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Volume 11
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Aerospace, Volume 11, Issue 12 (December 2024) – 102 articles

Cover Story (view full-size image): With the renewed interest in supersonic travel, understanding sonic booms is critical to setting reasonable noise regulations and ensuring public acceptance of future high-speed flight. The comparison of sonic boom prediction models shows how well each model captures the complexity of sonic boom propagation. While the simplified model provides fast and efficient predictions for the conceptual design phase, the state-of-the-art approach to sonic boom modeling quantifies the full sonic boom carpet under an aircraft and provides more detail at the expense of computational complexity. By testing these approaches against a variety of realistic scenarios—including different flight conditions and atmospheric variations—we gain insight into the strengths and limitations of each model. View this paper
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23 pages, 5690 KiB  
Article
Orbital Transfers in a Binary Asteroid System Considering Flattening of the Bodies and Solar Radiation Pressure
by L. B. T. Santos, V. Y. Razoumny, V. M. Gomes and A. F. B. A. Prado
Aerospace 2024, 11(12), 1058; https://doi.org/10.3390/aerospace11121058 - 23 Dec 2024
Viewed by 265
Abstract
This paper aims to investigate the effects of asteroid size and shape and solar radiation pressure in the trajectories of a spacecraft in transfers between the collinear equilibrium points of a binary non-spherical asteroid system. As an example, we consider the physical and [...] Read more.
This paper aims to investigate the effects of asteroid size and shape and solar radiation pressure in the trajectories of a spacecraft in transfers between the collinear equilibrium points of a binary non-spherical asteroid system. As an example, we consider the physical and orbital characteristics of the asteroid system 2001SN263. The goal is not to study this system in detail, but to use its parameters to search for transfers considering elongated bodies for the asteroids and compare the results with the solutions obtained when modeling the bodies as point masses. For the propulsion system, bi-impulsive transfers were investigated. In a system composed of asteroids, it is important to take into account the elongation of the asteroids, particularly the body with the most irregular shape, as this has been shown to change the optimal transfer trajectories. By incorporating solar radiation pressure and the size of the bodies into the dynamics, solutions with both lower and higher fuel consumption can be identified. Although the irregular shape and radiation pressure were not used as controls, their effects on the transfers are analyzed. For a system of small bodies, such as an asteroid system, it is very important to consider these perturbations to ensure that the spacecraft will reach the desired point. Full article
(This article belongs to the Special Issue Deep Space Exploration)
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27 pages, 14679 KiB  
Article
A Convolutional Neural Network-Based Stress Prediction Method for Airfoil Structures
by Wendi Jia and Quanlong Chen
Aerospace 2024, 11(12), 1057; https://doi.org/10.3390/aerospace11121057 - 23 Dec 2024
Viewed by 272
Abstract
As a vital component of an aircraft, the structural integrity of the wing is closely linked to both flight performance and safety, making it essential to accurately predict the stresses within its structure. However, conventional stress calculation methods often encounter significant computational costs [...] Read more.
As a vital component of an aircraft, the structural integrity of the wing is closely linked to both flight performance and safety, making it essential to accurately predict the stresses within its structure. However, conventional stress calculation methods often encounter significant computational costs and lengthy analysis times when addressing highly nonlinear and complex geometries. To address these challenges, this paper introduces a deep learning-based stress prediction approach called the Multi-scale Attention Enhanced Unet (MA-Unet) model. The model incorporates a multi-scale feature extraction and attention mechanism based on Unet to capture complex stress distribution features more efficiently, and is applied to the stress prediction of wing skin structures. A stress field dataset is generated through numerical simulation, which is then used to train and evaluate the MA-Unet model. The prediction results are compared with those obtained from traditional convolutional neural networks (CNNs) and the Unet model. Experimental results demonstrate that the MA-Unet model achieves higher accuracy in predicting wing skin stresses and shows strong robustness across various testing conditions. This model serves as an effective method and provides valuable data support for the rapid and accurate assessment of wing structures, highlighting its significant practical applications. Full article
(This article belongs to the Section Aeronautics)
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13 pages, 1616 KiB  
Article
A Rational Design Method for the Nagoya Type-III Antenna
by Daniele Iannarelli, Francesco Napoli, Antonella Ingenito, Alessandro Cardinali, Antonella De Ninno and Simone Mannori
Aerospace 2024, 11(12), 1056; https://doi.org/10.3390/aerospace11121056 - 23 Dec 2024
Viewed by 396
Abstract
The current study, as part of a PhD project on the design of a helicon thruster, aims to provide a rational methodology for the design of the helicon thruster’s main component, i.e., the helicon antenna. A helicon thruster is an innovative electrodeless plasma [...] Read more.
The current study, as part of a PhD project on the design of a helicon thruster, aims to provide a rational methodology for the design of the helicon thruster’s main component, i.e., the helicon antenna. A helicon thruster is an innovative electrodeless plasma thruster that works by exciting helicon waves in a magnetized plasma, and its antenna is capable of producing a uniform, low-temperature, high-density plasma. A magnetic nozzle is used to accelerate the exhaust plasma in order to generate a propulsive thrust. In this paper, we consider a simple helicon antenna, specifically the Nagoya type-III antenna. We consider a common experimental setup consisting of a quartz tube with finite length containing a uniform magnetized plasma and a Nagoya type-III antenna placed at the tube centre. Considering previous studies on helicon waves theory, we compare three different design methods, each based on simplifying different modelling assumptions, and evaluate the predictions of these models with results from full-wave 3D simulations. In particular, we concentrate on deriving a rational design method for the helicon antenna length, given the dimension of the quartz tube and the desired target plasma parameters. This work aims to provide a practical and fast method for dimensioning the antenna length, useful for initializing more accurate but computationally heavier full-wave simulations in 3D geometry or simply for a rapid prototyping of the helicon antenna. These results can be useful for the development of a helicon thruster but also for the design of a high-density radiofrequency plasma source. Full article
(This article belongs to the Special Issue Numerical Simulations in Electric Propulsion)
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31 pages, 10213 KiB  
Article
Autonomous Maneuvering Decision-Making Algorithm for Unmanned Aerial Vehicles Based on Node Clustering and Deep Deterministic Policy Gradient
by Xianyong Jing, Fuzhong Cong, Jichuan Huang, Chunyan Tian and Zikang Su
Aerospace 2024, 11(12), 1055; https://doi.org/10.3390/aerospace11121055 - 23 Dec 2024
Viewed by 258
Abstract
Decision-making for autonomous maneuvering in dynamic, uncertain, and nonlinear environments represents a challenging frontier problem. Deep deterministic policy gradient (DDPG) is an effective method to solve such problems, but it is found that complex strategies require extensive computation and time in the learning [...] Read more.
Decision-making for autonomous maneuvering in dynamic, uncertain, and nonlinear environments represents a challenging frontier problem. Deep deterministic policy gradient (DDPG) is an effective method to solve such problems, but it is found that complex strategies require extensive computation and time in the learning process. To address this issue, we propose a node clustering (NC) method, inspired by grid clustering, integrated into the DDPG algorithm for the learning of complex strategies. In the NC method, the node membership degree is defined according to the specific characteristics of the maneuvering decision-making problem, and error handling strategies are designed to reduce the number of transitions in the replay database effectively, ensuring that the most typical transitions are retained. Then, combining NC and DDPG, an autonomous learning and decision-making algorithm of maneuvering is designed. The algorithm flow and the pseudo-code of the algorithm are given. Finally, the NC_DDPG algorithm is applied to a typical short-range air combat maneuvering decision problem for verification. The results show that the NC_DDPG algorithm significantly accelerates the autonomous learning and decision-making process under both balanced and disadvantageous conditions, taking only about 77% of the time required by Vector DDPG. The scale of NC impacts learning speed; the simulation results across five scales indicate that smaller clustering scales significantly increase learning time, despite a high degree of randomness. Compared with Twin Delayed DDPG (TD3), NC_DDPG consumes only 0.58% of the time of traditional TD3. After applying the NC method to TD3, NC_DDPG requires approximately 20–30% of the time of NC_TD3. Full article
(This article belongs to the Special Issue Application of Multidisciplinary Optimization and Artificial Intelligence Techniques to Aerospace Engineering (Volume II))
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17 pages, 5343 KiB  
Article
Numerical Study on Pressure Oscillations in a Solid Rocket Motor with Backward Step Configuration Under Two-Phase Flow Interactions
by Chao Huo, Hongbo Xu, Jie Hu and Tengfei Luo
Aerospace 2024, 11(12), 1054; https://doi.org/10.3390/aerospace11121054 - 23 Dec 2024
Viewed by 369
Abstract
The pressure oscillation caused by vortex–acoustic coupling is one of the main gain factors that results in the combustion instability of motors. Focusing on a solid rocket motor with a backward step configuration that can generate a corner vortex, this study aims to [...] Read more.
The pressure oscillation caused by vortex–acoustic coupling is one of the main gain factors that results in the combustion instability of motors. Focusing on a solid rocket motor with a backward step configuration that can generate a corner vortex, this study aims to investigate the pressure oscillation characteristics in a combustion chamber under two-phase flow interactions through numerical simulations. The two-phase flow discrete phase model (DPM) was chosen to study particle motion and two-phase interactions. The numerical methodology was hence established by coupling the DPM with the large eddy simulation (LES) method. Taking the Clx motor as a reference and introducing aluminum oxide particles, two important particle parameters (diameter and concentration) and the key geometric parameters of the backward step were numerically studied. The numerical results show that both increased particle diameter and concentration can decrease the frequency and amplitude of pressure oscillations; additionally, the effects of geometric parameters on the pressure oscillations of the backward step, such as the downstream aspect ratio, the expansion ratio, and the step position, are basically consistent under both pure gas and two-phase flows. The influences of those geometric parameters are mainly reflected in defining the space for the development of upstream flow instability and the motion of downstream vortices. Compared with the pure-gas flow, the presence of aluminum oxide particles in two-phase flow globally decreases the vortex shedding frequency, the primary frequency, and the amplitude of pressure oscillations. It can also weaken the effects of vortex–acoustic coupling due to increased turbulent viscosity, which hinders the orderly development of vortices. Full article
(This article belongs to the Section Aeronautics)
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19 pages, 6560 KiB  
Article
Analyzing Engine Performance and Combustor Performance to Assess Sustainable Aviation Fuel Blends
by Ziyu Liu and Xiaoyi Yang
Aerospace 2024, 11(12), 1053; https://doi.org/10.3390/aerospace11121053 - 23 Dec 2024
Viewed by 373
Abstract
FT blends derived from biomass have been confirmed to benefit reductions in GHG and particulate matter (PM). An improvement in combustibility is predicted to reduce fuel consumption and lead to further emission reduction. Various FT fuel blends (7%, 10%, 23%, and 50%) were [...] Read more.
FT blends derived from biomass have been confirmed to benefit reductions in GHG and particulate matter (PM). An improvement in combustibility is predicted to reduce fuel consumption and lead to further emission reduction. Various FT fuel blends (7%, 10%, 23%, and 50%) were assessed in terms of their potential for energy savings and emission reduction in a ZF850 jet engine. The engine performance, including the thrust, fuel consumption, emissions, exhaust gas temperature (EGT), acceleration, and deceleration, was investigated in terms of the whole thrust output, while combustor performance parameters, including EIUHC, EIPM2.5, EICO, EINox, and combustion efficiency, were also discussed. The benefit gained in engine performance was nonlinearly related to the blend ratio, which indicated that the available FT blends required appropriate fuel properties coupled with the engine design. According to the superior improvements derived from the 7% FT fuel blend and 23% FT fuel blend, an appropriate lower C/H ratio and higher combustion efficiency with low PM emissions led to a reduction in fuel consumption. Through global sensitivity analysis, changes in the thrust-specific fuel consumption (TSFC) and the thrust and combustion efficiency with various fuel properties were captured. These can be classified as engine-influenced and fuel-influenced (EIFI) parameters. EICO and EINOx are mainly dependent on the combustor and engine design and can be categorized as engine-influenced and fuel-less-influenced parameters (EIFLI), while EIUHC and EIPM2.5 can be categorized as EIFI parameters. The results of this work could extend our understanding of the impact of FT blends on engine performance and GHG reduction. Full article
(This article belongs to the Section Aeronautics)
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19 pages, 5326 KiB  
Article
Sensitivity Analysis of Scallop Damper Seal Design Parameters for Leakage and Static Performance
by Minglong Yao, Wanfu Zhang, Qianqian Zhao, Qianlei Gu, Liyun Zhang and Jianing Yin
Aerospace 2024, 11(12), 1052; https://doi.org/10.3390/aerospace11121052 - 23 Dec 2024
Viewed by 326
Abstract
The leakage characteristics and static stiffness of scallop damper seals have a significant impact on rotor vibration and stability. A parameter sensitivity analysis model for geometrical parameters in scallop damper seals was developed using a design of experiments (DOE) approach. The method employed [...] Read more.
The leakage characteristics and static stiffness of scallop damper seals have a significant impact on rotor vibration and stability. A parameter sensitivity analysis model for geometrical parameters in scallop damper seals was developed using a design of experiments (DOE) approach. The method employed a central composite design, integrating factorial, axial, and center points to assess non-linear effects efficiently. And the effects of radial clearance, cavity depth, and length–diameter ratios on leakage performance and rotor stability were investigated. The leakage rate, flow-induced force, and static stiffness coefficient for 15 different combinations of geometric parameters at eccentricities of 0.2 and 0.4 were numerically calculated. The results show that eccentricity has little effect on leakage and its parameter sensitivity. Larger cavity depths and length–diameter ratios are beneficial for seal leakage performance. The tangential force increases with increasing eccentricity but decreases with increasing radial clearance, while it first decreases and then increases with the increase in the cavity depth and length–diameter ratios. Additionally, the radial force decreases with the increase in the length-to-diameter ratio and increases first and then decreases with the increase in radial clearance. The parameter level in this study is defined as the ratio of the actual parameter value to the maximum parameter value. Static direct stiffness reaches its maximum value at a radial clearance level of 30.2%. It remains positive within a cavity depth range of 92.3~100%, as well as a length–diameter ratio range of 0~20.3%. The static cross-coupled stiffness gradually decreases with the increase in radial clearance but first decreases and then increases with the increase in the cavity depth or length–diameter ratio levels. The research results presented in this paper can serve as a reference for the analysis of the performance and design of scallop damper seals. Full article
(This article belongs to the Section Aeronautics)
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18 pages, 7396 KiB  
Article
Design and Performance Optimization of a Radial Turbine Using Hydrogen Combustion Products
by Pengfei Su, Weifeng He, Abdalazeem Adam, Omer Musa, Wang Chen and Zeyu Lou
Aerospace 2024, 11(12), 1051; https://doi.org/10.3390/aerospace11121051 - 23 Dec 2024
Viewed by 564
Abstract
The combustion of hydrogen increases the water content of the combustion products, affecting the aerodynamic performance of turbines using hydrogen as a fuel. This study aims to design a radial turbine using the differential evolution (DE) algorithm to improve its characteristics and optimize [...] Read more.
The combustion of hydrogen increases the water content of the combustion products, affecting the aerodynamic performance of turbines using hydrogen as a fuel. This study aims to design a radial turbine using the differential evolution (DE) algorithm to improve its characteristics and optimize its aerodynamic performance through an orthogonal experiment and analysis of means (ANOM). The effects of varying water content in combustion products, ranging from 12% to 22%, on the performance of the radial turbine are also investigated. After optimization, the total–static efficiency of the radial turbine increased to 89.12%, which was 1.59% higher than the preliminary design. The study found that flow loss in the impeller primarily occurred at the leading edge, trailing edge, and the inlet of the suction surface tip and outlet. With a 10% increase in water content, the enthalpy dropped, Mach number increased, and turbine power increased by 4.64%, 1.71%, and 2.41%, respectively. However, the total static efficiency and mass flow rate decreased by 0.71% and 2.13%, respectively. These findings indicate that higher water content in hydrogen combustion products enhances the turbine’s output power while reducing the combustion products’ mass flow rate. Full article
(This article belongs to the Special Issue Revolutionizing Aerospace Mobility: Green Hydrogen As the Sustainable Fuel of the Future)
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33 pages, 22828 KiB  
Article
Comparison of Two Fourier-Based Methods for Simulating Inlet Distortion Unsteady Flows in Transonic Compressors
by Lei Wu, Pengcheng Du and Fangfei Ning
Aerospace 2024, 11(12), 1050; https://doi.org/10.3390/aerospace11121050 - 22 Dec 2024
Viewed by 371
Abstract
The aerodynamic performance of transonic compressors, particularly the stall margin, is significantly influenced by inlet distortion. While time-marching methods accurately simulate such unsteady flows, they can be time-consuming. To enhance the computational efficiency, two Fourier-based methods are proposed in this paper: the time-accurate [...] Read more.
The aerodynamic performance of transonic compressors, particularly the stall margin, is significantly influenced by inlet distortion. While time-marching methods accurately simulate such unsteady flows, they can be time-consuming. To enhance the computational efficiency, two Fourier-based methods are proposed in this paper: the time-accurate method with interface filtering and the time–space collocation (TSC) method. The time-accurate method with interface filtering ignores the rotor–stator interaction effects, enabling a larger time step and faster convergence. In contrast, the TSC method accounts for harmonics of conservative variables and transforms the unsteady simulation into multiple steady-state calculations, thereby reducing computational costs. The two Fourier-based methods are validated using NASA Stage 67 and a two-stage transonic fan. Near the peak efficiency point, the results from both methods closely match that of URANS simulation and experimental data. The time-accurate method with interface filtering demonstrates a speed enhancement of 4 to 5 times as a result of a reduction in the iteration steps. In contrast, the TSC method exhibits a speed improvement of at least 20 times in two specific cases, attributable to the significantly smaller mesh size and iteration steps employed in the TSC method compared to the URANS method. Near the stall point, more harmonics for inlet distortion are necessary in TSC simulation to accurately capture flow separation. In the two-stage transonic fan simulations, the strong rotor–stator interaction effects lead to deviations from the URANS simulation; nevertheless, the Fourier-based simulations accurately reflect the trend of the stall margin under total pressure distortion. Overall, the Fourier-based methods show promising potential for engineering applications in estimating the performance degradation of compressors subjected to inlet distortion. Full article
(This article belongs to the Section Aeronautics)
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23 pages, 19555 KiB  
Article
Dynamics Model and Its Verification of Aerospace Three-Ring Gear Reducer
by Jinyong Lai, Lan Luo, Guangzhao Luo and Shiyuan Chao
Aerospace 2024, 11(12), 1049; https://doi.org/10.3390/aerospace11121049 - 21 Dec 2024
Viewed by 509
Abstract
This paper proposes a nonlinear dynamic modeling method based on the lumped mass approach to address the challenge of modeling the vibrations of the output external gear and internal gear plate in an aerospace three-ring gear reducer. A vibration model of bending–torsion coupling [...] Read more.
This paper proposes a nonlinear dynamic modeling method based on the lumped mass approach to address the challenge of modeling the vibrations of the output external gear and internal gear plate in an aerospace three-ring gear reducer. A vibration model of bending–torsion coupling with 12 degrees of freedom was established by comprehensively considering factors such as the time-varying meshing stiffness, gear transmission error, tooth side clearance, bearing support stiffness, and damping. Finite element modal analysis and vibration test results verified the vibration model’s accuracy and applicability, indicating that the model is both precise and valid. The vibration model was solved using the fourth-order, five-level Runge–Kutta method. The results show that the symmetrical arrangement design of the internal gear plate cancels the vibrations in all directions and suppresses the vibration displacement response on the output shaft. Full article
(This article belongs to the Section Aeronautics)
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27 pages, 9474 KiB  
Article
Design of Equilateral Array Polygonal Gravitational-Wave Observatory Formation near Lagrange Point L1—Equilateral Triangle and Equilateral Tetrahedral Configurations
by Zhengxu Pan, Mai Bando, Zhanxia Zhu and Shinji Hokamoto
Aerospace 2024, 11(12), 1048; https://doi.org/10.3390/aerospace11121048 - 21 Dec 2024
Viewed by 284
Abstract
To observe lower-frequency gravitational waves (GWs), it is effective to utilize a large spacecraft formation baseline, spanning hundreds of thousands to millions of kilometers. To overcome the limitations of a gravitational-wave observatory (GWO) on specific orbits, a scientific observation mode and a non-scientific [...] Read more.
To observe lower-frequency gravitational waves (GWs), it is effective to utilize a large spacecraft formation baseline, spanning hundreds of thousands to millions of kilometers. To overcome the limitations of a gravitational-wave observatory (GWO) on specific orbits, a scientific observation mode and a non-scientific observation mode for GWOs are proposed. For the non-scientific observation mode, this paper designs equilateral triangle and equilateral tetrahedral array formations for a space-based GWO near a collinear libration point. A stable configuration is the prerequisite for a GWO; however, the motion near the collinear libration points is highly unstable. Therefore, the output regulation theory is applied. By leveraging the tracking aspect of the theory, the equilateral triangle and equilateral tetrahedral array formations are achieved. For an equilateral triangle array formation, two geometric configuration design methods are proposed, addressing the fuel consumption required for initialization and maintenance. To observe GWs in different directions and avoid configuration/reconfiguration, the multi-layer equilateral tetrahedral array formation is given. Additionally, the control errors are calculated. Finally, the effectiveness of the control method is demonstrated using the Sun–Earth circular-restricted three-body problem (CRTBP) and the ephemeris model located at Lagrange point L1. Full article
(This article belongs to the Section Astronautics & Space Science)
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19 pages, 7453 KiB  
Article
Velocity Observer Design for Tether Deployment in Hamiltonian Framework
by Jihang Yang, Guanzheng Chen, Mingming Zhang, Gangqiang Li and Jinyu Liu
Aerospace 2024, 11(12), 1047; https://doi.org/10.3390/aerospace11121047 - 20 Dec 2024
Viewed by 353
Abstract
This paper presents a nonlinear velocity observer of tether deployment using the immersion and invariance technique, and the velocity observer design problem is recast as a problem of designing an attractive and invariant manifold inside the Hamiltonian framework. The passivity-based control theory is [...] Read more.
This paper presents a nonlinear velocity observer of tether deployment using the immersion and invariance technique, and the velocity observer design problem is recast as a problem of designing an attractive and invariant manifold inside the Hamiltonian framework. The passivity-based control theory is used to define an expected Hamiltonian function, and the stability of the designed velocity observer is addressed by using the passivity-based methodology. Finally, a simple tension control law with measurable and unmeasurable states is employed for controlling the tether deployment, where the unmeasurable states use the proposed velocity observer. Numerical simulations demonstrate that the proposed velocity observer is working successfully. Sensitivity analyses are conducted to test the effectiveness and robustness of the proposed velocity observer. Full article
(This article belongs to the Special Issue Application of Tether Technology in Space)
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21 pages, 6925 KiB  
Article
Nonlinear Orbit Acquisition and Maintenance of a Lunar Navigation Constellation Using Low-Thrust Propulsion
by Edoardo Maria Leonardi, Giulio De Angelis and Mauro Pontani
Aerospace 2024, 11(12), 1046; https://doi.org/10.3390/aerospace11121046 - 20 Dec 2024
Viewed by 436
Abstract
In this research, a feedback nonlinear control law was designed and tested to perform acquisition and station-keeping maneuvers for a lunar navigation constellation. Each satellite flies an Elliptical Lunar Frozen Orbit (ELFO) and is equipped with a steerable and throttleable low-thrust propulsion system. [...] Read more.
In this research, a feedback nonlinear control law was designed and tested to perform acquisition and station-keeping maneuvers for a lunar navigation constellation. Each satellite flies an Elliptical Lunar Frozen Orbit (ELFO) and is equipped with a steerable and throttleable low-thrust propulsion system. Lyapunov stability theory was employed to design a real-time feedback control law, capable of tracking all orbital elements (including the true anomaly), expressed in terms of modified equinoctial elements (MEEs). Unlike previous research, control synthesis was developed in the complete nonlinear dynamical model, and allows for driving the spacecraft toward a time-varying desired state, which includes correct phasing. Orbit propagation was performed in a high-fidelity framework, which incorporated several relevant harmonics of the selenopotential, as well as third-body effects due to the gravitational pull of the Earth and Sun. The control strategy at hand was successfully tested through two Monte Carlo campaigns in the presence of nonnominal flight conditions related to estimation errors of orbit perturbations, accompanied by the temporary unavailability and misalignment of the propulsive thrust. Full article
(This article belongs to the Special Issue Deep Space Exploration)
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35 pages, 11125 KiB  
Article
Analysis of Static Aeroelastic Characteristics of Distributed Propulsion Wing
by Junlei Sun, Zhou Zhou, Tserendondog Tengis and Huailiang Fang
Aerospace 2024, 11(12), 1045; https://doi.org/10.3390/aerospace11121045 - 20 Dec 2024
Viewed by 374
Abstract
The static aeroelastic characteristics of the distributed propulsion wing (DPW) were studied using the CFD/CSD loose coupling method in this study. The momentum source method of the Reynolds-averaged Navier–Stokes equation based on the k-ω SST turbulence model solution was used as the CFD [...] Read more.
The static aeroelastic characteristics of the distributed propulsion wing (DPW) were studied using the CFD/CSD loose coupling method in this study. The momentum source method of the Reynolds-averaged Navier–Stokes equation based on the k-ω SST turbulence model solution was used as the CFD solution module. The upper and lower surfaces of the DPW were established using the cubic B-spline basis function method, and the surfaces of the inlet and outlet were established using the fourth-order Bezier curve. Finally, a three-dimensional parametric model of the DPW was established. A structural finite-element model of the DPW was established, a multipoint array method program based on the three-dimensional radial basis function (RBF) was written as a data exchange module to realize the aerodynamic and structural data exchange of the DPW’s static aeroelastic analysis process, and, finally, an aeroelastic analysis of the DPW was achieved. The results show that the convergence rate of the CFD/CSD loosely coupled method is fast, and the structural static aeroelastic deformation is mainly manifested as bending deformation and positive torsion deformation, which are typical static aeroelastic phenomena of the straight wing. Under the influence of static aeroelastic deformation, the increase in the lift characteristics of the DPW is mainly caused by the slipstream region of the lower surface and the non-slipstream region of the upper and lower surface. Meanwhile, the increase in its nose-up moment and the increase in the longitudinal static stability margin may have an impact on the longitudinal stability of the UAV. To meet the requirements of engineering applications, a rapid simulation method of equivalent airfoil, which can be applied to commercial software for analysis, was developed, and the effectiveness of the method was verified via comparison with the CFD/CSD loose coupling method. On this basis, the static aeroelastic characteristics of the UAV with DPWs were studied. The research results reveal the static aeroelastic characteristics of the DPW, which hold some significance for engineering guidance for this kind of aircraft. Full article
(This article belongs to the Section Aeronautics)
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35 pages, 13315 KiB  
Article
Feasibility of Conflict Prediction of Drone Trajectories by Means of Machine Learning Techniques
by Victor Gordo, Javier A. Perez-Castan, Luis Perez Sanz, Lidia Serrano-Mira and Yan Xu
Aerospace 2024, 11(12), 1044; https://doi.org/10.3390/aerospace11121044 - 20 Dec 2024
Viewed by 466
Abstract
The expected number of drone operations in the coming decades, together with the fact that most of them will take place in very-low-level airspace, will lead to a density of drone flights much greater than that of conventional manned aviation. In this context, [...] Read more.
The expected number of drone operations in the coming decades, together with the fact that most of them will take place in very-low-level airspace, will lead to a density of drone flights much greater than that of conventional manned aviation. In this context, the number of conflicts (i.e., 4D convergence of drone trajectories below the safe separation minima) will be much more frequent than in manned aviation and, therefore, conventional air traffic management methods or even the specific proposed mechanisms for drone traffic management are unlikely to be able to solve them safely. This paper considers a set of simulated drone trajectories in a high-density urban environment to analyze the applicability of machine learning regression and classification techniques to detect conflicts among such trajectory times in advance of their occurrence in order to provide new methods to manage the expected drone traffic density safely and efficiently. This would not be possible with current drone traffic management solutions. The obtained results suggest that the Random Forest, Artificial Neural Networks and Logistic Regression algorithms could detect nearly all near-collisions up to 10 s before they occur, and the first two algorithms could also detect a significant number of near-collisions more than 60 s earlier. Full article
(This article belongs to the Special Issue Future Airspace and Air Traffic Management Design)
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18 pages, 4645 KiB  
Article
Passive Aeroelastic Control of a Near-Ground Airfoil with a Nonlinear Vibration Absorber
by Kailash Dhital and Benjamin Chouvion
Aerospace 2024, 11(12), 1043; https://doi.org/10.3390/aerospace11121043 - 20 Dec 2024
Viewed by 394
Abstract
This study explores the use of a passive control technique to mitigate aeroelastic effects on a wing operating near the ground. An aeroelastic model, based on a typical airfoil section, equipped with a nonlinear tuned vibration absorber (NLTVA), is established to study the [...] Read more.
This study explores the use of a passive control technique to mitigate aeroelastic effects on a wing operating near the ground. An aeroelastic model, based on a typical airfoil section, equipped with a nonlinear tuned vibration absorber (NLTVA), is established to study the interactions between the airfoil’s dynamics, aerodynamics, and the nonlinear energy dissipation mechanisms. Geometric nonlinearity is incorporated into the airfoil’s dynamics to account for possible large wing deflection and rotation. The flow is modeled based on the nonlinear unsteady discrete vortex method with the ground effect simulated using the mirror image method. Stability analyses are conducted to study the influence of NLTVA parameters on flutter mitigation and the bifurcation behavior of the airfoil near the ground. The numerical results demonstrate that the NLTVA effectively delays the onset of flutter and promotes a supercritical bifurcation in the presence of ground effect. Optimally tuning the NLTVA’s linear parameters significantly increases flutter speed, while selecting the optimal nonlinear parameter is key to preventing subcritical behavior near the ground and reducing the amplitude of post-flutter limit cycle oscillations. Overall, this study highlights the potential of the NLTVA in enhancing the aeroelastic stability of flying vehicles with highly flexible wings, especially under the influence of ground effects during takeoff and landing. Full article
(This article belongs to the Special Issue Aeroelasticity, Volume IV)
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31 pages, 35055 KiB  
Article
Microscopic-Level Collaborative Optimization Framework for Integrated Arrival-Departure and Surface Operations: Integrated Runway and Taxiway Aircraft Sequencing and Scheduling
by Chaoyu Xia, Yi Wen, Minghua Hu, Hanbing Yan, Changbo Hou and Weidong Liu
Aerospace 2024, 11(12), 1042; https://doi.org/10.3390/aerospace11121042 - 20 Dec 2024
Viewed by 545
Abstract
Integrated arrival–departure and surface scheduling (IADS) is a critical research task in next-generation air traffic management that aims to harmonize the complex and interrelated processes of airspace and airport operations in the Metroplex. This paper investigates the microscopic-level collaborative optimization framework for IADS [...] Read more.
Integrated arrival–departure and surface scheduling (IADS) is a critical research task in next-generation air traffic management that aims to harmonize the complex and interrelated processes of airspace and airport operations in the Metroplex. This paper investigates the microscopic-level collaborative optimization framework for IADS operations, i.e., the problem of coordinating aircraft scheduling on runways and taxiways. It also describes the mixed-integer linear programming (MILP) bi-layer decision support for solving this problem. In runway scheduling, a combined arrival–departure scheduling method is introduced based on our previous research, which can identify the optimal sequence of arrival and departure streams to minimize runway delays. For taxiway scheduling, the Multi-Route Airport Surface Scheduling Method (MASM) is proposed, aiming to determine the routes and taxi metering for each aircraft while minimizing the gap compared with the runway scheduling solution. Furthermore, this paper develops a feedback mechanism to further close the runway and taxiway schedule deviation. To demonstrate the universality and validity of the proposed bi-layer decision support method, two hub airports, Chengdu Shuangliu International Airport (ICAO code: ZUUU) and Chengdu Tianfu International Airport (ICAO code: ZUTF), within the Cheng-Yu Metroplex, were selected for validation. The obtained results show that the proposed method could achieve closed-loop decision making for runway scheduling and taxiway scheduling and reduce runway delay and taxi time. The key anticipated mechanisms of benefits from this research include improving the efficiency and predictability of operations on the airport surface and maintaining situational awareness and coordination between the stand and the tower. Full article
(This article belongs to the Special Issue Advances in Air Traffic and Airspace Control and Management (2nd Edition))
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20 pages, 7374 KiB  
Article
Optimal Guidance Law for Critical Safe Miss Distance Evasion
by Chengze Wang, Jiamin Yan, Rui Lyu, Zhuo Liang and Yang Chen
Aerospace 2024, 11(12), 1041; https://doi.org/10.3390/aerospace11121041 - 19 Dec 2024
Viewed by 378
Abstract
In pursuit–evasion scenarios, the pursuer typically possesses a lethal zone. If the evader effectively utilizes perceptual information, they can narrowly escape the lethal zone while minimizing energy consumption, thereby avoiding excessive and unnecessary maneuvers. Based on optimal control theory, we propose a guidance [...] Read more.
In pursuit–evasion scenarios, the pursuer typically possesses a lethal zone. If the evader effectively utilizes perceptual information, they can narrowly escape the lethal zone while minimizing energy consumption, thereby avoiding excessive and unnecessary maneuvers. Based on optimal control theory, we propose a guidance law for achieving critical safe miss distance evasion under bounded control. First, we establish the zero-effort miss (ZEM) state equation for the evader, while approximating disturbances from the pursuer. Next, we formulate an optimal control problem with energy consumption as the objective function and the ZEM at the terminal time as the terminal constraint. Subsequently, we design an iterative algorithm that combines the homotopy method and Newton’s iteration to solve the optimal control problem, applying Pontryagin’s Maximum Principle. The simulation results indicate that the designed iterative method converges effectively; through online updates, the proposed guidance law can successfully achieve critical safe miss distance evasion. Compared to programmatic maneuvering and norm differential game guidance law, this approach not only stabilizes the evader’s evasion capabilities but also significantly reduces energy consumption. Full article
(This article belongs to the Section Aeronautics)
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29 pages, 1017 KiB  
Article
Comparative Analysis of Deep Reinforcement Learning Algorithms for Hover-to-Cruise Transition Maneuvers of a Tilt-Rotor Unmanned Aerial Vehicle
by Mishma Akhtar and Adnan Maqsood
Aerospace 2024, 11(12), 1040; https://doi.org/10.3390/aerospace11121040 - 19 Dec 2024
Viewed by 463
Abstract
Work on trajectory optimization is evolving rapidly due to the introduction of Artificial-Intelligence (AI)-based algorithms. Small UAVs are expected to execute versatile maneuvers in unknown environments. Prior studies on these UAVs have focused on conventional controller design, modeling, and performance, which have posed [...] Read more.
Work on trajectory optimization is evolving rapidly due to the introduction of Artificial-Intelligence (AI)-based algorithms. Small UAVs are expected to execute versatile maneuvers in unknown environments. Prior studies on these UAVs have focused on conventional controller design, modeling, and performance, which have posed various challenges. However, a less explored area is the usage of reinforcement-learning algorithms for performing agile maneuvers like transition from hover to cruise. This paper introduces a unified framework for the development and optimization of a tilt-rotor tricopter UAV capable of performing Vertical Takeoff and Landing (VTOL) and efficient hover-to-cruise transitions. The UAV is equipped with a reinforcement-learning-based control system, specifically utilizing algorithms such as Deep Deterministic Policy Gradient (DDPG), Trust Region Policy Optimization (TRPO), and Proximal Policy Optimization (PPO). Through extensive simulations, the study identifies PPO as the most robust algorithm, achieving superior performance in terms of stability and convergence compared with DDPG and TRPO. The findings demonstrate the efficacy of DRL in leveraging the unique dynamics of tilt-rotor UAVs and show a significant improvement in maneuvering precision and control adaptability. This study demonstrates the potential of reinforcement-learning algorithms in advancing autonomous UAV operations by bridging the gap between dynamic modeling and intelligent control strategies, underscoring the practical benefits of DRL in aerial robotics. Full article
(This article belongs to the Section Aeronautics)
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17 pages, 6724 KiB  
Article
Distributed Localization of Non-Cooperative Targets in Non-Coplanar Rendezvous Processes
by Zihan Zhen and Feng Yu
Aerospace 2024, 11(12), 1039; https://doi.org/10.3390/aerospace11121039 - 19 Dec 2024
Viewed by 397
Abstract
Precise positioning of non-cooperative targets is important for maintaining spacecraft operational environments in orbit. In order to address the challenges of non-cooperative target localization during non-coplanar rendezvous, this study develops a distributed cooperative localization scheme. First, a three-line-of-sight positioning method for long-range targets [...] Read more.
Precise positioning of non-cooperative targets is important for maintaining spacecraft operational environments in orbit. In order to address the challenges of non-cooperative target localization during non-coplanar rendezvous, this study develops a distributed cooperative localization scheme. First, a three-line-of-sight positioning method for long-range targets in non-coplanar orbits is proposed. Second, a distributed extended Kalman filter based on a consensus algorithm is designed, which reduces observation dimensions and increases system robustness. Subsequently, the rendezvous configuration optimization problem for long-range non-coplanar targets is transformed into a numerical optimization problem. Finally, an improved NSGA-III algorithm is proposed by introducing normal distribution crossover (NDX) and a cosine-like mutation distribution index to optimize the rendezvous configuration. A simulation shows that the methods proposed are effective, and the improved NSGA-III is superior to traditional algorithms in terms of search range and convergence speed. After configuration optimization, the performance of the system has been greatly improved, with better positioning accuracy and stronger robustness. Full article
(This article belongs to the Special Issue Advances on Autonomous Navigation for Spacecraft Proximity Operations and Formation Flying: Algorithms Development and Verification Methods)
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32 pages, 8142 KiB  
Article
Robust Design Optimization of Viscoelastic Damped Composite Structures Integrating Model Order Reduction and Generalized Stochastic Collocation
by Tianyu Wang, Chao Xu and Teng Li
Aerospace 2024, 11(12), 1038; https://doi.org/10.3390/aerospace11121038 - 19 Dec 2024
Viewed by 428
Abstract
This study presents a novel approach that integrates model order reduction (MOR) and generalized stochastic collocation (gSC) to enhance robust design optimization (RDO) of viscoelastic damped composite structures under material and geometric uncertainties. The proposed methodology systematically reduces computational burden while maintaining the [...] Read more.
This study presents a novel approach that integrates model order reduction (MOR) and generalized stochastic collocation (gSC) to enhance robust design optimization (RDO) of viscoelastic damped composite structures under material and geometric uncertainties. The proposed methodology systematically reduces computational burden while maintaining the required accuracy. A projection-based MOR is chosen to alleviate the substantial computational costs associated with nonlinear eigenvalue problems. To minimize the sampling size for uncertainty propagation (UP) while effectively addressing diverse probability density distributions, a gSC method incorporating statistical moment computation techniques is developed. Pareto optimal solutions are determined by combining the proposed MOR and gSC approaches with a well-established Non-dominated Sorting Genetic Algorithm II (NSGA-II) algorithm, which accounts for robustness in handling design variables, objectives, and constraints. The results of the four examples illustrate the efficacy of the proposed MOR and gSC methods, as well as the overall RDO framework. Notably, the findings demonstrate the feasibility of this approach for practical applications, driven by a significant reduction in computational costs. This establishes a solid foundation for addressing complex optimization challenges in real-world scenarios characterized by various uncertainties. Full article
(This article belongs to the Section Aeronautics)
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12 pages, 3991 KiB  
Article
Reducing Antenna Leakage in Quasi-Monostatic Satellite Radar Using Planar Metamaterials
by Mohammad Reza Khalvati and Dominique Bovey
Aerospace 2024, 11(12), 1037; https://doi.org/10.3390/aerospace11121037 - 19 Dec 2024
Viewed by 337
Abstract
In an autonomous robotic space debris removal mission, an essential sensor used for navigation is an FMCW radar designed for close-range relative navigation. To achieve the required range performance, minimizing RF leakage between the transmitter (Tx) and receiver (Rx) antennas is essential for [...] Read more.
In an autonomous robotic space debris removal mission, an essential sensor used for navigation is an FMCW radar designed for close-range relative navigation. To achieve the required range performance, minimizing RF leakage between the transmitter (Tx) and receiver (Rx) antennas is essential for the accurate detection of the range and velocity of the targeted space debris. Antennas positioned above the metallic satellite front face are highly susceptible to RF leakage, primarily caused by surface current propagation and lateral waves traveling parallel to the platform. This study presents two lightweight, single-layer planar metamaterials—a novel compact electromagnetic bandgap (EBG) and a non-uniform high-impedance surface (HIS)—optimized to suppress both surface waves and interact with space waves within the 9.3–9.8 GHz frequency range. These designs address strict size, weight, and power (SWaP) constraints while ensuring compatibility with extreme space conditions and resistance to mechanical shocks. Experimental validation indicates that a minimum Tx/Rx isolation improvement of 10 dB is achieved using the HIS, and 20 dB is achieved using the EBG across the radar’s operational bandwidth (5%). Full article
(This article belongs to the Section Astronautics & Space Science)
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14 pages, 1342 KiB  
Article
Multi-Frequency Aeroelastic ROM for Transonic Compressors
by Marco Casoni, Andrea Magrini and Ernesto Benini
Aerospace 2024, 11(12), 1036; https://doi.org/10.3390/aerospace11121036 - 19 Dec 2024
Viewed by 423
Abstract
The accurate prediction of the aeroelastic behavior of turbomachinery for aircraft propulsion poses a difficult yet fundamental challenge, since modern aircraft engines tend to adopt increasingly slender blades to achieve a higher aerodynamic efficiency, incurring an increased aeroelastic interaction as a drawback. In [...] Read more.
The accurate prediction of the aeroelastic behavior of turbomachinery for aircraft propulsion poses a difficult yet fundamental challenge, since modern aircraft engines tend to adopt increasingly slender blades to achieve a higher aerodynamic efficiency, incurring an increased aeroelastic interaction as a drawback. In the present work, we present a reduced order model for flutter prediction in axial compressors. The model exploits the aerodynamic influence coefficients technique with the adoption of a broadband frequency signal to compute the aerodynamic damping for multiple reduced frequencies using a single training simulation. The normalized aerodynamic work is computed for a single oscillation mode at three different vibration frequencies, comparing the outputs of aerodynamic input/output models trained with a chirp signal to those from single-frequency harmonic simulations. The results demonstrate the ability of the adopted model to accurately and efficiently reproduce the aerodynamic damping at multiple frequencies and arbitrary nodal diameters with a single simulation. Full article
(This article belongs to the Special Issue Progress in Turbomachinery Technology for Propulsion)
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20 pages, 7301 KiB  
Article
Multi-Stage Design Method for Complex Gas Supply and Exhaust System of Space Station
by Dongcai Guo, Qinglin Zhu, Lu Zhang, Jule Zhang, Dong Guo, Fufu Wang, Anping Wang, Ying Xu, Qiang Sheng and Ke Wang
Aerospace 2024, 11(12), 1035; https://doi.org/10.3390/aerospace11121035 - 18 Dec 2024
Viewed by 439
Abstract
The supply and exhaust system of the experimental rack on the Chinese space station is a complex integrated system. In this paper, a multi-stage simulation, testing, and verification method is designed for a multi-team, multi-location, and multi-stage integrated gas system. This method is [...] Read more.
The supply and exhaust system of the experimental rack on the Chinese space station is a complex integrated system. In this paper, a multi-stage simulation, testing, and verification method is designed for a multi-team, multi-location, and multi-stage integrated gas system. This method is designed to solve the problem of missing input parameters between the gas supply system and the exhaust system. Preliminary tests and strategy verifications were carried out through theoretical simulation and semi-physical simulation, and good calculation results were obtained for the single-rack product. The external systems were tested using a simulation system, and a calculation method was designed to obtain relatively accurate parameters. In the early stage, the performance of the product was predicted using the parameter library of Flomaster and semi-physical simulation methods, but the error was large. In the middle and late stages of development, as some products became realistic, multi-stage testing was carried out using a vacuum simulator, simulated flow resistance, and other methods, achieving a performance prediction with an error of 12% before ground testing. The final ground test and on-orbit test showed that the design and calculation method of this paper is effective. The multi-stage design method proposed in this paper was successfully applied to the integrated gas system of the Chinese space station, which can provide a reference for the design of fluid components in long-term system engineering. Full article
(This article belongs to the Special Issue Aerospace Human–Machine and Environmental Control Engineering)
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16 pages, 2882 KiB  
Communication
Mathematical Mechanism of Gini Index Used for Multiple-Impulse Phenomenon Characterization
by Guofeng Jin, Anbo Ming and Wei Zhang
Aerospace 2024, 11(12), 1034; https://doi.org/10.3390/aerospace11121034 - 18 Dec 2024
Viewed by 281
Abstract
The Gini index (GI) is widely used for measuring the sparsity of signals and has been proven to be effective in the extraction of fault features. A fault-induced vibration, which involves the obvious phenomenon of multiple impulses, is a kind of sparse signal [...] Read more.
The Gini index (GI) is widely used for measuring the sparsity of signals and has been proven to be effective in the extraction of fault features. A fault-induced vibration, which involves the obvious phenomenon of multiple impulses, is a kind of sparse signal and the GI has been widely used in the diagnosis of rotating machine faults. However, why the GI can be used to evaluate the sparsity or impulsiveness of a signal has not been revealed directly. In this study, the mathematical mechanism of the GI, used for the representation of the multiple-impulse phenomenon, is deeply researched based on the theoretical deviation of the GI with regard to several typical signals. The theoretical results show that the GI increases with the increment in the number of impulses in the signal when the signal is interrupted by relatively low degrees of white noise. The bigger the difference between the amplitude of the impulse and the variance in the noise, the bigger the value of the GI. Namely, the signal-to-noise ratio has a great influence on the value of the GI. However, the GI is still a powerful tool for the characterization of the impulsive intensity of the multiple-impulse phenomenon. Both simulation and experimental data analysis are introduced to show the application of the GI in practice. It is shown that the fault diagnosis method based on the maximization of the GI is more powerful than that of kurtosis in terms of the extraction of fault features of rolling element bearings (REBs). Full article
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11 pages, 5727 KiB  
Article
Experimental Verification of the Flexible Wheels for Planetary Rovers with the Push–Pull Locomotion Function
by Qingze He, Daisuke Fujiwara and Kojiro Iizuka
Aerospace 2024, 11(12), 1033; https://doi.org/10.3390/aerospace11121033 - 17 Dec 2024
Viewed by 410
Abstract
For push–pull locomotion, it has been confirmed by this research group that the support force of the wheels is enhanced by performing the sinking operation to provide support force. However, the sinking operation is an additional operation used for the rover to travel. [...] Read more.
For push–pull locomotion, it has been confirmed by this research group that the support force of the wheels is enhanced by performing the sinking operation to provide support force. However, the sinking operation is an additional operation used for the rover to travel. Ideally, if the rover can operate without sinking, travel efficiency is improved. On the other hand, flexible wheels are often used for the rover. Due to stress dispersion, these wheels are less likely to damage the ground. Therefore, it would be beneficial if the use of these wheels could improve the travel ability of the push–pull motion. In this study, we focused on whether the use of flexible wheels can avoid subsidence and tested their performance through different parameters. Full article
(This article belongs to the Section Astronautics & Space Science)
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14 pages, 2917 KiB  
Article
Numerical Investigation of Non-Equilibrium Condensation in a Supersonic Nozzle Based on Spontaneous Nucleation
by Saman Javadi Kouchaksaraei and Mohammad Akrami
Aerospace 2024, 11(12), 1032; https://doi.org/10.3390/aerospace11121032 - 17 Dec 2024
Viewed by 464
Abstract
Non-equilibrium condensation involves intricate physics, making it crucial to thoroughly investigate the factors that influence it. Understanding these factors is essential for optimizing the system performance and minimizing the negative effects associated with non-equilibrium condensation. This study focused on examining the impact of [...] Read more.
Non-equilibrium condensation involves intricate physics, making it crucial to thoroughly investigate the factors that influence it. Understanding these factors is essential for optimizing the system performance and minimizing the negative effects associated with non-equilibrium condensation. This study focused on examining the impact of various operational conditions in a saturated mode on non-equilibrium condensation within a supersonic nozzle. The operation conditions under investigation involved pressures of 25 kPa, 50 kPa, 75 kPa, and 100 kPa. Each saturation state was examined to assess its effect on various parameters, such as temperature, pressure, liquid mass fraction, droplet radius, nucleation rate, Mach number, and droplet count. A consistent pattern emerged across all samples. As the gas accelerated through the converging section of the nozzle, both pressure and temperature gradually decreased. However, upon reaching the throat and entering the divergent section, a phenomenon known as condensation shock occurred. This shock wave caused a sudden and significant spike in both pressure and temperature. Following the shock, both parameters resumed their downward trend along the remaining length of the nozzle. Interestingly, increasing the initial pressure of the gas led to a less intense condensation shock. Additionally, raising the saturation pressure at the nozzle inlet resulted in larger droplets and a higher concentration of liquid within the gas flow. By quadrupling the inlet saturation pressure from 25 to 100 kPa, a substantial 106.9% increase in droplet radius and a 9.65% increase in liquid mass fraction were observed at the nozzle outlet. Full article
(This article belongs to the Special Issue Innovation and Challenges in Hypersonic Propulsion)
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15 pages, 1694 KiB  
Article
SSMBERT: A Space Science Mission Requirement Classification Method Based on BERT
by Yiming Zhu, Yuzhu Zhang, Xiaodong Peng, Changbin Xue, Bin Chen and Yu Cao
Aerospace 2024, 11(12), 1031; https://doi.org/10.3390/aerospace11121031 - 17 Dec 2024
Viewed by 392
Abstract
Model-Based Systems Engineering (MBSE) has demonstrated importance in the aerospace field. However, the MBSE modeling process is often tedious and heavily reliant on specialized knowledge and experience; thus, a new modeling method is urgently required to enhance modeling efficiency. This article focuses on [...] Read more.
Model-Based Systems Engineering (MBSE) has demonstrated importance in the aerospace field. However, the MBSE modeling process is often tedious and heavily reliant on specialized knowledge and experience; thus, a new modeling method is urgently required to enhance modeling efficiency. This article focuses on the MBSE modeling in space science mission phase 0, during which the mission requirements are collected, and the corresponding dataset is constructed. The dataset is utilized to fine-tune the BERT pre-training model for the classification of requirements pertaining to space science missions. This process supports the subsequent automated creation of the MBSE requirement model, which aims to facilitate scientific objective analysis and enhances the overall efficiency of the space science mission design process. Based on the characteristics of space science missions, this paper categorized the requirements into four categories: scientific objectives, performance, payload, and engineering requirements, and constructed a requirements dataset for space science missions. Then, utilizing this dataset, the BERT model is fine-tuned to obtain a space science mission requirements classification model (SSMBERT). Finally, SSMBERT is compared with other models, including TextCNN, TextRNN, and GPT-2, in the context of the space science mission requirement classification task. The results indicate that SSMBERT performs effectively under Few-Shot conditions, achieving a precision of 95%, which is at least 10% higher than other models, demonstrating superior performance and generalization capabilities. Full article
(This article belongs to the Special Issue Artificial Intelligence in Aerospace Propulsion)
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14 pages, 1573 KiB  
Article
Autonomous Decision-Making for Air Gaming Based on Position Weight-Based Particle Swarm Optimization Algorithm
by Anqi Xu, Hui Li, Yun Hong and Guoji Liu
Aerospace 2024, 11(12), 1030; https://doi.org/10.3390/aerospace11121030 - 17 Dec 2024
Viewed by 378
Abstract
As the complexity of air gaming scenarios continues to escalate, the demands for heightened decision-making efficiency and precision are becoming increasingly stringent. To further improve decision-making efficiency, a particle swarm optimization algorithm based on positional weights (PW-PSO) is proposed. First, important parameters, such [...] Read more.
As the complexity of air gaming scenarios continues to escalate, the demands for heightened decision-making efficiency and precision are becoming increasingly stringent. To further improve decision-making efficiency, a particle swarm optimization algorithm based on positional weights (PW-PSO) is proposed. First, important parameters, such as the aircraft in the scenario, are modeled and abstracted into a multi-objective optimization problem. Next, the problem is adapted into a single-objective optimization problem using hierarchical analysis and linear weighting. Finally, considering a problem where the convergence of the particle swarm optimization (PSO) is not enough to meet the demands of a particular scenario, the PW-PSO algorithm is proposed, introducing position weight information and optimizing the speed update strategy. To verify the effectiveness of the optimization, a 6v6 aircraft gaming simulation example is provided for comparison, and the experimental results show that the convergence speed of the optimized PW-PSO algorithm is 56.34% higher than that of the traditional PSO; therefore, the algorithm can improve the speed of decision-making while meeting the performance requirements. Full article
(This article belongs to the Section Aeronautics)
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17 pages, 5782 KiB  
Article
A Novel Approach to High Stability Engine Control for Aero-Propulsion Systems in Supersonic Conditions
by Fengyong Sun, Jitai Han and Changpo Song
Aerospace 2024, 11(12), 1029; https://doi.org/10.3390/aerospace11121029 - 16 Dec 2024
Viewed by 467
Abstract
In a supersonic state, the aero-engine operates under harsh circumstances of elevated temperature, high pressure, and rapid rotor speed. This work provides an innovative high-stability control technique for engines with fixed-geometry inlets, addressing stability control issues at the aero-propulsion system level. The discussion [...] Read more.
In a supersonic state, the aero-engine operates under harsh circumstances of elevated temperature, high pressure, and rapid rotor speed. This work provides an innovative high-stability control technique for engines with fixed-geometry inlets, addressing stability control issues at the aero-propulsion system level. The discussion begins with the importance of an integrated model for the intake and the aero-engine, introducing two stability indices (surge margin and buzz margin) to characterize inlet stability. A novel predictive model for engine air mass flow is developed to address the indeterminate issue of engine air mass flow. The integration of input parameters in the predictive model is refined using the least squares support vector regression (LSSVR) algorithm, and historical input data is used to enhance predictive performance, as validated by numerical simulation results. A data-driven adaptive augmented linear quadratic regulator (d-ALQR) control technique is suggested to adaptively modify the control parameters of the augmented linear quadratic regulator. A highly stable control strategy is finally proposed, integrating the predictive model with the d-ALQR controller. The simulation results conducted during maneuvering flight operations demonstrate that the developed high-stability controller can maintain the inlet in an efficient and safe condition, ensuring optimal compatibility between the engine and the inlet. Full article
(This article belongs to the Section Aeronautics)
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