Technical mechanics最新文献

{"title":"Determination of the force characteristic of head car’s passive safety system – large road vehicle interaction in a collision","authors":"M. Sobolevska, D. Horobets, S. Syrota","doi":"10.15407/itm2021.04.118","DOIUrl":"https://doi.org/10.15407/itm2021.04.118","url":null,"abstract":"One of the priorities of the National Economic Strategy of Ukraine for the Period up to 2030 is the development of the transport sector, in particular railway vehicle renewal, the introduction of high-speed railway passenger transport, and railway traffic safety improvement. The home motor-car trains must be renewed in compliance with new home standards harmonized with European ones, among which one should mention the Ukrainian State Standard DSTU EN 15227, which specifies the passive safety of a passenger train in its emergency collisions with different obstacles. New car designs must provide not only effective up-to-date braking systems to prevent emergency collisions, but also passive safety systems with energy-absorbing devices. The main purpose of these devices is to reduce the longitudinal forces in the intercar connections and the car accelerations to an acceptable level for the three collision scenarios specified in the DSTU EN 15227. The Department of Statistical Dynamics and Multidimensional Mechanical Systems Dynamics, Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine, developed a passive protection concept for home high-speed passenger trains in emergency collisions by the DSTU EN 15227 scenarios, proposals on the passive protection of a motor-car train head car, and honeycomb designs of lower- and upper-level energy-absorbing devices (EAD 1 and UL EAD, respectively), which are integrated into the head car front part and serve to damp the major part of the impact energy in front collisions with obstacles. This paper considers DSTU EN 15227 Scenario 3: a collision of a reference motor-car train at a speed of 110 km/h at a railway crossing with a large 15 t road vehicle, which is simulated as a large-size deformable obstacle (LSDO). The aim of the paper is to determine the force characteristic of the interaction of energy-absorbing devices mounted on the head car front part with a large road vehicle in a collision to assess the compliance of the proposed passive protection with the normative requirements. Finite-element models were constructed to analyze the plastic deformation of the elements of the EAD 1 – LSDO, UL EAD – LSDO, and EAD 1 – UL EAD –LSDO systems in a collision with account for geometric and physical nonlinearities, steel dynamic hardening as a function of the impact speed, and varying contact interaction between the elements of the systems considered. The studies conducted made it possible to determine the force characteristics of energy-absorbing device – obstacle interaction and the total characteristic of the contact force between two lower-level devices and two upper-level ones as a function of the obstacle center of mass displacement in a collision. The proposed mathematical models and the calculated force characteristics may be used in the study of the dynamics of a reference motor-car train – large road vehicle collision with the aim to assess the","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131735120","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":"Use of a “green” propellant in low-thrust control jet engine systems","authors":"V. I. Timoshenko, L.K. Patryliak, Yu.V. Knyshenko, V. Durachenko, A.S. Dolinkevych","doi":"10.15407/itm2021.04.029","DOIUrl":"https://doi.org/10.15407/itm2021.04.029","url":null,"abstract":"The aim of this work is to analyze the state of the art in the development and use of pollution-free (“green”) propellants in low-thrust jet engines used as actuators of spacecraft stabilization and flight control systems and to adapt computational methods to the determination of “green”-propellant engine thrust characteristics. The monopropellant that is now widely used in the above-mentioned engines is hydrazine, whose decomposition produces a jet thrust due to the gaseous reaction products flowing out of a supersonic nozzle. Because of the high toxicity of hydrazine and the complex technology of hydrazine filling, it is important to search for its less toxic substitutes that would compare well with it in energy and mass characteristics. A promising line of this substitution is the use of ion liquids classed with “green” ones. The main components of these propellants are a water solution of an ion liquid and a fuel component. The exothermic thermocatalytic decomposition of a “green” propellant is combined with the combustion of its fuel component and increases the combustion chamber pressure due to the formation of gaseous products, which produces an engine thrust. It is well known that a “green” propellant itself and the products of its decomposition and combustion are far less toxic that hydrazine and the products of its decomposition, The paper presents data on foreign developments of “green” propellants of different types, which are under test in ground (bench) conditions and on a number of spacecraft. The key parameter that governs the efficiency of the jet propulsion system thrust characteristics is the performance of the decomposition and combustion products, which depends on their temperature and chemical composition. The use of equilibrium high-temperature process calculation methods for this purpose is too idealized and calls for experimental verification. Besides, a substantial contribution to the end effect is made by the design features of propellant feed and flow through a fine-dispersed catalyst layer aimed at maximizing the monopropellant-catalyst contact area. As a result, in addition to the computational determination of the thrust characteristics of a propulsion system under design, its experimental tryout is mandatory. The literature gives information on the performance data of “green”-propellant propulsion systems for single engines. However, in spacecraft control engine systems their number may amount to 8–16; in addition, they operate in different regimes and may differ in thrust/throttling characteristics, which leads to unstable propellant feed to operating engines. To predict these processes, the paper suggests a mathematical model developed at the Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine and adapted to “green”-propellant engine systems. The model serves to calculate the operation of low-thrust jet engine systems and describes the propellant f","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"321 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132481748","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":"Gas mass flow control in jet equipment","authors":"N. Pryadko, A. D. Yhnatev, H. Shevelova, K. Ternova","doi":"10.15407/itm2021.04.137","DOIUrl":"https://doi.org/10.15407/itm2021.04.137","url":null,"abstract":"Based on a numerical simulation of gas flows in an ejector unit and an analysis of grinding chamber acoustic signals, this paper shows ways to increase the efficiency of jet grinding. To prevent ejector speed-up tube wear and to obtain a ground product without impurities, the effect of feeding an additional energy carrier flow on the flow pattern in the speed-up tube of a jet mill was studied. A comparative analysis of the ejector flow pattern as a function of the presence of an additional feed and the speed-up tube shape was carried out. It was shown that the use of a conical nozzle offers a more uniform flow at the ejector outlet. The additional energy carrier feed provides a uniform increase in flow speed and reduces speed-up tube wall wear. The acoustic signals of the mill working zones were related to the jet grinding process parameters, around which a ground product quality control method was developed. The paper presents a technique for determining the material particle size in the energy carrier flow from the results of acoustic monitoring of the process. The technique uses the established relationship between the dispersion of the acoustic signal characteristic frequency and the mass of the corresponding fracture of the mixture in in-flow material transportation. The technique speeds up material particle size determination and improves the finished product quality. An automatic system was developed to control the grinding process by controlling the loading process according to the characteristics of the grinding zone acoustic signals. An operating model of a controlled hopper of a gas jet mill was made. The operability of the control system was verified on a simulation model, which includes a control objet (mill) model and a control system model. It was shown that the system of mill loading automatic control by the characteristics of the grinding zone acoustic signals offers an up to 10 percent increase in mill capacity, which was verified in industrial conditions at Vilnohorsk Mining and Metallurgical Plant.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"118 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122627638","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":"Modeling of centrifugal deployment of three-section minisatellite boom","authors":"S. Khoroshylov, V.K. Shamakhanov, V. Vasyliev","doi":"10.15407/itm2021.04.056","DOIUrl":"https://doi.org/10.15407/itm2021.04.056","url":null,"abstract":"The aim of the article is to model the processes of centrifugal deployment of a three-section boom and preliminary analyze the feasibility of this deployment method for an Earth remote sensing (ERS) minisatellite (MS). During the research, methods of theoretical mechanics, multibody dynamics, control theory, and computer modeling were used. Centrifugal deployment of multi-section booms have been successfully used on spin stabilized satellites, but not on ERS satellites, which have other features of operation and require additional studies. The main part of the MS is a platform to which a transformable antenna is attached by means of a transformable boom. Before deployment, the stowed boom and antenna are attached to the MS platform. The boom sections are connected by joints with one rotational degree of freedom and deployed sequentially due to centrifugal forces when the MS rotates in the required direction. Each of the boom joints has a locking mechanism that latches when a predetermined deploy angle is reached. To model the processes of the boom deployment, the MS is presented as a system of connected bodies, where the platform and the stowed antenna are absolutely rigid bodies, and the boom consists of three flexible beams of a tubular cross-section. The differential equations of the MS dynamics during the deployment are obtained using the Lagrangian formalism, which are supplemented by algebraic equations describing the constraints from the joints. The scenarios of the boom deployment with a constant control torque and a constant angular velocity of the MS are considered. These scenarios are simulated, and estimates of the control actions needed to ensure full deployment of the boom and the stabilization of the MS after latching of the joints are calculated. Dependences of variations of the loads on the boom structure during deployment are obtained. The simulation results allow us to conclude that it is feasible to implement the method of the boom centrifugal deployment for the MS, which can perform fast rotations about the three axes of the body reference frame. Implementation of this method allows designers to reduce mass of the MS because it does not require any servo drives in the boom deployment system.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130511577","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":"Compact silencers with discrete baffle elements for new-generation light small arms","authors":"O. Pylypenko, N. A. Konovalov, V. I. Kovalenko, D. Semenchuk","doi":"10.15407/itm2021.04.018","DOIUrl":"https://doi.org/10.15407/itm2021.04.018","url":null,"abstract":"This paper presents the results of the development of silencers, whose design features discrete baffle elements. The advisability of silencers of this type is confirmed by their operational reliability and shot sound suppression efficiency in their actual service as part of light small arms of different types. To design advanced silencers, technical requirements for their design were developed. The paper describes the possibility of using discrete elements (cones, hemispheres, flat baffles, etc.) as the key component of a powder gas spreader. Differently shaped elements are used as additional elements that form a powder gas flow inside a silencer: for example, cylindrical elements, including perforated ones to provide a powder gas flow between the expansion chambers. One way to increase silencer efficiency is an additional expansion chamber that embraces the external part of the barrel and is gas-dynamically connected to a traditional muzzle silencer. In deciding on an optimum design for compact silencers, the following was redetermined: the number of expansion chambers and the dimensions thereof, the powder gas energy converter design, the baffle type, the presence of a gas flow between the chambers near the inner surface of the silencer body, and, if so, the gas flow rate. The silencer design was optimized based on simulating the processes inside the silencer using the authors’ efficiency calculation procedure for silencers with different internal components. Comparison tests of the silencers developed and foreign silencers confirmed a high efficiency of the former. The silencers with discrete baffles for light small arms developed at the Institute of Technical Mechanics of the National Academy of Ukraine and the State Space Agency of Ukraine compare well in performance with their best foreign counterparts. The designs of some of them are covered by Ukrainian patents.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124582392","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 the efficiency of Earth remote sensing means","authors":"P. P. Khorolskyi, V. T. Marchenko, N. Sazina","doi":"10.15407/itm2021.04.079","DOIUrl":"https://doi.org/10.15407/itm2021.04.079","url":null,"abstract":"The aim of this paper is to analyze the efficiency of use of Earth remote sensing (ERS) means in the light of the trends in their development in the past ten years. The paper analyzes the efficiency of use of ERS means in the interests of socioeconomic development (in cartography, meteorology, climatology, oceanology, hydrology, agriculture, forestry, in local and regional management tasks, and in emergencies), the efficiency of the Indian ERS segment (as an example of one of the leading ERS countries), the basic trends in the development of ERS systems that increase their efficiency (open access to ERS data, private and public-private partnership, information delivery promptness, onboard ERS data processing, and ERS-based analysis), and a comparison of the ERS data market fraction of drones with that of satellites. As a result, the following global ERS trends that increase the efficiency of ERS data use are identified: - gradual reorientation from purely obtaining ERS data to making an analysis based thereon; - intensive development of methods of geospatial monitoring, business analysis, machine learning, neural networks, cloud architecture, and automatic processing of large ERS data arrays; - despite the ample scope for ERS data use and the reduction of space imagery prices, this information, as estimated by some analysts, is used in the solution of socioeconomic problems only to quite a small extent because less than one per cent of the ERS satellite data can ever find their users; - in India, China, the Russian Federation, and Ukraine, ERS is funded from the state budget, which is no longer the case in most of the developed countries, where public-private and commercial ERS structures are dominant; - in the countries where ERS is mostly funded from the state budget, the approach to the distribution of ERS products on the home market with the aim to compensate for the capital costs of ERS satellite development inevitably produces negative results; - the formation of national ERS data markets is in progress; the features of these markets are open access to ERS data, private and public-private partnership, information delivery promptitude due to the use of web servers and cloud computing, ERS-based analysis, and onboard ERS data processing in the near future; - in the long term, the future of ERS will depend on breakthrough technologies, innovative solutions, new applications, and the integration of technologies such as VR (virtual reality), AR (added reality), AI (artificial intelligence), Ml (machine learning), Big Data, Cloud Computing, and IoT (Internet of things), which will be of crucial importance in the ERS segment. In the paper, the system analysis method is used. The practical significance of the paper lies in the possibility of using the global ERS advancement trends in the development and operation of national ERS spacecraft.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"31 10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116355423","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":"Nonlinear oscillations of a sandwich plate with a 3D-printed honeycomb core","authors":"K. Avramov, B. Uspensky, I. Derevianko","doi":"10.15407/itm2021.04.104","DOIUrl":"https://doi.org/10.15407/itm2021.04.104","url":null,"abstract":"A three-layer sandwich plate with a FDM-printed honeycomb core made of polycarbonate is considered. The upper and lower faces of the sandwich are made of a carbon fiber-reinforced composite. To study the response of the sandwich plate, the honeycomb core is replaced with a homogeneous layer with appropriate mechanical properties. To verify the honeycomb core model, a finite-element simulation of the representative volume of the core was performed using the ANSYS software package. A modification of the high-order shear theory is used to describe the structure dynamics. The assumed-mode method is used to simulate nonlinear forced oscillations of the plate. The Rayleigh–Ritz method is used to calculate the eigenfrequencies and eigenmodes of the plate, in which the displacement of the plate points during nonlinear oscillations are expanded. This technique allows one to obtain a finite-degree-of-freedom nonlinear dynamic system, which describes the oscillations of the plate. The frequency response of the system is calculated using the continuation approach applied to a two-point boundary value problem for nonlinear ordinary differential equations and the Floquet multiplier method, which allows one to determine the stability and bifurcations of periodic solutions. The resonance behavior of the system is analyzed using its frequency response. The proposed technique is used to analyze the forced oscillations of a square three-layer plate clamped along the contour. The results of the analysis of the free oscillations of the plate are compared with those of ANSYS finite-element simulation, and the convergence of the results with increasing number of basis functions is analyzed. The comparison shows that the results are in close agreement. The analysis of the forced oscillations shows that the plate executes essentially nonlinear oscillations with two saddle-node bifurcations in the frequency response curve, in which the periodic motion stability of the system changes. The nonlinear oscillations of the plate near the first fundamental resonance are mostly monoharmonic. They may be calculated using the describing function method.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"87 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126404266","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":"Minimum altitude variation orbits. Analysis of characteristics and stability","authors":"A. Maslova, A. Pirozhenko, V.V. Vasylіev","doi":"10.15407/itm2021.04.044","DOIUrl":"https://doi.org/10.15407/itm2021.04.044","url":null,"abstract":"The article discusses the regularities of satellite motion in almost circular orbits under the influence of the second zonal harmonic of the geopotential. The aim of the research is to determine the parameters of orbits with a minimum change in radius and to study the properties of these orbits. It is shown that the problem of determining the parameters of orbits with a minimum change in radius is of theoretical and practical interest. These orbits are the closest to Keplerian circular orbits. The practical interest in such orbits is determined by the possibility of using them for scientific research and Earth observation systems. Based on the analysis of the literature, it was concluded that the solution of the problem under consideration is not complete by now: the algorithm for determining the parameters of the orbits are not well founded and unnecessarily complicated; there is no analytical analysis of the stability of the orbits of the minimum change in radius. The efficiency of application of the previously developed theory of describing the motion of satellites in almost circular orbits for determining the parameters of orbits with a minimum change in radius is shown. For this purpose, the solutions of the first approximation of the motion of satellites in almost circular orbits under the influence of the second zonal harmonic of the geopotential have been improved. These solutions make it easy to determine the parameters of the orbits of the minimum change in radius. The averaged equations of the second approximation of the influence of the second zonal harmonic on the satellite motion are constructed and, on their basis, the stability of the orbits with a minimum change in radius is proved. It is shown that the second approximation in small parameters completely describes the main regularities of the long-period satellite motion under the influence of the second zonal harmonic of the geopotential. With the help of numerical studies, the instability of orbits with a minimum change in radius is shown with allowance for the effect of higher order harmonics of the geopotential. Analysis of the area of possible application of orbits with a minimum change in radius showed that such orbits can be of practical importance for very low and ultra low orbits, where the control action on the satellite movement is carried out at least once every two days.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124499844","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":"Mathematical model for determining the design parameters of an inflatable payload-bearing space platform","authors":"E. Lapkhanov, O. Palii","doi":"10.15407/itm2021.04.066","DOIUrl":"https://doi.org/10.15407/itm2021.04.066","url":null,"abstract":"The development and application of inflatable space structures is of considerable interest in modern space science and technology. Today, these structures enjoy wide application from aerodynamic inflatable deorbit means to inflatable residential sections for the International Space Station. This is because the masses of inflatable structures are smaller in comparison with others, which in turn minimizes the cost of their orbital injection. In view of the considerable interest in orbital constellations, the authors of this article propose the use of an inflatable space aerodynamic system as a platform for a payload. In doing so, we obtain a distributed satellite system on an inflatable space platform. The advantage of this technology is that it assures the maintenance of the relative position of the elements (payload) of a distributed satellite system of this type with minimal energy consumption. In its turn, to analyze the features of the operation of a particular space technology, its mathematical model is required. Because if this, the aim of the article is to develop a mathematical model for estimating the design parameters of an inflatable payload-bearing space platform. The mathematical model of the operation of an inflatable payload-bearing space platform developed in this work consists of three modules: a module of orbital motion, a module of calculation of the thermodynamic parameters of the inflatable platform, and a module of calculation of its variable inertia tensor. The article also identifies four gas modes of operation of the inflatable segment of the space platform and gives the inertia tensor as a function of the ambient temperature, which is necessary for further research. It should be noted that the application of the mathematical model allows a priori analysis of a wide range of inflatable space platform design parameters. On this basis, a design parameter analysis method that uses this model was developed. The application of this method may greatly simplify further research into the synthesis of an angular motion controller for an inflatable payload-bearing space platform, the choice of the design parameters of inflatable segment shell materials, and the study of the platform operation in different gas modes.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127794228","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":"Procedure for determining the effect of internal and external factors on the startup thrust spread of a liquid-propellant rocket engine","authors":"O. Pylypenko, S. Dolgopolov, N. Khoriak, N.D. Nikolayev","doi":"10.15407/itm2021.04.007","DOIUrl":"https://doi.org/10.15407/itm2021.04.007","url":null,"abstract":"Despite of the package of measures to adjust a liquid-propellant rocket engine (LPRE) to a specified operating regime, minimum acceptable spreads in the geometrical parameters and operating conditions of its units and assemblies steel remain. These internal factors together with external ones (the pressure and temperature of the propellant components at the engine inlet) govern the engine thrust spread. To provide an acceptable engine thrust spread according to the engine requirements specification, it is important to know the spread value as early as at the stage of off-engine tryout of the engine units and assemblies. The aim of this work is to develop a procedure for calculating the effect of external and internal factors on the LPRE startup thrust spread. This paper presents a procedure for determining the effect of internal and external factors on the LPRE startup thrust spread. The procedure includes the development of a mathematical model of engine startup that accounts for the maximum number of internal factors, the choice of internal factors that produce the maximum effect on the LPRE startup thrust spread, the choice of a method for specifying the external and internal factor spread, engine startup calculations at different combinations of external and internal factor spread values, engine thrust spread determination, determining the statistical and the theoretical distributions of the 90 percent thrust time spread and the steady thrust spread, and assessing their goodness of fit using Pearson’s chi-squared test. The paper gives an example of calculating the effect of the external and internal factor spread on the LPRE startup thrust spread for a staged-combustion oxidizer-rich sustainer LPRE. Using the results of previous calculations, 12 internal factors that produce the maximum effect on the engine startup thrust spread are identified. It is shown that the calculated spread of the 90 percent thrust (combustion chamber pressure) time lies in the range – 0.08220s to +0.07300s about its nominal value, and the calculated steady engine thrust (combustion chamber pressure) spread lies in the range –6.4 percent to +6.6 percent of the nominal thrust. Using Pearson’s chi-squared test, an estimate is obtained for the goodness of fit of the anticipated theoretical distributions of the 90 percent thrust time spread and the steady thrust spread to the obtained statistical ones.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"2011 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121350061","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}