Pub Date : 2024-10-23DOI: 10.1016/j.actaastro.2024.10.008
Cheng Chen, Xiangyu Li, Dong Qiao
The Sun-Earth libration point configuration is one of the options for space-based gravitational wave detection. Long-term configuration stability is crucial for high-precision measurements, challenged by the strong nonlinear dynamics of the Sun-Earth three-body system. This paper proposes an efficient design method and determines the feasible parameter domain for the libration point gravitational wave observatory. First, the dynamic model for the libration point configuration is established, and the stability indexes are defined. The sensitive parameters that affect the relative geometric configuration are discussed and the phase angle is found to be the key factor. Then, an efficient design method is proposed, and the procedure is divided into two steps. The phase angle of the Earth phase offset orbit and the libration point configuration are optimized successively. Finally, the proposed method is applied to the LAGRANGE mission concept. The results show that the three stability indexes decrease by 59%, 42% and 23%, respectively. Moreover, a mapping between configuration parameters and stability indexes is established. The feasible parameter domain for the stable libration point configuration is discussed. The feasible amplitudes domain in the and directions of the libration point orbit should be less than 6200 km and 42000 km, respectively, to guarantee configuration stability. This research could provide a reference for the stable design and implementation of gravitational wave detection missions utilizing libration point configuration in the future.
太阳-地球 L2 天平点配置是天基引力波探测的选项之一。由于日地三体系统具有很强的非线性动力学特性，长期的配置稳定性对高精度测量至关重要。本文提出了一种高效的设计方法，并确定了天平点引力波观测站的可行参数域。首先，建立了天枰点构型的动力学模型，并定义了稳定性指标。讨论了影响相对几何构型的敏感参数，发现相位角是关键因素。然后，提出了一种高效的设计方法，并将设计过程分为两个步骤。先后优化了地球相位偏移轨道的相位角和天平点配置。最后，将提出的方法应用于 LAGRANGE 任务概念。结果表明，三个稳定性指数分别降低了 59%、42% 和 23%。此外，还建立了配置参数与稳定性指数之间的映射关系。讨论了稳定的天平点配置的可行参数域。为保证构型的稳定性，秤锤点轨道 x 和 z 方向的可行振幅域应分别小于 6200 千米和 42000 千米。该研究可为未来利用 "秤锤点 "构型稳定设计和实施引力波探测任务提供参考。
{"title":"Stable configuration design for libration point gravitational wave observatory","authors":"Cheng Chen, Xiangyu Li, Dong Qiao","doi":"10.1016/j.actaastro.2024.10.008","DOIUrl":"10.1016/j.actaastro.2024.10.008","url":null,"abstract":"<div><div>The Sun-Earth <span><math><msub><mrow><mi>L</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> libration point configuration is one of the options for space-based gravitational wave detection. Long-term configuration stability is crucial for high-precision measurements, challenged by the strong nonlinear dynamics of the Sun-Earth three-body system. This paper proposes an efficient design method and determines the feasible parameter domain for the libration point gravitational wave observatory. First, the dynamic model for the libration point configuration is established, and the stability indexes are defined. The sensitive parameters that affect the relative geometric configuration are discussed and the phase angle is found to be the key factor. Then, an efficient design method is proposed, and the procedure is divided into two steps. The phase angle of the Earth phase offset orbit and the libration point configuration are optimized successively. Finally, the proposed method is applied to the LAGRANGE mission concept. The results show that the three stability indexes decrease by 59%, 42% and 23%, respectively. Moreover, a mapping between configuration parameters and stability indexes is established. The feasible parameter domain for the stable libration point configuration is discussed. The feasible amplitudes domain in the <span><math><mi>x</mi></math></span> and <span><math><mi>z</mi></math></span> directions of the libration point orbit should be less than 6200 km and 42000 km, respectively, to guarantee configuration stability. This research could provide a reference for the stable design and implementation of gravitational wave detection missions utilizing libration point configuration in the future.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"226 ","pages":"Pages 248-261"},"PeriodicalIF":3.1,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534902","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-23DOI: 10.1016/j.actaastro.2024.10.050
Wu Zhigang, Wang Weiwei, Liu Lu, Liu Jiafu
A cislunar suspension tether (CST) is a kind of ultra-long tether anchored to the lunar surface and extends to the vicinity of the Earth, looks like hanging to the Moon, could be used as cislunar pathway for interstellar freightage easier. Its feasibility on material mechanics and dynamics has been verified by the authors. This paper focuses on the process of the cargo transport along the CST. A single coupling model is established, which couples the cargo with one single node of the discrete CST model. Merely the interactive force between the coupled node and cargo is considered, with a proper definition description of the cargo's velocity along the CST. The description defines the direction of the cargo's velocity to the next one node on the CST all the time. The dynamic equations of the whole system are established based on afore stipulations. Several examples will be simulated and presented, their results will prove the effectiveness of the single coupling model, while, reflect some interesting phenomena of the CST's work. This paper also explains the advantage of the model by contrasting to some other models with multi nodes actions to the cargo.
{"title":"Dynamic simulation of cargo transport along cislunar suspension tether by single node coupling model","authors":"Wu Zhigang, Wang Weiwei, Liu Lu, Liu Jiafu","doi":"10.1016/j.actaastro.2024.10.050","DOIUrl":"10.1016/j.actaastro.2024.10.050","url":null,"abstract":"<div><div>A cislunar suspension tether (CST) is a kind of ultra-long tether anchored to the lunar surface and extends to the vicinity of the Earth, looks like hanging to the Moon, could be used as cislunar pathway for interstellar freightage easier. Its feasibility on material mechanics and dynamics has been verified by the authors. This paper focuses on the process of the cargo transport along the CST. A single coupling model is established, which couples the cargo with one single node of the discrete CST model. Merely the interactive force between the coupled node and cargo is considered, with a proper definition description of the cargo's velocity along the CST. The description defines the direction of the cargo's velocity to the next one node on the CST all the time. The dynamic equations of the whole system are established based on afore stipulations. Several examples will be simulated and presented, their results will prove the effectiveness of the single coupling model, while, reflect some interesting phenomena of the CST's work. This paper also explains the advantage of the model by contrasting to some other models with multi nodes actions to the cargo.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"226 ","pages":"Pages 262-274"},"PeriodicalIF":3.1,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534903","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The relevance of research aimed at developing diagnostic technologies for electromechanical actuators is due to the need to improve flight safety in conditions of increasing intensity of highly electrified aircraft and spacecraft operations. The paper discusses one of the promising approaches to electromechanical actuator health management, which involves the use of machine learning methods to synthesize health monitoring algorithms. Machine learning methods make it possible to build classification models based on empirical data, which are used to generate recommendations for making operational decisions. Empirical data, which is a source of valuable experience and the basis of a training sample necessary for formalizing patterns in classification models, can be formed as a result of life tests, mathematical modeling, and actuator operation. In order to improve the safety of space flights, the article focuses on the integration of electromechanical actuator mathematical model methods, optimal space filling, and machine learning. Optimal space filling methods are used to reduce the computational costs associated with representative training sampling. Examples of developing classification models are given to determine failures associated with changes in gear (backlash, Coulomb friction and viscous friction) which is the most critical actuator link. As a result of computational studies, the main advantages of the proposed approach to the synthesis of electromechanical actuator health assessment algorithms are shown.
{"title":"Machine learning-based synthesis of diagnostic algorithms for electromechanical actuators to improve the aerospace flight safety","authors":"G.S. Veresnikov , S.G. Bazhenov , I.G. Bashkirov , S.L. Chernyshev , V.I. Goncharenko , A.V. Skryabin , D.A. Petrov","doi":"10.1016/j.actaastro.2024.10.054","DOIUrl":"10.1016/j.actaastro.2024.10.054","url":null,"abstract":"<div><div>The relevance of research aimed at developing diagnostic technologies for electromechanical actuators is due to the need to improve flight safety in conditions of increasing intensity of highly electrified aircraft and spacecraft operations. The paper discusses one of the promising approaches to electromechanical actuator health management, which involves the use of machine learning methods to synthesize health monitoring algorithms. Machine learning methods make it possible to build classification models based on empirical data, which are used to generate recommendations for making operational decisions. Empirical data, which is a source of valuable experience and the basis of a training sample necessary for formalizing patterns in classification models, can be formed as a result of life tests, mathematical modeling, and actuator operation. In order to improve the safety of space flights, the article focuses on the integration of electromechanical actuator mathematical model methods, optimal space filling, and machine learning. Optimal space filling methods are used to reduce the computational costs associated with representative training sampling. Examples of developing classification models are given to determine failures associated with changes in gear (backlash, Coulomb friction and viscous friction) which is the most critical actuator link. As a result of computational studies, the main advantages of the proposed approach to the synthesis of electromechanical actuator health assessment algorithms are shown.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"226 ","pages":"Pages 239-247"},"PeriodicalIF":3.1,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534901","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-23DOI: 10.1016/j.actaastro.2024.10.052
Carlo Sgorlon Gaiatto , Federico Antonello , Daniele Segneri , Bruno Sousa , Beatriz Abascal Palacios , Anna Schiavo , Mauro Bartesaghi , Jan Maass , Aniris Inojosa
Accurate modeling and simulation (M&S) of spacecraft solar array power under degradation is essential for mission planning, remaining useful life assessment, and lifetime extension. A relevant example is ESA’s Cluster spacecraft fleet, launched in 2000 and operated at the European Space Operation Centre (ESOC), whose solar arrays have suffered severe degradation due to space radiation that has caused challenges to routine operations and mission planning. However, currently available physics-based and machine learning models have been proven ineffective in modeling the drastic reduction in power generation over the long operational life of the spacecraft.
In response to these limitations, this work introduces a framework to model solar array degradation and predict power generation. It embeds a novel simplified physics-based model and a meta-heuristic optimization algorithm which exploits domain-specific knowledge and monitoring data for robust model parameter calibration and accurate power generation predictions. The results show the effectiveness of the proposed approach in avoiding overfitting and providing an accurate estimate of Cluster solar array power evolution.
{"title":"A novel physics-based computational framework to model spacecraft solar array power under degradation: Application to European Space Agency (ESA) Cluster mission","authors":"Carlo Sgorlon Gaiatto , Federico Antonello , Daniele Segneri , Bruno Sousa , Beatriz Abascal Palacios , Anna Schiavo , Mauro Bartesaghi , Jan Maass , Aniris Inojosa","doi":"10.1016/j.actaastro.2024.10.052","DOIUrl":"10.1016/j.actaastro.2024.10.052","url":null,"abstract":"<div><div>Accurate modeling and simulation (M&S) of spacecraft solar array power under degradation is essential for mission planning, remaining useful life assessment, and lifetime extension. A relevant example is ESA’s Cluster spacecraft fleet, launched in 2000 and operated at the European Space Operation Centre (ESOC), whose solar arrays have suffered severe degradation due to space radiation that has caused challenges to routine operations and mission planning. However, currently available physics-based and machine learning models have been proven ineffective in modeling the drastic reduction in power generation over the long operational life of the spacecraft.</div><div>In response to these limitations, this work introduces a framework to model solar array degradation and predict power generation. It embeds a novel simplified physics-based model and a meta-heuristic optimization algorithm which exploits domain-specific knowledge and monitoring data for robust model parameter calibration and accurate power generation predictions. The results show the effectiveness of the proposed approach in avoiding overfitting and providing an accurate estimate of Cluster solar array power evolution.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"226 ","pages":"Pages 341-348"},"PeriodicalIF":3.1,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142538883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-23DOI: 10.1016/j.actaastro.2024.10.059
Yulong Feng , Jinglei Liu , Renjie Li , Huaming Jia , Yuhong Cui
<div><div>The sharp morphological features of lunar dust particles generate significant elastic–plastic contact forces and deformations upon contact with material surfaces, which considerably affect the mechanical properties of lunar dust particles, including their contact, collision, adhesion, transport, and wear characteristics. Despite these severe effects, valid models considering the contact characteristics of typical sharp-featured lunar dust particles are currently lacking. This study proposes an elastic–plastic contact model for nonrotationally symmetric lunar dust particles showing typical sharp features. Detailed derivations of the expressions for various physical responses observed when lunar dust particles establish normal contacts with elastic and elastic–plastic half-spaces under adhesive conditions are also provided. These include derivations for elastic forces, elastic–plastic forces, contact areas, pull-off forces, residual displacements, and plastic deformation areas. Furthermore, the tangential pull-off force during the tangential loading of lunar dust particles is derived, and the tangential contact characteristics are explored. Comparisons of the results of the proposed model with those of previous experiments reveal that the proposed model shows errors of only 6.06 % and 1.03 % in the maximum indentation depth and residual displacement, respectively. These errors are substantially lower than those of conventional spherical models (60.30 % and 60.13 %, respectively), confirming the superior accuracy of the proposed model. Furthermore, the discrete element method is employed to analyze the effects of normal and tangential contacts, dynamic characteristics, and plastic deformations on the considered lunar dust particles. The results are then compared with those of existing contact models. They reveal that maximum elastic–plastic forces under normal contact conditions are positively correlated with the initial velocity but negatively correlated with the lateral angle. Furthermore, the tangential pull-off force is positively correlated with the normal force and surface energy. In addition, the contact duration of lunar dust particles is positively correlated with their initial velocities, while the residual displacement is negatively correlation. For instance, as the initial velocity increases from 10 to 50 m/s, the maximum elastic–plastic force increases from 37.64 to 321.72 mN. Comparisons of the proposed model with other contact models reveal that the maximum elastic–plastic force of the elastic–plastic triangular pyramid model is only 14.93 % that of the cylindrical model, 34.23 % that of the spherical model, and 76.27 % that of the conical model, indicating significant reductions in the maximum elastic–plastic force owing to the plastic deformations of particles with typical sharp features. Overall, the results of this study offer crucial insights into the mechanical characteristics of nonspherical lunar dust particles under
{"title":"Modeling the elastic–plastic contact forces and deformations of nonrotationally symmetric lunar dust particles","authors":"Yulong Feng , Jinglei Liu , Renjie Li , Huaming Jia , Yuhong Cui","doi":"10.1016/j.actaastro.2024.10.059","DOIUrl":"10.1016/j.actaastro.2024.10.059","url":null,"abstract":"<div><div>The sharp morphological features of lunar dust particles generate significant elastic–plastic contact forces and deformations upon contact with material surfaces, which considerably affect the mechanical properties of lunar dust particles, including their contact, collision, adhesion, transport, and wear characteristics. Despite these severe effects, valid models considering the contact characteristics of typical sharp-featured lunar dust particles are currently lacking. This study proposes an elastic–plastic contact model for nonrotationally symmetric lunar dust particles showing typical sharp features. Detailed derivations of the expressions for various physical responses observed when lunar dust particles establish normal contacts with elastic and elastic–plastic half-spaces under adhesive conditions are also provided. These include derivations for elastic forces, elastic–plastic forces, contact areas, pull-off forces, residual displacements, and plastic deformation areas. Furthermore, the tangential pull-off force during the tangential loading of lunar dust particles is derived, and the tangential contact characteristics are explored. Comparisons of the results of the proposed model with those of previous experiments reveal that the proposed model shows errors of only 6.06 % and 1.03 % in the maximum indentation depth and residual displacement, respectively. These errors are substantially lower than those of conventional spherical models (60.30 % and 60.13 %, respectively), confirming the superior accuracy of the proposed model. Furthermore, the discrete element method is employed to analyze the effects of normal and tangential contacts, dynamic characteristics, and plastic deformations on the considered lunar dust particles. The results are then compared with those of existing contact models. They reveal that maximum elastic–plastic forces under normal contact conditions are positively correlated with the initial velocity but negatively correlated with the lateral angle. Furthermore, the tangential pull-off force is positively correlated with the normal force and surface energy. In addition, the contact duration of lunar dust particles is positively correlated with their initial velocities, while the residual displacement is negatively correlation. For instance, as the initial velocity increases from 10 to 50 m/s, the maximum elastic–plastic force increases from 37.64 to 321.72 mN. Comparisons of the proposed model with other contact models reveal that the maximum elastic–plastic force of the elastic–plastic triangular pyramid model is only 14.93 % that of the cylindrical model, 34.23 % that of the spherical model, and 76.27 % that of the conical model, indicating significant reductions in the maximum elastic–plastic force owing to the plastic deformations of particles with typical sharp features. Overall, the results of this study offer crucial insights into the mechanical characteristics of nonspherical lunar dust particles under","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"226 ","pages":"Pages 283-297"},"PeriodicalIF":3.1,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-23DOI: 10.1016/j.actaastro.2024.10.051
Junlin Li , Yan Shen
The application of Ionic Liquid Electrospray Thrusters (ILETs) in micro/nanosatellites is very promising. However, the divergent beam of ILETs significantly affects their performance, including thrust, specific impulse, lifetime, propulsion efficiency, and more. Therefore, in order to improve the performance of ILETs, it is essential to optimize the beam. In this study, a focus structure was designed and fabricated. A series of beam focusing experiments were performed using a conical porous tungsten emitter and the ionic liquid EMI-BF4 as a propellant. The operational state of ILETs was demonstrated, with over 95 % of the beam composed of ions. After configuring the focus structure, the electric field in the emission region is weakened by the focus electrode, which has a certain negative effect on the starting voltage and emission current. Analysis of the beam focusing results showed that the focus structure reduced the beam divergence half-angle (half-angle) from 40° to 11° and concentrated the beam current within a half-angle of 7.3°. By estimating the thrust and specific impulse of the thruster, it was found that the focus structure could maximize the specific impulse by up to 22.4 % at the same voltage and increase it by approximately 23 % at the same power-to-thrust ratio. This focus structure demonstrated excellent focusing effect on a single conical emitter, making this research valuable as a reference for designing a focus structure for other types of emitters.
{"title":"Experimental study on beam focusing of ionic liquid electrospray thruster with focus structure","authors":"Junlin Li , Yan Shen","doi":"10.1016/j.actaastro.2024.10.051","DOIUrl":"10.1016/j.actaastro.2024.10.051","url":null,"abstract":"<div><div>The application of Ionic Liquid Electrospray Thrusters (ILETs) in micro/nanosatellites is very promising. However, the divergent beam of ILETs significantly affects their performance, including thrust, specific impulse, lifetime, propulsion efficiency, and more. Therefore, in order to improve the performance of ILETs, it is essential to optimize the beam. In this study, a focus structure was designed and fabricated. A series of beam focusing experiments were performed using a conical porous tungsten emitter and the ionic liquid EMI-BF<sub>4</sub> as a propellant. The operational state of ILETs was demonstrated, with over 95 % of the beam composed of ions. After configuring the focus structure, the electric field in the emission region is weakened by the focus electrode, which has a certain negative effect on the starting voltage and emission current. Analysis of the beam focusing results showed that the focus structure reduced the beam divergence half-angle (half-angle) from 40° to 11° and concentrated the beam current within a half-angle of 7.3°. By estimating the thrust and specific impulse of the thruster, it was found that the focus structure could maximize the specific impulse by up to 22.4 % at the same voltage and increase it by approximately 23 % at the same power-to-thrust ratio. This focus structure demonstrated excellent focusing effect on a single conical emitter, making this research valuable as a reference for designing a focus structure for other types of emitters.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"226 ","pages":"Pages 827-838"},"PeriodicalIF":3.1,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142661035","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-22DOI: 10.1016/j.actaastro.2024.10.046
C. Cottenot , R. Beauchet , B. Boust , L. Prévost , Y. Batonneau , M. Bellenoue
Two different diameters of Pt/Al2O3 spherical catalysts (1 mm and 2 mm) for HTP 98 % decomposition were tested to compare the catalytic activity and catalyst ageing. Comparable decomposition performance efficiencies were obtained during thruster-like tests in a catalytic decomposition setup, even though the 1-mm showed a better reactivity and temperature rising time, including in cold-start operation. However, a rapid physical degradation accompanied by pressure peaks observed throughout testing of the 1-mm catalyst led to damage of the catalyst and apparition of fines, causing partial clogging of the bed.
{"title":"Influence of hydrogen peroxide catalyst grain size on performance and ageing","authors":"C. Cottenot , R. Beauchet , B. Boust , L. Prévost , Y. Batonneau , M. Bellenoue","doi":"10.1016/j.actaastro.2024.10.046","DOIUrl":"10.1016/j.actaastro.2024.10.046","url":null,"abstract":"<div><div>Two different diameters of Pt/Al<sub>2</sub>O<sub>3</sub> spherical catalysts (1 mm and 2 mm) for HTP 98 % decomposition were tested to compare the catalytic activity and catalyst ageing. Comparable decomposition performance efficiencies were obtained during thruster-like tests in a catalytic decomposition setup, even though the 1-mm showed a better reactivity and temperature rising time, including in cold-start operation. However, a rapid physical degradation accompanied by pressure peaks observed throughout testing of the 1-mm catalyst led to damage of the catalyst and apparition of fines, causing partial clogging of the bed.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"226 ","pages":"Pages 332-340"},"PeriodicalIF":3.1,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142538882","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-21DOI: 10.1016/j.actaastro.2024.10.038
A. Kiverin, A. Yarkov, I. Yakovenko
In the framework of comprehensive assessment of explosion risks on board of spacecrafts and on the facilities of launch places, the paper is focused on the detailed analysis of particular scenarios of deflagration-to-detonation transition taking place in smooth tubes filled with acetylene-oxygen mixtures of different compositions. By means of precise numerical simulation it is demonstrated that various scenarios of detonation onset can take place depending on the mixture composition and its initial thermodynamic state. It is demonstrated that independent on the particular scenario always the basic mechanism of detonation onset via the formation of strong enough shock wave takes place. In more reactive mixtures the strong shock originates from the self-sustained process of joint pressure build up and reaction intensification exactly at the flame front. In less reactive mixtures the transient flow behavior leads to the shock waves generation and interaction. As a result, a brand new reaction kernel could arise in the area of shock waves interaction. In number of cases, that leads to the coupling between the shock wave and the newborn reaction front and results in the strong shock formation and further detonation onset.
{"title":"Explosion risks: Variety of deflagration-to-detonation transition scenarios in smooth tubes","authors":"A. Kiverin, A. Yarkov, I. Yakovenko","doi":"10.1016/j.actaastro.2024.10.038","DOIUrl":"10.1016/j.actaastro.2024.10.038","url":null,"abstract":"<div><div>In the framework of comprehensive assessment of explosion risks on board of spacecrafts and on the facilities of launch places, the paper is focused on the detailed analysis of particular scenarios of deflagration-to-detonation transition taking place in smooth tubes filled with acetylene-oxygen mixtures of different compositions. By means of precise numerical simulation it is demonstrated that various scenarios of detonation onset can take place depending on the mixture composition and its initial thermodynamic state. It is demonstrated that independent on the particular scenario always the basic mechanism of detonation onset via the formation of strong enough shock wave takes place. In more reactive mixtures the strong shock originates from the self-sustained process of joint pressure build up and reaction intensification exactly at the flame front. In less reactive mixtures the transient flow behavior leads to the shock waves generation and interaction. As a result, a brand new reaction kernel could arise in the area of shock waves interaction. In number of cases, that leads to the coupling between the shock wave and the newborn reaction front and results in the strong shock formation and further detonation onset.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"226 ","pages":"Pages 325-331"},"PeriodicalIF":3.1,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142538881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-20DOI: 10.1016/j.actaastro.2024.10.022
Prasad N. Dal, Suril V. Shah
Space robots will play a crucial role in on-orbit operations like refuelling, servicing, and capture of debris. This paper focuses on capturing a non-cooperative target using a multi-arm space robot and its post-capture control. In the post-capture phase, a target object gets rigidly attached to end-effectors, and arms get into a closed-loop configuration, resulting in added constraints. Further, due to a target object’s unknown inertial parameters, system behaviour becomes unpredictable and poses difficulty in achieving reactionless manipulation to minimize base attitude disturbance. We present acceleration-based adaptive reactionless manipulation in the post-capture phase considering the unknown inertial parameter of a target. The regressor form required for adapting the joint states is derived using the acceleration-based approach. To update unknown parameters recursively immediately after impact, three methods, namely, recursive least square (RLS), weighted recursive least square (WRLS), and Kalman filter (KF), are used and compared. The efficacy of these methods has been demonstrated by using numerical studies of a dual-arm space robot that captures a non-cooperative target. Further, the acceleration-based and the velocity-based approaches are individually compared with RLS, WRLS and KF methods. Investigations have also been carried out to study the effects of change in ratios of base-to-target and base-to-robot masses, as well as angular velocities of a target.
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Pub Date : 2024-10-19DOI: 10.1016/j.actaastro.2024.10.042
A.V. Zvyagin , A.S. Udalov
Spacecraft parts accumulate damage during operation and defects that are invariably present even in new designs may grow. This leads to changes in the behavior of individual parts of the space vehicle and, consequently, to the risk of fracture. A more accurate assessment of spacecraft safety requires internal defects to be included in the material models under consideration. One of the main hazardous effects on space objects is multiple temperature heating and cooling due to periodic action of solar rays. This paper presents a study of thermal conduction of media containing cracks. It is carried out with the help of a technique developed by the authors to determine the effective thermal conductivity of materials and based on approximate numerical solution of the steady-state thermal conduction problem for a three-dimensional medium with cracks by the boundary element method. This technique allows to obtain the distribution of the temperature field and heat flux density at any point of the body under consideration, as well as to calculate the effective parameters of materials with high accuracy at relatively low calculation time using ordinary personal computers of average power. The basis of the numerical method presented in this paper is the decomposition of the desired solution into a series of some pre-calculated analytical solutions of the heat conduction equations. The dependence of the effective thermal conductivity on the density of thermally insulated cracks was considered. The formula of this dependence is proposed. Verification of the proposed methodology was carried out by comparing the numerical results of a number of problems with the results of other authors.
{"title":"Numerical search for the effective thermal conductivity of cracked media","authors":"A.V. Zvyagin , A.S. Udalov","doi":"10.1016/j.actaastro.2024.10.042","DOIUrl":"10.1016/j.actaastro.2024.10.042","url":null,"abstract":"<div><div>Spacecraft parts accumulate damage during operation and defects that are invariably present even in new designs may grow. This leads to changes in the behavior of individual parts of the space vehicle and, consequently, to the risk of fracture. A more accurate assessment of spacecraft safety requires internal defects to be included in the material models under consideration. One of the main hazardous effects on space objects is multiple temperature heating and cooling due to periodic action of solar rays. This paper presents a study of thermal conduction of media containing cracks. It is carried out with the help of a technique developed by the authors to determine the effective thermal conductivity of materials and based on approximate numerical solution of the steady-state thermal conduction problem for a three-dimensional medium with cracks by the boundary element method. This technique allows to obtain the distribution of the temperature field and heat flux density at any point of the body under consideration, as well as to calculate the effective parameters of materials with high accuracy at relatively low calculation time using ordinary personal computers of average power. The basis of the numerical method presented in this paper is the decomposition of the desired solution into a series of some pre-calculated analytical solutions of the heat conduction equations. The dependence of the effective thermal conductivity on the density of thermally insulated cracks was considered. The formula of this dependence is proposed. Verification of the proposed methodology was carried out by comparing the numerical results of a number of problems with the results of other authors.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"226 ","pages":"Pages 97-101"},"PeriodicalIF":3.1,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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