in hydraulic shock. If the self-similar solutions that were obtained earlier have a power-law character for the velocity distribution in the shock wave, then the simultaneous consideration in the model of convection and friction on the pipeline walls (according to the Weisbach-Darcy model) made it possible to obtain a distribution in the form of an exponential function that decays with increasing distance from the shock wave front. In addition, the work includes an original approach to solving a nonlinear system of differential equations that describes the propagation of a shock wave without considering the friction on the walls. Analytical solutions were obtained in the form of a function of pressure versus the velocity of shock wave propagation. Research methods. This work uses purely theoretical approaches based on the use of well-known fluid flow models, methods of analytical solution of differential equations and their systems, asymptotic methods, derivation of self-model equations, and finding their solutions. Conclusions. Analytical solutions of systems of differential equations were obtained, which describe models of hydraulic shock without considering viscous effects. A comparison of the obtained results with the results of other studies is given.","PeriodicalId":418062,"journal":{"name":"Aerospace technic and technology","volume":"54 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140424052","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Визначення швидкості корозії основного конструкційного матеріалу сіток капілярних розділювачів фаз","authors":"O. Minai","doi":"10.32620/aktt.2024.1.04","DOIUrl":"https://doi.org/10.32620/aktt.2024.1.04","url":null,"abstract":"The subject of this study is the corrosion processes that occur in the fuel tanks of spacecraft with a long service life, the engines of which operate on chemically aggressive fuel components (FC): nitrogen tetroxide (NT) and asymmetric dimethylhydrazine (NDMH). The goal is to determine the reduction of wire diameters and the increase of cell sizes of capillary phase separator grids (PSG) because of the corrosion effect of the main structural material of the 12X18H10T stainless steel grid. Task: establishing the presence, type, and rate of corrosion of the main structural material of the PSG nets. The methods used are as follows: to determine the presence of corrosion by studying the composition of substances found on the surface of the grids – X- ray fluorescence, X- ray structural, atomic absorption, potentiometric, turbodimetric, infrared spectroscopy, and chromato-mass spectrometry; to determine the type of corrosion-metallographic studies of mesh samples; to determine the rate of corrosion-measuring the geometric dimensions of mesh samples. The following results were obtained. The metal cations detected on the surface of the mesh samples correspond to the elements that make up the alloy of aluminum and steel - the main structural materials of the fuel tanks of launch vehicles; 12Х18Н10Т steel is not susceptible to local types of corrosion (pitting, intercrystalline, dot, contact, crevice, and stress corrosion cracking) in high-pressure and low-pressure tanks; the presence of a continuous (uniform) corrosion effect on the surface of the grid wires was established; dependences of changes in the main geometric parameters of the grids (wire diameters and cell sizes) over time were obtained, according to which the limits of the corrosion rates of stainless steel grade 12X18N10T in the liquid phase of NT and NDMG and in the gas phase were established; and coefficients of the maximum corrosion rate were calculated. Conclusions. The scientific novelty of the obtained results is as follows: for the first time, the presence, type, and rate of corrosion of the main structural material of the PSG grids because of their long-term operation (14...31 years) in the liquid phase of AT and NDMH and in the gas phase were determined using cross-methods.","PeriodicalId":418062,"journal":{"name":"Aerospace technic and technology","volume":"43 10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140424071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Використання методу верифікації FMEDA/FIT для оцінювання кібербезпеки програмованого логічного контролера: нова інтерпретація принципу SIS","authors":"Oleksandr Ivasiuk, V. Kharchenko","doi":"10.32620/aktt.2024.1.07","DOIUrl":"https://doi.org/10.32620/aktt.2024.1.07","url":null,"abstract":"The object of this study is a programmable logic controller (safety PLC), which is part of an information and control system designed for safe management of important technological processes. The subject of this study is the substantiation of the legality of reusing the results obtained during the development of the safety PLC in accordance with the requirements of functional safety to assess the level of its cyber security. The purpose of this work is to investigate the possibility of \"cross\" evaluation of the safety characteristics of the safety PLC, namely, the possibility of evaluating the level of cyber security of the programmable logic controller based on known data regarding its level of functional safety, in order to optimize the use of available resources in the project. The study tasks are following: to provide a theoretical basis for the relationship between safety PLC characteristics such as functional safety and cybersecurity. Determine the metrics by which it will be possible to assess the degree of reuse of existing results. Perform an analysis of potential cyberattacks depending on the architecture of the information and control system, which performs security functions, as well as on the possible modes of its use. Determine and evaluate the degree of \"cross\" influence of critical characteristics of the research object. To perform a calculation analysis of the potential financial and time gain from the reuse of already known results for the minimum configuration of the safety PLC. Conclusions. The study demonstrated the relevance of the question of assessing the cybersecurity of a programmable logic controller based on the use of existing data, regarding its level of functional security (SIL). The proposed approach provides opportunities to significantly optimize the use of resources in safety PLC certification projects. However, the main methodological conclusion is that the well-known principle of Security Informed Safety can be developed and used in practice in the opposite direction, as Security supported/assessed by Safety. That is, to the principle of \"assessment of functional safety taking into account/on information (cyber) security\" the principle of \"assessment of information (cyber) security with the support of/taking into account the results of the assessment of functional security\" is added.","PeriodicalId":418062,"journal":{"name":"Aerospace technic and technology","volume":"23 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140424906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simulating multi-particle deposition based on CEL method: studing the effects of particle and substrate temperature on deposition","authors":"Kun Tan, Wenjie Hu, O. Shorinov, Yurong Wang","doi":"10.32620/aktt.2024.1.06","DOIUrl":"https://doi.org/10.32620/aktt.2024.1.06","url":null,"abstract":"The subject matter of this study is to use numerical simulation methods to study the influence of the temperature of particles and substrates on the post-deposition coating during the multi-particle deposition process of cold spray. The goal is to study the temperature of Al6061 particles and the temperature of the substrate, which are factors that have a greater impact on the deposited coating, and to observe the shape of the coating and the temperature distribution of the cross-section of the substrate after deposition. The tasks to be solved are as follows: use Python scripts to model multi-particles, generate and randomly assign positions according to particle size distribution in the Euler domain, and establish a cold spray multi-particle collision model to simulate the process of cold spray deposition. The following methods were used: The influence of temperature and substrate temperature on the deposited coating was studied through a single variable method; the Coupled Eulerian Lagrangian (CEL) method was used to simulate the collision process of cold-sprayed Al6061 multi-particles. The following results were obtained: changing the temperature of Al6061 particles has a more obvious control effect on the porosity of the deposited coating; after particles of different temperatures impact the constant-temperature substrate, the high-temperature area on the surface of the substrate is mainly located at the junction of pits; after the particle temperature reaches 650K, the coating changes after deposition are no longer significant, indicating an optimal temperature range for Al6061 particle deposition; increasing the temperature of the substrate can increase the depth of particle deposition on the substrate; at the same time, it serves as a reference basis for further using the CEL method to predict the porosity of the Al6061 coating. Conclusions. The scientific novelty of the results obtained is as follows: 1) powder preheating can effectively reduce the porosity of Al6061 coating; 2) the CEL method has good robustness and is used to simulate cold spray multi-particle deposition to monitor the porosity of the coating, which cannot be achieved by the SPH and ALE methods.","PeriodicalId":418062,"journal":{"name":"Aerospace technic and technology","volume":"34 13","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140425928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Експериментальне дослідження впливу плівкоутворюючих антикорозійних сполук на втому заклепкових з’єднань","authors":"Eugene Gavrylov","doi":"10.32620/aktt.2024.1.05","DOIUrl":"https://doi.org/10.32620/aktt.2024.1.05","url":null,"abstract":"The subject matter of this article is the influence of film-forming corrosion preventive compounds on aviation riveted joints fatigue life. The goal of this work is to develop a method for the assessment of negative side effects caused by the application of corrosion preventive compounds. Tasks of the work are as follows: analysis of the aircraft corrosion problem; critical review of existing publications concerning possible negative side effects caused by the application of corrosion preventive compounds  for protection of aviation riveted joints against corrosion, where reduction of the fatigue life is considered as a result of the preventive compounds penetration into the gaps of riveted joints; development of the specimen for fatigue tests, with features of contemporary transport aircraft typical design; fatigue tests of the riveted specimens treated with preventive compounds and without treatment; investigation of the preventive compounds penetration into the gap of riveted joint. The main method of this research is fatigue loading of the riveted specimens at loads close to those the aircraft encounters in service. The main result is the experimentally proven possibility of negative side effects of corrosion preventive compound application. The observed effect is explained by the change in friction in joints and the corresponding redistributions of the forces between the joint elements. It was found that a factor influencing friction force is the viscosity of the preventive compounds. The possibility of preventing negative side effects by optimizing the protective procedure has been experimentally proven. Conclusions. The results presented in the paper show the probability of the negative side effects of corrosion preventive compound application. Considering the variety of these materials and their physical and chemical characteristics, the necessity   of the grounded selection of the protective compounds is evident as well as the optimization of the treatment technology. Conducted research has revealed an example of the negative influence of preventive compounds on riveted joints fatigue life and has opened the way for this effect prevention. The described research procedure is a component of the complex method for exploring corrosion preventive compounds’ negative side effects.","PeriodicalId":418062,"journal":{"name":"Aerospace technic and technology","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140425446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of environmentally friendly commercial aviation development ways","authors":"Ruslan Tsukanov, Sergiy Yepifanov","doi":"10.32620/aktt.2024.1.01","DOIUrl":"https://doi.org/10.32620/aktt.2024.1.01","url":null,"abstract":"The goal of this study is to identify effective directions to decrease the greenhouse gas emissions of commercial aviation. The subject matter of this research is to analyze ways known from literature to decrease the greenhouse gas emissions of commercial aviation: continued evolution (which includes a lot of various methods for partial reduction of greenhouse gas emissions with decreasing in fuel consumption), «net zero» (which includes the following methods: offsets and sustainable aviation fuel utilization), electric hybrid power plants (parallel, series, series/parallel, turboelectric, and partial turboelectric), «zero carbon» (replacing kerosene combustion with hydrogen combustion in modified gas-turbine engines), «true zero» (transition to electric cruise motors with hydrogen fuel cells or electric batteries). The tasks to be solved are as follows: learning of the ways and detection of advantages and problems from the point of view of efficiency, technical complexity, economy, ecology, and implementation possibility in conditions of limited funding. The methods used are: search of the corresponding information sources in the Internet and their analysis on the basis of operational experience in the aviation branch. The following results were obtained: in terms of found information sources, data about existing greenhouse gas emissions and their predictive estimations, history of international agreement development as for greenhouse gas emission reduction were briefly stated; actuality of this problem with a view to mitigate the environmental impact was stressed; and the advantages and problems, which should be solved to implement each of the considered ways, were summarized. Conclusions. The scientific novelty of the results obtained is as follows: 1) information from numerous sources of literature that clarifies classification, the advantages, and the problems that should be overcome for each ways implementation, was summed up in the review article; 2) additional inherent disadvantages, which are integral to some of the ways (low efficiency, high technical complexity, schedule delays, cost overruns, funding instability, doubts in their reasonability from ecological considerations), are shown as a result of analysis and historical analogy. The direction of the following research in this field is outlined.","PeriodicalId":418062,"journal":{"name":"Aerospace technic and technology","volume":"82 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140426718","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Аналіз можливості застосування комерційних мікротурбореактивних двигунів для високошвидкісних малорозмірних БПЛА оперативно-тактичного рівня","authors":"Olexander Khrulev","doi":"10.32620/aktt.2023.4sup2.01","DOIUrl":"https://doi.org/10.32620/aktt.2023.4sup2.01","url":null,"abstract":"Despite the technological advances that made it possible to create serial commercial micro-turbojet engines with a thrust of up to 1.0 kN, engines of this type in the class of high-speed unmanned aerial vehicles (UAVs) weighing up to 200 kg have not yet received wide distribution. Nevertheless, the use of micro-turbojet engines continues to be considered as promising, and a large amount of work has been devoted to the study of these engines. However, existing studies often show a simplistic approach when a micro-turbojet is considered in isolation from its possible aviation application. The object of this study is micro turbojet engines for high-speed UAVs. The purpose of this study was to evaluate the effectiveness of the use of serial commercial micro turbine engines on high-speed UAVs. The task: to select a gas-dynamic calculation program, perform a mathematical modeling of the characteristics of a micro-turbojet engine, and analyze the conditions and effectiveness of the application of the considered type of engine on high-speed UAVs. Method of the study. The GasTurb14 standard program for gas-dynamic calculation of gas turbine engines was used, with the help of which gas-dynamic calculations were carried out, a structural diagram was obtained, and mathematical modeling of micro-turbojet characteristics was performed. The results. Possible manufacturers and models of engines produced by them and their equipment were identified. It was found that for the considering UAV class, the engine should have a pressure ratio in compressor in the range of 4.2-4.7, and it is advisable to choose the flight operating mode of the micro-turbojet engine at a speed of 92-95% of the maximum. It has also been determined that UAVs with micro-turbojet engines, in comparison with piston engines, easily provide the same flight range with the same fuel relative mass due to at least three times higher speed. Conclusions. The use of a micro-turbojet turns out to be more effective at a flight range of over 300 km, and at a flight speed of more than 150 m/s (540 km/h), a micro-turbojet engine provides a significant advantage over a piston engine for a number of operational and tactical tasks.","PeriodicalId":418062,"journal":{"name":"Aerospace technic and technology","volume":"102 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125538986","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Формування математичної моделі турбовального двигуна","authors":"Sergiy Yepifanov, Oleksii Bondarenko","doi":"10.32620/aktt.2023.4sup1.12","DOIUrl":"https://doi.org/10.32620/aktt.2023.4sup1.12","url":null,"abstract":"The subject of the study is the process of forming a mathematical model (MM) of a turboshaft gas turbine engine and a twin-engine helicopter power plant, which provides the determination of parameters of the working process in steady and transient operating modes for use in the estimation of dynamic characteristics, in the analysis and synthesis of engine and helicopter automatic control systems. The goal is to substantiate the structure and methodology of MM formation intended for use in real and accelerated time scale systems. Tasks: implementation of the previously proposed MM structure taking into account the turboshaft engine performances, development of a methodology for determining the MM coefficients based on known information about the static and dynamic properties of the engine, and formation of the MM structure of a two-engine helicopter power plant. For this, the methods of the theory of airjet engines and the theory of linear dynamic systems are used. The following results were obtained: the structure of a multimode high-speed MM of a turboshaft engine and a two-engine power plant was formed and tested. The scientific and practical novelty of the obtained results is as follows: the structure of the multimode linearized MM of the turboshaft engine is formed, which consists of static and dynamic submodels implemented in corrected parameters; the modeling technique was worked out on a simplified model, compiled considering expert information about the static and dynamic properties of the engine in the considered operation area. Formulas were obtained that relate the coefficients of the linear dynamic model to the values of the time constants of the rotors and the sensitivities obtained from the static characteristics; transient characteristics of the engine based on changes in fuel consumption and load power are determined, which correspond to physical knowledge about the engine; the modeling methodology and MM structure of a two-engine power plant were formed, which is distinguished by the combination of individual static and linear dynamic models of two engines with a single nonlinear dynamic model of the helicopter rotor; a simplified MM load necessary for testing the MM of the engine installation is proposed, which provides the calculation of the power consumed by the rotor, depending on the angular position of the blades.","PeriodicalId":418062,"journal":{"name":"Aerospace technic and technology","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131340389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Технологія відновлення форми ротора гідрогенератора","authors":"Pavlo Makarov","doi":"10.32620/aktt.2023.4sup2.13","DOIUrl":"https://doi.org/10.32620/aktt.2023.4sup2.13","url":null,"abstract":"The object of research in this article is the change in the rotor shape during the operation of hydraulic units. The subject of study in this article is the design and geometric state of the shape of a rotor with irregular geometry of hydraulic generators-engines. This study produced a three-dimensional mechanical calculation of the rotor segment for further use during strain gauge tests. Tasks: investigate the peculiarities of the rotor shape restoration technology; to describe the basic assumptions for the three-dimensional mechanical calculation of rotor deformations at the overspeed; and perform a three-dimensional calculation of rotor movements considering the main forces falling on the pole connection, which are obtained using classical methods. The methods used are: finite element method of mathematical modeling of the thermal stress state of nodes. The following results were obtained: a detailed description of the technological process of restoring the shape of the rotor using the hot wedging method is given. Three-dimensional models of the rotor segment were developed, and a three-dimensional mechanical calculation of this model was performed, as a result of which satisfactory values of the displacement of the rotor of the hydraulic generator at the overspeed were obtained, considering the recovery technology. To reconstruct the rotor rim, it is necessary to heat the rotor rim to a temperature difference between the rim and the frame of at least 60 °C. Next, the hot wedging of the rotor rim is performed with the driving of each of the driving wedges by the same amount, which ensures the creation of the necessary diametrical tension between the rim and the frame of the rotor and avoids the displacement of the rotor rim relative to the frame. The control of this process is performed using strain gauges. If necessary, it is necessary to cool the rotor rim until the temperatures of the rim and the frame of the rotor are equal. Conclusions. The scientific novelty consists of a combined approach to the evaluation of the deformation of the rotor rim after restoring its shape, which includes elements of analytical mechanical calculation and calculation in a three-dimensional setting. The presented technology for the rotor restoration process meets European requirements.","PeriodicalId":418062,"journal":{"name":"Aerospace technic and technology","volume":"7 8","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131751867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}