Pub Date : 2024-11-06DOI: 10.1016/j.actaastro.2024.11.012
Che Bixuan, Wu Jianjun, Zhang Yu, Li Xiaokang, Cheng Mousen, Wang Moge
Inductive pulsed plasma thrust generates thrust by ionizing and accelerating plasma through pulsed inductive electromagnetic field. The spatial distribution of the magnetic field within the discharge region influences both the Lorentz force exerted on plasma and the electromagnetic coupling between plasma and circuit. An experimental prototype of inductive pulsed plasma thruster with high repeatability and a three-dimensional transient magnetic field measurement system with low integration error are established. Time-dependent spatial distribution of the magnetic field in the plasma is obtained by scanning measurement employing repeated pulse discharges. Combined with the results of high-speed photographing and electrical parameter measurements, the relationship between the evolution of plasma structure and the magnetic field penetration is discussed.
{"title":"Experimental study on the time-dependent spatial distribution of the three-dimensional magnetic field in an inductive pulsed plasma thruster","authors":"Che Bixuan, Wu Jianjun, Zhang Yu, Li Xiaokang, Cheng Mousen, Wang Moge","doi":"10.1016/j.actaastro.2024.11.012","DOIUrl":"10.1016/j.actaastro.2024.11.012","url":null,"abstract":"<div><div>Inductive pulsed plasma thrust generates thrust by ionizing and accelerating plasma through pulsed inductive electromagnetic field. The spatial distribution of the magnetic field within the discharge region influences both the Lorentz force exerted on plasma and the electromagnetic coupling between plasma and circuit. An experimental prototype of inductive pulsed plasma thruster with high repeatability and a three-dimensional transient magnetic field measurement system with low integration error are established. Time-dependent spatial distribution of the magnetic field in the plasma is obtained by scanning measurement employing repeated pulse discharges. Combined with the results of high-speed photographing and electrical parameter measurements, the relationship between the evolution of plasma structure and the magnetic field penetration is discussed.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"226 ","pages":"Pages 601-609"},"PeriodicalIF":3.1,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660949","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 : 2024-11-06DOI: 10.1016/j.actaastro.2024.10.067
Yang Wang , Fang Chen , Yu Meng , Elena Victorovna Mikhalchenko , Evgeniya Igorevna Skryleva
Ensuring safe flight is a fundamental prerequisite for developing hypersonic propulsion systems. A comprehensive investigation of the steady boundary associated with oblique detonation wave in a wide speed range was conducted, with the aim of exploring the feasibility of oblique detonation engine across a diverse array of flight conditions. In this study, the wedge angle applicable in a wide-speed range was acquired via the analysis of oblique detonation wave polar curve. The configuration of the internal injection oblique detonation engine was subsequently designed and established, considering the effect of fuel-air inhomogeneity and complex wave system interactions within a confined combustor. The compressible Euler equations coupled with a 9-species and 19-step chemical reaction mechanism are employed to simulate the oblique detonation process. Ultimately, the safe flight envelope of an air-breathing vehicle equipped with the internal injection oblique detonation engine is mapped across a broad range of Mach numbers, demonstrating the engine’s capability to operate within the Mach 8 to 12 range. Furthermore, the findings reveal that decreasing either the flight Mach number or altitude results in unsteady oblique detonation wave within the internal injection oblique detonation engine combustor, however, reducing the equivalence ratio can stabilize the oblique detonation wave once again. This study provides valuable guidance for the design and wide-speed-range operation of an internal injection oblique detonation engine.
{"title":"Numerical study on flow and combustion properties of oblique detonation engine in a wide speed range","authors":"Yang Wang , Fang Chen , Yu Meng , Elena Victorovna Mikhalchenko , Evgeniya Igorevna Skryleva","doi":"10.1016/j.actaastro.2024.10.067","DOIUrl":"10.1016/j.actaastro.2024.10.067","url":null,"abstract":"<div><div>Ensuring safe flight is a fundamental prerequisite for developing hypersonic propulsion systems. A comprehensive investigation of the steady boundary associated with oblique detonation wave in a wide speed range was conducted, with the aim of exploring the feasibility of oblique detonation engine across a diverse array of flight conditions. In this study, the wedge angle applicable in a wide-speed range was acquired via the analysis of oblique detonation wave polar curve. The configuration of the internal injection oblique detonation engine was subsequently designed and established, considering the effect of fuel-air inhomogeneity and complex wave system interactions within a confined combustor. The compressible Euler equations coupled with a 9-species and 19-step chemical reaction mechanism are employed to simulate the oblique detonation process. Ultimately, the safe flight envelope of an air-breathing vehicle equipped with the internal injection oblique detonation engine is mapped across a broad range of Mach numbers, demonstrating the engine’s capability to operate within the Mach 8 to 12 range. Furthermore, the findings reveal that decreasing either the flight Mach number or altitude results in unsteady oblique detonation wave within the internal injection oblique detonation engine combustor, however, reducing the equivalence ratio can stabilize the oblique detonation wave once again. This study provides valuable guidance for the design and wide-speed-range operation of an internal injection oblique detonation engine.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"226 ","pages":"Pages 637-647"},"PeriodicalIF":3.1,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660953","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}
In this paper, the numerical simulation of the swept strut ramjet combustor was carried out under wide-range conditions (Ma3 = 1.8 ∼ 5.0), and the pressure drag characteristics of the swept strut were discussed. The results show that the pressure drag characteristics of the swept strut are related to the Mach number of the combustor inlet and the swept angle of the strut. The decreased boundary of the strut pressure drag coefficient gradually advances with the decrease of the Mach number of the combustor inlet. When Ma3 = 1.8 ∼ 2.0, the pressure drag reduction boundary is α = 15°. When Ma3 = 2.2 ∼ 2.8, the pressure drag reduction boundary is α = 45°. When Ma3 = 3.0 ∼ 4.0, the pressure drag reduction boundary is α = 60°. When Ma3 = 5.0, the pressure drag reduction boundary is α = 65°. In addition, with the decrease of the Mach number of the combustor inlet, the pressure drag reduction performance benefit brought by increasing the swept angle of the strut will gradually increase. Furthermore, a pressure drag coefficient prediction model suitable for wide-range conditions and multiple configurations of swept struts was proposed based on deep learning. The prediction model consists of two parts in series, which includes the prediction model of the surface pressure coefficient of the swept strut based on multilayer perceptron (MLP) and the prediction model of the pressure drag coefficient of the swept strut based on convolutional neural network (CNN). To improve the prediction accuracy of the MLP model, new training samples were added based on the ensemble-based uncertainty quantification, and the improved MLP model was obtained by retraining. The results show that both the two prediction models have high prediction accuracy under the effect of multiple complex flow characteristics on the strut. The results of this study are helpful to provide a reference for the aerodynamic drag reduction design of the strut in the wide-speed supersonic combustor.
{"title":"Study on characteristics and prediction of the pressure drag of the swept strut under supersonic wide-range conditions","authors":"Guowei Luan, Junlong Zhang, Guangjun Feng, Xiaosi Li, Hongchao Qiu, Wen Bao","doi":"10.1016/j.actaastro.2024.11.005","DOIUrl":"10.1016/j.actaastro.2024.11.005","url":null,"abstract":"<div><div>In this paper, the numerical simulation of the swept strut ramjet combustor was carried out under wide-range conditions (<em>Ma</em><sub>3</sub> = 1.8 ∼ 5.0), and the pressure drag characteristics of the swept strut were discussed. The results show that the pressure drag characteristics of the swept strut are related to the Mach number of the combustor inlet and the swept angle of the strut. The decreased boundary of the strut pressure drag coefficient gradually advances with the decrease of the Mach number of the combustor inlet. When <em>Ma</em><sub>3</sub> = 1.8 ∼ 2.0, the pressure drag reduction boundary is <em>α</em> = 15°. When <em>Ma</em><sub>3</sub> = 2.2 ∼ 2.8, the pressure drag reduction boundary is <em>α</em> = 45°. When <em>Ma</em><sub>3</sub> = 3.0 ∼ 4.0, the pressure drag reduction boundary is <em>α</em> = 60°. When <em>Ma</em><sub>3</sub> = 5.0, the pressure drag reduction boundary is <em>α</em> = 65°. In addition, with the decrease of the Mach number of the combustor inlet, the pressure drag reduction performance benefit brought by increasing the swept angle of the strut will gradually increase. Furthermore, a pressure drag coefficient prediction model suitable for wide-range conditions and multiple configurations of swept struts was proposed based on deep learning. The prediction model consists of two parts in series, which includes the prediction model of the surface pressure coefficient of the swept strut based on multilayer perceptron (MLP) and the prediction model of the pressure drag coefficient of the swept strut based on convolutional neural network (CNN). To improve the prediction accuracy of the MLP model, new training samples were added based on the ensemble-based uncertainty quantification, and the improved MLP model was obtained by retraining. The results show that both the two prediction models have high prediction accuracy under the effect of multiple complex flow characteristics on the strut. The results of this study are helpful to provide a reference for the aerodynamic drag reduction design of the strut in the wide-speed supersonic combustor.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"226 ","pages":"Pages 846-859"},"PeriodicalIF":3.1,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142702673","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 new scenarios foreseen in forthcoming space missions have increased interest towards optical-based relative navigation techniques, which have demonstrated efficacy in a variety of operational conditions. Although object detection methods have predominantly been used within the visible spectrum, optical payloads struggle in weak lighting conditions and are susceptible to overexposure. Consequently, thermal imaging systems are being investigated as a potential solution, as their integration into the current systems would greatly extend future mission capabilities. This study seeks to fill the gap in literature by assessing the performance of state-of-the-art object detection algorithms with images captured in the thermal spectrum. Given the scarcity of readily available thermal infrared (TIR) images captured in orbit, a novel rendering pipeline is implemented to generate physically accurate thermal images relevant to close-proximity scenarios. These synthetic representations feature a simplified target spacecraft against Earth and deep space backgrounds, including variations in illumination conditions, material properties, relative state, and scale. To ensure realistic outputs, the radiative field of the Earth is modelled based on satellite measurements collected in the cloud and Earth radiant energy system (CERES) database. To enrich the fidelity of the outputs, a thermal sensor model and the corresponding noise levels are introduced in the pipeline. The generated images are then used to test the performance of traditional object detection algorithms in discerning the region of interest (ROI) under different orbital scenarios. The results demonstrate the effectiveness of the selected methodologies in mitigating the influence of the Earth in the ROI extraction process, while also revealing a performance degradation due to the presence of multi-material targets.
即将到来的太空任务中预计会出现的新情况增加了人们对基于光学的相对导航技术的兴趣，这些技术已在各种操作条件下证明了其有效性。虽然物体探测方法主要是在可见光谱范围内使用，但光学有效载荷在微弱的照明条件下很难发挥作用，而且容易受到过度曝光的影响。因此，热成像系统正被作为一种潜在的解决方案进行研究，因为将其集成到现有系统中将大大扩展未来的任务能力。本研究试图通过评估最先进的物体检测算法在热光谱图像中的性能来填补文献空白。鉴于在轨捕获的现成热红外（TIR）图像很少，因此采用了一种新颖的渲染流水线来生成与近距离场景相关的物理上精确的热图像。这些合成图像以地球和深空背景下的简化目标航天器为特征，包括光照条件、材料属性、相对状态和比例的变化。为确保输出结果逼真，根据云层和地球辐射能量系统（CERES）数据库中收集的卫星测量数据对地球辐射场进行建模。为了提高输出结果的保真度，在管道中引入了热传感器模型和相应的噪声水平。生成的图像随后用于测试传统物体检测算法在不同轨道场景下辨别感兴趣区域（ROI）的性能。结果表明，所选方法能够有效减轻地球在 ROI 提取过程中的影响，同时也揭示了由于多材料目标的存在而导致的性能下降。
{"title":"Synthetic thermal image generation and processing for close proximity operations","authors":"Lucia Bianchi, Michele Bechini, Matteo Quirino, Michèle Lavagna","doi":"10.1016/j.actaastro.2024.10.061","DOIUrl":"10.1016/j.actaastro.2024.10.061","url":null,"abstract":"<div><div>The new scenarios foreseen in forthcoming space missions have increased interest towards optical-based relative navigation techniques, which have demonstrated efficacy in a variety of operational conditions. Although object detection methods have predominantly been used within the visible spectrum, optical payloads struggle in weak lighting conditions and are susceptible to overexposure. Consequently, thermal imaging systems are being investigated as a potential solution, as their integration into the current systems would greatly extend future mission capabilities. This study seeks to fill the gap in literature by assessing the performance of state-of-the-art object detection algorithms with images captured in the thermal spectrum. Given the scarcity of readily available thermal infrared (TIR) images captured in orbit, a novel rendering pipeline is implemented to generate physically accurate thermal images relevant to close-proximity scenarios. These synthetic representations feature a simplified target spacecraft against Earth and deep space backgrounds, including variations in illumination conditions, material properties, relative state, and scale. To ensure realistic outputs, the radiative field of the Earth is modelled based on satellite measurements collected in the cloud and Earth radiant energy system (CERES) database. To enrich the fidelity of the outputs, a thermal sensor model and the corresponding noise levels are introduced in the pipeline. The generated images are then used to test the performance of traditional object detection algorithms in discerning the region of interest (ROI) under different orbital scenarios. The results demonstrate the effectiveness of the selected methodologies in mitigating the influence of the Earth in the ROI extraction process, while also revealing a performance degradation due to the presence of multi-material targets.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"226 ","pages":"Pages 611-625"},"PeriodicalIF":3.1,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660951","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}
Pub Date : 2024-11-03DOI: 10.1016/j.actaastro.2024.10.066
Nadine M. Trummer, Amit Reza, Michael A. Steindorfer, Christiane Helling
The growing number of man-made debris in Earth’s orbit poses a threat to active satellite missions due to the risk of collision. Characterizing unknown debris is, therefore, of high interest. Light Curves (LCs) are temporal variations of object brightness and have been shown to contain information such as shape, attitude, and rotational state. Since 2015, the Satellite Laser Ranging (SLR) group of Space Research Institute (IWF) Graz has been building a space debris LC catalogue. The LCs are captured on a Single Photon basis, which sets them apart from CCD-based measurements. In recent years, Machine Learning (ML) models have emerged as a viable technique for analysing LCs. This work aims to classify Single Photon Space Debris LCs using the ML framework. We have explored LC classification using k-Nearest Neighbour (k-NN), Random Forest (RDF), XGBoost (XGB), and Convolutional Neural Network (CNN) classifiers in order to assess the difference in performance between traditional and deep models. Instead of performing classification on the direct LC data, we extracted features from the data first using an automated pipeline. We apply our models on three tasks, which are classifying individual objects, objects grouped into families according to origin, and grouping into general types. We successfully classified Space Debris LCs captured on Single Photon basis, obtaining accuracies as high as 90.7%. Further, our experiments show that the classifiers provide better classification accuracy with automated extracted features than other methods.
{"title":"Machine learning-based classification for Single Photon Space Debris Light Curves","authors":"Nadine M. Trummer, Amit Reza, Michael A. Steindorfer, Christiane Helling","doi":"10.1016/j.actaastro.2024.10.066","DOIUrl":"10.1016/j.actaastro.2024.10.066","url":null,"abstract":"<div><div>The growing number of man-made debris in Earth’s orbit poses a threat to active satellite missions due to the risk of collision. Characterizing unknown debris is, therefore, of high interest. Light Curves (LCs) are temporal variations of object brightness and have been shown to contain information such as shape, attitude, and rotational state. Since 2015, the Satellite Laser Ranging (SLR) group of Space Research Institute (IWF) Graz has been building a space debris LC catalogue. The LCs are captured on a Single Photon basis, which sets them apart from CCD-based measurements. In recent years, Machine Learning (ML) models have emerged as a viable technique for analysing LCs. This work aims to classify Single Photon Space Debris LCs using the ML framework. We have explored LC classification using k-Nearest Neighbour (k-NN), Random Forest (RDF), XGBoost (XGB), and Convolutional Neural Network (CNN) classifiers in order to assess the difference in performance between traditional and deep models. Instead of performing classification on the direct LC data, we extracted features from the data first using an automated pipeline. We apply our models on three tasks, which are classifying individual objects, objects grouped into families according to origin, and grouping into general types. We successfully classified Space Debris LCs captured on Single Photon basis, obtaining accuracies as high as 90.7%. Further, our experiments show that the classifiers provide better classification accuracy with automated extracted features than other methods.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"226 ","pages":"Pages 542-554"},"PeriodicalIF":3.1,"publicationDate":"2024-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142592792","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 : 2024-11-02DOI: 10.1016/j.actaastro.2024.10.062
Ying Zhang , Changqing Wang , Yuriy Zabolotnov , Aijun Li , Hongshi Lu
This paper aims to analyze the impact of unideal end-body configurations on attitude motion during the tether deployment process in a linear three-body tethered system (LTBTS). A main challenge in this process is the resonance between the nutation and spin angles caused by the unideal end-body configurations, leading to severe nutation angle oscillations. These oscillations can result in tether entanglement with the end-bodies or even tether rupture. To address this issue, the deployment model for the LTBTS is first established using the Lagrangian equations, with the end-body attitude described by Eulerian angles. Secondly, the system involves the separation of two subsatellites from the central main satellite in opposite directions. The dynamics response of the deployment process under unideal configuration of end-bodies is investigated. Resonance phenomena in nutation and spin angles are observed due to errors in initial angles/angular velocities, offset errors of tether connection points, and unideal structural characteristics of the satellites. Thirdly, to further understand this resonance, analytical solutions for resonance are derived by transforming the nutation angle equations, and satellite attitude equations are systematically solved via integral manifold methods. Potential resonance issues are mitigated by reducing system asymmetry and minimizing initial disturbances. Finally, the effectiveness of the dynamic analysis is validated through simulations.
{"title":"Analysis of satellite attitude motion in a three-body tethered system during deployment via integral manifolds","authors":"Ying Zhang , Changqing Wang , Yuriy Zabolotnov , Aijun Li , Hongshi Lu","doi":"10.1016/j.actaastro.2024.10.062","DOIUrl":"10.1016/j.actaastro.2024.10.062","url":null,"abstract":"<div><div>This paper aims to analyze the impact of unideal end-body configurations on attitude motion during the tether deployment process in a linear three-body tethered system (LTBTS). A main challenge in this process is the resonance between the nutation and spin angles caused by the unideal end-body configurations, leading to severe nutation angle oscillations. These oscillations can result in tether entanglement with the end-bodies or even tether rupture. To address this issue, the deployment model for the LTBTS is first established using the Lagrangian equations, with the end-body attitude described by Eulerian angles. Secondly, the system involves the separation of two subsatellites from the central main satellite in opposite directions. The dynamics response of the deployment process under unideal configuration of end-bodies is investigated. Resonance phenomena in nutation and spin angles are observed due to errors in initial angles/angular velocities, offset errors of tether connection points, and unideal structural characteristics of the satellites. Thirdly, to further understand this resonance, analytical solutions for resonance are derived by transforming the nutation angle equations, and satellite attitude equations are systematically solved via integral manifold methods. Potential resonance issues are mitigated by reducing system asymmetry and minimizing initial disturbances. Finally, the effectiveness of the dynamic analysis is validated through simulations.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"226 ","pages":"Pages 716-727"},"PeriodicalIF":3.1,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142661037","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 : 2024-11-02DOI: 10.1016/j.actaastro.2024.11.003
JinZe Wu , GuoXiu Li , HongMeng Li , Shuo Zhang , ZhaoPu Yao , Tao Zhang
High performance green propellant represented by ammonium dinitramide-based liquid propellant and its new ignition method are the research hotspots of space propulsion in the 21st century. Exploring the complex multi-scale physical properties of multi-component ammonium dinitramide-based liquid propellant droplets in the electrical ignition mode has wide application significance for spray, propulsion system design and combustion control. The droplet dynamics behavior and combustion characteristics of propellant droplets at different ignition voltages were studied experimentally. The droplet dynamics behavior during the evaporation process, including violent volume oscillation, approximate steady-state expansion, contraction, secondary expansion, puffing and micro-explosion, have been determined by the generation, growth, and discharge of vapor bubbles. In the initial evaporation process, the heterogeneous nucleation is dominant. As the droplet is continuously heated, homogenization nucleation gradually dominates. The main physical and chemical mechanisms of bubble evolution driven by temperature involve methanol boiling, water overheating, ammonium dinitramide decomposition and combustion reaction between vapor molecules. Increasing the ignition voltage increases the droplet dynamics behavior and the combustion, but promotes the combustion instability. Increasing the ignition voltage increases the ignition delay time, puffing delay time, droplet lifetime, maximum temperature of droplet, and reduces the ignition critical diameter. It is proposed that the method of suppressing the droplet breakup dynamics at decomposition area and enhancing the droplet breakup dynamics at the combustion area are conducive to the combustion control of the thruster in electrical ignition mode. This research provides novel insight into the study of the electrical ignition mechanism of liquid fuels.
{"title":"Experimental study on droplet dynamics behavior and combustion characteristics of high performance green propellant in electrical ignition mode","authors":"JinZe Wu , GuoXiu Li , HongMeng Li , Shuo Zhang , ZhaoPu Yao , Tao Zhang","doi":"10.1016/j.actaastro.2024.11.003","DOIUrl":"10.1016/j.actaastro.2024.11.003","url":null,"abstract":"<div><div>High performance green propellant represented by ammonium dinitramide-based liquid propellant and its new ignition method are the research hotspots of space propulsion in the 21st century. Exploring the complex multi-scale physical properties of multi-component ammonium dinitramide-based liquid propellant droplets in the electrical ignition mode has wide application significance for spray, propulsion system design and combustion control. The droplet dynamics behavior and combustion characteristics of propellant droplets at different ignition voltages were studied experimentally. The droplet dynamics behavior during the evaporation process, including violent volume oscillation, approximate steady-state expansion, contraction, secondary expansion, puffing and micro-explosion, have been determined by the generation, growth, and discharge of vapor bubbles. In the initial evaporation process, the heterogeneous nucleation is dominant. As the droplet is continuously heated, homogenization nucleation gradually dominates. The main physical and chemical mechanisms of bubble evolution driven by temperature involve methanol boiling, water overheating, ammonium dinitramide decomposition and combustion reaction between vapor molecules. Increasing the ignition voltage increases the droplet dynamics behavior and the combustion, but promotes the combustion instability. Increasing the ignition voltage increases the ignition delay time, puffing delay time, droplet lifetime, maximum temperature of droplet, and reduces the ignition critical diameter. It is proposed that the method of suppressing the droplet breakup dynamics at decomposition area and enhancing the droplet breakup dynamics at the combustion area are conducive to the combustion control of the thruster in electrical ignition mode. This research provides novel insight into the study of the electrical ignition mechanism of liquid fuels.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"226 ","pages":"Pages 653-668"},"PeriodicalIF":3.1,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660955","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 : 2024-11-02DOI: 10.1016/j.actaastro.2024.10.072
Ting-Han Pei
We build a model to describe the net charges existing in the Sun and Earth. According to statistical mechanics, electrons on average move much faster than protons and neutrons at the same temperature. Electrons escape the Sun more easily than protons and neutrons, so the Sun becomes a charged star. We estimate the maximal net charges in the Sun by using statistical mechanics first. Then, we analyze the dynamical cycles between the positive and negative charged states. At a distance far away from the Sun, the effective net charges including the leaving protons and electrons are about with energies of 1 GeV initially. We also use another way based on the observations of the Earth's perihelion precession to estimate the minimum and maximum net charges between and in space from the Sun to Earth. The most charged particles from the Sun to the Earth are electrons, so both the Moon and Earth are impacted by them and very possibly have the same electricity. Next, we propose new physical mechanisms causing the slowdown of the Earth's spin and propose Coulomb's repulsive force resulting in the increasing distance between the Moon and Earth. As a result, it gives the net charges of surrounding the Earth and surrounding the Moon. Our estimations also correspond to early works. The charges surrounding the Sun and Earth cause the Earth to be long-term accelerated in the radial direction by Coulomb's force. Finally, using the effective net charges of the Sun and Earth, we calculate the increasing distance between 11.4 m and 19.4 m on average per century if the initial radial velocities of the Earth are in between and , which satisfies the observed reports.
{"title":"The additionally charged forces in the Sun-Earth and Earth-Moon systems","authors":"Ting-Han Pei","doi":"10.1016/j.actaastro.2024.10.072","DOIUrl":"10.1016/j.actaastro.2024.10.072","url":null,"abstract":"<div><div>We build a model to describe the net charges existing in the Sun and Earth. According to statistical mechanics, electrons on average move much faster than protons and neutrons at the same temperature. Electrons escape the Sun more easily than protons and neutrons, so the Sun becomes a charged star. We estimate the maximal net charges in the Sun by using statistical mechanics first. Then, we analyze the dynamical cycles between the positive and negative charged states. At a distance far away from the Sun, the effective net charges including the leaving protons and electrons are about <span><math><mrow><mn>6.3</mn><mo>×</mo><msup><mn>10</mn><mn>9</mn></msup><mspace></mspace><mi>C</mi></mrow></math></span> with energies of 1 GeV initially. We also use another way based on the observations of the Earth's perihelion precession to estimate the minimum and maximum net charges between <span><math><mrow><mn>1.15</mn><mo>×</mo><msup><mn>10</mn><mn>8</mn></msup><mspace></mspace><mi>C</mi></mrow></math></span> and <span><math><mrow><mn>2.80</mn><mo>×</mo><msup><mn>10</mn><mn>10</mn></msup><mspace></mspace><mi>C</mi></mrow></math></span> in space from the Sun to Earth. The most charged particles from the Sun to the Earth are electrons, so both the Moon and Earth are impacted by them and very possibly have the same electricity. Next, we propose new physical mechanisms causing the slowdown of the Earth's spin and propose Coulomb's repulsive force resulting in the increasing distance between the Moon and Earth. As a result, it gives the net charges of <span><math><mrow><mn>1.11</mn><mo>×</mo><msup><mn>10</mn><mn>6</mn></msup><mspace></mspace><mi>C</mi></mrow></math></span> surrounding the Earth and <span><math><mrow><mn>8.29</mn><mo>×</mo><msup><mn>10</mn><mn>3</mn></msup><mspace></mspace><mi>C</mi></mrow></math></span> surrounding the Moon. Our estimations also correspond to early works. The charges surrounding the Sun and Earth cause the Earth to be long-term accelerated in the radial direction by Coulomb's force. Finally, using the effective net charges of the Sun and Earth, we calculate the increasing distance between 11.4 <em>m</em> and 19.4 <em>m</em> on average per century if the initial radial velocities of the Earth are in between <span><math><mrow><mn>3.59</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>9</mn></mrow></msup><mspace></mspace><mi>m</mi><mo>/</mo><mi>s</mi></mrow></math></span> and <span><math><mrow><mn>6.12</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>9</mn></mrow></msup><mspace></mspace><mi>m</mi><mo>/</mo><mi>s</mi></mrow></math></span>, which satisfies the observed reports.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"226 ","pages":"Pages 555-569"},"PeriodicalIF":3.1,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142593299","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 : 2024-11-01DOI: 10.1016/j.actaastro.2024.10.055
Antonella Caldarelli , Raoul Andriulli , Fabrizio Ponti , John Cater , Nicholas Rattenbury
Exploring the physics of low pressure plasmas expanding in a diverging magnetic nozzle, and the resulting acceleration mechanisms, plays an important role in the development of a new-type of electrode-less plasma propulsion systems. This study discusses the effects of input power on plasma expansion and ion beam acceleration in a magnetic nozzle electrode-less plasma thruster. The experiments were conducted in a radio-frequency magnetic nozzle plasma device at The University of Auckland with four different power configurations . Different plasma diagnostics were used to measure the characteristics of the plasma plume. A planar Langmuir probe was used to measure the floating potential and ion saturation current both in the plasma source and in the expansion chamber. The potential drop in the plasma source was obtained with an emissive probe. A retarding field energy analyser was employed to evaluate the local plasma and ion beam potentials, the ion energy distribution functions, and to estimate the ion beam speed in the expansion region. Measurements showed that, as expected, increasing the power input resulted in a higher plasma and supersonic ion density, while the ion beam speed did not increase further for W. Interestingly, and contrary to the idealised physical model, the ion sonic transition did not occur at the magnetic nozzle throat, but instead close to the geometrical expansion point, i.e. near the interface between the source tube and the expansion chamber. This feature would result in a lower performance of the thruster given the reduced expansion ratio. An E-H mode change is also observed to occur in the device with increasing radio-frequency power that would help explain the different plasma characteristics observed at the 200 W transition point.
探索低压等离子体在发散磁性喷嘴中膨胀的物理学原理以及由此产生的加速机制，对于开发新型无电极等离子体推进系统具有重要作用。本研究讨论了输入功率对磁性喷嘴无电极等离子体推进器中等离子体膨胀和离子束加速的影响。实验在奥克兰大学的射频磁性喷嘴等离子装置中进行，采用了四种不同的功率配置 PRF。使用了不同的等离子体诊断技术来测量等离子体羽流的特性。使用平面朗缪尔探针测量等离子源和膨胀腔中的浮动电势和离子饱和电流。等离子体源中的电位降是通过发射探针获得的。使用阻滞场能量分析仪评估了局部等离子体和离子束电位、离子能量分布函数，并估算了膨胀区域的离子束速度。测量结果表明，正如预期的那样，增加输入功率会导致更高的等离子体和超音速离子密度，而在 PRF>100 W 时，离子束速度并没有进一步增加。有趣的是，与理想化物理模型相反，离子声速转换并没有发生在磁性喷嘴喉部，而是发生在几何膨胀点附近，即源管和膨胀腔之间的界面附近。由于膨胀比降低，这一特征将导致推进器性能降低。还观察到随着射频功率的增加，装置中出现了 E-H 模式变化，这有助于解释在 200 W 过渡点观察到的不同等离子体特性。
{"title":"Effect of input power on plasma expansion and ion acceleration in a radio-frequency plasma thruster","authors":"Antonella Caldarelli , Raoul Andriulli , Fabrizio Ponti , John Cater , Nicholas Rattenbury","doi":"10.1016/j.actaastro.2024.10.055","DOIUrl":"10.1016/j.actaastro.2024.10.055","url":null,"abstract":"<div><div>Exploring the physics of low pressure plasmas expanding in a diverging magnetic nozzle, and the resulting acceleration mechanisms, plays an important role in the development of a new-type of electrode-less plasma propulsion systems. This study discusses the effects of input power on plasma expansion and ion beam acceleration in a magnetic nozzle electrode-less plasma thruster. The experiments were conducted in a radio-frequency magnetic nozzle plasma device at The University of Auckland with four different power configurations <span><math><msub><mrow><mi>P</mi></mrow><mrow><mi>RF</mi></mrow></msub></math></span>. Different plasma diagnostics were used to measure the characteristics of the plasma plume. A planar Langmuir probe was used to measure the floating potential and ion saturation current both in the plasma source and in the expansion chamber. The potential drop in the plasma source was obtained with an emissive probe. A retarding field energy analyser was employed to evaluate the local plasma and ion beam potentials, the ion energy distribution functions, and to estimate the ion beam speed in the expansion region. Measurements showed that, as expected, increasing the power input resulted in a higher plasma and supersonic ion density, while the ion beam speed did not increase further for <span><math><mrow><msub><mrow><mi>P</mi></mrow><mrow><mi>RF</mi></mrow></msub><mo>></mo><mn>100</mn></mrow></math></span> <!--> <!-->W. Interestingly, and contrary to the idealised physical model, the ion sonic transition did not occur at the magnetic nozzle throat, but instead close to the geometrical expansion point, i.e. near the interface between the source tube and the expansion chamber. This feature would result in a lower performance of the thruster given the reduced expansion ratio. An E-H mode change is also observed to occur in the device with increasing radio-frequency power that would help explain the different plasma characteristics observed at the 200<!--> <!-->W transition point.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"226 ","pages":"Pages 521-530"},"PeriodicalIF":3.1,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142593297","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}
Pub Date : 2024-11-01DOI: 10.1016/j.actaastro.2024.10.073
S. Chernyshev , K. Sypalo , S. Bazhenov
An overview of the architectures, functions and algorithms of aircraft-type aerospace vehicles equipped with fly-by-wire (FBW) digital integrated control systems (ICS) is given. The ICS has a hierarchical architecture, including the primary, backup and emergency control systems with a sophisticated control reconfiguration logic in the event of failures. Digital control computers have dissimilar redundancy of equipment and software. At the atmospheric flight stage, integrator control laws provide the specified control characteristics, flight envelope protection, automatic trim of vehicle and crew workload alleviation. Further integration of manual and automatic control, implementation of the control philosophy as a continuation of the pilot's actions, more intellectual control system and human-machine interface, use of multiple control surfaces to ensure optimal vehicle configuration and alleviate structural loading together with basic control functions are considered as promising areas for ICS improvement.
{"title":"Intelligent control algorithms to ensure the flight safety of aerospace vehicles","authors":"S. Chernyshev , K. Sypalo , S. Bazhenov","doi":"10.1016/j.actaastro.2024.10.073","DOIUrl":"10.1016/j.actaastro.2024.10.073","url":null,"abstract":"<div><div>An overview of the architectures, functions and algorithms of aircraft-type aerospace vehicles equipped with fly-by-wire (FBW) digital integrated control systems (ICS) is given. The ICS has a hierarchical architecture, including the primary, backup and emergency control systems with a sophisticated control reconfiguration logic in the event of failures. Digital control computers have dissimilar redundancy of equipment and software. At the atmospheric flight stage, integrator control laws provide the specified control characteristics, flight envelope protection, automatic trim of vehicle and crew workload alleviation. Further integration of manual and automatic control, implementation of the control philosophy as a continuation of the pilot's actions, more intellectual control system and human-machine interface, use of multiple control surfaces to ensure optimal vehicle configuration and alleviate structural loading together with basic control functions are considered as promising areas for ICS improvement.</div></div>","PeriodicalId":44971,"journal":{"name":"Acta Astronautica","volume":"226 ","pages":"Pages 782-790"},"PeriodicalIF":3.1,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142661040","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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