O. Pylypenko, O. Nikolayev, I. D. Bashliy, N. Khoriak
The “core and strap-on boosters” layout of launch vehicle (LV) stages is quite common in heavy LV development. However, POGO oscillations in liquid-propellant LVs with this stage layout have some features. It is shown that the structure of LVs of this type as a dynamic object has a dense spectrum of natural frequencies and complex spatial mode shapes. The longitudinal oscillations of the identical elements of the LV side strap-on boosters may be in phase or in antiphase, while the longitudinal mode shapes of the LV central core and strap-on boosters may differ both in phase and in amplitude. In flight, the thrust of the engines of the side strap-on boosters may also oscillate in phase or in antiphase, as a result of which the interaction of the LV structure with the sustainer propulsion systems of the side strap-on boosters may have both a stabilizing and a destabilizing effect on the POGO stability of a liquid-propellant LV. This paper presents a mathematical model of the “liquid-propellant propulsion systems – LV structure” dynamic system. The model describes the interaction of the longitudinal vibrations of the structure of a two-stage “core and strap-on boosters” LV with the core and strap-on booster propulsion systems. The free longitudinal vibrations of the structure of a ‘core and strap-on boosters’ LV were simulated using computer-aided finite element design tools (CAE systems). The simulation was the first to account for the dissipation of the liquid propellant and LV structure oscillation energy. The paper suggests an approach to analyzing the POGO stability of liquid-propellant “core and strap-on boosters” LVs with the use of the Nyquist criterion generalized to the case of multidimensional dynamic systems. The approach is based on opening the thrust feedback loops of the “liquid-propellant propulsion systems – structure” closed-loop dynamic system and studying the stability of the one-channel systems obtained in this way. Based on the proposed approach, the interaction between the longitudinal vibrations of the “core and strap-on boosters” LV structure and low-frequency processes in the liquid-propellant sustainer propulsion systems of the LV first stage was studied numerically.
{"title":"Approach to the POGO stability analysis of a liquid-propellant “core and strap-on boosters” launch vehicle","authors":"O. Pylypenko, O. Nikolayev, I. D. Bashliy, N. Khoriak","doi":"10.15407/itm2022.03.003","DOIUrl":"https://doi.org/10.15407/itm2022.03.003","url":null,"abstract":"The “core and strap-on boosters” layout of launch vehicle (LV) stages is quite common in heavy LV development. However, POGO oscillations in liquid-propellant LVs with this stage layout have some features. It is shown that the structure of LVs of this type as a dynamic object has a dense spectrum of natural frequencies and complex spatial mode shapes. The longitudinal oscillations of the identical elements of the LV side strap-on boosters may be in phase or in antiphase, while the longitudinal mode shapes of the LV central core and strap-on boosters may differ both in phase and in amplitude. In flight, the thrust of the engines of the side strap-on boosters may also oscillate in phase or in antiphase, as a result of which the interaction of the LV structure with the sustainer propulsion systems of the side strap-on boosters may have both a stabilizing and a destabilizing effect on the POGO stability of a liquid-propellant LV. This paper presents a mathematical model of the “liquid-propellant propulsion systems – LV structure” dynamic system. The model describes the interaction of the longitudinal vibrations of the structure of a two-stage “core and strap-on boosters” LV with the core and strap-on booster propulsion systems. The free longitudinal vibrations of the structure of a ‘core and strap-on boosters’ LV were simulated using computer-aided finite element design tools (CAE systems). The simulation was the first to account for the dissipation of the liquid propellant and LV structure oscillation energy. The paper suggests an approach to analyzing the POGO stability of liquid-propellant “core and strap-on boosters” LVs with the use of the Nyquist criterion generalized to the case of multidimensional dynamic systems. The approach is based on opening the thrust feedback loops of the “liquid-propellant propulsion systems – structure” closed-loop dynamic system and studying the stability of the one-channel systems obtained in this way. Based on the proposed approach, the interaction between the longitudinal vibrations of the “core and strap-on boosters” LV structure and low-frequency processes in the liquid-propellant sustainer propulsion systems of the LV first stage was studied numerically.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114894643","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}
Shell structures are widely used in various branches of technology and industry due to a combination of a high strength and a relatively light weight. In the majority of cases, actual structures have openings for manufacturing or design reasons, thus leading to a sharp increase in local stresses and, as a result, to a decrease in the strength and reliability of the structure as a whole. That is why reducing stress concentration in thin-walled structural elements is an important and topical problem in deformable body mechanics. This paper presents the results of a computer simulation and finite-element analysis of the stress and strain field of a thin-walled spherical shell with an elongated elliptical opening and an annular inclusion that surrounds the opening at a certain distance therefrom. The effect of the geometrical and mechanical parameters of the inclusion and its distance from the opening contour on the concentration of the stress and strain field parameters of the shell is studied. The stress and strain intensity distribution in the local stress concentration zones is obtained. It is shown that a rigid annular inclusion located at a certain distance from an opening allows one to reduce the stress concentration factor by nearly 27 percent with a proportional decrease in strain intensity in the vicinity of the opening. The elliptical opening elongation degree greatly affects the concentration of the stress and strain field parameters. If an opening is reinforced with a rigid annular inclusion immediately along its contour, the stress intensity in its vicinity increases, while the strain intensity decreases. The numerical calculations conducted show that surrounding an opening with a rigid annular inclusion located remotely therefrom reduces both the stress and the strain intensity in the vicinity of the opening. If an opening is reinforced immediately along its contour, a decrease in the maximum strain intensity is somewhat greater in comparison with the case where the rigid annual inclusion surrounding the opening is located at some distance therefrom. The use of specially selected and located reinforcements of elongated elliptical openings in spherical shells allows one to control the stress and strain intensity distribution and magnitude in the zones of local concentration of their stress and strain field parameters.
{"title":"Simulation of the effect of an annular inclusion on stress concentration near an elongated elliptical opening in a spherical shell","authors":"V. Hudramovich, E. Hart, O. A. Marchenko","doi":"10.15407/itm2022.03.023","DOIUrl":"https://doi.org/10.15407/itm2022.03.023","url":null,"abstract":"Shell structures are widely used in various branches of technology and industry due to a combination of a high strength and a relatively light weight. In the majority of cases, actual structures have openings for manufacturing or design reasons, thus leading to a sharp increase in local stresses and, as a result, to a decrease in the strength and reliability of the structure as a whole. That is why reducing stress concentration in thin-walled structural elements is an important and topical problem in deformable body mechanics. This paper presents the results of a computer simulation and finite-element analysis of the stress and strain field of a thin-walled spherical shell with an elongated elliptical opening and an annular inclusion that surrounds the opening at a certain distance therefrom. The effect of the geometrical and mechanical parameters of the inclusion and its distance from the opening contour on the concentration of the stress and strain field parameters of the shell is studied. The stress and strain intensity distribution in the local stress concentration zones is obtained. It is shown that a rigid annular inclusion located at a certain distance from an opening allows one to reduce the stress concentration factor by nearly 27 percent with a proportional decrease in strain intensity in the vicinity of the opening. The elliptical opening elongation degree greatly affects the concentration of the stress and strain field parameters. If an opening is reinforced with a rigid annular inclusion immediately along its contour, the stress intensity in its vicinity increases, while the strain intensity decreases. The numerical calculations conducted show that surrounding an opening with a rigid annular inclusion located remotely therefrom reduces both the stress and the strain intensity in the vicinity of the opening. If an opening is reinforced immediately along its contour, a decrease in the maximum strain intensity is somewhat greater in comparison with the case where the rigid annual inclusion surrounding the opening is located at some distance therefrom. The use of specially selected and located reinforcements of elongated elliptical openings in spherical shells allows one to control the stress and strain intensity distribution and magnitude in the zones of local concentration of their stress and strain field parameters.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129089612","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}
Microwave methods for the study and control of the dielectric properties of substances using regular and irregular rectangular metal waveguides have many applications and are of great practical interest. The dielectric properties of materials are assessed based on the determination of the reflection and transmission coefficients in a resonant system. This article considers resonant phenomena of electromagnetic oscillations in a prismatic cavity based on a length of a rectangular waveguide with two diaphragms and with a dielectric specimen in the form of a cylinder centrally positioned between them. The goal of this work is to evaluate the resonant properties of a prismatic cavity based on a length of a rectangular waveguide with two diaphragms as a function of the geometrical dimensions of the rectangular diaphragm windows, the distance between the diaphragms, and the dimensions and dielectric properties of the specimen located at the center of the waveguide length. By computer simulation, the resonant properties of the system were determined as a function of the dielectric constant and diameter of the specimen and the geometrical dimensions of the diaphragm windows. It was found that for each value of the specimen diameter there exists a maximum allowable value of the dielectric constant at which the resonant properties of the system are kept in a selected operating frequency range. The effect of the height of the diaphragm windows on the resonant frequency of a prismatic cavity and the reflection and transmission coefficients was studied, and the behavior of the intrinsic Q factor was assessed qualitatively. A minimum possible diaphragm window height was found such that both the required coupling between the rectangular cavity and the external microwave line is provided and the maximum value of the loaded Q factor in the absence of a dielectric specimen is kept. The results of this work may be used in the design of high-frequency sensors for controlling the dielectric properties of materials in various industries.
{"title":"Characterization of a resonant system based on a rectangular waveguide with two diaphragms","authors":"I. V. Grymaliuk","doi":"10.15407/itm2022.03.108","DOIUrl":"https://doi.org/10.15407/itm2022.03.108","url":null,"abstract":"Microwave methods for the study and control of the dielectric properties of substances using regular and irregular rectangular metal waveguides have many applications and are of great practical interest. The dielectric properties of materials are assessed based on the determination of the reflection and transmission coefficients in a resonant system. This article considers resonant phenomena of electromagnetic oscillations in a prismatic cavity based on a length of a rectangular waveguide with two diaphragms and with a dielectric specimen in the form of a cylinder centrally positioned between them. The goal of this work is to evaluate the resonant properties of a prismatic cavity based on a length of a rectangular waveguide with two diaphragms as a function of the geometrical dimensions of the rectangular diaphragm windows, the distance between the diaphragms, and the dimensions and dielectric properties of the specimen located at the center of the waveguide length. By computer simulation, the resonant properties of the system were determined as a function of the dielectric constant and diameter of the specimen and the geometrical dimensions of the diaphragm windows. It was found that for each value of the specimen diameter there exists a maximum allowable value of the dielectric constant at which the resonant properties of the system are kept in a selected operating frequency range. The effect of the height of the diaphragm windows on the resonant frequency of a prismatic cavity and the reflection and transmission coefficients was studied, and the behavior of the intrinsic Q factor was assessed qualitatively. A minimum possible diaphragm window height was found such that both the required coupling between the rectangular cavity and the external microwave line is provided and the maximum value of the loaded Q factor in the absence of a dielectric specimen is kept. The results of this work may be used in the design of high-frequency sensors for controlling the dielectric properties of materials in various industries.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126096002","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}
O. Ihnatiev, N. Pryadko, G. Strelnikov, K. Ternova
This paper presents the results of a thrust performance study of an unconventionally shaped supersonic nozzle in the form of a truncated Laval nozzle with a bell-shaped tip. This nozzle shape may be used in the development of compact layouts of multistage rockets. The study was carried out using the ANSYS software package in a 3D formulation. The methodological approaches to the numerical calculation of a complex separated gas flow used in this study were verified in a previous study of the flow pattern in similar nozzle. Some results of exact calculations were compared with the results of experimental studies carried out at the Institute of Technical mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine for a model of a similar truncated nozzle with a bell-shaped tip blown with a cold air. This study detailed the features of the separated gas flow in a spherical tip connected (at the corner point) to a truncated supersonic Laval nozzle of conical shape. It was found that the pattern of the separated flow in the tip depends on the nozzle flow expansion degree (nozzle inlet pressure). At a relatively low nozzle inlet pressure, a developed separation zone is observed in the nozzle tip (between the jet boundary and the nozzle wall) with a subsonic flow from the external environment, which forms an almost constant static pressure from the tip inlet cross-section to the tip exit. At a nozzle inlet pressure at which the free boundary of the jet flowing from the truncated nozzle adjoins the nozzle wall, the static pressure in the tip varies almost linearly along the tip length from the corner point with the minimum pressure to the tip exit. The dependence of the thrust of a tipped nozzle on the nozzle inlet pressure is nonlinear. As the pressure upstream of the nozzle increases (or the ambient pressure decreases), the effect of the external environment on the tipped-nozzle thrust diminishes. It is shown that under "terrestrial conditions" the thrust of a truncated nozzle with a tip exceeds the thrust of a profiled nozzle with the same geometric expansion degree (due to the atmosphere “entering” the tip). Under "vacuum” conditions, the former is 8% less than the latter.
{"title":"Thrust characteristics of a truncated Laval nozzle with a bell-shaped tip","authors":"O. Ihnatiev, N. Pryadko, G. Strelnikov, K. Ternova","doi":"10.15407/itm2022.03.035","DOIUrl":"https://doi.org/10.15407/itm2022.03.035","url":null,"abstract":"This paper presents the results of a thrust performance study of an unconventionally shaped supersonic nozzle in the form of a truncated Laval nozzle with a bell-shaped tip. This nozzle shape may be used in the development of compact layouts of multistage rockets. The study was carried out using the ANSYS software package in a 3D formulation. The methodological approaches to the numerical calculation of a complex separated gas flow used in this study were verified in a previous study of the flow pattern in similar nozzle. Some results of exact calculations were compared with the results of experimental studies carried out at the Institute of Technical mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine for a model of a similar truncated nozzle with a bell-shaped tip blown with a cold air. This study detailed the features of the separated gas flow in a spherical tip connected (at the corner point) to a truncated supersonic Laval nozzle of conical shape. It was found that the pattern of the separated flow in the tip depends on the nozzle flow expansion degree (nozzle inlet pressure). At a relatively low nozzle inlet pressure, a developed separation zone is observed in the nozzle tip (between the jet boundary and the nozzle wall) with a subsonic flow from the external environment, which forms an almost constant static pressure from the tip inlet cross-section to the tip exit. At a nozzle inlet pressure at which the free boundary of the jet flowing from the truncated nozzle adjoins the nozzle wall, the static pressure in the tip varies almost linearly along the tip length from the corner point with the minimum pressure to the tip exit. The dependence of the thrust of a tipped nozzle on the nozzle inlet pressure is nonlinear. As the pressure upstream of the nozzle increases (or the ambient pressure decreases), the effect of the external environment on the tipped-nozzle thrust diminishes. It is shown that under \"terrestrial conditions\" the thrust of a truncated nozzle with a tip exceeds the thrust of a profiled nozzle with the same geometric expansion degree (due to the atmosphere “entering” the tip). Under \"vacuum” conditions, the former is 8% less than the latter.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"212 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114842187","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}
At present, satellite systems, each comprising hundreds of satellites, are, and are to be, deployed in low orbits. In addition, existing satellite systems are replenished. There has appeared a trend towards the development of modular satellites, which will lead to the development of easy-to-maintain spacecraft consisting of many small structural modules with standardized interface mechanisms. To extend the life of all these systems and reduce their maintenance cost, it is advisable to develop a system for their maintenance. Despite the relatively large number of works on the rendezvous problem, this problem is considered in a somewhat simplified formulation, which is not sufficient for spacecraft servicing in low orbits. As a rule, the consideration is limited to coplanar rendezvous problems in an impulse formulation. In real conditions, rendezvous maneuvers in low orbits are nontrivial. As is known, the orbital parameters of low-orbit spacecraft may differ significantly: the difference in the longitude of ascending nodes (LAN) may reach tens and even hundreds of degrees. Because of this, the energy consumption for an orbital plane change becomes unacceptably high for modern service spacecraft. This energy consumption can be reduced by using the precession of the line of nodes due to the non-centrality of the Earth's gravitational field. A waiting maneuver of a service spacecraft in a well-chosen orbit makes it possible to eliminate the mismatch between the LANs of the service spacecraft’s parking and destination orbits, thus significantly reducing the orbital transfer energy consumption. However, the long wait time of the service spacecraft in its parking orbit significantly increases the total orbital transfer time. The aim of this article is to develop a mathematical model of bicriteria optimization of a transfer of a service spacecraft with a low constant thrust engine between low near-circular orbits with significantly different LANs. This problem is solved by averaging the service spacecraft’s dynamics equations over a fast parameter and using a genetic algorithm of global Pareto optimization. The novelty of the results obtained lies in a formulation of a bicriteria optimization problem and the development of a mathematical model for choosing an optimal service spacecraft parking orbit. The mathematical model developed may be used in planning service spacecraft transfers between low near-circular orbits with significantly different LANs.
{"title":"Optimization of transfers between low orbits with significantly different longi-tudes of ascending nodes","authors":"Yu.M. Holdshtein, O. Fokov","doi":"10.15407/itm2022.03.063","DOIUrl":"https://doi.org/10.15407/itm2022.03.063","url":null,"abstract":"At present, satellite systems, each comprising hundreds of satellites, are, and are to be, deployed in low orbits. In addition, existing satellite systems are replenished. There has appeared a trend towards the development of modular satellites, which will lead to the development of easy-to-maintain spacecraft consisting of many small structural modules with standardized interface mechanisms. To extend the life of all these systems and reduce their maintenance cost, it is advisable to develop a system for their maintenance. Despite the relatively large number of works on the rendezvous problem, this problem is considered in a somewhat simplified formulation, which is not sufficient for spacecraft servicing in low orbits. As a rule, the consideration is limited to coplanar rendezvous problems in an impulse formulation. In real conditions, rendezvous maneuvers in low orbits are nontrivial. As is known, the orbital parameters of low-orbit spacecraft may differ significantly: the difference in the longitude of ascending nodes (LAN) may reach tens and even hundreds of degrees. Because of this, the energy consumption for an orbital plane change becomes unacceptably high for modern service spacecraft. This energy consumption can be reduced by using the precession of the line of nodes due to the non-centrality of the Earth's gravitational field. A waiting maneuver of a service spacecraft in a well-chosen orbit makes it possible to eliminate the mismatch between the LANs of the service spacecraft’s parking and destination orbits, thus significantly reducing the orbital transfer energy consumption. However, the long wait time of the service spacecraft in its parking orbit significantly increases the total orbital transfer time. The aim of this article is to develop a mathematical model of bicriteria optimization of a transfer of a service spacecraft with a low constant thrust engine between low near-circular orbits with significantly different LANs. This problem is solved by averaging the service spacecraft’s dynamics equations over a fast parameter and using a genetic algorithm of global Pareto optimization. The novelty of the results obtained lies in a formulation of a bicriteria optimization problem and the development of a mathematical model for choosing an optimal service spacecraft parking orbit. The mathematical model developed may be used in planning service spacecraft transfers between low near-circular orbits with significantly different LANs.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133058943","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}
The goal of this work is to analyze the possibility of using existing monopropellant compositions based on aqueous solutions of high-energy nitrogen-containing substances as the main propellant for low-thrust engines, for example, for meteorological rockets, for upper-stage engines, and in spacecraft control engine systems. This paper presents an approach that considers the selection and justification of ingredients based on renewable energy sources, the analysis being carried out primarily from standpoint of the availability of propellant components and their safety and energy efficiency. It is proposed that the energy of unitary reducing agent – oxidizer chemical propellants (energy-saturated compositions) be used as an alternative source. The development of nonhydrocarbon nitrogen-containing alternative energy sources with the possibility of their conversion and accumulation into the planetary nitrogen, oxygen, and water cycles is an urgent problem. The paper presents detailed information on propellant mixtures of nitrogen-containing substances as oxidizers and considers a number of reducing agents, such as alcohols, amides, etc. in composition with high-energy additives (aluminum, magnesium). The calculated results obtained meet the objectives and demonstrate that the compositions considered can be used as the main propellant for low-thrust engines. The advantages of the new propellant technology: availability, a low cost, produceability, environmental friendliness, a relatively low toxicity, and, primarily, a simpler design of the propulsion system and launch equipment. The proposed propellant composition, which is under test, is planned for use in the sustainer engines of ultralight suborbital rockets with the possibility of further development to an orbital rocket system.
{"title":"Prospects for the use of nitrogen-containing single-component rocket propellants","authors":"O. Ponomarov, O.O. Dobrodomov, O. Kulyk","doi":"10.15407/itm2022.03.085","DOIUrl":"https://doi.org/10.15407/itm2022.03.085","url":null,"abstract":"The goal of this work is to analyze the possibility of using existing monopropellant compositions based on aqueous solutions of high-energy nitrogen-containing substances as the main propellant for low-thrust engines, for example, for meteorological rockets, for upper-stage engines, and in spacecraft control engine systems. This paper presents an approach that considers the selection and justification of ingredients based on renewable energy sources, the analysis being carried out primarily from standpoint of the availability of propellant components and their safety and energy efficiency. It is proposed that the energy of unitary reducing agent – oxidizer chemical propellants (energy-saturated compositions) be used as an alternative source. The development of nonhydrocarbon nitrogen-containing alternative energy sources with the possibility of their conversion and accumulation into the planetary nitrogen, oxygen, and water cycles is an urgent problem. The paper presents detailed information on propellant mixtures of nitrogen-containing substances as oxidizers and considers a number of reducing agents, such as alcohols, amides, etc. in composition with high-energy additives (aluminum, magnesium). The calculated results obtained meet the objectives and demonstrate that the compositions considered can be used as the main propellant for low-thrust engines. The advantages of the new propellant technology: availability, a low cost, produceability, environmental friendliness, a relatively low toxicity, and, primarily, a simpler design of the propulsion system and launch equipment. The proposed propellant composition, which is under test, is planned for use in the sustainer engines of ultralight suborbital rockets with the possibility of further development to an orbital rocket system.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131187836","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}
The aim of this work is to modify a comprehensive mathematical model of a system of two-component low-thrust jet engines using the numerical method of characteristics in the propellant pipeline system with account for different sound speeds in the oxidizer and the fuel employing a unified method of pipeline discretization. This paper presents a unified approach to a numerical implementation of the method of characteristics for both fuel components and for regular computational cross-sections (internal for structural sections with constant geometrical and elastic parameters) and terminal cross-sections at the pipeline system inlets, the section joints, and the engine inlets for each propellant components. The approach accounts for the hydraulic resistances of the propellant injectors and electric propellant valves and the actual pressures in the engine combustion chambers. The performance of the mathematical model is illustrated by the example of the predesigning of a system of different-scale low-thrust engines to control the motion of a spacecraft relative to its center of mass in pitch, yaw, and roll and transfer the spacecraft to a new orbit (higher of lower) for maneuvering and docking with another spacecraft. The computed results show the possibility of determining the key hydraulic and gas-dynamic parameters of the system in transient conditions: the pressure and propellant component flow rate distribution at the inlet of any of the engines, the combustion chamber pressure and thrust characteristics of each engine, and the mutual effect of the engines on their thrust characteristics by the example of varying the flow areas of the propellant manifolds in the steady (continuous) and unsteady pulsed operation of all engines or some of them. The proposed mathematical model may be used in the computational justification of design parameters and operating conditions in the preparation of a draft proposal or in the predesign determination of an engine system configuration. Detailed information on the hydraulic and gas-dynamic performance parameters of an engine system is an important complement to the results of a ground tryout of both single engines and an engine system in conditions that simulate the flight environment.
{"title":"Mathematical model of the operation of a different-scale two-component low-thrust jet engine system","authors":"Yu.V. Knyshenko, V. Durachenko","doi":"10.15407/itm2022.03.047","DOIUrl":"https://doi.org/10.15407/itm2022.03.047","url":null,"abstract":"The aim of this work is to modify a comprehensive mathematical model of a system of two-component low-thrust jet engines using the numerical method of characteristics in the propellant pipeline system with account for different sound speeds in the oxidizer and the fuel employing a unified method of pipeline discretization. This paper presents a unified approach to a numerical implementation of the method of characteristics for both fuel components and for regular computational cross-sections (internal for structural sections with constant geometrical and elastic parameters) and terminal cross-sections at the pipeline system inlets, the section joints, and the engine inlets for each propellant components. The approach accounts for the hydraulic resistances of the propellant injectors and electric propellant valves and the actual pressures in the engine combustion chambers. The performance of the mathematical model is illustrated by the example of the predesigning of a system of different-scale low-thrust engines to control the motion of a spacecraft relative to its center of mass in pitch, yaw, and roll and transfer the spacecraft to a new orbit (higher of lower) for maneuvering and docking with another spacecraft. The computed results show the possibility of determining the key hydraulic and gas-dynamic parameters of the system in transient conditions: the pressure and propellant component flow rate distribution at the inlet of any of the engines, the combustion chamber pressure and thrust characteristics of each engine, and the mutual effect of the engines on their thrust characteristics by the example of varying the flow areas of the propellant manifolds in the steady (continuous) and unsteady pulsed operation of all engines or some of them. The proposed mathematical model may be used in the computational justification of design parameters and operating conditions in the preparation of a draft proposal or in the predesign determination of an engine system configuration. Detailed information on the hydraulic and gas-dynamic performance parameters of an engine system is an important complement to the results of a ground tryout of both single engines and an engine system in conditions that simulate the flight environment.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129377273","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}
This paper addresses the construction of an efficient mathematical model to be used in the numerical simulation of unsteady liquid flows in hydraulic systems with cavitating restrictors. Existing approaches to cavitation simulation are based either on accounting for a two-phase flow structure or on representing a cavitating flow as a homogeneous medium of variable density. In the latter case, the pressure and the density are related via the barotropic equation of liquid–vapor mixture state. The goal of this work is to verify the applicability of a cavitation model based on the barotropic equation of liquid–vapor mixture state to the numerical simulation of an unsteady flow in a hydraulic system with a cavitating ring plate. The method employed is a numerical flow simulation in the axisymmetric approximation using the complete averaged Navier–Stokes equations. It is shown that the use of the barotropic equation of liquid–vapor mixture state provides a satisfactory agreement between the computed results and the experimental data available in the literature. In agreement are the peak-to-valley values of the oscillating pressure on the pipe wall immediately downstream of the cavitating ring plate and the presence of a pronounced periodic component in the pressure vs. time relationship. It is shown that the parameters of the unsteady flow downstream of the cavitating ring plate vary when going from the ring plate to the cavity collapse location: the peak-to-valley value of the oscillating pressure on the pipe wall increases and so does the contribution of high-frequency periodic components to the pressure vs. time relationship. It seems desirable that the turbulence model employed be refined further to correctly simulate cavitation oscillations generated by periodically detached cavitation in Venturi tubes, which are used in various cavitation pulse plants.
{"title":"Numerical simulation of an unsteady flow in a hydraulic system with a cavitat-ing ring plate","authors":"O. Pylypenko, N. V. Petrushenko, Y. Kvasha","doi":"10.15407/itm2022.03.016","DOIUrl":"https://doi.org/10.15407/itm2022.03.016","url":null,"abstract":"This paper addresses the construction of an efficient mathematical model to be used in the numerical simulation of unsteady liquid flows in hydraulic systems with cavitating restrictors. Existing approaches to cavitation simulation are based either on accounting for a two-phase flow structure or on representing a cavitating flow as a homogeneous medium of variable density. In the latter case, the pressure and the density are related via the barotropic equation of liquid–vapor mixture state. The goal of this work is to verify the applicability of a cavitation model based on the barotropic equation of liquid–vapor mixture state to the numerical simulation of an unsteady flow in a hydraulic system with a cavitating ring plate. The method employed is a numerical flow simulation in the axisymmetric approximation using the complete averaged Navier–Stokes equations. It is shown that the use of the barotropic equation of liquid–vapor mixture state provides a satisfactory agreement between the computed results and the experimental data available in the literature. In agreement are the peak-to-valley values of the oscillating pressure on the pipe wall immediately downstream of the cavitating ring plate and the presence of a pronounced periodic component in the pressure vs. time relationship. It is shown that the parameters of the unsteady flow downstream of the cavitating ring plate vary when going from the ring plate to the cavity collapse location: the peak-to-valley value of the oscillating pressure on the pipe wall increases and so does the contribution of high-frequency periodic components to the pressure vs. time relationship. It seems desirable that the turbulence model employed be refined further to correctly simulate cavitation oscillations generated by periodically detached cavitation in Venturi tubes, which are used in various cavitation pulse plants.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130842389","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}
The goal of this paper is to develop mass models of a space industrial platform and its modules. At the initial stage of development of a new spacecraft, a limited set of basic data is available. For a space industrial platform, they are as follows: the configuration of its main and auxiliary modules, the parameters of the technological processes to be implemented on the platform (the vacuum and the microgravity level, the equipment energy capacity), and the manufacturing equipment configuration. A feature of industrial platform design is that there are few, if any, theoretical works on the choice of platform parameters and the logic of platform conceptual design. In this paper, the design process is considered as applied to the conceptual design stage. This stage is characterized by that nothing is known about the system to be developed except for the general concept of the platform layout, the expected types of the main service systems, some basic data, and the parameters of the technological processes to be implemented on the platform. The process of designing a new complex space system such as an industrial platform is a multilevel iterative and optimization process, during which its characteristics and the mass fractions of its components are determined and refined. The paper presents a mass model of an industrial platform and its modules, in whose development the platform and its components were decomposed to the level of system elements. A statistical analysis of the mass fractions of the onboard spacecraft systems was carried out. The mean values of the mass fractions for the sample of spacecraft under study and their scattering coefficients (the dispersion and the mean square deviation) were determined. For the mean values and the dispersion, 99.9 confidence intervals were determined. Further studies on the design of space industrial platforms are planned to be carried using the mass fractions of satellite systems and the confidence intervals, namely, the minimum and the maximum possible mass for a particular system, determined in this study.
{"title":"Model for assessing the mass of a space industrial platform and its modules","authors":"O. Palii","doi":"10.15407/itm2022.03.075","DOIUrl":"https://doi.org/10.15407/itm2022.03.075","url":null,"abstract":"The goal of this paper is to develop mass models of a space industrial platform and its modules. At the initial stage of development of a new spacecraft, a limited set of basic data is available. For a space industrial platform, they are as follows: the configuration of its main and auxiliary modules, the parameters of the technological processes to be implemented on the platform (the vacuum and the microgravity level, the equipment energy capacity), and the manufacturing equipment configuration. A feature of industrial platform design is that there are few, if any, theoretical works on the choice of platform parameters and the logic of platform conceptual design. In this paper, the design process is considered as applied to the conceptual design stage. This stage is characterized by that nothing is known about the system to be developed except for the general concept of the platform layout, the expected types of the main service systems, some basic data, and the parameters of the technological processes to be implemented on the platform. The process of designing a new complex space system such as an industrial platform is a multilevel iterative and optimization process, during which its characteristics and the mass fractions of its components are determined and refined. The paper presents a mass model of an industrial platform and its modules, in whose development the platform and its components were decomposed to the level of system elements. A statistical analysis of the mass fractions of the onboard spacecraft systems was carried out. The mean values of the mass fractions for the sample of spacecraft under study and their scattering coefficients (the dispersion and the mean square deviation) were determined. For the mean values and the dispersion, 99.9 confidence intervals were determined. Further studies on the design of space industrial platforms are planned to be carried using the mass fractions of satellite systems and the confidence intervals, namely, the minimum and the maximum possible mass for a particular system, determined in this study.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125659930","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}
The thrust spread of a stand-alone rocket engine caused by external (the pressure and temperature of the propellant components at the engine inlet) and internal (spread in the geometry and operating conditions of the engine units and assemblies) factors is known from experimental tests or can be computed by a known procedure. As a rule, liquid-propellant propulsion systems (LPPSs) of launch vehicle lower stages include a cluster of several engines, whose thrust spread cannot often be determined from firing tests due to limited capabilities of bench equipment. The aim of this work is to develop an approach to determining the thrust spread of an LPPS comprising a cluster of two and more engines. For a multiengine propulsion system, this methodological approach also includes the development of a mathematical model of engine interaction in an LPPS and calculations of an LPPS startup at different combinations of spread in the external and internal factors in cases where the parameter spreads of all engines are both identical and different. For an LPPS with two engines and a common oxidizer feed pipeline, the paper gives an example of calculating the effect of external and internal factors on the thrust spread of each engine and the LPPS as a whole during an LPPS startup. . It is shown that the calculated spread of the 90 percent thrust (combustion chamber pressure) time lies in the range – 0.0917 s to +0.0792 s (engine 1) and –0.0941 s to +0.0618 s (engine 2). The calculated variations of the combustion chamber pressure (engine thrust) from its nominal value lie in the range –6.2 percent to +7.0 percent (engine 1) and -6.8 percent to +6.3 percent (engine 2). The calculated spreads of the 90 percent thrust time and the thrust for the LPPS as a whole are far smaller (about by 40 percent) and lie in the range – 0.0733 s to +0.0457 s for the time and – 4.8 percent to +4.8 percent for the thrust (about 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 both for the two engines and for the LPPS as a whole.
{"title":"Determination of the effect of internal and external factors on the thrust spread of a cluster propulsion system","authors":"S. Dolgopolov","doi":"10.15407/itm2022.02.047","DOIUrl":"https://doi.org/10.15407/itm2022.02.047","url":null,"abstract":"The thrust spread of a stand-alone rocket engine caused by external (the pressure and temperature of the propellant components at the engine inlet) and internal (spread in the geometry and operating conditions of the engine units and assemblies) factors is known from experimental tests or can be computed by a known procedure. As a rule, liquid-propellant propulsion systems (LPPSs) of launch vehicle lower stages include a cluster of several engines, whose thrust spread cannot often be determined from firing tests due to limited capabilities of bench equipment. The aim of this work is to develop an approach to determining the thrust spread of an LPPS comprising a cluster of two and more engines. For a multiengine propulsion system, this methodological approach also includes the development of a mathematical model of engine interaction in an LPPS and calculations of an LPPS startup at different combinations of spread in the external and internal factors in cases where the parameter spreads of all engines are both identical and different. For an LPPS with two engines and a common oxidizer feed pipeline, the paper gives an example of calculating the effect of external and internal factors on the thrust spread of each engine and the LPPS as a whole during an LPPS startup. . It is shown that the calculated spread of the 90 percent thrust (combustion chamber pressure) time lies in the range – 0.0917 s to +0.0792 s (engine 1) and –0.0941 s to +0.0618 s (engine 2). The calculated variations of the combustion chamber pressure (engine thrust) from its nominal value lie in the range –6.2 percent to +7.0 percent (engine 1) and -6.8 percent to +6.3 percent (engine 2). The calculated spreads of the 90 percent thrust time and the thrust for the LPPS as a whole are far smaller (about by 40 percent) and lie in the range – 0.0733 s to +0.0457 s for the time and – 4.8 percent to +4.8 percent for the thrust (about 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 both for the two engines and for the LPPS as a whole.","PeriodicalId":287730,"journal":{"name":"Technical mechanics","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115147616","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}
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