Location via proxy:   [ UP ]  
[Report a bug]   [Manage cookies]                
Next Issue
Volume 11, October
Previous Issue
Volume 11, August
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Aerospace
Volume 11
Issue 9
share announcement

Aerospace, Volume 11, Issue 9 (September 2024) – 95 articles

Cover Story (view full-size image): Numerical simulations are performed for flows over a circular cylinder at a Reynolds number ranging from 150 to 5000 assess the predictive capability of different turbulence and hybrid RANS-LES models for acoustic wave generation and propagation. In addition, direct numerical simulations (DNS) are utilized to generate validation datasets and to provide more insight into any issues. The DNS predictions demonstrate that noise induced by the vortex shedding is radiated primarily at a 90-degree angle with respect to the wake direction, and it dictates the dominant frequency of the sound pressure waves. Turbulence dominates the noise in the near-field wake, resulting in a broadband pressure spectrum. View this paper
  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Reader to open them.
Order results
Result details
Section
Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
31 pages, 24798 KiB  
Article
A Study of Cislunar-Based Small Satellite Constellations with Sustainable Autonomy
by Mohammed Irfan Rashed and Hyochoong Bang
Aerospace 2024, 11(9), 787; https://doi.org/10.3390/aerospace11090787 - 23 Sep 2024
Viewed by 453
Abstract
The Cislunar economy is thriving with innovative space systems and operation techniques to enhance and uplift the traditional approaches significantly. This paper brings about an approach for sustainable small satellite constellations to retain autonomy for long-term missions in the Cislunar space. The methodology [...] Read more.
The Cislunar economy is thriving with innovative space systems and operation techniques to enhance and uplift the traditional approaches significantly. This paper brings about an approach for sustainable small satellite constellations to retain autonomy for long-term missions in the Cislunar space. The methodology presented is to align the hybrid model of the constellation for Earth and Moon as an integral portion of the Cislunar operations. These hybrid constellations can provide a breakthrough in optimally utilizing the Cislunar space to efficiently deploy prominent missions to be operated and avoid conjunction or collisions forming additional debris. Flower and walker constellation patterns have been combined to form a well-defined orientation for these small satellites to operate and deliver the tasks satisfying the mission objectives. The autonomous multi-parametric analysis for each constellation based in Earth and Moon’s environment has been attained with due consideration to local environments. Specifically, the Solar Radiation Pressure (SRP) is a critical constraint in Cislunar operations and is observed during simulations. These are supported by conjunction analysis using the Monte Carlo technique and also the effect of the SRP on the operating small satellites in real-time scenarios. This is followed by the observed conclusions and the way forward in this fiercely competent Cislunar operation. Full article
(This article belongs to the Special Issue Guidance, Navigation and Control Algorithms for Satellite Formation Flying)
►▼ Show Figures

Figure 1

16 pages, 4261 KiB  
Article
Large Debris Removal: Using Features of Attitude Motion for Load Factor Regulation during Re-Entry
by Vladimir S. Aslanov and Dmitry A. Sizov
Aerospace 2024, 11(9), 786; https://doi.org/10.3390/aerospace11090786 - 23 Sep 2024
Viewed by 439
Abstract
This paper focuses on the active removal of spent upper stages from LEO using de-orbiting devices. It proposes a method of regulating aerodynamic loads on the target during its re-entry by utilizing the features of spatial attitude motion. A mathematical model of the [...] Read more.
This paper focuses on the active removal of spent upper stages from LEO using de-orbiting devices. It proposes a method of regulating aerodynamic loads on the target during its re-entry by utilizing the features of spatial attitude motion. A mathematical model of the re-entry process is developed, and numerical simulations are conducted, demonstrating that the nature of the attitude motion during the descent influences the load factors and, thus, the breakup altitude. It is shown that the respective de-orbiting devices should control both the initial tumbling and spin of the target to achieve different mission outcomes, such as minimizing the debris footprint size or maximizing the breakup altitude. Full article
(This article belongs to the Section Astronautics & Space Science)
►▼ Show Figures

Figure 1

32 pages, 9195 KiB  
Article
Sequential Convex Programming for Reentry Trajectory Optimization Utilizing Modified hp-Adaptive Mesh Refinement and Variable Quadratic Penalty
by Zhe Liu, Naigang Cui, Lifu Du and Jialun Pu
Aerospace 2024, 11(9), 785; https://doi.org/10.3390/aerospace11090785 - 23 Sep 2024
Viewed by 410
Abstract
Due to the strong nonlinearity in the reentry trajectory planning problem for reusable launch vehicles (RLVs), the scale of the problem after high-precision discretization can become significantly large, and the non-convex path constraints are prone to exceed limits. Meanwhile, the objective function oscillation [...] Read more.
Due to the strong nonlinearity in the reentry trajectory planning problem for reusable launch vehicles (RLVs), the scale of the problem after high-precision discretization can become significantly large, and the non-convex path constraints are prone to exceed limits. Meanwhile, the objective function oscillation phenomenon may occur due to successive convexification, which results in poor convergence. To address these issues, a novel sequential convex programming (SCP) method utilizing modified hp-adaptive mesh refinement and variable quadratic penalty is proposed in this paper. Firstly, a local mesh refinement algorithm based on constraint violation is proposed. Additional mesh intervals and mesh points are added in the vicinity of the constraint violation points, which improves the satisfaction of non-convex path constraints. Secondly, a sliding window-based mesh reduction algorithm is designed and introduced into the hp-adaptive pseudospectral (PS) method. Unnecessary mesh intervals are merged to reduce the scale of the problem. Thirdly, a variable quadratic penalty-based SCP method is proposed. The quadratic penalty term related to the iteration direction and the weight coefficient updating strategy is designed to eliminate the oscillation. Numerical simulation results show that the proposed method can strictly satisfy path constraints while the computational efficiency and convergence of SCP are improved. Full article
(This article belongs to the Special Issue Dynamics, Guidance and Control of Aerospace Vehicles)
►▼ Show Figures

Figure 1

13 pages, 34329 KiB  
Article
Targeting Shallow Subsurface Sampling for Mars at Oxia Planum Using Fluvial Erosion–Deposition Modeling
by Vilmos Steinmann and Ákos Kereszturi
Aerospace 2024, 11(9), 784; https://doi.org/10.3390/aerospace11090784 - 23 Sep 2024
Viewed by 316
Abstract
A model-based surface fluvial erosion and deposition approach was adapted to Martian conditions to forecast the potential locations for shallow subsurface sampling by the Rosalind Franklin ExoMars rover at Oxia Planum. While remote and on-site images show only the surface visible features, former [...] Read more.
A model-based surface fluvial erosion and deposition approach was adapted to Martian conditions to forecast the potential locations for shallow subsurface sampling by the Rosalind Franklin ExoMars rover at Oxia Planum. While remote and on-site images show only the surface visible features, former fluvial-related accumulation sites might be hidden. During the fluvial activity, most accumulation-related areas are interesting with regard to clay-like sediments, which could adsorb organics effectively—such sites could be identified by modeling. By applying the SIMWE fluvial erosion/deposition model, substantial variability in accumulation and deposition-dominated areas with their specific pattern and spatial distribution could be outlined, indicating that sophisticated targeting of future sampling could use such a model-based approach. At the main valley-like feature, former water flow tracks were identified, as well as deposition-dominated locations, which are the best targets for shallow subsurface sampling. Joint evaluation of safety aspects like slope angle and loose sand dunes with scientific aspects provide the best sampling locations. Such model-based targeting is important as by using only orbital images, these locations could not be identified. Full article
(This article belongs to the Special Issue Space Sampling and Exploration Robotics)
►▼ Show Figures

Figure 1

25 pages, 55903 KiB  
Article
Control of a Circular Jet with a Disk-Type Bluff Body Using a Dielectric Barrier Discharge Plasma Actuator
by Masato Akimoto, Hiroyuki Nakagawa and Motoaki Kimura
Aerospace 2024, 11(9), 783; https://doi.org/10.3390/aerospace11090783 - 23 Sep 2024
Viewed by 368
Abstract
In this study, a disk-type bluff body was installed at the upper part of a nozzle exit, and the circular jet inside the nozzle was controlled using a dielectric barrier discharge (DBD) plasma actuator (DBD-PA). The effects of the changes in the excitation [...] Read more.
In this study, a disk-type bluff body was installed at the upper part of a nozzle exit, and the circular jet inside the nozzle was controlled using a dielectric barrier discharge (DBD) plasma actuator (DBD-PA). The effects of the changes in the excitation frequency of the jet induced by the DBD-PA on the jet diffusion were elucidated. The experiments included visualization of the jet cross-section, particle image velocimetry analysis, and velocity measurements using an I-type hot-wire anemometer. When the DBD-PA was driven at a specific burst frequency (900–1400 Hz), a lock-in phenomenon occurred, in which the frequency of vortices generated in the initial jet coincided with the burst frequency. This lock-in phenomenon suppressed the merging of vortices by generating vortices at regular intervals. When vortex merging was suppressed, the jet was less likely to be entrained into the recirculation flow generated by the bluff body, thereby increasing the downstream jet width and average flow rate. Full article
(This article belongs to the Special Issue Dielectric Barrier Discharge Plasma Actuator)
►▼ Show Figures

Figure 1

14 pages, 1907 KiB  
Article
Form-Finding of Tensegrity Basic Unit with Equal Cable Length
by Yingyu Zhao, Ani Luo and Heping Liu
Aerospace 2024, 11(9), 782; https://doi.org/10.3390/aerospace11090782 - 23 Sep 2024
Viewed by 361
Abstract
Tensegrity is a lightweight, self-stressing, and self-stabilizing structure made up of cables and bars, with each member bearing either tension or compression but not affected by shear stress. This design allows for optimal utilization of the material properties of the members. In a [...] Read more.
Tensegrity is a lightweight, self-stressing, and self-stabilizing structure made up of cables and bars, with each member bearing either tension or compression but not affected by shear stress. This design allows for optimal utilization of the material properties of the members. In a tensegrity basic unit, the bar members are of equal length, while the cable members come in three lengths: lower-end surface horizontal cable, upper-end surface horizontal cable, and stayed cable. The tensegrity basic unit with equal cable length simplifies this further by ensuring that all cables are the same length, resulting in a structure with only two member lengths, i.e., bar length and cable length, enhancing interchangeability. In order to find the form without the action of external forces, the force density coefficient ratio is introduced. By performing a force balance analysis on any node of the unit, the equilibrium equation of the structure is determined, incorporating the additional constraint of equal cable length. Two methods are employed to ascertain the force density coefficient ratio of each member in the unit: the theoretical derivation method based on the stable configuration condition of the tensegrity basic unit with equal cable length, and the method of solving the characteristic equations of the force density matrix. A program is developed to validate the form-finding method using basic units with three, four, five, and six bars as examples. The results show that the model accurately represents the physical structure, confirming the reliability of the form-finding methods. Full article
(This article belongs to the Section Astronautics & Space Science)
►▼ Show Figures

Figure 1

13 pages, 4690 KiB  
Article
Numerical Investigation on Electromagnetic Scattering Characteristics of Circulation Control Wing Surface
by Dechen Wang, Peng Cui, Wei Du and Hao Liu
Aerospace 2024, 11(9), 781; https://doi.org/10.3390/aerospace11090781 - 22 Sep 2024
Viewed by 404
Abstract
In order to study the effect of the circulation control technology on the electromagnetic scattering characteristics of the wing, a variety of low-scattering carrier models were designed based on the characteristics of the circulation control wing and the mechanical rudder surface. The radar [...] Read more.
In order to study the effect of the circulation control technology on the electromagnetic scattering characteristics of the wing, a variety of low-scattering carrier models were designed based on the characteristics of the circulation control wing and the mechanical rudder surface. The radar scattering cross sections of the different models were then calculated by using the multilayer fast multipole algorithm. A comparative analysis of different models revealed that the use of the circulation control technique can reduce the front RCS level of the wing. Furthermore, the scaling effect was found to be more significant for the HH-polarised RCS at high frequency and the VV-polarised RCS at low frequency. The air source cavity structure of the jet system will increase the front and back RCS levels of the wing. Conversely, the back RCS level can be reduced by the oblique design of the jet nozzle. In the process of achieving attitude control, the wing applying the circulation control technique can significantly reduce its own front and side RCS levels, as well as the fluctuations of RCS levels throughout manoeuvres, in comparison to the usage of mechanical rudders. The findings of the study elucidate the scattering characteristics of the circulation control wing, which can serve as a reference for the stealth performance of unconventional layout aircraft. Full article
(This article belongs to the Section Aeronautics)
►▼ Show Figures

Figure 1

16 pages, 7507 KiB  
Article
Numerical Investigation on the Thermal Characteristics of Lightweight Metal Mesh-Based Reflector Antenna with Various Knitting Conditions
by Min-Young Son, Bong-Geon Chae, Hyun-Mo Sung and Hyun-Ung Oh
Aerospace 2024, 11(9), 780; https://doi.org/10.3390/aerospace11090780 - 20 Sep 2024
Viewed by 389
Abstract
Proper prediction of the temperature variation in a metallic wire mesh for spaceborne large deployable reflector antennas is essential for evaluating the dimensional stability of the antenna under extreme on-orbit thermal environments. However, predicting the temperature of a mesh is difficult because of [...] Read more.
Proper prediction of the temperature variation in a metallic wire mesh for spaceborne large deployable reflector antennas is essential for evaluating the dimensional stability of the antenna under extreme on-orbit thermal environments. However, predicting the temperature of a mesh is difficult because of its complex yarn configuration. To analyze the thermal behavior of the spaceborne mesh antenna reflector, the thermal optical characteristics with various knitting methods of the metallic mesh were obtained experimentally in this study. Subsequently, to analyze the thermal sensitivity of the reflector based on its optical properties, an on-orbit thermal analysis of the mesh reflector was performed based on measurements of the mesh specimen. We also investigated the influence of deployable solar panels on the thermal gradient of the reflector. Full article
(This article belongs to the Section Astronautics & Space Science)
►▼ Show Figures

Figure 1

18 pages, 7525 KiB  
Article
Fixed-Time Anti-Saturation Tracking Control for Agile Missiles with Multiple Actuators
by Jiaxun Li and Jianqiao Yu
Aerospace 2024, 11(9), 779; https://doi.org/10.3390/aerospace11090779 - 20 Sep 2024
Viewed by 281
Abstract
This paper investigates the fixed-time tracking control problem for agile missiles with multiple heterogeneous actuators in the presence of saturation constraints and external disturbances. To reduce the turning radius and promote maneuvering envelope, a novel combination scheme for blended actuators is introduced in [...] Read more.
This paper investigates the fixed-time tracking control problem for agile missiles with multiple heterogeneous actuators in the presence of saturation constraints and external disturbances. To reduce the turning radius and promote maneuvering envelope, a novel combination scheme for blended actuators is introduced in this paper, consisting of a flexible mechanism control system (FCS), reaction-jet control system (RCS), and aerodynamic control. Based on the proposed nonsingular terminal sliding mode surface, a fixed-time anti-saturation controller with an auxiliary system is presented first to ensure global fixed-time stability and to compensate for the adverse effects of input saturation. Subsequently, a fixed-time disturbance observer is constructed to estimate uncertainties and lumped disturbances, and to address the chattering problem. To assign the total virtual control command to different actuators, a control allocation based on dynamic programming considering actuator dynamics is established. Finally, detailed numerical simulations and comparisons are provided to verify the effectiveness and superiority of the proposed control scheme. Full article
(This article belongs to the Section Aeronautics)
►▼ Show Figures

Figure 1

24 pages, 10209 KiB  
Article
An Attitude Determination and Sliding Mode Control Method for Agile Whiskbroom Scanning Maneuvers of Microsatellites
by Xinyan Yang, Zhaoming Li, Lei Li and Yurong Liao
Aerospace 2024, 11(9), 778; https://doi.org/10.3390/aerospace11090778 - 20 Sep 2024
Viewed by 322
Abstract
Microsatellites have significantly impacted space missions by offering advanced technology at a low cost. This study introduces an attitude determination and control algorithm for agile whiskbroom scanning maneuvers in microsatellites to enable wide-swath target detection for low-Earth-orbit microsatellites. First, an angular velocity calculation [...] Read more.
Microsatellites have significantly impacted space missions by offering advanced technology at a low cost. This study introduces an attitude determination and control algorithm for agile whiskbroom scanning maneuvers in microsatellites to enable wide-swath target detection for low-Earth-orbit microsatellites. First, an angular velocity calculation model for agile whiskbroom scanning is established. A methodology has been developed to calculate the maximum available time for whiskbroom scanning from one side of the sub-satellite point to the other while ensuring the seamless joining of adjacent strips to avoid missing targets. Thereafter, a gyro- and magnetometer-based cubature Kalman filter is put forward for microsatellite attitude estimation. Furthermore, for attitude control, a hybrid manipulation law capable of preventing singularities and escaping singularity surfaces is designed to ensure high-precision torque output from the control moment gyroscopes (CMGs) used as actuators. The benefits of the linear sliding mode and fast terminal sliding mode are integrated, and a non-singular sliding surface is designed, yielding a non-singular fast terminal sliding mode attitude control algorithm for tracking the desired trajectory. This algorithm effectively suppresses chattering and enhances dynamic performance without using a switching term. A semi-physical simulation experiment system is also conducted on the ground to validate the proposed algorithm’s high-precision tracking of the planned whiskbroom scanning path. The experimental results demonstrate an attitude angle control accuracy of 4 × 10−2 degrees and angular velocity control accuracy of 0.01°/s and thus the effectiveness of the proposed algorithm. Full article
(This article belongs to the Section Aeronautics)
►▼ Show Figures

Figure 1

14 pages, 11754 KiB  
Article
Drag Reduction on the Basis of the Area Rule of the Small-Scale Supersonic Flight Experiment Vehicle Being Developed at Muroran Institute of Technology (Second Report)
by Kazuhide Mizobata, Taichi Mio and Katsuya Miyamoto
Aerospace 2024, 11(9), 777; https://doi.org/10.3390/aerospace11090777 - 20 Sep 2024
Viewed by 334
Abstract
A small-scale supersonic flight experiment vehicle named OWASHI is being developed at Muroran Institute of Technology as a flying testbed for verification of innovative technologies for high-speed atmospheric flights. Drag reduction in the transonic and supersonic regimes is quite crucial for attainability of [...] Read more.
A small-scale supersonic flight experiment vehicle named OWASHI is being developed at Muroran Institute of Technology as a flying testbed for verification of innovative technologies for high-speed atmospheric flights. Drag reduction in the transonic and supersonic regimes is quite crucial for attainability of its supersonic flights. This study aims to obtain configuration modification for transonic drag reduction on the basis of the so-called area rule. In order to prevent accumulation of compression waves, various profiles of the bottleneck and the bulge are designed by using arcs with constant and large radii and spline curves approximating them. Their effects are assessed through CFD analysis, wind tunnel tests, and wave drag analysis. As a result, an area-rule-based configuration with a sharpened conical nose and a large-radius bottleneck achieves significant drag reduction in a transonic Mach range, as well as 57-count (57 × 10−4) reduction at the design Mach number of 1.1. However, the drag reduction effects of bulges are small and apparent only in a narrow Mach range. On the other hand, in the practical vehicle configuration, rearward fuselage extension shows a large amount of drag reduction, whereas the addition of an intake cancels the drag reduction effects of area-rule-based configurations. Full article
(This article belongs to the Special Issue Research and Development of Supersonic Aircraft)
►▼ Show Figures

Figure 1

15 pages, 9259 KiB  
Article
Experimental Investigation of Pulse Detonation Combustion Characteristics via Atomizer Geometry
by Yoojin Oh, Myeung Hwan Choi and Sungwoo Park
Aerospace 2024, 11(9), 776; https://doi.org/10.3390/aerospace11090776 - 20 Sep 2024
Viewed by 700
Abstract
Recent studies have increasingly focused on integrating detonation processes into engine technologies, advancing beyond the fundamental research phase of detonation research. The present study investigates the detonability and combustion characteristics of liquid fuels, specifically ethanol, with an emphasis on the effects of atomization [...] Read more.
Recent studies have increasingly focused on integrating detonation processes into engine technologies, advancing beyond the fundamental research phase of detonation research. The present study investigates the detonability and combustion characteristics of liquid fuels, specifically ethanol, with an emphasis on the effects of atomization properties facilitated by different atomizer designs to implement pulse detonation combustion engines. Oxygen was used as the oxidizer. We employed internal injectors (I45, I90, IB4) and atomizer venturis (VA, VB, VR) to examine how variations in liquid fuel atomization and atomizer configurations influence detonation. The occurrence of detonation was assessed using predicted Sauter mean diameters (SMDs) and exit velocities for different atomizer setups. Additionally, we evaluated the effects of nitrogen dilution at concentrations of 0%, 25%, and 50% on velocity variations and changes in detonation characteristics. The findings suggest that while higher exit velocities decrease SMD, facilitating detonation, excessively high velocities hinder detonation initiation. Conversely, lower exit velocities emphasize the role of SMD in initiating detonation. However, the introduction of nitrogen, which reduces the SMD, was found to decrease reactivity and impede detonation. Full article
(This article belongs to the Special Issue Supersonic Combustion in Scramjet Engine)
►▼ Show Figures

Figure 1

20 pages, 9655 KiB  
Article
Dynamic RCS Modeling and Aspect Angle Analysis for Highly Maneuverable UAVs
by Kerem Sen, Sinan Aksimsek and Ali Kara
Aerospace 2024, 11(9), 775; https://doi.org/10.3390/aerospace11090775 - 20 Sep 2024
Viewed by 400
Abstract
Unmanned aerial vehicles (UAVs) are increasingly significant in modern warfare due to their versatility and capacity to perform high-risk missions without risking human lives. Beyond surveillance and reconnaissance, UAVs with jet propulsion and engagement capabilities are set to play roles similar to conventional [...] Read more.
Unmanned aerial vehicles (UAVs) are increasingly significant in modern warfare due to their versatility and capacity to perform high-risk missions without risking human lives. Beyond surveillance and reconnaissance, UAVs with jet propulsion and engagement capabilities are set to play roles similar to conventional jets. In various scenarios, military aircraft, drones, and UAVs face multiple threats while ground radar systems continuously monitor their positions. The interaction between these aerial platforms and radars causes temporal fluctuations in scattered echo power due to changes in aspect angle, impacting radar tracking accuracy. This study utilizes the potential radar cross-section (RCS) dynamics of an aircraft throughout its flight, using ground radar as a reference. Key factors influencing RCS include time, frequency, polarization, incident angle, physical geometry, and surface material, with a focus on the complex scattering geometry of the aircraft. The research evaluates the monostatic RCS case and examines the impact of attitude variations on RCS scintillation. Here, we present dynamic RCS modeling by examining the influence of flight dynamics on the RCS fluctuations of a UAV-sized aircraft. Dynamic RCS modeling is essential in creating a robust framework for operational analysis and developing effective countermeasure strategies, such as advanced active decoys. Especially in the cognitive radar concept, aircraft will desperately need more dynamic and adaptive active decoys. A methodology for calculating target aspect angles is proposed, using the aircraft’s attitude and spherical position relative to the radar system. A realistic 6DoF (6 degrees of freedom) flight data time series generated by a commercial flight simulator is used to derive aircraft-to-radar aspect angles. By estimating aspect angles for a simulated complex flight trajectory, RCS scintillation throughout the flight is characterized. The study highlights the importance of maneuver parameters such as roll and pitch on the RCS measured at the radar by comparing datasets with and without these parameters. Significant differences were found, with a 32.44% difference in RCS data between full maneuver and no roll and pitch changes. Finally, proposed future research directions and insights are discussed. Full article
(This article belongs to the Section Aeronautics)
►▼ Show Figures

Figure 1

21 pages, 6862 KiB  
Article
Research on Self-Learning Control Method of Reusable Launch Vehicle Based on Neural Network Architecture Search
by Shuai Xue, Zhaolei Wang, Hongyang Bai, Chunmei Yu and Zian Li
Aerospace 2024, 11(9), 774; https://doi.org/10.3390/aerospace11090774 - 20 Sep 2024
Viewed by 815
Abstract
Reusable launch vehicles need to face complex and diverse environments during flight. The design of rocket recovery control law based on traditional deep reinforcement learning (DRL) makes it difficult to obtain a set of network architectures that can adapt to multiple scenarios and [...] Read more.
Reusable launch vehicles need to face complex and diverse environments during flight. The design of rocket recovery control law based on traditional deep reinforcement learning (DRL) makes it difficult to obtain a set of network architectures that can adapt to multiple scenarios and multi-parameter uncertainties, and the performance of deep reinforcement learning algorithm depends on manual trial and error of hyperparameters. To solve this problem, this paper proposes a self-learning control method for launch vehicle recovery based on neural architecture search (NAS), which decouples deep network structure search and reinforcement learning hyperparameter optimization. First, using network architecture search technology based on a multi-objective hybrid particle swarm optimization algorithm, the proximal policy optimization algorithm of deep network architecture is automatically designed, and the search space is lightweight design in the process. Secondly, in order to further improve the landing accuracy of the launch vehicle, the Bayesian optimization (BO) method is used to automatically optimize the hyperparameters of reinforcement learning, and the control law of the landing phase in the recovery process of the launch vehicle is obtained through training. Finally, the algorithm is transplanted to the rocket intelligent learning embedded platform for comparative testing to verify its online deployment capability. The simulation results show that the proposed method can satisfy the landing accuracy of the launch vehicle recovery mission, and the control effect is basically the same as the landing accuracy of the trained rocket model under the untrained condition of model parameter deviation and wind field interference, which verifies the generalization of the proposed method. Full article
(This article belongs to the Special Issue Advanced GNC Solutions for VTOL Systems)
►▼ Show Figures

Figure 1

14 pages, 8735 KiB  
Article
Knowledge Graph Construction Method for Commercial Aircraft Fault Diagnosis Based on Logic Diagram Model
by Huanchun Peng and Weidong Yang
Aerospace 2024, 11(9), 773; https://doi.org/10.3390/aerospace11090773 - 20 Sep 2024
Viewed by 408
Abstract
Commercial aircraft fault diagnosis is an important means to ensure the reliability and safety of commercial aircraft. Traditional knowledge-driven and data-driven fault diagnosis methods lack interpretability in engineering mechanisms, making them difficult to promote and apply. To address the issue of lack of [...] Read more.
Commercial aircraft fault diagnosis is an important means to ensure the reliability and safety of commercial aircraft. Traditional knowledge-driven and data-driven fault diagnosis methods lack interpretability in engineering mechanisms, making them difficult to promote and apply. To address the issue of lack of interpretability, this paper conducts a fault knowledge graph for commercial aircraft fault diagnosis, using the fault logic in the logic diagram to increase the interpretability of diagnostic work. Firstly, to avoid the inefficiency of logic diagram applications, an executable logic diagram model is established, which can perform mathematical analysis and achieve fault diagnosis and localization using operational data as input. Then, the logic diagram is sorted out to obtain the hidden fault knowledge in the logic diagram, which is used to construct a fault knowledge graph to help achieve cause localization and rapid troubleshooting. The methods proposed in this paper are all validated through case studies of abnormal low-pressure faults in domestic commercial aircraft hydraulic systems. The results show that the logic diagram model can perform model simulation and fault diagnosis based on operational data, and the fault knowledge graph can quickly locate abnormal monitoring parameters and guide troubleshooting work based on existing information. Full article
(This article belongs to the Special Issue State Monitoring and Health Management of Complex Equipment (2nd Edition))
►▼ Show Figures

Figure 1

21 pages, 6983 KiB  
Article
An Efficient Drogue Detection Algorithm for Unmanned Aerial Vehicle Autonomous Refueling Docking Phase
by Mingyuan Zhai, Shiming Hu, Dong Xiao, Hanquan Zhang, Mengyuan Xu and Yachun Mao
Aerospace 2024, 11(9), 772; https://doi.org/10.3390/aerospace11090772 - 19 Sep 2024
Viewed by 431
Abstract
Autonomous aerial refueling technology can significantly extend the operational endurance of unmanned aerial vehicles (UAVs), enhancing their ability to perform long-duration missions efficiently. In this paper, we address the identification of refueling drogues in the close docking phase of autonomous aerial refueling. We [...] Read more.
Autonomous aerial refueling technology can significantly extend the operational endurance of unmanned aerial vehicles (UAVs), enhancing their ability to perform long-duration missions efficiently. In this paper, we address the identification of refueling drogues in the close docking phase of autonomous aerial refueling. We propose a high-precision real-time drogue recognition network called DREP-Net. The backbone of this network employs the DGST module for efficient feature extraction and improved representation of multi-scale information. For occlusion and complex background problems, we designed the RGConv module, which combines the re-parameterization module with the GhostNet idea to improve the detection of an occluded drogue. Meanwhile, we introduced the efficient local attention mechanism into the neck network to enhance the overall attention to the target region. Then, we designed Phead, a lightweight detection head that combines the advantages of decoupling and coupling heads to improve the detection speed. Finally, we compared our network with mainstream algorithms on a real drogue dataset, and the results show that DREP-Net has 2.7% higher mean average precision (mAP) compared to the YOLOv8n model, and the detection speed is improved by 31.4 frames per second. Full article
(This article belongs to the Section Aeronautics)
►▼ Show Figures

Figure 1

29 pages, 8518 KiB  
Article
Differential Game-Based Cooperative Interception Guidance Law with Collision Avoidance
by Xueping Zhu, Xinxing Wang, Yue Li and Jun Yang
Aerospace 2024, 11(9), 771; https://doi.org/10.3390/aerospace11090771 - 19 Sep 2024
Viewed by 491
Abstract
To deal with the offense-defense confrontation problem of multi-missile cooperative intercepting a high-speed and large-maneuvering target, a differential game-based cooperative interception guidance law with collision avoidance is proposed, in which the offense-defense parties are the incoming target and the interceptors, respectively. Given that [...] Read more.
To deal with the offense-defense confrontation problem of multi-missile cooperative intercepting a high-speed and large-maneuvering target, a differential game-based cooperative interception guidance law with collision avoidance is proposed, in which the offense-defense parties are the incoming target and the interceptors, respectively. Given that both offense-defense parties have uniformly decreasing speeds and first-order biproper dynamics, the relative motion models among the offense-defense parties are established, and the performance indices of the target and the interceptors are proposed. After that, the cooperative interception guidance law with collision avoidance is derived based on a differential game. The guidance law considers the effects of speed variations and rudder layouts on the motions of both offense-defense parties, ensuring excellent algorithmic real-time property and interception accuracy while introducing inter-missile collision avoidance constraints. In addition, the parameters of the target performance index are set according to the target acceleration information estimated by the interceptors. The simulation results verify the effectiveness of the guidance law designed in this paper, under various three-to-one scenarios, the interceptors could achieve collision-free interceptions with the interception accuracy of less than 5 m and the interception time difference of less than 0.1 s. Full article
(This article belongs to the Section Aeronautics)
►▼ Show Figures

Figure 1

24 pages, 12996 KiB  
Article
An Interval Neural Network Method for Identifying Static Concentrated Loads in a Population of Structures
by Yang Cao, Xiaojun Wang, Yi Wang, Lianming Xu and Yifei Wang
Aerospace 2024, 11(9), 770; https://doi.org/10.3390/aerospace11090770 - 19 Sep 2024
Viewed by 463
Abstract
During the design and validation of structural engineering, the focus is on a population of similar structures, not just one. These structures face uncertainties from external environments and internal configurations, causing variability in responses under the same load. Identifying the real load from [...] Read more.
During the design and validation of structural engineering, the focus is on a population of similar structures, not just one. These structures face uncertainties from external environments and internal configurations, causing variability in responses under the same load. Identifying the real load from these dispersed responses is a significant challenge. This paper proposes an interval neural network (INN) method for identifying static concentrated loads, where the network parameters are internalized to create a new INN architecture. Additionally, the paper introduces an improved interval prediction quality loss function indicator named coverage and mean square criterion (CMSC), which balances the interval coverage rate and interval width of the identified load, ensuring that the median of the recognition interval is closer to the real load. The efficiency of the proposed method is assessed through three examples and validated through comparative research against other loss functions. Our research findings indicate that this approach enhances the interval accuracy, robustness, and generalization of load identification. This improvement is evident even when faced with challenges such as limited training data and significant noise interference. Full article
(This article belongs to the Special Issue Aircraft Structural Health Monitoring and Digital Twin)
►▼ Show Figures

Figure 1

25 pages, 14059 KiB  
Article
Aerodynamic Analysis and Simulation for a Z-Shaped Folding Wing UAV
by Jin-Gang Wang and Xiang-Ying Guo
Aerospace 2024, 11(9), 769; https://doi.org/10.3390/aerospace11090769 - 19 Sep 2024
Viewed by 712
Abstract
The potential of folding wing unmanned aerial vehicles (UAVs) in enhancing the adaptability of complex missions is substantial. Analyzing the aerodynamic characteristics of these UAVs is vital for optimizing the design of their folding wing configuration and airfoil shape. In this study, a [...] Read more.
The potential of folding wing unmanned aerial vehicles (UAVs) in enhancing the adaptability of complex missions is substantial. Analyzing the aerodynamic characteristics of these UAVs is vital for optimizing the design of their folding wing configuration and airfoil shape. In this study, a model of a Z-shaped folding wing UAV was established with the objective of enhancing UAV maneuverability. An integrated vortex lattice method (VLM) was employed to analyze the aerodynamic characteristics of the Z-shaped folding wing and numerical simulations were utilized to validate the obtained results, which prove the effectiveness of the integrated VLM in studying aerodynamic characteristics at a high angle of attack of the Z-shaped folding wing UAV. This is a new way to reduce computation time while maintaining accuracy to calculate such complex folding structures in high fidelity. Furthermore, the Z-shaped folding wing configuration demonstrates enhanced maneuverability at high angles of attack, and a Simulink flight simulation model based on the aerodynamic coefficients of the Z-shaped folding wing verifies this property. This analysis can properly predict the post-stall characteristics for the Z-shaped folding wing UAV to ensure the safety of the vehicle during flight. Full article
(This article belongs to the Section Aeronautics)
►▼ Show Figures

Figure 1

19 pages, 5364 KiB  
Article
Rapid SLAM Method for Star Surface Rover in Unstructured Space Environments
by Zhengpeng Zhang, Yan Cheng, Lijing Bu and Jiayan Ye
Aerospace 2024, 11(9), 768; https://doi.org/10.3390/aerospace11090768 - 19 Sep 2024
Viewed by 464
Abstract
The space environment is characterized by unstructured features, sparsity, and poor lighting conditions. The difficulty in extracting features from the visual frontend of traditional SLAM methods results in poor localization and time-consuming issues. This paper proposes a rapid and real-time localization and mapping [...] Read more.
The space environment is characterized by unstructured features, sparsity, and poor lighting conditions. The difficulty in extracting features from the visual frontend of traditional SLAM methods results in poor localization and time-consuming issues. This paper proposes a rapid and real-time localization and mapping method for star chart surveyors in unstructured space environments. Improved localization is achieved using multiple sensor fusion to sense the space environment. We replaced the traditional feature extraction module with an enhanced SuperPoint feature extraction network to tackle the challenge of challenging feature extraction in unstructured space environments. By dynamically adjusting detection thresholds, we achieved uniform detection and description of image keypoints, ultimately resulting in robust and accurate feature association information. Furthermore, we minimized redundant information to achieve precise positioning with high efficiency and low power consumption. We established a star surface rover simulation system and created simulated environments resembling Mars and the lunar surface. Compared to the LVI-SAM system, our method achieved a 20% improvement in localization accuracy for lunar scenarios. In Mars scenarios, our method achieved a positioning accuracy of 0.716 m and reduced runtime by 18.682 s for the same tasks. Our approach exhibits higher localization accuracy and lower power consumption in unstructured space environments. Full article
(This article belongs to the Section Astronautics & Space Science)
►▼ Show Figures

Figure 1

16 pages, 3632 KiB  
Article
Numerical Study of High-g Combustion Characteristics in a Channel with Backward-Facing Steps
by Zhen Gong and Hao Tang
Aerospace 2024, 11(9), 767; https://doi.org/10.3390/aerospace11090767 - 19 Sep 2024
Viewed by 362
Abstract
High gravity (high-g) combustion can significantly increase flame propagation speed, thereby potentially shortening the axial length of aero-engines and increasing their thrust-to-weight ratio. In this study, we utilized the large eddy simulation model to investigate the combustion characteristics and flame morphology evolution of [...] Read more.
High gravity (high-g) combustion can significantly increase flame propagation speed, thereby potentially shortening the axial length of aero-engines and increasing their thrust-to-weight ratio. In this study, we utilized the large eddy simulation model to investigate the combustion characteristics and flame morphology evolution of premixed propane–air flames in a channel with a backward-facing step. The study reveals that both the increase in centrifugal force and flow velocity can enhance pressure fluctuations during combustion and increase the turbulence intensity. The presence of centrifugal force promotes the occurrence of Rayleigh–Taylor instability (RTI) between hot and cold fluids. The combined effects of RTI and Kelvin–Helmholtz instability (KHI) enhance the disturbance between hot and cold fluids, shorten the fuel combustion time, and intensify the dissipation of large-scale vortices. The increase in fluid flow velocity can raise the flame front’s hydrodynamic stretch rate, thereby enhancing the turbulence level during combustion to a certain extent and increasing the fuel consumption rate. When a strong centrifugal force is applied, the global flame propagation speed can be more than doubled. Within a certain range, the increase in high-g field strength can enhance the intensity of RTI and accelerate the transition of RTI to the nonlinear stage. Full article
(This article belongs to the Topic Theoretical, Numerical and Experimental Studies on Clean Energy and Combustion)
►▼ Show Figures

Figure 1

16 pages, 7966 KiB  
Article
A Modified Robust Homotopic Method for the Low-Thrust Fuel-Optimal Orbital Control Problem
by Yuyang Huang, Lifei Zhang and Xianjian Zhang
Aerospace 2024, 11(9), 766; https://doi.org/10.3390/aerospace11090766 - 18 Sep 2024
Viewed by 399
Abstract
This study focuses on improving the application of the quadratic penalty smoothing technique for solving the fuel-optimal problem of low-thrust trajectory. Some practical techniques, including the Particle Swarm Optimization algorithm (PSO), the co-state normalization technique, and the single shooting method, are employed. These [...] Read more.
This study focuses on improving the application of the quadratic penalty smoothing technique for solving the fuel-optimal problem of low-thrust trajectory. Some practical techniques, including the Particle Swarm Optimization algorithm (PSO), the co-state normalization technique, and the single shooting method, are employed. These approaches can enhance convergence to the globally optimal solution. The application of PSO is improved through the introduction of the diversity termination term. Furthermore, a new parameter, the maximum thrust to initial mass ratio (CTm), is introduced and analyzed. The relationships among Lagrange multipliers for different CTm in the energy-optimal auxiliary problem are also derived. These relationships can be used in scenarios with high CTm to reduce the variable search space, leading to a significant decrease in computation time. Nonetheless, few researchers have proposed a well-defined strategy for the homotopic process. We propose a robust iteration strategy, involving the determination of the maximum step size and the distinction of sub-optimal solutions. This iterative strategy could ensure a robust convergence toward the optimal solutions. An interplanetary rendezvous example is provided to demonstrate the effectiveness of the presented techniques and strategy. Full article
(This article belongs to the Section Astronautics & Space Science)
►▼ Show Figures

Figure 1

25 pages, 13851 KiB  
Article
The Generation Mechanism of the Side Force and Yawing Moment of a Rotating Missile with Wrap-Around Fins
by Zheng Yong, Juanmian Lei and Jintao Yin
Aerospace 2024, 11(9), 765; https://doi.org/10.3390/aerospace11090765 - 18 Sep 2024
Viewed by 326
Abstract
The rotation of a missile generates a side force perpendicular to the plane containing the attack angle and produces a yawing moment that tilts the body out of the plane, significantly affecting the flight stability of rotating missiles. The non-planar asymmetry of the [...] Read more.
The rotation of a missile generates a side force perpendicular to the plane containing the attack angle and produces a yawing moment that tilts the body out of the plane, significantly affecting the flight stability of rotating missiles. The non-planar asymmetry of the wrap-around-fin rotating missile determines its more complex rotational effects. This study utilizes the dual time-step method to solve the unsteady Navier–Stokes equations, investigating the characteristics of the side force and yawing moment of the wrap-around-fin rotating missile under supersonic conditions and uncovering the mechanism behind the generation of the side force and yawing moment. The results reveal that the side force and yawing moment of the wrap-around-fin missile are composed of static values and induced values from rotation. The static side force and yawing moment of the wrap-around-fin missile are not zero, while those of the flat-plate-fin missile are zero. This difference is primarily caused by the non-axisymmetric nature of the wrap-around fin, resulting in the static side force and yawing moment of the wrap-around-fin missile being 40% greater than those of the flat-plate-fin missile. The rotation of the missile increases the effective angle of attack on the convex surface of the fin and decreases it on the concave surface, leading to an imbalance in the pressure changes on the windward and leeward sides. This is the main reason for the generation of the induced side force and yawing moment due to rotation. The induced values from rotation vary linearly with the rotation rate, and their magnitudes can be several times those of the static values. Full article
(This article belongs to the Section Aeronautics)
►▼ Show Figures

Figure 1

17 pages, 6120 KiB  
Article
Virtual Dynamic Vibration Absorber Trap Fusion Active Vibration Suppression Algorithm Based on Inertial Actuators for Large Flexible Space Trusses
by Chao Qin, Anpeng Xu, Shuai He, Chunyang Han and Zhenbang Xu
Aerospace 2024, 11(9), 764; https://doi.org/10.3390/aerospace11090764 - 18 Sep 2024
Viewed by 447
Abstract
This paper presents a virtual dynamic vibration absorber (DVA) trap fusion active vibration suppression algorithm based on inertial actuators as a solution to the harmonic vibration control problem of large flexible space trusses. Firstly, the mechanism of the inertial actuator is analyzed, and [...] Read more.
This paper presents a virtual dynamic vibration absorber (DVA) trap fusion active vibration suppression algorithm based on inertial actuators as a solution to the harmonic vibration control problem of large flexible space trusses. Firstly, the mechanism of the inertial actuator is analyzed, and the relationship between the bandwidth of the algorithm and the intrinsic frequency of the inertial actuator is derived. Secondly, a dynamic model of the space truss is constructed. Subsequently, an analysis is conducted to determine the manner in which the virtual DVA exerts influence on the system’s dynamic characteristics. Based on this analysis, a virtual DVA trap fusion active vibration suppression algorithm is designed. Finally, the efficacy of the proposed algorithm in suppressing vibration is demonstrated through experimentation. The algorithm was demonstrated to be effective in suppressing both single-frequency harmonic vibration and multi-frequency harmonic vibration under the working conditions of single-degree-of-freedom and multi-degree-of-freedom of a flexible truss. The vibration suppression efficiency was found to be greater than 60%. It is therefore evident that the proposed algorithm has the potential to be applied to the vibration suppression of telescopes assembled in orbit in the future. Full article
(This article belongs to the Section Astronautics & Space Science)
►▼ Show Figures

Figure 1

19 pages, 3517 KiB  
Article
Flight Schedule Optimization Considering Fine-Grained Configuration of Slot Coordination Parameters
by Jingyi Yu, Minghua Hu, Zheng Zhao and Bin Jiang
Aerospace 2024, 11(9), 763; https://doi.org/10.3390/aerospace11090763 - 17 Sep 2024
Viewed by 437
Abstract
In response to the rapid growth of air passenger and cargo transportation services and the sharp increase in congestion at various airports, it is necessary to optimize the allocation of flight schedules. On the basis of reducing the total airport delay time and [...] Read more.
In response to the rapid growth of air passenger and cargo transportation services and the sharp increase in congestion at various airports, it is necessary to optimize the allocation of flight schedules. On the basis of reducing the total airport delay time and ensuring the total deviation of flight schedules applied by airlines, it is necessary to consider finely configuring flight schedules with slot coordination parameters, introducing a 5 min slot coordination parameter, and optimizing airport flight schedules in different time periods. This article considers factors such as flight schedule uniqueness, corridor flow restrictions, and time adjustment range limitations to establish a three-objective flight-schedule refinement configuration model, which is solved using the NSGA-II algorithm based on the entropy weight method. Taking Beijing Capital International Airport as an example, the optimized results show that the total flight delay was reduced from 4130 min to 1142 min, and the original delay of 389 flights was reduced to 283 flights. Therefore, flight schedule optimization considering the fine-grained configuration of slot coordination parameters can effectively reduce airport delays, fully utilize time resources, and reduce waste of time slot resources. Full article
(This article belongs to the Section Air Traffic and Transportation)
►▼ Show Figures

Figure 1

16 pages, 859 KiB  
Article
Consensus SE(3)-Constrained Extended Kalman Filter for Close Proximity Orbital Relative Pose Estimation
by S. Mathavaraj and Eric A. Butcher
Aerospace 2024, 11(9), 762; https://doi.org/10.3390/aerospace11090762 - 17 Sep 2024
Viewed by 376
Abstract
In this paper, a recently proposed SE(3)-constrained extended Kalman filter (EKF) is extended to formulate a strategy for relative orbit estimation in a space-based sensor network. The resulting consensus SE(3)-constrained EKF utilizes space-based [...] Read more.
In this paper, a recently proposed SE(3)-constrained extended Kalman filter (EKF) is extended to formulate a strategy for relative orbit estimation in a space-based sensor network. The resulting consensus SE(3)-constrained EKF utilizes space-based sensor fusion and is applied to the problem of spacecraft proximity operations and formation flying. The proposed filter allows for the state (i.e., pose and velocities) estimation of the deputy satellite while accounting for measurement error statistics using the rotation matrix to represent attitude. Via a comparison with a conventional filter in the literature, it is shown that the use of the proposed consensus SE(3)-constrained EKF can improve the convergence performance of the existing filter for satellite formation flying. Moreover, the benefits of faster convergence and consensus speed by using communication networks with more connections are illustrated to show the significance of the proposed sensor fusion strategy in spacecraft proximity operations. Full article
(This article belongs to the Special Issue Guidance, Navigation and Control Algorithms for Satellite Formation Flying)
►▼ Show Figures

Figure 1

19 pages, 5665 KiB  
Article
Multi-Objective Optimization of the Pre-Swirl System in a Twin-Web Turbine Disc Cavity
by Yueteng Guo, Suofang Wang and Wenjie Shen
Aerospace 2024, 11(9), 761; https://doi.org/10.3390/aerospace11090761 - 17 Sep 2024
Viewed by 418
Abstract
Enhancing thermal efficiency and minimizing weight are prevailing issues in aero engines. Owing to its hollow structure, the twin-web turbine disc exhibits remarkable weight reduction properties, while its enhanced cooling constitutes a novel challenge. In this study, a twin-web turbine disc cavity system [...] Read more.
Enhancing thermal efficiency and minimizing weight are prevailing issues in aero engines. Owing to its hollow structure, the twin-web turbine disc exhibits remarkable weight reduction properties, while its enhanced cooling constitutes a novel challenge. In this study, a twin-web turbine disc cavity system is numerically investigated. To enhance the cooling effect and minimize pressure loss, a multi-objective genetic algorithm and Kriging surrogate model are employed to optimize the radial height of the pre-swirl nozzle and receiver hole in the disc cavity system. The results indicate that the overall performance of Opt-3, derived from the Technique for Order Preference by Similarity to the Ideal Solution method within the Pareto frontier, is superior. This configuration achieves a uniform low distribution of rotor temperatures while maintaining moderate pressure losses. Notably, the maximum temperature is reduced by 21.1 K compared to the basic model, with pressure losses remaining largely unchanged. Additionally, an increase in the flow ratio leads to a reduction in both the maximum temperature and average temperature of the back web while simultaneously increasing the temperature of the front web and augmenting pressure losses. However, it is important to note that the degree of variation in these parameters diminishes with increasing flow ratios. Full article
(This article belongs to the Special Issue Advances in Thermal Fluid, Dynamics and Control)
►▼ Show Figures

Figure 1

20 pages, 22717 KiB  
Article
Görtler Vortices in the Shock Wave/Boundary-Layer Interaction Induced by Curved Swept Compression Ramp
by Liang Chen, Yue Zhang, Juanjuan Wang, Hongchao Xue, Yixuan Xu, Ziyun Wang and Huijun Tan
Aerospace 2024, 11(9), 760; https://doi.org/10.3390/aerospace11090760 - 17 Sep 2024
Viewed by 406
Abstract
This study builds on previous research into the basic flow structure of a separated curved swept compression ramp shock wave/turbulence boundary layer interaction (CSCR-SWBLI) at the leading edge of an inward-turning inlet. We employ the ice-cluster-based planar laser scattering (IC-PLS) technique, which integrates [...] Read more.
This study builds on previous research into the basic flow structure of a separated curved swept compression ramp shock wave/turbulence boundary layer interaction (CSCR-SWBLI) at the leading edge of an inward-turning inlet. We employ the ice-cluster-based planar laser scattering (IC-PLS) technique, which integrates multiple observation directions and positions, to experimentally investigate a physical model with typical parameter states at a freestream Mach number of 2.85. This study captures the fine structure of some sections of the flow field and identifies the presence of Görtler vortices (GVs) in the CSCR-SWBLI. It is observed that due to the characteristics of variable sweep angle, variable intensity interaction, and centrifugal force, GVs exhibit strong three-dimensional characteristics in the curved section. Additionally, their position is not fixed in the spanwise direction, demonstrating strong intermittence. As the vortices develop downstream, their size gradually increases while the number decreases, always corresponding to the local boundary layer thickness. When considering the effects of coupling of bilateral walls, it is noted that the main difference between double-sided coupling and single-sided uncoupling conditions is the presence of a large-scale vortex in the central plane and an odd number of GVs in the double-sided model. Finally, the existence of GVs in CSCR-SWBLI is verified through the classical determine criteria Görtler number (GT) and Floryan number (F) decision basis. Full article
(This article belongs to the Special Issue Vortex Flow Phenomena and Physics of Aerospace Engineering Applications)
►▼ Show Figures

Figure 1

14 pages, 34977 KiB  
Article
Experimental Study on Submerged Nozzle Damping Characteristics of Solid Rocket Motor
by Xinyan Li, Zhenglong Chen, Xiaosi Li, Bo Xu and Shengnan Wang
Aerospace 2024, 11(9), 759; https://doi.org/10.3390/aerospace11090759 - 16 Sep 2024
Viewed by 709
Abstract
Acoustic instabilities in solid rocket motors (SRMs) can lead to severe performance deterioration and structural damage. Nozzle damping accounts for the main acoustic dissipation source, and it is highly dependent on geometric parameters and operating conditions. This study experimentally investigated the acoustic damping [...] Read more.
Acoustic instabilities in solid rocket motors (SRMs) can lead to severe performance deterioration and structural damage. Nozzle damping accounts for the main acoustic dissipation source, and it is highly dependent on geometric parameters and operating conditions. This study experimentally investigated the acoustic damping characteristics of submerged nozzles in SRMs, focusing on the effects of submerged cavity dimensions, nozzle convergent angle, throat-to-port area ratio, and mean pressure variations on the longitudinal instability. The steady-state wave decay method was used to quantify the acoustic damping, and a designed rotary valve system was employed to introduce periodic pressure oscillations in the high-pressure combustion chamber. The results revealed that a larger submerged cavity would reduce the nozzle damping efficiency, with the elimination of the submerged cavity enhancing the nozzle decay coefficient magnitude by 41.9%. Furthermore, increasing the nozzle convergent angle was found to amplify acoustic wave reflection, thereby diminishing damping performance. A linear inverse relationship was observed between the throat-to-port area ratio and the decay coefficient, with a 125% increase in the ratio resulting in a 24.3% reduction in the decay coefficient. Interestingly, despite the formation of complex vortices in the submerged cavity, the mean pressure variation presented negligible effects on acoustic damping characteristics, and its damping performance is similar to a simple nozzle without a cavity. These findings provide valuable experimental data for predicting the stability of a solid rocket motor with a submerged nozzle and offer insights into the optimization of submerged nozzle designs for higher acoustic damping in SRMs. Full article
(This article belongs to the Section Aeronautics)
►▼ Show Figures

Figure 1

52 pages, 5903 KiB  
Article
Preliminary Design of Satellite Systems through the Integration of Model-Based System Engineering and Agile Methodologies: Application to the 3ColStar Mission
by Jeimmy Nataly Buitrago-Leiva, Juan José Mejía, Juan Francisco Puerta-Ibarra, Ignacio Francisco Acero-Niño, Andrés Felipe Guarnizo-Saavedra, Julian Rodriguez-Ferreira, Leandro Rojas-Rodriguez, Francisco Luis Hernández-Torres, Cristian Esteban Arango-Cotacio, Jorge Enrique Salazar-Morales, Miguel Angel Herrera-Cruz, Mario Linares-Vásquez, Jose Fernando Jiménez-Vargas, Jorge Enríque Espíndola-Díaz, Óscar Javier Montañez-Sogamoso and Adriano Camps
Aerospace 2024, 11(9), 758; https://doi.org/10.3390/aerospace11090758 - 14 Sep 2024
Viewed by 1288
Abstract
This paper presents a case study on integrating Agile Systems Engineering methodologies in the preliminary design phase of satellite systems, focusing on the 3ColStar satellite mission. Through Model-Based Systems Engineering (MBSE), technical consistency was rigorously managed across various architectural documents, ensuring coherency [...] Read more.
This paper presents a case study on integrating Agile Systems Engineering methodologies in the preliminary design phase of satellite systems, focusing on the 3ColStar satellite mission. Through Model-Based Systems Engineering (MBSE), technical consistency was rigorously managed across various architectural documents, ensuring coherency and minimizing errors. Furthermore, the preliminary design was developed, with the implementation of the Arcadia Method, supported by the Capella modeling tool. This allowed the digitalization of the system, which was represented by models that contain requirements, architecture, and interfaces between the different parts of the system. At the same time, the preliminary design process was streamlined and completed within an accelerated time frame of 4 months, with weekly sprints driving progress based on the scrum methodology. This case study highlights the effectiveness of Agile Systems Engineering principles to improve the team communication accuracy, communication, and efficiency of satellite systems preliminary design, providing valuable insights for future missions. Full article
(This article belongs to the Special Issue Space Systems Preliminary Design)
►▼ Show Figures

Figure 1

Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
 
Displaying articles 1-95
Previous Issue
Next Issue
Back to TopTop