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Keywords = atmospheric drag

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23 pages, 3056 KiB  
Article
Methodology for Evaluating Collision Avoidance Maneuvers Using Aerodynamic Control
by Desiree González Rodríguez, Pedro Orgeira-Crespo, Jose M. Nuñez-Ortuño and Fernando Aguado-Agelet
Remote Sens. 2025, 17(14), 2437; https://doi.org/10.3390/rs17142437 - 14 Jul 2025
Viewed by 185
Abstract
The increasing congestion of low Earth orbit (LEO) has raised the need for efficient collision avoidance strategies, especially for CubeSats without propulsion systems. This study proposes a methodology for evaluating passive collision avoidance maneuvers using aerodynamic control via a satellite’s Attitude Determination and [...] Read more.
The increasing congestion of low Earth orbit (LEO) has raised the need for efficient collision avoidance strategies, especially for CubeSats without propulsion systems. This study proposes a methodology for evaluating passive collision avoidance maneuvers using aerodynamic control via a satellite’s Attitude Determination and Control System (ADCS). By adjusting orientation, the satellite modifies its exposed surface area, altering atmospheric drag and lift forces to shift its orbit. This new approach integrates atmospheric modeling (NRLMSISE-00), aerodynamic coefficient estimation using the ADBSat panel method, and orbital simulations in Systems Tool Kit (STK). The LUME-1 CubeSat mission is used as a reference case, with simulations at three altitudes (500, 460, and 420 km). Results show that attitude-induced drag modulation can generate significant orbital displacements—measured by Horizontal and Vertical Distance Differences (HDD and VDD)—sufficient to reduce collision risk. Compared to constant-drag models, the panel method offers more accurate, orientation-dependent predictions. While lift forces are minor, their inclusion enhances modeling fidelity. This methodology supports the development of low-resource, autonomous collision avoidance systems for future CubeSat missions, particularly in remote sensing applications where orbital precision is essential. Full article
(This article belongs to the Special Issue Advances in CubeSat Missions and Applications in Remote Sensing)
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21 pages, 4831 KiB  
Article
Aerodynamic Optimization and Thermal Deformation Effects on Mid-Altitude Sounding Rockets: A Computational and Structural Analysis
by Aslam Abdullah, Mohd Fadhli Zulkafli, Muhammad Akmal Abdul Halim, Ramanathan Ashwin Thanneermalai and Bambang Basuno
Dynamics 2025, 5(3), 28; https://doi.org/10.3390/dynamics5030028 - 9 Jul 2025
Viewed by 242
Abstract
Mid-altitude sounding rockets are essential for atmospheric research and suborbital experimentation, where aerodynamic optimization and structural integrity are crucial for achieving targeted apogees. This study uses OpenRocket v23.09 for preliminary flight performance prediction and SolidWorks 2024 to integrate aerodynamic and structural analyses through [...] Read more.
Mid-altitude sounding rockets are essential for atmospheric research and suborbital experimentation, where aerodynamic optimization and structural integrity are crucial for achieving targeted apogees. This study uses OpenRocket v23.09 for preliminary flight performance prediction and SolidWorks 2024 to integrate aerodynamic and structural analyses through Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA). SolidWorks Flow Simulation and SolidWorks Simulation are used to assess how nose cone and fin geometries, as well as thermal deformation, influence flight performance. Among nine tested configurations, the ogive nose cone with trapezoidal fins achieved the highest simulated apogee of 2639 m, with drag coefficients of 0.480 (OpenRocket) and 0.401 (SolidWorks Flow Simulation). Thermal–structural analysis revealed a maximum nose tip displacement of 0.7249 mm for the rocket with the ogive nose cone, leading to an increasing drag coefficient of 0.404. However, thermal deformation of the ellipsoid nose cone led to a reduction in the drag coefficient from 0.419 to 0.399, even though it exhibited a slightly higher maximum displacement of 0.7443 mm. Mesh independence was confirmed with outlet velocity deviations below 1% across refinements. These results highlight the importance of integrated CFD–FEA approaches, geometric optimization, and material resilience for enhancing the aerodynamic performance of subsonic sounding rockets. Full article
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22 pages, 4467 KiB  
Article
Modification of Airfoil Thickness and Maximum Camber by Inverse Design for Operation Under Icing Conditions
by Ibrahim Kipngeno Rotich and László E. Kollár
Modelling 2025, 6(3), 64; https://doi.org/10.3390/modelling6030064 - 8 Jul 2025
Viewed by 263
Abstract
Wind turbine performance in cold regions is affected by icing which can lead to power reduction due to the aerodynamic degradation of the turbine blade. The development of airfoil shapes applied as blade sections contributes to improving the aerodynamic performance under a wide [...] Read more.
Wind turbine performance in cold regions is affected by icing which can lead to power reduction due to the aerodynamic degradation of the turbine blade. The development of airfoil shapes applied as blade sections contributes to improving the aerodynamic performance under a wide range of weather conditions. The present study considers inverse design coupled with numerical modelling to simulate the effects of varying airfoil thickness and maximum camber. The inverse design process was implemented in MATLAB R2023a, whereas the numerical models were constructed using ANSYS Fluent and FENSAP ICE 2023 R1. The inverse design process applied the modified Garabedian–McFadden (MGM) iterative technique. Shear velocities were calculated from the flow over an airfoil with slip conditions, and then this velocity distribution was modified according to the prevailing icing conditions to obtain the target velocities. A parameter was proposed to consider the airfoil thickness as well when calculating the target velocities. The airfoil generated was then exposed to various atmospheric conditions to check the improvement in the aerodynamic performance. The ice mass and lift-to-drag ratio were determined considering cloud characteristics under varying liquid water content (LWC) from mild to severe (0.1 g/m3 to 1 g/m3), median volume diameter (MVD) of 50 µm, and two ambient temperatures (−4 °C and −20 °C) that characterize freezing drizzle and in-cloud icing conditions. The ice mass on the blade section was not significantly impacted by modifying the shape after applying the process developed (i.e., <5%). However, the lift-to-drag ratio that describes the aerodynamic performance may even be doubled in the icing scenarios considered. Full article
(This article belongs to the Section Modelling in Engineering Structures)
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26 pages, 4569 KiB  
Article
Orbit Determination for Continuously Maneuvering Starlink Satellites Based on an Unscented Batch Filtering Method
by Anqi Lang and Yu Jiang
Sensors 2025, 25(13), 4079; https://doi.org/10.3390/s25134079 - 30 Jun 2025
Viewed by 399
Abstract
Orbit determination for non-cooperative low Earth orbit (LEO) objects undergoing continuous low-thrust maneuvers remains a significant challenge, particularly for large satellite constellations like Starlink. This paper presents a method that integrates the unscented transformation into a batch filtering framework with an optimized rho-minimum [...] Read more.
Orbit determination for non-cooperative low Earth orbit (LEO) objects undergoing continuous low-thrust maneuvers remains a significant challenge, particularly for large satellite constellations like Starlink. This paper presents a method that integrates the unscented transformation into a batch filtering framework with an optimized rho-minimum sigma points sampling strategy. The proposed approach uses a reduced dynamics model that considers Earth’s non-spherical gravity and models the combined effects of low-thrust and atmospheric drag as an equivalent along-track acceleration. Numerical simulations under different measurement noise levels, initial state uncertainties, and across multiple satellites confirm the method’s reliable convergence and favorable accuracy, even in the absence of prior knowledge of the along-track acceleration. The method consistently converges within 10 iterations and achieves 24 h position predictions with root mean square errors of less than 3 km under realistic noise conditions. Additional validation using a higher-fidelity model that explicitly accounts for atmospheric drag demonstrates improved accuracy and robustness. The proposed method can provide accurate orbit knowledge for space situational awareness associated with continuously maneuvering Starlink satellites. Full article
(This article belongs to the Section Remote Sensors)
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17 pages, 2302 KiB  
Article
Temporal Evolution of Small-Amplitude Internal Gravity Waves Generated by Latent Heating in an Anelastic Fluid Flow
by Amir A. M. Sayed, Amna M. Grgar and Lucy J. Campbell
AppliedMath 2025, 5(3), 80; https://doi.org/10.3390/appliedmath5030080 - 30 Jun 2025
Viewed by 176
Abstract
A two-dimensional time-dependent model is presented for upward-propagating internal gravity waves generated by an imposed thermal forcing in a layer of fluid with uniform background velocity and stable stratification under the anelastic approximation. The configuration studied is representative of a situation with deep [...] Read more.
A two-dimensional time-dependent model is presented for upward-propagating internal gravity waves generated by an imposed thermal forcing in a layer of fluid with uniform background velocity and stable stratification under the anelastic approximation. The configuration studied is representative of a situation with deep or shallow latent heating in the lower atmosphere where the amplitude of the waves is small enough to allow linearization of the model equations. Approximate asymptotic time-dependent solutions, valid for late time, are obtained for the linearized equations in the form of an infinite series of terms involving Bessel functions. The asymptotic solution approaches a steady-amplitude state in the limit of infinite time. A weakly nonlinear analysis gives a description of the temporal evolution of the zonal mean flow velocity and temperature resulting from nonlinear interaction with the waves. The linear solutions show that there is a vertical variation of the wave amplitude which depends on the relative depth of the heating to the scale height of the atmosphere. This means that, from a weakly nonlinear perspective, there is a non-zero divergence of vertical momentum flux, and hence, a non-zero drag force, even in the absence of vertical shear in the background flow. Full article
(This article belongs to the Special Issue Exploring the Role of Differential Equations in Climate Modeling)
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18 pages, 2232 KiB  
Article
Optimal Selection of Gravity Field Model Order for Spaceborne GNSS Receivers: A Study on System Resources and Real-Time Orbit Determination Accuracy
by Chongao Zhou, Jing Hu, Xiangyu Li, Meng Wang and Xianyang Liu
Appl. Sci. 2025, 15(10), 5607; https://doi.org/10.3390/app15105607 - 17 May 2025
Viewed by 410
Abstract
In this study, different data types are employed according to the objectives of each experiment. Simulated orbit data are used for analyzing the effects of atmospheric drag modeling in order to ensure controlled and consistent comparisons. In contrast, real on-orbit data from the [...] Read more.
In this study, different data types are employed according to the objectives of each experiment. Simulated orbit data are used for analyzing the effects of atmospheric drag modeling in order to ensure controlled and consistent comparisons. In contrast, real on-orbit data from the Gaofen-7 satellite are used for evaluating gravity field models with the aim of validating the accuracy and adaptability of the proposed method in real orbital environments. By examining the effects of various gravity field orders on orbit determination accuracy, computation time, and other factors using spaceborne GNSS navigation receivers, the study concludes that setting the gravity field model order to 60 is the best option for LEO satellites at 500 km altitude. With this setup, the orbit determination accuracies in the radial, tangential, and normal directions are 0.420 m, 0.191 m, and 0.225 m, respectively, for a three-dimensional position accuracy of 0.522 m. The computation time is 286 ms. Full article
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19 pages, 4898 KiB  
Article
Near-Real-Time Global Thermospheric Density Variations Unveiled by Starlink Ephemeris
by Zhuoliang Ou, Jiahao Zhong, Yongqiang Hao, Ruoxi Li, Xin Wan, Kang Wang, Jiawen Chen, Hao Han, Xingyan Song, Wenyu Du and Yanyan Tang
Remote Sens. 2025, 17(9), 1549; https://doi.org/10.3390/rs17091549 - 27 Apr 2025
Viewed by 645
Abstract
Previous efforts to retrieve thermospheric density using satellite payloads have been limited to a small number of satellites equipped with GNSS (Global Navigation Satellite System) receivers and accelerometers. These satellites are confined to a few orbital planes, and analysis can only be conducted [...] Read more.
Previous efforts to retrieve thermospheric density using satellite payloads have been limited to a small number of satellites equipped with GNSS (Global Navigation Satellite System) receivers and accelerometers. These satellites are confined to a few orbital planes, and analysis can only be conducted after the data are processed and updated, resulting in sparse and delayed thermospheric density datasets. In recent years, the Starlink constellation, developed and deployed by SpaceX, has emerged as the world’s largest low Earth orbit (LEO) satellite constellation, with over 6000 satellites in operations as of October 2024. Through the strategic use of multiple orbital shells featuring various inclinations and altitudes, Starlink ensures continuous near-global coverage. Due to extensive coverage and frequent maneuvers, SpaceX has publicly released predicted ephemeris data for all Starlink satellites since May 2021, with updates approximately every 8 h. With the ephemeris data of Starlink satellites, we first apply a maneuver detection algorithm based on mean orbital elements to analyze their maneuvering behavior. The results indicate that Starlink satellites exhibit more frequent maneuvers during thermospheric disturbances. Then, we calculate the mechanical energy loss caused by non-conservative forces (primarily atmospheric drag) through precise dynamical models. The results demonstrate that, despite certain limitations in Starlink ephemeris data, the calculated mechanical energy loss still effectively captures thermospheric density variations during both quiet and disturbed geomagnetic periods. This finding is supported by comparisons with Swarm-B data, revealing that SpaceX incorporates the latest space environment conditions into its orbit extrapolation models during each ephemeris update. With a maximum lag of only 8 h, this approach enables near-real-time monitoring of thermospheric density variations using Starlink ephemeris. Full article
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13 pages, 2345 KiB  
Article
Effect of Al2O3 Particle Addition on Fluidized Bed Thermochemical Heat Storage Performance of Limestone: From Instability Mitigation to Efficiency Enhancement
by Hongmei Yin, Yang Liu, Liguo Yang, Yingjie Li, Xiaoyi Zhu, Lei Zhang, Yu Ruan, Ming Ma and Xiaoxu Fan
Energies 2025, 18(7), 1791; https://doi.org/10.3390/en18071791 - 2 Apr 2025
Viewed by 315
Abstract
This study elucidates the mechanism of fluidization instability during limestone carbonation under a 100% CO2 atmosphere and determines the influence of Al2O3 fluidization aids (dosage and particle size) on exothermic performance. The experiments demonstrate that rapid CO2 absorption [...] Read more.
This study elucidates the mechanism of fluidization instability during limestone carbonation under a 100% CO2 atmosphere and determines the influence of Al2O3 fluidization aids (dosage and particle size) on exothermic performance. The experiments demonstrate that rapid CO2 absorption in the emulsion phase, coupled with insufficient gas replenishment from the bubble phase, disrupts the balance between drag force and buoyancy, leading to localized defluidization. This instability impedes gas exchange between the bubble and emulsion phases, resulting in bubble coalescence and channeling across the bed. The fluidization instability reduces the maximum exothermic temperature and causes significant temperature heterogeneity in the bed. With repeated thermal cycles (20 cycles), the CO2 absorption capacity of limestone diminishes (the effective conversion rate drops to 0.25), and the instability disappears. The addition of 5wt.% Al2O3 (particle size: 0.05–0.075 mm) stabilizes the fluidization state during carbonation, significantly homogenizing the bed temperature distribution, with maximum and average temperature differentials reduced by 63% and 89%, respectively, compared to pure limestone systems. Full article
(This article belongs to the Section D: Energy Storage and Application)
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9 pages, 2536 KiB  
Proceeding Paper
Integrated Power and Thermal Management System in a Parallel Hybrid-Electric Aircraft: An Exploration of Passive and Active Cooling and Temperature Control
by Zeyu Ouyang, Theoklis Nikolaidis, Soheil Jafari and Evangelia Pontika
Eng. Proc. 2025, 90(1), 36; https://doi.org/10.3390/engproc2025090036 - 13 Mar 2025
Viewed by 599
Abstract
Hybrid-electric aircraft (HEAs) represent a promising solution for reducing fuel consumption and emissions. However, the additional heat loads generated by the electrical propulsion systems in HEAs can diminish these benefits. To address this, an integrated power and thermal management system (IPTMS) is essential [...] Read more.
Hybrid-electric aircraft (HEAs) represent a promising solution for reducing fuel consumption and emissions. However, the additional heat loads generated by the electrical propulsion systems in HEAs can diminish these benefits. To address this, an integrated power and thermal management system (IPTMS) is essential to mitigate these challenges by optimizing the interaction between thermal management and power management. This paper presents a preliminary IPTMS design for a parallel HEA operating under International Standard Atmosphere (ISA) conditions. The design includes an evaluation of active cooling, passive cooling, and active temperature control strategies. The IPTMS accounts for heat loads from the engine system, including the generators, shaft bearings, and power gearboxes, as well as from the electrical propulsion system, such as motors, batteries, converters, and the electric bus. This study investigates the impact of battery power (BP) contribution to cooling power on required coolant pump power and induced ram air drag. A comparison of IPTMS performance under 0% and 100% BP conditions revealed that the magnitude of battery power contribution to cooling power does not significantly impact the thermal management system (TMS) performance due to the large disparity between the total battery power (maximum 950 kW) and the required cooling power (maximum 443 W). Additionally, it was determined that the motor-inverter loop accounts for 95% of the pump power and 97% of the ram air drag. These findings suggest that IPTMS optimization should prioritize the thermal domain, particularly the motor-inverter loop. This study provides new insights into IPTMS design for HEAs, paving the way for further exploration of IPTMS performance under various operating conditions and refinement of cooling strategies. Full article
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16 pages, 4406 KiB  
Article
The Impact of Air–Sea Flux Parameterization Methods on Simulating Storm Surges and Ocean Surface Currents
by Li Cai, Bin Wang, Wenqian Wang and Xingru Feng
J. Mar. Sci. Eng. 2025, 13(3), 541; https://doi.org/10.3390/jmse13030541 - 12 Mar 2025
Viewed by 680
Abstract
As the primary driver of energy transfer between atmospheric and oceanic systems, the air–sea momentum flux fundamentally governs coupled model dynamics through its regulation of wind stress partitioning. Given the complexity of the physical processes involved, simplified representations of these interactions are widely [...] Read more.
As the primary driver of energy transfer between atmospheric and oceanic systems, the air–sea momentum flux fundamentally governs coupled model dynamics through its regulation of wind stress partitioning. Given the complexity of the physical processes involved, simplified representations of these interactions are widely adopted to balance computational efficiency and physical fidelity. This systematic evaluation of five wind stress parameterizations reveals scheme-dependent variability in momentum partitioning efficiency, particularly under typhoon conditions. Our results quantify how the wind stress drag coefficient’s formulation alters atmosphere–ocean feedback, with wave-state aware schemes exhibiting superior surge prediction accuracy compared to wind-speed-dependent approaches. Specifically, a larger wind stress drag coefficient leads to increased atmospheric bottom stress and sea surface stress, resulting in weaker winds and larger sea surface currents and storm surges. These findings provide actionable guidelines into the performance and sensitivity of various air–sea coupled models and offer useful suggestions for improving operational marine forecasting systems. Full article
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29 pages, 10206 KiB  
Article
Finite-Time Control for Satellite Formation Reconfiguration and Maintenance in LEO: A Nonlinear Lyapunov-Based SDDRE Approach
by Majid Bakhtiari, Amirhossein Panahyazdan and Ehsan Abbasali
Aerospace 2025, 12(3), 201; https://doi.org/10.3390/aerospace12030201 - 28 Feb 2025
Cited by 2 | Viewed by 1249
Abstract
This paper introduces a nonlinear Lyapunov-based Finite-Time State-Dependent Differential Riccati Equation (FT-SDDRE) control scheme, considering actuator saturation constraints and ensuring that the control system operates within safe operational limits designed for satellite reconfiguration and formation-keeping in low Earth orbit (LEO) missions. This control [...] Read more.
This paper introduces a nonlinear Lyapunov-based Finite-Time State-Dependent Differential Riccati Equation (FT-SDDRE) control scheme, considering actuator saturation constraints and ensuring that the control system operates within safe operational limits designed for satellite reconfiguration and formation-keeping in low Earth orbit (LEO) missions. This control approach addresses the challenges of reaching the relative position and velocity vectors within a defined timeframe amid various orbital perturbations. The proposed approach guarantees precise formation control by utilizing a high-fidelity relative motion model that incorporates all zonal harmonics and atmospheric drag, which are the primary environmental disturbances in LEO. Additionally, the article presents an optimization methodology to determine the most efficient State-Dependent Coefficient (SDC) form regarding fuel consumption. This optimization process minimizes energy usage through a hybrid genetic algorithm and simulated annealing (HGASA), resulting in improved performance. In addition, this paper includes a sensitivity analysis to identify the optimized SDC parameterization for different satellite reconfiguration maneuvers. These maneuvers encompass radial, along-track, and cross-track adjustments, each with varying baseline distances. The analysis provides insights into how different parameterizations affect reconfiguration performance, ensuring precise and efficient control for each type of maneuver. The finite-time controller proposed here is benchmarked against other forms of SDRE controllers, showing reduced error margins. To further assess the control system’s effectiveness, an input saturation constraint is integrated, ensuring that the control system operates within safe operational limits, ultimately leading to the successful execution of the mission. Full article
(This article belongs to the Section Astronautics & Space Science)
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20 pages, 11536 KiB  
Article
Enhancing Storm Wave Predictions in the Gulf of Mexico: A Study on Wind Drag Parameterization in WAVEWATCH III
by C. Gowri Shankar and Mustafa Kemal Cambazoglu
J. Mar. Sci. Eng. 2025, 13(3), 403; https://doi.org/10.3390/jmse13030403 - 21 Feb 2025
Viewed by 678
Abstract
This study focuses on the significance of wind input source terms and their impact on wave generation in the wave model, WAVEWATCH III. Storm wave modeling capabilities were assessed with three different wind source term schemes ST4, ST6, and a new implementation ST6-IWD [...] Read more.
This study focuses on the significance of wind input source terms and their impact on wave generation in the wave model, WAVEWATCH III. Storm wave modeling capabilities were assessed with three different wind source term schemes ST4, ST6, and a new implementation ST6-IWD in a wave model to study Hurricane Ida (2021). A nested modeling approach was employed with high-resolution atmospheric wind forcing products obtained from the NOAA and the ECMWF. The model results were compared to field observations from NDBC buoys. One key finding indicates that the ST4 physical scheme is not necessarily suitable for modeling waves under extreme wind conditions. The ST6 and ST6-IWD schemes performed well for the hurricane scenario and the wave parameters obtained from these two sets of simulations were in good agreement with the observed values. The wind source term derived in the ST6 scheme holds good for wind speeds up to 50 m/s, whereas the drag method in ST6-IWD could remain stable up to ~113 m/s wind speeds. Therefore, this study recommends the ST6-IWD scheme, as it is suitable for more extreme hurricane wind conditions. It was also identified that the ST6-IWD method better estimates the peak wave periods and peak directions for Ida’s conditions. Full article
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23 pages, 6073 KiB  
Article
A VMD-SVM Method for LEO Satellite Orbit Prediction with Space Weather Parameters
by Hao Xu, Jiahao Liao, Yufei Luo and Yunhe Meng
Remote Sens. 2025, 17(5), 746; https://doi.org/10.3390/rs17050746 - 21 Feb 2025
Viewed by 833
Abstract
The technology of satellite orbit prediction (OP) is crucial in space engineering. However, it is difficult to precisely predict medium and long-term orbit for the low Earth-orbit (LEO) satellites because of time-varying space weather and inaccurate atmospheric density models. To address the problem, [...] Read more.
The technology of satellite orbit prediction (OP) is crucial in space engineering. However, it is difficult to precisely predict medium and long-term orbit for the low Earth-orbit (LEO) satellites because of time-varying space weather and inaccurate atmospheric density models. To address the problem, a novel intelligent OP method based on the variational mode decomposition-support vector machine (VMD-SVM) framework is presented. First, the concept of a pseudo-drag coefficient is defined, transforming the OP problem into a pseudo-drag coefficient prediction problem. Second, the relationship between space weather parameters and the pseudo-drag coefficient is analyzed using the VMD method, from which a strong correlation is shown. Furthermore, an SVM model combined with space weather characteristic parameters is employed to predict the pseudo-drag coefficient, significantly improving the precision of OP when further integrated into the orbital dynamics model. Experiments with data from engineering applications show that VMD-SVM medium and long-term OP technology is practical and effective. Full article
(This article belongs to the Special Issue Autonomous Space Navigation (Second Edition))
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26 pages, 8455 KiB  
Article
Re-Entry Comparison of a Spacecraft in Low Earth Orbit: Propulsion-Assisted vs. Non-Propulsive Configurations
by Antonio Sannino, Dylan De Prisco, Sergio Cassese, Stefano Mungiguerra, Anselmo Cecere and Raffaele Savino
Aerospace 2025, 12(2), 79; https://doi.org/10.3390/aerospace12020079 - 23 Jan 2025
Viewed by 1759
Abstract
This paper presents a mission concept for a Low Earth Orbit (LEO) satellite equipped with a payload for space experiments, designed to be recovered on Earth post-mission. The focus of this study is on developing a mission concept with fast de-orbit and accurate [...] Read more.
This paper presents a mission concept for a Low Earth Orbit (LEO) satellite equipped with a payload for space experiments, designed to be recovered on Earth post-mission. The focus of this study is on developing a mission concept with fast de-orbit and accurate landing capability for a small satellite payload. Two re-entry configurations are analyzed: one employing a deployable aero-brake heat shield for aerodynamic descent and another integrating a propulsion system. Aerodynamic analysis of the capsule, including drag coefficient and stability at relevant altitudes, was conducted using the Direct Simulation Monte Carlo (DSMC) method. A trade-off analysis, accounting for uncertainties such as CD, atmospheric density, and ignition timing, revealed significant differences in mission profiles. A propulsion system providing a ΔV of approximately 100 m/s reduces descent time from 54 days (aerodynamic-only re-entry) to under 1 h, without altering trajectory. Drag-related uncertainties contribute to a landing dispersion of ~100 km, while a ±1% error in total impulse increases dispersion to 400 km. A monopropellant rocket engine was preliminarily designed, meeting constraints such as catalytic chamber pressure and performance targets. The resulting thruster, weighing under 4 kg and contained within a 250 mm-high, 350 mm-diameter cylinder, supports three potential component layouts. Full article
(This article belongs to the Special Issue Space Propulsion: Advances and Challenges (3rd Volume))
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18 pages, 12499 KiB  
Article
Windbreak Effectiveness of Single and Double-Arranged Shelterbelts: A Parametric Study Using Large Eddy Simulation
by Jingxue Wang, Luca Patruno, Zhongcan Chen, Qingshan Yang and Yukio Tamura
Forests 2024, 15(10), 1760; https://doi.org/10.3390/f15101760 - 8 Oct 2024
Cited by 2 | Viewed by 1300
Abstract
Shelterbelts provide essential protection against wind erosion and soil degradation, as well as protection for fruit-bearing plants and crops from strong winds. Enhancing their sheltering capabilities requires optimizing their pattern and orientation, as well as defining their height and desired canopy shape, according [...] Read more.
Shelterbelts provide essential protection against wind erosion and soil degradation, as well as protection for fruit-bearing plants and crops from strong winds. Enhancing their sheltering capabilities requires optimizing their pattern and orientation, as well as defining their height and desired canopy shape, according to the desired performance. In this work, Large Eddy Simulation is employed to investigate the flow field and windbreak effectiveness of single and double-arranged shelterbelts characterized by different geometry and resistance to the air passage for neutral atmospheric condition. In particular, the canopy of the shelterbelts is modeled as an isotropic porous medium immersed in atmospheric boundary layer flow using the Darcy–Forchheimer model. Results show that a shelterbelt with a rectangular-shaped cross-section and a large canopy height results in the most significant reduction in mean wind speed and TKE, thus providing a large wind-protection region. As the spacing distance of double-arranged shelterbelts increases, the protection zones formed by both shelterbelts are reduced. The systematic comparisons of flow patterns, drag force coefficients, and windbreak effectiveness indicators of a series of single and double-arranged shelterbelts are essential for optimizing the design and management of shelterbelts. Full article
(This article belongs to the Section Forest Meteorology and Climate Change)
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