Aerospace

16 pages, 1533 KiB

Open AccessArticle

Adaptive Scheduling Method for Passenger Service Resources in a Terminal

by Qifeng Mou, Qianyu Liang, Jie Tian and Xin Jing

Aerospace 2024, 11(7), 528; https://doi.org/10.3390/aerospace11070528 - 27 Jun 2024

To alleviate the tense situation of limited passenger service resources in the terminal and to achieve the matching of resource scheduling with the flight support process, the process–resource interdependent network is constructed according to its mapping relationship and the time-varying characteristics of the [...] Read more.

To alleviate the tense situation of limited passenger service resources in the terminal and to achieve the matching of resource scheduling with the flight support process, the process–resource interdependent network is constructed according to its mapping relationship and the time-varying characteristics of the empirical network and network evolution conditions are analyzed. Then, node capacity, node load, and the cascading failure process are investigated, the impact of average service rate and service quality standard on queue length is considered, the node capacity model is constructed under the condition of resource capacity constraints, and the load-redistribution resource adaptive scheduling method based on cascading failure is proposed. Finally, the method’s effectiveness is verified by empirical analysis, the service efficiency is assessed using the total average service time and variance, and the network robustness is assessed using the proportion of maximum connected subgraph. The results indicate that the resource adaptive scheduling method is effective in improving service efficiency, and the average value of its measurement is smaller than that of the resource average allocation method by 0.069; in terms of the robustness improvement of the interdependent network, the phenomenon of re-failure after the load redistribution is significantly reduced. Full article

(This article belongs to the Special Issue Future Airspace and Air Traffic Management Design)

25 pages, 4194 KiB

Open AccessArticle

Development of Carbon Composite Blades within the Context of the Experimental Validation of a CFD-Based Design Tool for Contra-Rotating, Electric Fan Engines

by Sebastian Hawner, Lukas Rduch, Henry Baumhöfener and Andreas Hupfer

Aerospace 2024, 11(7), 527; https://doi.org/10.3390/aerospace11070527 - 27 Jun 2024

Viewed by 28

Abstract

Electric propulsion systems have emerged as a disruptive technological approach towards achieving sustainable and climate-neutral aviation. To expand the operational envelope of such propulsion units in terms of altitude and velocity, an enclosing duct and counter-rotating rotors to enhance efficiency can be utilized. [...] Read more.

Electric propulsion systems have emerged as a disruptive technological approach towards achieving sustainable and climate-neutral aviation. To expand the operational envelope of such propulsion units in terms of altitude and velocity, an enclosing duct and counter-rotating rotors to enhance efficiency can be utilized. In this study, an iterative CFD-based design tool developed for these novel propulsion systems is utilized to design a reference engine, having a classic rotor–stator configuration. Being the key component of this propulsor, a manufacturing process for composite blades is presented. This effort aims to make state-of-the-art technology accessible to smaller research projects, promoting the widespread adoption of electric propulsion technology in the aviation sector. By experimental investigations of the blade elongation both in tensile tests and engine operation, measuring the tip clearance with a high-speed camera, this process could be validated to facilitate the transferability of research. Finally, the performance of the manufactured engine is measured by a five-hole miniature probe, not only in design point but also in off-design operation. The results indicate that a substantial reduction in discrepancies between initial specifications, subsequent CFD simulations, and experimental investigations compared to conventional design tools relying on empirical formulations can be achieved due to the CFD-based approach. This allows the CFD-based tool to be validated for designing scalable contra-rotating fan engines. Full article

(This article belongs to the Special Issue Advanced Aircraft Technology)

14 pages, 764 KiB

Open AccessArticle

Non-Cooperative Spacecraft Pose Estimation Based on Feature Point Distribution Selection Learning

by Haoran Yuan, Hanyu Chen, Junfeng Wu and Guohua Kang

Aerospace 2024, 11(7), 526; https://doi.org/10.3390/aerospace11070526 - 27 Jun 2024

Viewed by 36

Abstract

To address the limitations of inadequate real-time performance and robustness encountered in estimating the pose of non-cooperative spacecraft during on-orbit missions, a novel method of feature point distribution selection learning is proposed. This approach utilizes a non-coplanar key point selection network with uncertainty [...] Read more.

To address the limitations of inadequate real-time performance and robustness encountered in estimating the pose of non-cooperative spacecraft during on-orbit missions, a novel method of feature point distribution selection learning is proposed. This approach utilizes a non-coplanar key point selection network with uncertainty prediction, pioneering in its capability to accurately estimate the pose of non-cooperative spacecraft, thereby representing a significant advancement in the field. Initially, the feasibility of designing a non-coplanar key point selection network was analyzed based on the influence of sensor layout on the pose measurement. Subsequently, the key point selection network was designed and trained, leveraging images extracted from the spacecraft detection network. The network detected 11 pre-selected key points with distinctive features and was able to accurately predict their uncertainties and relative positional relationships. Upon selection of the key points exhibiting low uncertainty and non-coplanar relative positions, we utilized the EPnP algorithm to achieve accurate pose estimation of the target spacecraft. Our experimental evaluation on the SPEED dataset, which comes from the International Satellite Attitude Estimation Competition, validates the effectiveness of our key point selection network, significantly enhancing estimation accuracy and timeliness compared to other monocular spacecraft attitude estimation methods. This advancement provides robust technological support for spacecraft guidance, control, and proximity operations in orbital service missions. Full article

(This article belongs to the Section Astronautics & Space Science)

32 pages, 5050 KiB

Open AccessArticle

Flow Topology Optimization at High Reynolds Numbers Based on Modified Turbulence Models

by Chenyu Wu and Yufei Zhang

Aerospace 2024, 11(7), 525; https://doi.org/10.3390/aerospace11070525 - 27 Jun 2024

Viewed by 89

Abstract

Flow topology optimization (TopOpt) based on Darcy’s source term is widely used in the field of TopOpt. It has a high degree of freedom, making it suitable for conceptual aerodynamic design. Two problems of TopOpt are addressed in this paper to apply the [...] Read more.

Flow topology optimization (TopOpt) based on Darcy’s source term is widely used in the field of TopOpt. It has a high degree of freedom, making it suitable for conceptual aerodynamic design. Two problems of TopOpt are addressed in this paper to apply the TopOpt method to high-Reynolds-number turbulent flow that is often encountered in aerodynamic design. First, a strategy for setting Darcy’s source term is proposed based on the relationship between the magnitude of the source term and some characteristic variables of the flow (length scale, freestream velocity, and fluid viscosity). Second, we construct two modified turbulence models, a modified Launder–Sharma k − ϵ (LSKE) model and a modified shear stress transport (SST) model, that consider the influence of Darcy’s source term on turbulence and the wall-distance field. The TopOpt of a low-drag profile in turbulent flow is studied using the modified LSKE model. It is demonstrated by comparing velocity profiles that the model can reflect the influence of solids on turbulence at Reynolds numbers as high as one million. The TopOpt of a rotor-like geometry, which is of great importance in aerodynamic design, is conducted using the modified SST model. In all the cases considered, the drag, the total pressure loss, and the energy dissipation are significantly reduced by TopOpt, indicating the proposed model’s ability to handle the TopOpt of turbulent flow. Full article

22 pages, 6420 KiB

Open AccessArticle

High-Resolution Wavenumber Bandpass Filtering of Guided Ultrasonic Wavefield for the Visualization of Subtle Structural Flaws

by Lee Shi Yn, Fairuz Izzuddin Romli, Norkhairunnisa Mazlan, Jung-Ryul Lee, Mohammad Yazdi Harmin and Chia Chen Ciang

Aerospace 2024, 11(7), 524; https://doi.org/10.3390/aerospace11070524 - 27 Jun 2024

Viewed by 72

Abstract

Guided ultrasonic wavefield propagation imaging (GUPI) is useful for visualizing hidden flaws in aerospace thin-walled structures, but the need for subjective signal processing involving three-dimensional Fourier transformation to increase the visibility of subtle flaws hinders its wider acceptance. A high-resolution wavenumber bandpass filter [...] Read more.

Guided ultrasonic wavefield propagation imaging (GUPI) is useful for visualizing hidden flaws in aerospace thin-walled structures, but the need for subjective signal processing involving three-dimensional Fourier transformation to increase the visibility of subtle flaws hinders its wider acceptance. A high-resolution wavenumber bandpass filter capable of consolidating subtle flaw-relevant information from a wide frequency band using only two-dimensional Fourier transformation was proposed. The filter overturns the long-standing belief that modes must be separated based on narrow-band data acquisition or processing to achieve high flaw visibility. Its characteristics and advantages were experimentally demonstrated through enhanced visualization of hidden wall-thinning flaws of a plate specimen. Its strength was further demonstrated through the first GUPI visualization of a partially loosened bolt, with unprecedented clarity to discern bolt tightness levels. The results conclusively proved that the proposed filter significantly enhances the resolution of GUPI within a structured processing framework. Full article

(This article belongs to the Special Issue Laser Ultrasound Techniques for Aerospace Applications)

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24 pages, 2919 KiB

Open AccessArticle

Lean Demonstration of On-Board Thermal Anomaly Detection Using Machine Learning

by Jan Thoemel, Konstantinos Kanavouras, Maanasa Sachidanand, Andreas Hein, Miguel Ortiz del Castillo, Leo Pauly, Arunkumar Rathinam and Djamila Aouada

Aerospace 2024, 11(7), 523; https://doi.org/10.3390/aerospace11070523 - 27 Jun 2024

Viewed by 53

Abstract

Moore’s law states that the performance of computers doubles about every two years. This has dramatic consequences for any modern high development and for satellites. The long development cycles cause these expensive assets to be obsolete before the start of their operations. The [...] Read more.

Moore’s law states that the performance of computers doubles about every two years. This has dramatic consequences for any modern high development and for satellites. The long development cycles cause these expensive assets to be obsolete before the start of their operations. The advancement also presents challenges to their design, particularly from a thermal perspective, as more heat is dissipated and circuits are more fragile. These challenges mandate that faster spacecraft development methods are found and thermal management technologies are developed. We elaborate on existing development methodologies and present our own lean method. We explore the development of a thermal anomaly-detection payload, extending from conception to in-orbit commissioning, to stimulate discussions on space hardware development approaches. The payload consists of four miniaturized infrared cameras, heating sources in view of the cameras simulating an anomaly, an on-board processor, and peripherals for electrical and communication interfaces. The paper outlines our methodology and its application, showcasing the success of our efforts with the first-light activation of our cameras in orbit. We show our lean method, featuring reference technical and management models, from which we derive further development tools; such details are normally not available in the scientific-engineering literature. Additionally, we address the shortcomings identified during our development, such as the failure of an on-board component and propose improvements for future developments. Full article

19 pages, 1320 KiB

Open AccessArticle

Interference Study of 5G System on Civil Aircraft Airborne Beidou RDSS System in Takeoff and Landing Phase

by Wantong Chen, Yuyin Tian, Shuguang Sun and Ruihua Liu

Aerospace 2024, 11(7), 522; https://doi.org/10.3390/aerospace11070522 - 27 Jun 2024

Viewed by 109

Abstract

Radio Determination Satellite Service (RDSS) is a characteristic service of BeiDou, which can provide users with short message communication services. Since the working frequency of an RDSS system is close to that of a 5G system, the RDSS system is very susceptible to [...] Read more.

Radio Determination Satellite Service (RDSS) is a characteristic service of BeiDou, which can provide users with short message communication services. Since the working frequency of an RDSS system is close to that of a 5G system, the RDSS system is very susceptible to interference from 5G out-of-band radiation. This paper analyzes the compatibility of 5G interference with an RDSS system from the perspective of the signal and the system. Firstly, the compatibility assessment is carried out from the perspective of the signal, the impact of interference on the capture and tracking performance of BeiDou is illustrated, and the safe coexistence distance of the two systems from the perspective of capture probability is obtained from the perspective of the signal. Subsequently, based on the link budget criterion, the interference of 5G base stations and 5G terminals to RDSS receivers under different frequency isolation and the required distance isolation for safe coexistence are analyzed from the system perspective. Finally, from the perspective of civil aviation safety, the aggregate interference is used as an evaluation index to evaluate the interference suffered by the aircraft during takeoff and landing and to obtain the interference suffered by the ground-based 5G base station during the takeoff and landing of the aircraft on different routes and in different 5G propagation environments. The simulation results show that when the airplane is closer to the ground, the ground 5G base stations will cause harmful interference to the RDSS receiver. In this study, the real flight data are combined with the simulation model to obtain the exact influence range of 5G interference on the RDSS system under different viewpoints. Full article

(This article belongs to the Special Issue AI-Enabled Signal Processing for Space–Air–Ground Integrated Networks)

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23 pages, 21901 KiB

Open AccessArticle

Numerical Study on Rotor–Building Coupled Flow Field and Its Influence on Rotor Aerodynamic Performance under an Atmospheric Boundary Layer

by Yang Liu, Yongjie Shi, Aqib Aziz and Guohua Xu

Aerospace 2024, 11(7), 521; https://doi.org/10.3390/aerospace11070521 - 27 Jun 2024

Viewed by 111

Abstract

In urban settings, buildings create complex turbulent conditions, affecting helicopter flight performance during missions and increasing safety risks during takeoff and landing. A numerical study on rotor–building coupled flow field is carried out to address rotor aerodynamic performance under building interferences in natural [...] Read more.

In urban settings, buildings create complex turbulent conditions, affecting helicopter flight performance during missions and increasing safety risks during takeoff and landing. A numerical study on rotor–building coupled flow field is carried out to address rotor aerodynamic performance under building interferences in natural atmospheric conditions. A high-fidelity atmospheric boundary layer (ABL) model described by an exponential law is established herein. The solution of the coupled flow field is based on the Reynolds-averaged Navier–Stokes (RANS) equations, with the rotor’s rotation achieved through the overset grid method. Based on the dominant wind features, the building flow field is distributed into four regions, where the updraft along the headwind side impacts the rotor, bringing about a 76% increase in pitching moment. On the lateral side of the building, distorted rotor wake squeezed upward into the rotor disk, leading to severe blade–vortex interaction (BVI). During low-altitude hovering over rooftops, the mixing of building shed vortices with forward flow wakes causes the formation of a circulation region on the rotor’s windward side, resulting in a thrust loss of approximately 7.8%. Meanwhile, the flow environment on the leeward side of the buildings is more stable. Therefore, it is recommended that helicopters adopt a headwind approach during rooftop operations. However, an 11.4% loss in the average hover figure of merit is observed due to consistent thrust losses caused by the recirculation region. Full article

(This article belongs to the Special Issue Gust Influences on Aerospace)

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22 pages, 9209 KiB

Open AccessArticle

Structural Damage Assessment of an Airfoil Anti-Icing System under Hailstorm Conditions

by Carlo Giovanni Ferro, Alessandro Cellini and Paolo Maggiore

Aerospace 2024, 11(7), 520; https://doi.org/10.3390/aerospace11070520 - 27 Jun 2024

Viewed by 108

Abstract

This paper presents a comprehensive comparative study of the resilience of leading edge anti-icing systems on business jets when exposed to severe hailstorm conditions. Using advanced simulation models correlated with experimental data, the study aims to determine the overall effectiveness of these systems [...] Read more.

This paper presents a comprehensive comparative study of the resilience of leading edge anti-icing systems on business jets when exposed to severe hailstorm conditions. Using advanced simulation models correlated with experimental data, the study aims to determine the overall effectiveness of these systems when exposed to the adverse effects of hail impact. Key aspects of the study include the examination of system structural response to varying sizes and densities of hailstones, and the impact on the leading edge structural integrity and on the overall aircraft safety. The simulations are designed to replicate realistic hailstorm scenarios, considering factors such as hailstone velocity, size, and impact angle. Results from the study reveal significant differences in the performance of piccolo-tube anti-icing system under hailstorm conditions. The study assesses the operational limitations and the energy absorption of a business jet anti icing system, providing valuable insights for anti-icing robust design in this category. Full article

(This article belongs to the Special Issue Aerospace Anti-icing Systems)

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29 pages, 9042 KiB

Open AccessArticle

Investigation of Fluid Dynamics in Various Aircraft Wing Tank Designs Using 1D and CFD Simulations

by Kerem Karahan and Sertac Cadirci

Aerospace 2024, 11(7), 519; https://doi.org/10.3390/aerospace11070519 - 27 Jun 2024

Viewed by 124

Abstract

Jet fuel in aircraft fuel tanks moves due to acceleration resulting from maneuvers. The movement mentioned here directly impacts the Center of Gravity (CG). The aircraft’s flight mechanics are significantly affected by the deviation of its CG on the aircraft body, and excessive [...] Read more.

Jet fuel in aircraft fuel tanks moves due to acceleration resulting from maneuvers. The movement mentioned here directly impacts the Center of Gravity (CG). The aircraft’s flight mechanics are significantly affected by the deviation of its CG on the aircraft body, and excessive deviation is undesirable. Preventing CG deviation is achieved by designing various baffles within the fuel tank. In this study, design details of the baffles were investigated with the help of an artificial neural network (ANN) model, 1D simulations, and computational fluid dynamics (CFD) calculations. The 1D simulations, which model the fuel movement, were used to understand the general behavior of the fluid in the tank. CFD calculations simulating turbulent fluid flow in three dimensions were used to confirm the results of the 1D simulations and provide more detailed information. A simulation set is created utilizing five parameters: barrier usage, volume fraction, cutout diameter, number of cutouts, and cutout location. Compared to the barrierless design, the barrier usage as a parameter changes either on baffle number 1, 3, and 6, or on baffle number 2, 4, and 7. The fuel volume fraction parameter accounts for 30%, 45%, and 60% of the interior volume. The diameters of the cutout holes vary between 30 mm and 156 mm and are used as categorized among the baffles. Cutout holes are applied on baffles in single, twin, and triplet forms and their locations are subjected to a divergence of either −20 mm or +20 mm from the z-axis. Based on these parameters, the maximum deviation and the retreat time of CG constitute the output parameters. The importance of the input parameters on the outputs was obtained with the help of an ANN algorithm created from the results of all possible combinations of a sufficient number of 1D simulations. To obtain more detailed results and confirm the importance of input parameters on outputs, selected cases were simulated with CFD. As a result of all analyses, it was revealed that barrier usage is the most dominant input parameter on CG deviation followed by volume fraction, cutout hole diameter, cutout divergence, and finally, the number of cutout holes. This study identifies the dominant input parameters to control fuel sloshing, specifically CG deviation and retreat time in the fuel tank, and proposes baffle designs to promote robust flight stability. Full article

(This article belongs to the Special Issue Flight Dynamics, Control & Simulation (2nd Edition))

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13 pages, 1644 KiB

Open AccessArticle

Optimization Design of Core Ultra-Stable Structure for Space Gravitational Wave Detection Satellite Based on Response Surface Methodology

by Changru Liu, Zhenbang Xu, Kang Han, Chengshan Han and Tao He

Aerospace 2024, 11(7), 518; https://doi.org/10.3390/aerospace11070518 - 26 Jun 2024

Viewed by 172

Abstract

Abstract: In order to meet the urgent demand for novel zero-expansion materials and ultra-stable structures in space gravitational wave detection, it is necessary to develop an ultra-stable structural spacecraft system. This paper focuses on the research of the optimization of the core [...] Read more.

Abstract: In order to meet the urgent demand for novel zero-expansion materials and ultra-stable structures in space gravitational wave detection, it is necessary to develop an ultra-stable structural spacecraft system. This paper focuses on the research of the optimization of the core ultra-stable structure design of spacecraft, proposing a cross-scale parameterized model of structural deformation response and a multi-objective optimization method. By satisfying the prerequisites of mass and fundamental frequency, this paper breaks through the limitations of current linear analysis methods, and the overall thermal deformation of nonlinear material composite structures is optimized by modifying structural parameters. Full article

(This article belongs to the Special Issue Advanced Design for Lightweight Space Materials and Structural Systems)

19 pages, 14051 KiB

Open AccessArticle

Design of an Automatic Sealing Mechanism for Extraterrestrial Sample-Collecting Robot

by Yujian Mu, Zihao Yuan, Ruinan Mu, Haifeng Zhao, Zhitao Ning, Xihan Li, Tianyue Gan, Tao Du, Zhiqiang Wang, Rujin Han and Zhenxing Shen

Aerospace 2024, 11(7), 517; https://doi.org/10.3390/aerospace11070517 - 26 Jun 2024

Viewed by 203

Abstract

Returning extraterrestrial samples to Earth for analysis is crucial for planetary geological research and resource utilization. However, during their return journey, these samples undergo significant environmental changes, such as varying pressure, temperature, impact, and vibration. Hence, a dependable sealing technique that preserves sample [...] Read more.

Returning extraterrestrial samples to Earth for analysis is crucial for planetary geological research and resource utilization. However, during their return journey, these samples undergo significant environmental changes, such as varying pressure, temperature, impact, and vibration. Hence, a dependable sealing technique that preserves sample integrity without requiring high-powered tools is necessary. This article aims to develop an automatic sealing system for collecting extraterrestrial samples, conducting parametric design and mechanical analysis on two types of proposed sealing structures with minimal sealing force as the benchmark. Additionally, the system will undergo validation through sealing and leakage detection experiments. An automated sealing system, capable of storing samples in multiple sampling tubes, is assembled for the extraterrestrial sampling device. Full article

(This article belongs to the Special Issue Planetary Exploration)

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19 pages, 8876 KiB

Open AccessArticle

Hybrid A*-Based Valley Path Planning Algorithm for Aircraft

by Tao Xue, Yueyao Cao, Yunmei Zhao, Jianliang Ai and Yiqun Dong

Aerospace 2024, 11(7), 516; https://doi.org/10.3390/aerospace11070516 - 26 Jun 2024

Viewed by 240

Abstract

This paper presents a valley path planning algorithm based on the Hybrid A* algorithm. This algorithm is aimed at finding the valley path for aircraft considering dynamics constraints and terrain limitations. The preliminaries involve the establishment of a 3D workspace based on digital [...] Read more.

This paper presents a valley path planning algorithm based on the Hybrid A* algorithm. This algorithm is aimed at finding the valley path for aircraft considering dynamics constraints and terrain limitations. The preliminaries involve the establishment of a 3D workspace based on digital elevation map (DEM) data and addressing methods of valley detection. Following this comprehensive groundwork, the Hybrid A*-based algorithm, employed to determine the valley path within the 3D workspace while accommodating dynamic constraints and terrain limitations, is then introduced. In the experimental test, to validate the effectiveness of the algorithm proposed in this paper, we tested the performance of the proposed algorithm and other three baseline algorithms based on four optimization objectives in three workspaces. The simulated results indicate that the algorithm proposed in this paper can effectively find the valley path while considering dynamic constraints and terrain limitations. Full article

(This article belongs to the Special Issue UAV Path Planning and Navigation)

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29 pages, 1388 KiB

Open AccessArticle

Study on Dynamic Scanning Trajectory of Large Aerospace Parts Based on 3D Scanning

by Jing Li, Yang Wang, Ligang Qu, Minghai Wang, Guangming Lv and Pengfei Su

Aerospace 2024, 11(7), 515; https://doi.org/10.3390/aerospace11070515 - 25 Jun 2024

Viewed by 192

Abstract

The aim of manufacturing large aerospace parts for the three-dimensional scanning field demands high precision and efficiency. However, it may be more challenging to meet the full coverage of the measurement problems for large aerospace parts with the scanning range of traditional three-dimensional [...] Read more.

The aim of manufacturing large aerospace parts for the three-dimensional scanning field demands high precision and efficiency. However, it may be more challenging to meet the full coverage of the measurement problems for large aerospace parts with the scanning range of traditional three-dimensional scanning methods. This paper establishes a dynamic posturing scanning measurement system for large aerospace parts with a six-degree-of-freedom posturing platform and a six-degree-of-freedom industrial robot linkage. It establishes a mathematical model of dynamic three-dimensional scanning posturing. It proposes a platform attitude adjustment strategy based on the field of view angle of a 3D scanner during the adjustment of a six-degree-of-freedom platform. The dynamic scanning path planning is carried out using the three-dimensional spatial decomposition method, and the vector coordinates of the critical points at the edges of the missing areas of the scan are used to re-scan the missing areas to establish the dynamic scanning paths of large aerospace parts. It is experimentally verified that the system can realize the dynamic scanning of complex curved large aerospace parts. The experimental results show that the measurement efficiency is improved by more than 75%, and the point cloud coverage of the scanning reconstruction is improved by 18% for large aerospace components with complex surfaces. Full article

14 pages, 2209 KiB

Open AccessArticle

Design and Rate Control of Large Titanium Alloy Springs for Aerospace Applications

by Lei Li, Qiufa Xu, Haiying Yang, Yang Ying, Zuhan Cao, Dizi Guo and Vincent Ji

Aerospace 2024, 11(7), 514; https://doi.org/10.3390/aerospace11070514 - 25 Jun 2024

Viewed by 193

Abstract

During the separation between satellite and launch vehicles, large steel springs are often used as compression separation spring sets in a catapult separation system. Replacing the steel springs with titanium alloy springs could reduce weight by about 50%. Although titanium alloy springs have [...] Read more.

During the separation between satellite and launch vehicles, large steel springs are often used as compression separation spring sets in a catapult separation system. Replacing the steel springs with titanium alloy springs could reduce weight by about 50%. Although titanium alloy springs have been widely used in the aerospace field due to their excellent performance, there are few reports on the design of high-precision titanium alloy springs. The current spring design standards mainly focus on steel springs with helix angles between 5° and 9°, which are not applicable to titanium springs. Moreover, the change in spring rate with ambient temperature should also be considered. In this paper, β-C titanium alloy was used to design and prepare large compression separation springs, replacing steel springs in the catapult separation system. The design of titanium alloy springs took into account the big helix angle. The relationship between helix angle and the number of active coils was calculated. The parameters of titanium alloy springs were determined by the shear stress of the spring at working length. The effects of aging temperature and aging duration on the mechanical properties and modulus of β-C alloy were studied. By adjusting the aging process, the β-C alloy spring rate was controlled to meet the design requirements. The effect of ambient temperature on the mechanical properties and modulus of β-C titanium alloy were also investigated. It was found that as the ambient temperature increased, the rate of the β-C alloy spring gradually decreased. Full article

(This article belongs to the Special Issue Advanced Design for Lightweight Space Materials and Structural Systems)

18 pages, 1647 KiB

Open AccessArticle

Application of Lee–Tarver Model for Energetic Materials Safety Assessment Utilized in Aerospace Applications

by Muhammad Saqib Awan, Zhengxiang Huang, Xudong Zu, Qiangqiang Xiao and Bin Ma

Aerospace 2024, 11(7), 513; https://doi.org/10.3390/aerospace11070513 - 25 Jun 2024

Viewed by 135

Abstract

Energetic materials, essential for rocket propulsion, play a crucial role in aerospace systems. These materials lack sufficient safety assessments and pose significant risks to life and infrastructure. The slow progress in this field is hindered by prohibitively high experimental costs and the inherently [...] Read more.

Energetic materials, essential for rocket propulsion, play a crucial role in aerospace systems. These materials lack sufficient safety assessments and pose significant risks to life and infrastructure. The slow progress in this field is hindered by prohibitively high experimental costs and the inherently destructive nature of these experiments. This study aimed to evaluate modeling-based safety assessments, primarily utilizing the Lee–Tarver model. It specifically addressed the threat posed by shaped charges during transportation. Experimental analyses employed 50 mm JH-2 shaped charges, targeting RDX-based JH-2 formulation, since RDX is widely used in various rocket motor propellant formulations. TNT was also used to enhance the validation of the Lee–Tarver model findings. Various logistical configurations were explored, testing steel container walls ranging from 10 mm thickness to reinforced walls of 50 mm, 60 mm, and 65 mm steel. Comparative analysis with experiments reinforced the accuracy of the Lee–Tarver model’s numerical predictions. Both simulations and experiments affirmed that a 65 mm steel protection suffices for the safe transportation of RDX-based JH-2 formulations and TNT within a 10 mm storage box in logistical setups. Furthermore, this study emphasizes the Lee–Tarver model’s reliability for most energetic materials safety assessments, while acknowledging certain limitations. Full article

23 pages, 32033 KiB

Open AccessArticle

RANS-Based Aerodynamic Shape Optimization of a Wing with a Propeller in Front of the Wingtip

by Shamsheer S. Chauhan and Joaquim R. R. A. Martins

Aerospace 2024, 11(7), 512; https://doi.org/10.3390/aerospace11070512 - 25 Jun 2024

Viewed by 150

Abstract

Accounting for propeller–wing interaction allows for the design of more efficient propeller aircraft through strategic propulsion integration. In this paper, the cruise drag of a wing with a propeller located in front of the wingtip is minimized using twist and airfoil-shape design variables. [...] Read more.

Accounting for propeller–wing interaction allows for the design of more efficient propeller aircraft through strategic propulsion integration. In this paper, the cruise drag of a wing with a propeller located in front of the wingtip is minimized using twist and airfoil-shape design variables. Reynolds-averaged Navier–Stokes computational fluid dynamics with an actuator-disk approach is used for the flow simulations, and a gradient-based algorithm is used for the optimization. Changing the rotation direction of the propeller and optimizing the twist and airfoil shapes of the wing are found to impact the aerodynamic performance significantly, as expected. However, optimizing the wing while accounting for the propeller slipstream during optimization provides little benefit over optimizing it without accounting for the propeller slipstream—a difference of less than one drag count. Full article

(This article belongs to the Section Aeronautics)

23 pages, 1572 KiB

Open AccessArticle

A Graph Reinforcement Learning-Based Handover Strategy for Low Earth Orbit Satellites under Power Grid Scenarios

by Haizhi Yu, Weidong Gao and Kaisa Zhang

Aerospace 2024, 11(7), 511; https://doi.org/10.3390/aerospace11070511 - 24 Jun 2024

Viewed by 259

Abstract

Amidst the escalating need for stable power supplies and high-quality communication services in remote regions globally, due to challenges associated with deploying a conventional power communication infrastructure and its susceptibility to natural disasters, LEO satellite networks present a promising solution for broad geographical [...] Read more.

Amidst the escalating need for stable power supplies and high-quality communication services in remote regions globally, due to challenges associated with deploying a conventional power communication infrastructure and its susceptibility to natural disasters, LEO satellite networks present a promising solution for broad geographical coverage and the provision of stable and high-speed communication services in remote regions. Given the necessity for frequent handovers to maintain service continuity, due to the high mobility of LEO satellites, a primary technical challenge confronting LEO satellite networks lies in efficiently managing the handover process between satellites, to guarantee the continuity and quality of communication services, particularly for power services. Thus, there is a critical need to explore satellite handover optimization algorithms. This paper presents a handover optimization scheme that integrates deep reinforcement learning (DRL) and graph neural networks (GNN) to dynamically optimize the satellite handover process and adapt to the time-varying satellite network environment. DRL models can effectively detect changes in the topology of satellite handover graphs across different time periods by leveraging the powerful representational capabilities of GNNs to make optimal handover decisions. Simulation experiments confirm that the handover strategy based on the fusion of message-passing neural network and deep Q-network algorithm (MPNN-DQN) outperforms traditional handover mechanisms and DRL-based strategies in reducing handover frequency, lowering communication latency, and achieving network load balancing. Integrating DRL and GNN into the satellite handover mechanism enhances the communication continuity and reliability of power systems in remote areas, while also offering a new direction for the design and optimization of future power system communication networks. This research contributes to the advancement of sophisticated satellite communication architectures that facilitate high-speed and reliable internet access in remote regions worldwide. Full article

(This article belongs to the Special Issue Advanced Technology of Distributed Space Systems: Formation-Flying, Swarms, and Constellations)

24 pages, 3006 KiB

Open AccessArticle

A Flexible Topology Control Strategy for Mega-Constellations via Inter-Satellite Links Based on Dynamic Link Optimization

by Yueyi Li, Junfeng Wu, Guohua Kang, Luyu Chen, Yuhuan Qiu and Wenwen Zhou

Aerospace 2024, 11(7), 510; https://doi.org/10.3390/aerospace11070510 - 24 Jun 2024

Viewed by 233

Abstract

In large-scale satellite constellations, the efficiency of inter-satellite communication is paramount. Traditional topology control strategies, such as the Manhattan configuration, provide stable links but can result in indirect communication paths, affecting the efficiency of information transfer. This paper addresses this issue by proposing [...] Read more.

In large-scale satellite constellations, the efficiency of inter-satellite communication is paramount. Traditional topology control strategies, such as the Manhattan configuration, provide stable links but can result in indirect communication paths, affecting the efficiency of information transfer. This paper addresses this issue by proposing an innovative “3 + 1” dynamic topology control scheme. The scheme retains three static links determined by the relative angular velocity and acceleration while introducing a dynamic link based on distance and angular velocity constraints to optimize the link duration and overall network communication efficiency. To address the complexity of matching dynamic links, this paper introduces an elite strategy-based maximum weighted matching algorithm for general graphs. Compared to traditional greedy algorithms, our proposed algorithm significantly improves the link duration and topological stability. Through simulation experiments comparing communication delays between Xiamen and Los Angeles, our results show that the proposed dynamic link scheme substantially reduces the average delay, enhancing the efficiency and flexibility of inter-satellite communication. This research not only extends the duration of inter-satellite links but also provides new perspectives and methodologies for further studies on inter-satellite topology control strategies. Full article

19 pages, 12017 KiB

Open AccessArticle

AI-Based Anomaly Detection Techniques for Structural Fault Diagnosis Using Low-Sampling-Rate Vibration Data

by Yub Jung, Eun-Gyo Park, Seon-Ho Jeong and Jeong-Ho Kim

Aerospace 2024, 11(7), 509; https://doi.org/10.3390/aerospace11070509 - 24 Jun 2024

Viewed by 371

Abstract

Rotorcrafts experience severe vibrations during operation. To ensure the safety of rotorcrafts, it is necessary to perform anomaly detection to detect small-scale structural faults in major components. To accurately detect small-scale faults before they grow to a fatal size, HR (high sampling rate) [...] Read more.

Rotorcrafts experience severe vibrations during operation. To ensure the safety of rotorcrafts, it is necessary to perform anomaly detection to detect small-scale structural faults in major components. To accurately detect small-scale faults before they grow to a fatal size, HR (high sampling rate) vibration data are required. However, to increase the efficiency of data storage media, only LR (low sampling rate) vibration data are generally collected during actual flight operation. Anomaly detection using only LR data can detect faults above a certain size, but may fail to detect small-scale faults. To address this problem, we propose an anomaly detection technique using the SR3 (Super-Resolution via Repeated Refinement) algorithm to upscale LR data to HR data, and then applying the LSTM-AE model. This technique is validated for two datasets (drone arm data, CWRU bearing data). First, the necessity for HR data is illustrated by showing that anomaly detection using LR data fails, and the upscaling performance of the SR3 algorithm is validated in the frequency and time domain. Finally, the anomaly detection for a structural fault diagnosis is performed for the upscaled data and the HR data using the LSTM-AE model. The quantitative evaluation of the Min–Max normalized reconstruction error distribution is performed through the MSE (Mean Square Error) value of the anomaly detection results. As a result, it is confirmed that the anomaly detection using upscaled test data can be performed as successfully as the anomaly detection using HR test data for both datasets by the proposed technique. Full article

(This article belongs to the Special Issue Machine Learning for Aeronautics (2nd Edition))

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13 pages, 944 KiB

Open AccessArticle

Effects of Different Materials and Structures on Mechanical Properties of Hail Used in Aviation Testing

by Yewei Liu, Lifen Zhang, Xin Ge and Zhenxia Liu

Aerospace 2024, 11(7), 508; https://doi.org/10.3390/aerospace11070508 - 24 Jun 2024

Viewed by 192

Abstract

Hail absorption test of aeroengine is one of the important components of airworthiness certification. The accurate test data are closely related to the density and mechanical properties of the artificial hail used in airworthiness tests. Through experimental research, this study explores the impact [...] Read more.

Hail absorption test of aeroengine is one of the important components of airworthiness certification. The accurate test data are closely related to the density and mechanical properties of the artificial hail used in airworthiness tests. Through experimental research, this study explores the impact of distilled water, carbonated water and deionized water on the density and mechanical properties of artificial hail. The study addresses the significant differences between the density and mechanical properties of artificial hail and natural hail in existing studies. Based on this, a new method for preparing airworthiness test hail is proposed. The results indicate that artificial hail samples with distilled water as the hail core and carbonated water as the hail shell have densities ranging from 0.87 cm³ to 0.89 cm³. Furthermore, the estimated average maximum compressive strength of samples is 6.538 MPa, with some samples as low as 3.681 MPa. The mechanical properties of this artificial hail are more similar to those of natural hail. This method can more realistically simulate natural hail environments and can be used for the fine design of airworthiness certification criteria. Full article

(This article belongs to the Special Issue Aerospace Anti-icing Systems)

23 pages, 12084 KiB

Open AccessArticle

Surface Pressure Measurement of Truncated, Linear Aerospike Nozzles Utilising Secondary Injection for Aerodynamic Thrust Vectoring

by Jan Sieder-Katzmann, Martin Propst, Ralf H. Stark, Dirk Schneider, Stephan General, Martin Tajmar and Christian Bach

Aerospace 2024, 11(7), 507; https://doi.org/10.3390/aerospace11070507 - 24 Jun 2024

Viewed by 294

Abstract

A cold-gas test campaign has been conducted at the DLR’s P6.2 test bench in Lampoldshausen, with the objective of investigating the linear aerospike nozzle flow in interaction with secondary injection thrust vector control (SITVC). In this campaign, the influence of nozzle truncation, injection [...] Read more.

A cold-gas test campaign has been conducted at the DLR’s P6.2 test bench in Lampoldshausen, with the objective of investigating the linear aerospike nozzle flow in interaction with secondary injection thrust vector control (SITVC). In this campaign, the influence of nozzle truncation, injection position and injection pressure on the nozzle surface and base pressure is analysed using pressure probes and Schlieren flow-visualisation techniques. The effects of injection position and truncation on the nozzle surface pressure development are comparable for all geometric variations, resulting in a locally increased static pressure upstream and a locally decreased static pressure downstream of the injection. The magnitude and dimension of these high- and low-pressure regions are correlated with the injection pressure. However, the influence of injection position and truncation on the base pressure is not entirely predictable by the named parameters, indicating an interdependence between both geometric parameters. Finally, the required pressure ratio of injection to the primary flow to ensure sonic injection has been analysed on TUD’s cold-gas test bench. This allows the respective injection position-dependent threshold to be identified. The analysis reveals that these experiments have been conducted under transsonic injection conditions. Full article

(This article belongs to the Special Issue Fluid Flow Mechanics (3rd Edition))

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19 pages, 20066 KiB

Open AccessArticle

Reduced-Order Modeling of Steady and Unsteady Flows with Deep Neural Networks

by Bryan Barraza and Andreas Gross

Aerospace 2024, 11(7), 506; https://doi.org/10.3390/aerospace11070506 - 24 Jun 2024

Viewed by 200

Abstract

Large-eddy and direct numerical simulations generate vast data sets that are challenging to interpret, even for simple geometries at low Reynolds numbers. This has increased the importance of automatic methods for extracting significant features to understand physical phenomena. Traditional techniques like the proper [...] Read more.

Large-eddy and direct numerical simulations generate vast data sets that are challenging to interpret, even for simple geometries at low Reynolds numbers. This has increased the importance of automatic methods for extracting significant features to understand physical phenomena. Traditional techniques like the proper orthogonal decomposition (POD) have been widely used for this purpose. However, recent advancements in computational power have allowed for the development of data-driven modal reduction approaches. This paper discusses four applications of deep neural networks for aerodynamic applications, including a convolutional neural network autoencoder, to analyze unsteady flow fields around a circular cylinder at Re = 100 and a supersonic boundary layer with Tollmien–Schlichting waves. The autoencoder results are comparable to those obtained with POD and spectral POD. Additionally, it is demonstrated that the autoencoder can compress steady hypersonic boundary-layer profiles into a low-dimensional vector space that is spanned by the pressure gradient and wall-temperature ratio. This paper also proposes a convolutional neural network model to estimate velocity and temperature profiles across different hypersonic flow conditions. Full article

(This article belongs to the Special Issue Fluid Flow Mechanics (3rd Edition))

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20 pages, 21605 KiB

Open AccessArticle

A Rapid Modeling Method for Airborne FSS Radomes Based on Dynamic Customizable Primitives

by Cunai Qiu, Shen Li, Wenwu Zhang, Liwei Song, Xiang Li, Zhongen Yan, Yue Chen and Saisai Suo

Aerospace 2024, 11(7), 505; https://doi.org/10.3390/aerospace11070505 - 23 Jun 2024

Viewed by 245

Abstract

The digital model of airborne frequency selective surface radomes (AFSSRs) is the basis of design, simulation analysis, manufacturing, and other related research on AFSSRs. This paper proposes a rapid modeling method for AFSSRs based on dynamic customizable primitives. Firstly, a layered digital model [...] Read more.

The digital model of airborne frequency selective surface radomes (AFSSRs) is the basis of design, simulation analysis, manufacturing, and other related research on AFSSRs. This paper proposes a rapid modeling method for AFSSRs based on dynamic customizable primitives. Firstly, a layered digital model construction scheme for AFSSRs is presented based on the typical radome wall structure. Then, according to the characteristics of various surface configurations and the complex wireframe information of AFSSRs, the dynamic primitives are raised to express the boundary and contour information of all kinds of radomes. Focusing on the undevelopable characteristics of the aerodynamic shape surface of the AFSSR, the arrangement solution and mapping method for frequency-selective elements on undevelopable surfaces are proposed. Furthermore, the implementation logic of this method for the creation of each layer model and the assembly of the whole machine model is introduced. Finally, a rapid modeling system (RMS) is established based on this method, enabling the automated creation of digital models of AFSSRs. Utilizing this system resulted in modeling time savings ranging from 20% to 97.5% compared to traditional methods, which verifies the feasibility and effectiveness of this method. Full article

20 pages, 1289 KiB

Open AccessArticle

Thermally Induced Vibration of a Flexible Plate with Enhanced Active Constrained Layer Damping

by Yueru Guo, Yongbin Guo, Yongxin Zhang, Liang Li, Dingguo Zhang, Sijia Chen and Mohamed A. Eltaher

Aerospace 2024, 11(7), 504; https://doi.org/10.3390/aerospace11070504 - 23 Jun 2024

Viewed by 227

Abstract

When spacecraft execute missions in space, their solar panels—crucial components—often need to be folded, unfolded, and adjusted at an angle. These operations can induce numerous detrimental nonlinear vibrations. This paper addresses the issues of nonlinear and thermal-coupled vibration control within the context of [...] Read more.

When spacecraft execute missions in space, their solar panels—crucial components—often need to be folded, unfolded, and adjusted at an angle. These operations can induce numerous detrimental nonlinear vibrations. This paper addresses the issues of nonlinear and thermal-coupled vibration control within the context of space-based flexible solar panel systems. Utilizing piezoelectric smart hybrid vibration control technology, this study focuses on a flexible plate augmented with an active constrained layer damping. The solar panel, under thermal field conditions, is modeled and simulated using the commercial finite element simulation software ABAQUS. The research examines variations in the modal frequencies and damping properties of the model in response to changes in the coverage location of the piezoelectric patches, their coverage rate, rotational angular velocity, and the thickness of the damping layer. Simulation results indicate that structural damping is more effective when the patches are closer to the rotation axis, the coverage area of the patches is larger, the rotational speed is lower, and the damping layer is thicker. Additionally, the effectiveness of vibration suppression is influenced by the interplay between the material shear modulus, loss factor, and specific working temperature ranges. The selection of appropriate parameters can significantly alter the system’s vibrational characteristics. This work provides necessary technical references for the analysis of thermally induced vibrations in flexible solar sails under complex space conditions. Full article

(This article belongs to the Special Issue Advanced Aerospace Composite Materials and Smart Structures)

21 pages, 18057 KiB

Open AccessArticle

SpaceLight: A Framework for Enhanced On-Orbit Navigation Imagery

by Zhang Zhang, Jiaqi Feng, Liang Chang, Lei Deng, Dong Li and Chaoming Si

Aerospace 2024, 11(7), 503; https://doi.org/10.3390/aerospace11070503 - 23 Jun 2024

Viewed by 180

Abstract

In the domain of space rendezvous and docking, visual navigation plays a crucial role. However, practical applications frequently encounter issues with poor image quality. Factors such as lighting uncertainties, spacecraft motion, uneven illumination, and excessively dark environments collectively pose significant challenges, rendering recognition [...] Read more.

In the domain of space rendezvous and docking, visual navigation plays a crucial role. However, practical applications frequently encounter issues with poor image quality. Factors such as lighting uncertainties, spacecraft motion, uneven illumination, and excessively dark environments collectively pose significant challenges, rendering recognition and measurement tasks during visual navigation nearly infeasible. The existing image enhancement methods, while visually appealing, compromise the authenticity of the original images. In the specific context of visual navigation, space image enhancement’s primary aim is the faithful restoration of the spacecraft’s mechanical structure with high-quality outcomes. To address these issues, our study introduces, for the first time, a dedicated unsupervised framework named SpaceLight for enhancing on-orbit navigation images. The framework integrates a spacecraft semantic parsing network, utilizing it to generate attention maps that pinpoint structural elements of spacecraft in poorly illuminated regions for subsequent enhancement. To more effectively recover fine structural details within these dark areas, we propose the definition of a global structure loss and the incorporation of a pre-enhancement module. The proposed SpaceLight framework adeptly restores structural details in extremely dark areas while distinguishing spacecraft structures from the deep-space background, demonstrating practical viability when applied to visual navigation. This paper is grounded in space on-orbit servicing engineering projects, aiming to address visual navigation practical issues. It pioneers the utilization of authentic on-orbit navigation images in the research, resulting in highly promising and unprecedented outcomes. Comprehensive experiments demonstrate SpaceLight’s superiority over state-of-the-art low-light enhancement algorithms, facilitating enhanced on-orbit navigation image quality. This advancement offers robust support for subsequent visual navigation. Full article

62 pages, 13575 KiB

Open AccessReview

Propulsion Technologies for CubeSats: Review

by Suood Alnaqbi, Djamal Darfilal and Sean Shan Min Swei

Aerospace 2024, 11(7), 502; https://doi.org/10.3390/aerospace11070502 - 21 Jun 2024

Viewed by 377

Abstract

This paper explores the wide-ranging topography of micro-propulsion systems that have been flown in different small satellite missions. CubeSats, known for their compact size and affordability, have gained popularity in the realm of space exploration. However, their limited propulsion capabilities have often been [...] Read more.

This paper explores the wide-ranging topography of micro-propulsion systems that have been flown in different small satellite missions. CubeSats, known for their compact size and affordability, have gained popularity in the realm of space exploration. However, their limited propulsion capabilities have often been a constraint in achieving certain mission objectives. In response to this challenge, space propulsion experts have developed a wide spectrum of miniaturized propulsion systems tailored to CubeSats, each offering distinct advantages. This literature review provides a comprehensive analysis of these micro-propulsion systems, categorizing them into distinct families based on their primary energy sources. The review provides informative graphs illustrating propulsion performance metrics, serving as beneficial resources for mission planners and satellite designers when selecting the most suitable propulsion system for a particular mission requirement. Full article

(This article belongs to the Special Issue Space Propulsion: Advances and Challenges (2nd Edition))

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26 pages, 4248 KiB

Open AccessArticle

Research on Convective Cooling and Thermal Protection Characteristics of Integrated Dual-Sided Deflector System

by Manman Zhang, Yi Jiang and Yueguang Deng

Aerospace 2024, 11(7), 501; https://doi.org/10.3390/aerospace11070501 - 21 Jun 2024

Viewed by 212

Abstract

Based on the goals of “high reliability, high frequency, rapid launch, and low cost” for space launch sites, an integrated dual-sided deflector system for convective cooling and thermal protection is presented. The interaction process between the gas jet and liquid water jet and [...] Read more.

Based on the goals of “high reliability, high frequency, rapid launch, and low cost” for space launch sites, an integrated dual-sided deflector system for convective cooling and thermal protection is presented. The interaction process between the gas jet and liquid water jet and its effect on the flow field environment are thoroughly studied using numerical calculation methods. Furthermore, considering the phase-change heat transfer issue in a compressible gas–liquid two-phase flow, and the varying distribution of different bubble shapes and sizes at the gas–liquid interface, a modified Lee model is derived. The research results show that compared to the classical Lee model, the modified Lee model can achieve a higher numerical accuracy in predicting the heat and mass transfer processes in gas–liquid two-phase flows. Through comparative analysis with the traditional dual-sided deflector and the conventional cooling system, the integrated dual-sided deflector system exhibits significant performance advantages in gas flow regulation and flow field environment improvement at the near-ground region of the space launch site. It not only achieves effective flow deflection, but also mitigates the degree of erosion caused by the gas jet on the deflector. This conclusion can provide theoretical references for the thermal protection design of commercial launch vehicle systems at space launch sites. Full article

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Aerospace, Volume 11, Issue 7 (July 2024) – 28 articles

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