Pub Date : 2024-12-11DOI: 10.1016/j.actaastro.2024.12.001
Ramy Mesalam, Paul C. Schmitz, Hannah M. Sargeant, Elizabeth R. Turnbull, Alessandra Barco, Scott Wilson, Jesse Stuck, Emily Jane Watkinson, Steven R. Oleson, Richard Ambrosi
Radioisotope Power Systems (RPS) are an invaluable resource for the exploration of our Solar System. Providing both heat and electricity, spacecraft using RPS can operate where it is impractical to use solar arrays and/or battery systems because of either limited solar illumination or mission durations which make a standalone battery impractical. Dynamic Radioisotope Power System (DRPS) have been designed using the decay of Plutonium-238 (238Pu) in the form of the General-Purpose Heat Source (GPHS) coupled with Stirling convertors, and Stirling-based generator technologies are being developed by NASA's RPS Program in an effort to realize high efficiency RPS. This paper describes the development of a new generator design based upon the European Large Heat Source (ELHS). The ELHS uses Americium-241 (241Am) rather than 238Pu as the heat producing isotope. The ELHS dimensions and shapes were optimized for use with thermoelectric power conversion and are different compared to a Step-2 GPHS Module, which impact implementation into the DRPS generator design. This ELHS-DRPS design assumes that the ELHS would be coupled to the same Stirling convertors under development for existing GPHS-based DRPS designs. Trades are performed on the number of convertors, fin lengths, housing configuration and hot-end temperature. Finally, this ELHS-DRPS design is compared with the existing GPHS-DRPS generator design completed by Aerojet Rocketdyne, along with the advantages and disadvantages of using americium as a heat source for RPS.
{"title":"Americium fuelled radioisotope stirling generator for lunar surface mobility systems","authors":"Ramy Mesalam, Paul C. Schmitz, Hannah M. Sargeant, Elizabeth R. Turnbull, Alessandra Barco, Scott Wilson, Jesse Stuck, Emily Jane Watkinson, Steven R. Oleson, Richard Ambrosi","doi":"10.1016/j.actaastro.2024.12.001","DOIUrl":"https://doi.org/10.1016/j.actaastro.2024.12.001","url":null,"abstract":"Radioisotope Power Systems (RPS) are an invaluable resource for the exploration of our Solar System. Providing both heat and electricity, spacecraft using RPS can operate where it is impractical to use solar arrays and/or battery systems because of either limited solar illumination or mission durations which make a standalone battery impractical. Dynamic Radioisotope Power System (DRPS) have been designed using the decay of Plutonium-238 (<ce:sup loc=\"post\">238</ce:sup>Pu) in the form of the General-Purpose Heat Source (GPHS) coupled with Stirling convertors, and Stirling-based generator technologies are being developed by NASA's RPS Program in an effort to realize high efficiency RPS. This paper describes the development of a new generator design based upon the European Large Heat Source (ELHS). The ELHS uses Americium-241 (<ce:sup loc=\"post\">241</ce:sup>Am) rather than <ce:sup loc=\"post\">238</ce:sup>Pu as the heat producing isotope. The ELHS dimensions and shapes were optimized for use with thermoelectric power conversion and are different compared to a Step-2 GPHS Module, which impact implementation into the DRPS generator design. This ELHS-DRPS design assumes that the ELHS would be coupled to the same Stirling convertors under development for existing GPHS-based DRPS designs. Trades are performed on the number of convertors, fin lengths, housing configuration and hot-end temperature. Finally, this ELHS-DRPS design is compared with the existing GPHS-DRPS generator design completed by Aerojet Rocketdyne, along with the advantages and disadvantages of using americium as a heat source for RPS.","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"6 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142823085","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 : 2024-12-11DOI: 10.1016/j.actaastro.2024.11.025
Qianlei Jia, Jiaping Xiao, Lu Bai, Yuhang Zhang, Rangya Zhang, Mir Feroskhan
With the rapid increase of space activities and the accumulation of space debris, the existing space situational awareness systems (SSAS) is facing increasingly severe challenges. This paper analyzes traditional approaches and describes their limitations in dealing with complex space environments. To address these challenges, we explore the application of artificial intelligence (AI) technology in SSAS and its future development scenarios. This paper gives a detailed overview of the basic principles and applications of traditional SSAS, and highlights its limitations. We focus on the application of AI to orbit determination and orbit prediction, highlighting its potential to enhance system flexibility and adaptability. In addition, we present possible directions for the future development of AI technology in SSAS. By combining traditional methods with AI technologies, we can expect more efficient and intelligent systems that are able to adapt to complex space environments. Through this comprehensive perspective, this paper aims to provide an in-depth understanding of SSAS and provide a valuable reference for future technological innovations and system upgrades.
{"title":"Space situational awareness systems: Bridging traditional methods and artificial intelligence","authors":"Qianlei Jia, Jiaping Xiao, Lu Bai, Yuhang Zhang, Rangya Zhang, Mir Feroskhan","doi":"10.1016/j.actaastro.2024.11.025","DOIUrl":"https://doi.org/10.1016/j.actaastro.2024.11.025","url":null,"abstract":"With the rapid increase of space activities and the accumulation of space debris, the existing space situational awareness systems (SSAS) is facing increasingly severe challenges. This paper analyzes traditional approaches and describes their limitations in dealing with complex space environments. To address these challenges, we explore the application of artificial intelligence (AI) technology in SSAS and its future development scenarios. This paper gives a detailed overview of the basic principles and applications of traditional SSAS, and highlights its limitations. We focus on the application of AI to orbit determination and orbit prediction, highlighting its potential to enhance system flexibility and adaptability. In addition, we present possible directions for the future development of AI technology in SSAS. By combining traditional methods with AI technologies, we can expect more efficient and intelligent systems that are able to adapt to complex space environments. Through this comprehensive perspective, this paper aims to provide an in-depth understanding of SSAS and provide a valuable reference for future technological innovations and system upgrades.","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"1 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142823088","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 : 2024-12-06DOI: 10.1016/j.actaastro.2024.11.056
Hong Zhao, Wei Zhang, Ming Xu, Gen Leng
This paper addresses the challenges of designing aerodynamic rotors for Mars helicopters, particularly in the highly variable Martian atmosphere. Traditional deterministic rotor designs targeted at a single atmospheric condition often result in significant performance deviations under varying conditions. This research initiates with an in-depth analysis of Martian atmospheric characteristics, followed by the establishment of a probabilistic model for atmospheric density. Subsequently, a robust aerodynamic model for a Mars coaxial rotor is developed, utilizing a combination of the viscous vortex particle method and the vortex in cell method. Through robust optimization, this study enhances the rotor's resilience to atmospheric fluctuations, ensuring improved flight safety and reliability. The findings underscore the necessity and effectiveness of robust optimization techniques in enhancing the adaptability and operational stability of rotorcraft on Mars in response to uncertainties in atmospheric density.
{"title":"Aerodynamic robust optimization design of the coaxial rotor for a Mars helicopter","authors":"Hong Zhao, Wei Zhang, Ming Xu, Gen Leng","doi":"10.1016/j.actaastro.2024.11.056","DOIUrl":"https://doi.org/10.1016/j.actaastro.2024.11.056","url":null,"abstract":"This paper addresses the challenges of designing aerodynamic rotors for Mars helicopters, particularly in the highly variable Martian atmosphere. Traditional deterministic rotor designs targeted at a single atmospheric condition often result in significant performance deviations under varying conditions. This research initiates with an in-depth analysis of Martian atmospheric characteristics, followed by the establishment of a probabilistic model for atmospheric density. Subsequently, a robust aerodynamic model for a Mars coaxial rotor is developed, utilizing a combination of the viscous vortex particle method and the vortex in cell method. Through robust optimization, this study enhances the rotor's resilience to atmospheric fluctuations, ensuring improved flight safety and reliability. The findings underscore the necessity and effectiveness of robust optimization techniques in enhancing the adaptability and operational stability of rotorcraft on Mars in response to uncertainties in atmospheric density.","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"20 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142790209","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 : 2024-12-03DOI: 10.1016/j.actaastro.2024.11.029
Helber Valério Farias Melo, Evandro José da Silva, Frank Cabral de Freitas Amaral, Arthur Durigan Bahdur
The New Space industry not only demands expanded spaceport capacity but also careful consideration of the environmental impact of ground infrastructure development. Focusing on the Alcântara Space Center in Brazil (CEA - Centro Espacial de Alcântara), a data-driven site selection framework is presented, emphasizing cost-effectiveness and environmental compliance. When applied to the CEA case, this framework incorporates expert preferences and aligns Geographic Information System-Multi-Criteria Decision Analysis (GIS-MCDA) with the development of launch site infrastructure and the assessment of environmental impact. The real case application results in robust ranking outcomes, despite some level of divergence amongst the experts. Contributions include expert clustering for sensitivity analysis, insights into spaceport impact on surrounding communities, and the proposal of an easily deployable decision-making process. The framework exhibits flexibility and can be adapted to different variations of the spaceport locational problems. Recommendations include the implementation of advanced geotechnical assessment protocols, enhanced quantification methodologies for environmental variables, and the utilization of comprehensive risk assessment techniques. These measures hold the potential to provide valuable insights for research and regulatory efforts within this rapidly evolving domain.
新航天工业不仅要求扩大航天发射场的容量，而且还需要仔细考虑地面基础设施发展对环境的影响。以巴西alc ntara空间中心（CEA - Centro Espacial de alc ntara）为例，提出了一个数据驱动的选址框架，强调成本效益和环境合规性。当应用于CEA案例时，该框架结合了专家偏好，并将地理信息系统-多标准决策分析（GIS-MCDA）与发射场基础设施的发展和环境影响评估相结合。尽管专家之间存在一定程度的分歧，但实际案例应用会产生稳健的排名结果。贡献包括灵敏度分析的专家聚类，对航天港对周围社区影响的见解，以及易于部署的决策过程的建议。该框架具有灵活性，可适应不同类型的航天发射场定位问题。建议包括实施先进的岩土工程评估规程，加强环境变量的量化方法，以及利用综合风险评估技术。这些措施有可能为这个快速发展的领域的研究和监管工作提供有价值的见解。
{"title":"Sustainable site planning for new launch facilities at spaceports","authors":"Helber Valério Farias Melo, Evandro José da Silva, Frank Cabral de Freitas Amaral, Arthur Durigan Bahdur","doi":"10.1016/j.actaastro.2024.11.029","DOIUrl":"https://doi.org/10.1016/j.actaastro.2024.11.029","url":null,"abstract":"The <ce:italic>New Space</ce:italic> industry not only demands expanded spaceport capacity but also careful consideration of the environmental impact of ground infrastructure development. Focusing on the Alcântara Space Center in Brazil (CEA - <ce:italic>Centro Espacial de Alcântara</ce:italic>), a data-driven site selection framework is presented, emphasizing cost-effectiveness and environmental compliance. When applied to the CEA case, this framework incorporates expert preferences and aligns Geographic Information System-Multi-Criteria Decision Analysis (GIS-MCDA) with the development of launch site infrastructure and the assessment of environmental impact. The real case application results in robust ranking outcomes, despite some level of divergence amongst the experts. Contributions include expert clustering for sensitivity analysis, insights into spaceport impact on surrounding communities, and the proposal of an easily deployable decision-making process. The framework exhibits flexibility and can be adapted to different variations of the spaceport locational problems. Recommendations include the implementation of advanced geotechnical assessment protocols, enhanced quantification methodologies for environmental variables, and the utilization of comprehensive risk assessment techniques. These measures hold the potential to provide valuable insights for research and regulatory efforts within this rapidly evolving domain.","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"51 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142790208","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 : 2024-12-03DOI: 10.1016/j.actaastro.2024.11.052
Emanuela Gaglio, Constantin Traub, Fabrizio Turco, Jhonathan O. Murcia Piñeros, Riccardo Bevilacqua, Stefanos Fasoulas
The increasing number of objects in Low Earth Orbit makes active collision avoidance imperative for satellites operating in this region. For satellites non equipped with propulsion systems, the collision risk can be mitigated by exploiting the active modulation of aerodynamic forces through the ballistic coefficient. This article proposes a novel and high-fidelity optimal control approach for collision avoidance via aerodynamic drag modulation for an unpropelled SmallSat. Central to this approach is a cost function that jointly maximizes the miss distance while minimizing orbital decay during the maneuver. Moreover, the proposed approach has been rigorously tested through its application to the real-world scenario of the SOURCE satellite, slated for launch in 2025. For the satellite under investigation and a maneuver altitude of 350km, an in-track separation distance of around 22km can be accomplished within a warning time of 24h, which is large enough to conclude that the collision was successfully avoided. As a downside, however, this results in an additional loss in the semi-major axis of 165m and thus a reduced lifetime of the satellite. This balance between separation distance and additional loss in altitude can be flexibly adjusted by the user, which is demonstrated extensively in the article by means of a parameter study. Compared to the widespread use of chemical propulsion systems, this strategy naturally demands longer warning times due to the significantly lower available forces, and also radial offsets to the potential collision object cannot be in this case. Nevertheless, it offers a very promising alternative for active collision avoidance, especially for low-altitude applications.
{"title":"Optimal drag-based collision avoidance: Balancing miss distance and orbital decay","authors":"Emanuela Gaglio, Constantin Traub, Fabrizio Turco, Jhonathan O. Murcia Piñeros, Riccardo Bevilacqua, Stefanos Fasoulas","doi":"10.1016/j.actaastro.2024.11.052","DOIUrl":"https://doi.org/10.1016/j.actaastro.2024.11.052","url":null,"abstract":"The increasing number of objects in Low Earth Orbit makes active collision avoidance imperative for satellites operating in this region. For satellites non equipped with propulsion systems, the collision risk can be mitigated by exploiting the active modulation of aerodynamic forces through the ballistic coefficient. This article proposes a novel and high-fidelity optimal control approach for collision avoidance via aerodynamic drag modulation for an unpropelled SmallSat. Central to this approach is a cost function that jointly maximizes the miss distance while minimizing orbital decay during the maneuver. Moreover, the proposed approach has been rigorously tested through its application to the real-world scenario of the SOURCE satellite, slated for launch in 2025. For the satellite under investigation and a maneuver altitude of 350<ce:hsp sp=\"0.16667\"></ce:hsp>km, an in-track separation distance of around 22<ce:hsp sp=\"0.16667\"></ce:hsp>km can be accomplished within a warning time of 24<ce:hsp sp=\"0.16667\"></ce:hsp>h, which is large enough to conclude that the collision was successfully avoided. As a downside, however, this results in an additional loss in the semi-major axis of 165<ce:hsp sp=\"0.16667\"></ce:hsp>m and thus a reduced lifetime of the satellite. This balance between separation distance and additional loss in altitude can be flexibly adjusted by the user, which is demonstrated extensively in the article by means of a parameter study. Compared to the widespread use of chemical propulsion systems, this strategy naturally demands longer warning times due to the significantly lower available forces, and also radial offsets to the potential collision object cannot be in this case. Nevertheless, it offers a very promising alternative for active collision avoidance, especially for low-altitude applications.","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"37 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142790193","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 : 2024-11-26DOI: 10.1016/j.actaastro.2024.11.051
Duo Zhang , Gongshun Guan , Shengjie Xu , Yu Yang , Chunyang Li , Jianing Zhang
This paper presents an estimation method for assessing the damage to the rear wall of spacecraft protective structures caused by hypervelocity impacts of space debris. Utilizing the smoothed particle hydrodynamics for numerical simulation, a kernel-function based kinetic energy mapping method is employed to analyze the kinetic energy distribution of the debris cloud generated by the initial impact upon the rear wall. This study establishes a correlation between the kinetic energy of the debris cloud and the resulting damage to the rear wall. This correlation allows for the estimation of damage characteristics, including the depth and volume of impact craters on the rear wall following exposure to a debris cloud. Taking the hypervelocity impacts of an Al-2017 projectile on an Al-6061 thin plate as examples, experimental validation has demonstrated the effectiveness, robustness and versatility of this method over a range of particle sizes and grid resolutions. This method enables rapid estimation of damage to protective structures and assessment of their residual protective performance.
{"title":"Damage estimation method for spacecraft protective structures exposed to hypervelocity impacts","authors":"Duo Zhang , Gongshun Guan , Shengjie Xu , Yu Yang , Chunyang Li , Jianing Zhang","doi":"10.1016/j.actaastro.2024.11.051","DOIUrl":"10.1016/j.actaastro.2024.11.051","url":null,"abstract":"<div><div>This paper presents an estimation method for assessing the damage to the rear wall of spacecraft protective structures caused by hypervelocity impacts of space debris. Utilizing the smoothed particle hydrodynamics for numerical simulation, a kernel-function based kinetic energy mapping method is employed to analyze the kinetic energy distribution of the debris cloud generated by the initial impact upon the rear wall. This study establishes a correlation between the kinetic energy of the debris cloud and the resulting damage to the rear wall. This correlation allows for the estimation of damage characteristics, including the depth and volume of impact craters on the rear wall following exposure to a debris cloud. Taking the hypervelocity impacts of an Al-2017 projectile on an Al-6061 thin plate as examples, experimental validation has demonstrated the effectiveness, robustness and versatility of this method over a range of particle sizes and grid resolutions. This method enables rapid estimation of damage to protective structures and assessment of their residual protective performance.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"227 ","pages":"Pages 96-113"},"PeriodicalIF":3.1,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142744614","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}
AQUARIUS (AQUA ResIstojet propUlsion System), a water resistojet propulsion system installed on a 6U CubeSat EQUULEUS (EQUilibriUm Lunar–Earth point 6U Spacecraft), successfully conducted multiple orbital transfers including the world’s first water-fueled propulsion system operation in deep space. We present the on-orbit performance analysis of AQUARIUS with a focus on reaction control thrusters responsible for the spacecraft’s angular momentum management. The reaction control thrusters were capable of producing torques about all axes for angular momentum management as intended. Additionally, they provided fine translational delta-V, demonstrating the thrusters’ dual functionality and reliability in critical maneuvers. The impulse vector of each reaction control thruster was estimated by considering the thrust vector direction. The calculated impulse in the translational axis was about 0.10 Ns per shot, which was validated by comparing the impulse obtained from the Doppler shift of the communication waves. The estimated on-orbit specific impulse of the reaction control thrusters was approximately 78 s, 1.3 times larger than the measured value in the ground test. This improvement on orbit could be due to the degradation of thrust coefficient efficiency in the ground test caused by low Reynolds number flows and high background pressure lowering the apparent pressure thrust. The consumed propellant mass on orbit was estimated but deviated from the expected value under high-temperature conditions, possibly due to temperature measurement uncertainties or the influence of the on-orbit environment.
{"title":"A water resistojet propulsion system on a 6U CubeSat EQUULEUS: Demonstration of reaction control in deep space","authors":"Isamu Moriai , Aoma Fujimori , Hokuto Sekine , Hiroyuki Koizumi , Mariko Akiyama , Shunichiro Nomura , Masaya Murohara , Masayuki Matsuura , Ten Arai , Naoto Aizawa , Kento Shirasu , Ryo Minematsu , Yosuke Kawabata , Shintaro Nakajima , Ryota Fuse , Ryu Funase","doi":"10.1016/j.actaastro.2024.11.037","DOIUrl":"10.1016/j.actaastro.2024.11.037","url":null,"abstract":"<div><div>AQUARIUS (AQUA ResIstojet propUlsion System), a water resistojet propulsion system installed on a 6U CubeSat EQUULEUS (EQUilibriUm Lunar–Earth point 6U Spacecraft), successfully conducted multiple orbital transfers including the world’s first water-fueled propulsion system operation in deep space. We present the on-orbit performance analysis of AQUARIUS with a focus on reaction control thrusters responsible for the spacecraft’s angular momentum management. The reaction control thrusters were capable of producing torques about all axes for angular momentum management as intended. Additionally, they provided fine translational delta-V, demonstrating the thrusters’ dual functionality and reliability in critical maneuvers. The impulse vector of each reaction control thruster was estimated by considering the thrust vector direction. The calculated impulse in the translational axis was about 0.10 N<span><math><mi>⋅</mi></math></span>s per shot, which was validated by comparing the impulse obtained from the Doppler shift of the communication waves. The estimated on-orbit specific impulse of the reaction control thrusters was approximately 78 s, 1.3 times larger than the measured value in the ground test. This improvement on orbit could be due to the degradation of thrust coefficient efficiency in the ground test caused by low Reynolds number flows and high background pressure lowering the apparent pressure thrust. The consumed propellant mass on orbit was estimated but deviated from the expected value under high-temperature conditions, possibly due to temperature measurement uncertainties or the influence of the on-orbit environment.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"227 ","pages":"Pages 114-125"},"PeriodicalIF":3.1,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142757597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Spectral proper orthogonal decomposition(SPOD) has been recently used to capture temporal and spatial characteristics of complex flows. Applying SPOD analysis to such flow fields can deepen the understanding of flow mechanism. To further study the external flow at high Reynolds numbers, large eddy simulation(LES) is applied to acquire the flow field data while SPOD is utilized to extract important flow structures. The considered external flow includes incompressible flow around the cylinder and transonic shock oscillation. For the flow around the cylinder, flow field under three different Reynolds numbers is studied. Power spectral density(PSD) results of lift coefficient show that the vortex shedding frequency of low Reynolds number is , which of moderate Reynolds number is , and for high Reynolds number flow. The increment of Reynolds number will lead to early instability of shear layer on the cylindrical surface. The modal results of SPOD and dynamic mode decomposition(DMD) at different Reynolds numbers show two antisymmetric structures at shedding vortex frequencies, indicating the resemblance in the process of vortex formation. For the shock wave/boundary layer interaction(SBLI) of transonic Royal Aircraft Establishment(RAE) 2822 airfoil, flow field under , is studied. The results show that the occurrence of unsteadiness is closely related to the normal shock wave/turbulent boundary layer interaction happening on the upper surface of the airfoil. Modal results of SPOD near the characteristic frequency show strong discontinuity near the shock wave.
{"title":"Spectral proper orthogonal decomposition of external flow at high Reynolds number","authors":"Feng-Yuan Zuo, Yu Shen, Jia-Rui Wei, Cheng-Hao Ren","doi":"10.1016/j.actaastro.2024.11.039","DOIUrl":"10.1016/j.actaastro.2024.11.039","url":null,"abstract":"<div><div>Spectral proper orthogonal decomposition(SPOD) has been recently used to capture temporal and spatial characteristics of complex flows. Applying SPOD analysis to such flow fields can deepen the understanding of flow mechanism. To further study the external flow at high Reynolds numbers, large eddy simulation(LES) is applied to acquire the flow field data while SPOD is utilized to extract important flow structures. The considered external flow includes incompressible flow around the cylinder and transonic shock oscillation. For the flow around the cylinder, flow field under three different Reynolds numbers is studied. Power spectral density(PSD) results of lift coefficient show that the vortex shedding frequency of low Reynolds number is <span><math><mrow><mi>S</mi><mi>t</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>24</mn></mrow></math></span>, which of moderate Reynolds number is <span><math><mrow><mi>S</mi><mi>t</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>203</mn></mrow></math></span>, and <span><math><mrow><mi>S</mi><mi>t</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>27</mn></mrow></math></span> for high Reynolds number flow. The increment of Reynolds number will lead to early instability of shear layer on the cylindrical surface. The modal results of SPOD and dynamic mode decomposition(DMD) at different Reynolds numbers show two antisymmetric structures at shedding vortex frequencies, indicating the resemblance in the process of vortex formation. For the shock wave/boundary layer interaction(SBLI) of transonic Royal Aircraft Establishment(RAE) 2822 airfoil, flow field under <span><math><mrow><msub><mrow><mi>M</mi></mrow><mrow><mi>∞</mi></mrow></msub><mo>=</mo><mn>0</mn><mo>.</mo><mn>729</mn></mrow></math></span>, <span><math><mrow><msub><mrow><mi>R</mi><mi>e</mi></mrow><mrow><mi>c</mi></mrow></msub><mo>=</mo><mn>1</mn><mo>.</mo><mn>94</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>7</mn></mrow></msup></mrow></math></span> is studied. The results show that the occurrence of unsteadiness is closely related to the normal shock wave/turbulent boundary layer interaction happening on the upper surface of the airfoil. Modal results of SPOD near the characteristic frequency show strong discontinuity near the shock wave.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"227 ","pages":"Pages 21-39"},"PeriodicalIF":3.1,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142744610","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 : 2024-11-23DOI: 10.1016/j.actaastro.2024.11.035
Ban Wang , Cheng Yu , Meina Wang , Maoying Zhou
The rapid increase of space activities has led to an urgent problem of space debris. Active debris removal based on flexible nets is promising in the control of space debris. Here the application of electromagnetic launch in the deployment of flexible net is considered. A lumped-parameter electromechanical model of the coil launcher is developed with emphasis on the analysis of the magnetic field involved. Analytical solution to the magnetostaic problem is given based on eigen-expansions on decomposed domains. Dynamic behavior of the iron slug is then computed and analyzed with optimal initial position of the iron slug found. Influence of the capacitance of the super-capacitor upon the launch performance is also investigated. Results are discussed and future directions of investigations are provided.
{"title":"Theoretical modeling and analysis of the launching process in an electromagnetic coil launcher","authors":"Ban Wang , Cheng Yu , Meina Wang , Maoying Zhou","doi":"10.1016/j.actaastro.2024.11.035","DOIUrl":"10.1016/j.actaastro.2024.11.035","url":null,"abstract":"<div><div>The rapid increase of space activities has led to an urgent problem of space debris. Active debris removal based on flexible nets is promising in the control of space debris. Here the application of electromagnetic launch in the deployment of flexible net is considered. A lumped-parameter electromechanical model of the coil launcher is developed with emphasis on the analysis of the magnetic field involved. Analytical solution to the magnetostaic problem is given based on eigen-expansions on decomposed domains. Dynamic behavior of the iron slug is then computed and analyzed with optimal initial position of the iron slug found. Influence of the capacitance of the super-capacitor upon the launch performance is also investigated. Results are discussed and future directions of investigations are provided.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"227 ","pages":"Pages 12-20"},"PeriodicalIF":3.1,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142744786","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 : 2024-11-23DOI: 10.1016/j.actaastro.2024.11.049
Hanwen Deng, Yiming Sun, Long Cheng, Xiaoming Kang
Electrospray technology has been widely applied in many fields, including materials science, chemical engineering, pharmaceuticals, and aerospace exploration. In particular, with the development of commercial space exploration and the demand for miniaturization of micro-nano satellites, capillary electrospray thrusters using ionic liquids as propellants have received extensive attention. However, the use of a single capillary emitter limits the overall performance of the thruster. To further enhance the emission performance of the thruster, the coaxial capillaries emitter with hybrid ionic liquids has been proposed. In this paper, the experimental observation was conducted on the situation where the same ionic liquid was injected into the inner and outer capillaries at different flow rates. It was observed that the outer cone-jet gradually envelops the inner cone-jet to evolute a coaxial cone-jet. Single ionic liquid coaxial electrospray has a limited effect on the stability of the cone-jet. Therefore, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM-BF4) and 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6) were separately supplied into the inner and outer capillaries to form a coaxial cone-jet. The results revealed a significant improvement in the current noise spectrum, and it was capable of stable emission current even at higher flow rates. Further analysis of the plume composition was conducted using the time-of-flight method. The results indicated that EMIM-BF4 and BMIM-PF6 supplied in outer and inner capillaries respectively as coaxial electrospray can provide the best specific impulse and thrust performances for the electrospray thruster in the conducted experiments. This greatly improves the thrust provided by a single emitter position of the thruster, which expands its application prospects.
{"title":"Study on the current stability and performances of electrospray thruster by coaxial capillary emitters of hybrid highly conductive ionic liquids","authors":"Hanwen Deng, Yiming Sun, Long Cheng, Xiaoming Kang","doi":"10.1016/j.actaastro.2024.11.049","DOIUrl":"10.1016/j.actaastro.2024.11.049","url":null,"abstract":"<div><div>Electrospray technology has been widely applied in many fields, including materials science, chemical engineering, pharmaceuticals, and aerospace exploration. In particular, with the development of commercial space exploration and the demand for miniaturization of micro-nano satellites, capillary electrospray thrusters using ionic liquids as propellants have received extensive attention. However, the use of a single capillary emitter limits the overall performance of the thruster. To further enhance the emission performance of the thruster, the coaxial capillaries emitter with hybrid ionic liquids has been proposed. In this paper, the experimental observation was conducted on the situation where the same ionic liquid was injected into the inner and outer capillaries at different flow rates. It was observed that the outer cone-jet gradually envelops the inner cone-jet to evolute a coaxial cone-jet. Single ionic liquid coaxial electrospray has a limited effect on the stability of the cone-jet. Therefore, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM-BF<sub>4</sub>) and 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF<sub>6</sub>) were separately supplied into the inner and outer capillaries to form a coaxial cone-jet. The results revealed a significant improvement in the current noise spectrum, and it was capable of stable emission current even at higher flow rates. Further analysis of the plume composition was conducted using the time-of-flight method. The results indicated that EMIM-BF<sub>4</sub> and BMIM-PF<sub>6</sub> supplied in outer and inner capillaries respectively as coaxial electrospray can provide the best specific impulse and thrust performances for the electrospray thruster in the conducted experiments. This greatly improves the thrust provided by a single emitter position of the thruster, which expands its application prospects.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"227 ","pages":"Pages 1-11"},"PeriodicalIF":3.1,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142744785","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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