Journal Description
Aerospace
Aerospace
is a peer-reviewed, open access journal of aeronautics and astronautics published monthly online by MDPI. The European Aeronautics Science Network (EASN), and the ECATS International Association are affiliated with Aerospace and their members receive a discount on the article processing charges.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, SCIE (Web of Science), Inspec, and other databases.
- Journal Rank: JCR - Q1 (Engineering, Aerospace) / CiteScore - Q2 (Aerospace Engineering)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 22.3 days after submission; acceptance to publication is undertaken in 2.7 days (median values for papers published in this journal in the second half of 2023).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
- Companion journal: Astronomy.
Impact Factor:
2.6 (2022);
5-Year Impact Factor:
2.6 (2022)
Latest Articles
Operational Angular Track Reconstruction in Space Surveillance Radars through an Adaptive Beamforming Approach
Aerospace 2024, 11(6), 451; https://doi.org/10.3390/aerospace11060451 - 1 Jun 2024
Abstract
In the last few years, many space surveillance initiatives have started to consider the problem represented by resident space object overpopulation. In particular, the European Space Surveillance and Tracking (EUSST) consortium is in charge of providing services like collision avoidance, fragmentation analysis, and
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In the last few years, many space surveillance initiatives have started to consider the problem represented by resident space object overpopulation. In particular, the European Space Surveillance and Tracking (EUSST) consortium is in charge of providing services like collision avoidance, fragmentation analysis, and re-entry, which rely on measurements obtained through ground-based sensors. BIRALES is an Italian survey radar belonging to the EUSST framework and is capable of providing measurements including Doppler shift, slant range, and angular profile. In recent years, the Music Approach for Track Estimate and Refinement (MATER) algorithm has been developed to retrieve angular tracks through an adaptive beamforming technique, guaranteeing the generation of more accurate and robust measurements with respect to the previous static beamforming approach. This work presents the design of a new data processing chain to be used by BIRALES to compute the angular track. The signal acquired by the BIRALES receiver array is down-converted and the receiver bandwidth is split into multiple channels, in order to maximize the signal-to-noise ratio of the measurements. Then, the signal passes through a detection block, where an isolation procedure creates, for each epoch, signal correlation matrices (CMs) related to the channels involved in the detection and then processes them to isolate the data stream related to a single detected source. Consequently, for each epoch and for each detected source, just the CM featuring the largest signal contribution is kept, allowing deriving the Doppler shift measurement from the channel illumination sequence. The MATER algorithm is applied to each CM stream, first estimating the signal directions of arrival, then grouping them in the observation time window, and eventually returning the target angular track. Ambiguous estimates may be present due to the configuration of the receiver array, which cause spatial aliasing phenomena. This problem can be addressed by either exploiting transit prediction (in the case of cataloged objects), or by applying tailored criteria (for uncatalogued objects). The performance of the new architecture was assessed in real operational scenarios, demonstrating the enhancement represented by the implementation of the channelization strategy, as well as the angular measurement accuracy returned by MATER, in both nominal and off-nominal scenarios.
Full article
(This article belongs to the Special Issue Track Detection of Resident Space Objects)
Open AccessArticle
Pilot Assistance Systems for Energy-Optimized Approaches: Is It Possible to Reduce Fuel Consumption and Noise at the Same Time?
by
Jean Marc Wunderli, Jonas Meister, Johan Boyer, Martin Gerber, Tobias Bauer and Fethi Abdelmoula
Aerospace 2024, 11(6), 450; https://doi.org/10.3390/aerospace11060450 - 1 Jun 2024
Abstract
Air traffic has appreciable environmental impacts, especially regarding gaseous emissions and noise. Recent studies have shown that the energy management during approach is a driving factor regarding environmental impact and is especially challenging for pilots. In a previous project, a newly developed pilot
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Air traffic has appreciable environmental impacts, especially regarding gaseous emissions and noise. Recent studies have shown that the energy management during approach is a driving factor regarding environmental impact and is especially challenging for pilots. In a previous project, a newly developed pilot assistance system called LNAS (Low Noise Augmentation System) showed the potential of energy-optimized approaches to reduce fuel consumption and noise. Within the SESAR Exploratory Research project DYNCAT, novel functions based on LNAS have been integrated in the flight management system. In this contribution, results from real-time simulations with the enhanced FMS are presented, and mitigation of the environmental impact is analyzed. It was shown that with DYNCAT, the energy management could be improved, resulting in a later configuration and engines mostly in idle. With DYNCAT, procedures were also flown more uniformly and the variability in noise and fuel outcomes was reduced. However, the results revealed a trade-off for optimizing noise and fuel consumption simultaneously, whereby both parameters can be improved along specific optimum curves. A perfect strategy to minimize noise would be to first reduce speed and only secondly height, as high speeds lead to higher levels of airframe noise and sound exposure increases with decreasing distance. In contrast, saving fuel might be achieved by reducing the flight time, as the engines consume fuel even when being in idle.
Full article
(This article belongs to the Special Issue Multidisciplinary Design Optimization for Climate-Neutral Transport Aviation)
Open AccessArticle
Exploring the Aerodynamic Effect of Blade Gap Size via a Transient Simulation of a Four-Stage Turbine
by
Xinlei Hu, Le Cai, Yingjie Chen, Xuejian Li, Songtao Wang, Xinglong Fang and Kanxian Fang
Aerospace 2024, 11(6), 449; https://doi.org/10.3390/aerospace11060449 - 1 Jun 2024
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With the impact of size on low-pressure turbines (LPTs) increasing, the gap between the blades has shrunk, inevitably influencing the unsteady effects inside the turbine. In this study, the aerodynamic effect of the blade gap size is investigated using a compressible unsteady Reynolds-averaged
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With the impact of size on low-pressure turbines (LPTs) increasing, the gap between the blades has shrunk, inevitably influencing the unsteady effects inside the turbine. In this study, the aerodynamic effect of the blade gap size is investigated using a compressible unsteady Reynolds-averaged Navier–Stokes (URANS) model on the basis of a four-stage LPT. Simulations are conducted in which the gap between the third-stage stator (S3) and rotor (R3) varies from 0.2 to 0.8 times the axial chord length of the R3 blade. The multi-stage environment reflects the complexity of real low-Reynolds flow fields. Computational fluid dynamics is used to analyze the flow field in detail. The results demonstrate that in the small-gap (AG-0.2) case, the turbulence kinetic energy (TKE) level of the S3 wake close to the R3 leading edge is four-thirds of that in the large-gap (AG-0.8) case. The higher intensity of the wake impacting on the blade results in a higher inverse pressure gradient in the rear part of the R3 suction surface, which increases the profile loss. However, the AG-0.2 case leads to fewer losses caused by the passage vortex in the hub area under the influence of the higher intensity of the wake.
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Open AccessArticle
Multi-Fidelity Adaptive Sampling for Surrogate-Based Optimization and Uncertainty Quantification
by
Andrea Garbo, Jigar Parekh, Tilo Rischmann and Philipp Bekemeyer
Aerospace 2024, 11(6), 448; https://doi.org/10.3390/aerospace11060448 - 31 May 2024
Abstract
Surrogate-based algorithms are indispensable in the aerospace engineering field for reducing the computational cost of optimization and uncertainty quantification analyses, particularly those involving computationally intensive solvers. This paper presents a novel approach for enhancing the efficiency of surrogate-based algorithms through a new multi-fidelity
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Surrogate-based algorithms are indispensable in the aerospace engineering field for reducing the computational cost of optimization and uncertainty quantification analyses, particularly those involving computationally intensive solvers. This paper presents a novel approach for enhancing the efficiency of surrogate-based algorithms through a new multi-fidelity sampling technique. Unlike existing multi-fidelity methods which are based on a single multiplicative acquisition function, the proposed technique decouples the identification of the new infill sample from the selection of the fidelity level. The location of the infill sample is determined by leveraging the highest fidelity surrogate model, while the fidelity level used for its performance evaluation is chosen as the cheapest one within the “accurate enough” models at the infill location. Moreover, the methodology introduces the application of the Jensen–Shannon divergence to quantify the accuracy of the different fidelity levels. Overall, the resulting technique eliminates some of the drawbacks of existing multiplicative acquisition functions such as the risk of continuous sampling from lower and cheaper fidelity levels. Experimental validation conducted in surrogate-based optimization and uncertainty quantification scenarios demonstrates the efficacy of the proposed approach. In an aerodynamic shape optimization task focused on maximizing the lift-to-drag ratio, the multi-fidelity strategy achieved comparable results to standard single-fidelity sampling but with approximately a five-fold improvement in computational efficiency. Likewise, a similar reduction in computational costs was observed in the uncertainty quantification problem, with the resulting statistical values aligning closely with those obtained using traditional single-fidelity sampling.
Full article
(This article belongs to the Special Issue Data-Driven Aerodynamic Modeling)
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Open AccessArticle
Built On-Orbit Robotically Assembled Gigatruss (BORG): Ground Robotic Demonstration
by
Samantha Chapin, Holly Everson, William Chapin and Erik Komendera
Aerospace 2024, 11(6), 447; https://doi.org/10.3390/aerospace11060447 - 31 May 2024
Abstract
The next generation of large space infrastructure will require crucial advancements in current technology. Current methodologies focus on large deployable structures folded into cramped payload fairings or revolutionary assembly techniques requiring many moving components. Utilizing both in-space assembly and deployable concepts, a hybrid
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The next generation of large space infrastructure will require crucial advancements in current technology. Current methodologies focus on large deployable structures folded into cramped payload fairings or revolutionary assembly techniques requiring many moving components. Utilizing both in-space assembly and deployable concepts, a hybrid mixed assembly scheme was posed using smaller deployable units interspersed with rigid connecting elements to assemble these large architectures. The Built On-Orbit Robotically Assembled Gigatruss (BORG) structure allows for modularity in assembly and repair with the number of separate elements comprising the structure to be reduced, compared to strut-by-strut assembly. The following documents the process of constructing and running physical trials on a prototype BORG architecture. Additionally, a Semantic and Fiducial Aided Graph Simultaneous Localization and Mapping (SF-GraphSLAM) approach is taken to verify the relation of assembled and deployed truss elements to aid in error evaluation and state estimation. This technology demonstration stands as a proof of concept in verifying the viability of the BORG architecture as a method for large structure assembly.
Full article
(This article belongs to the Special Issue Advanced Spacecraft/Satellite Technologies)
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Open AccessArticle
The Derivation of an Empirical Model to Estimate the Power Spectral Density of Turbulent Boundary Layer Wall Pressure in Aircraft Using Machine Learning Regression Techniques
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Zachary Huffman and Joana Rocha
Aerospace 2024, 11(6), 446; https://doi.org/10.3390/aerospace11060446 - 31 May 2024
Abstract
Aircraft cabin noise poses a health risk for regular passengers and crew, being connected to a heightened risk of cardiovascular disease, hearing loss, and sleep deprivation. At cruise conditions, its most significant cause is random pressure fluctuations in the turbulent boundary layer of
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Aircraft cabin noise poses a health risk for regular passengers and crew, being connected to a heightened risk of cardiovascular disease, hearing loss, and sleep deprivation. At cruise conditions, its most significant cause is random pressure fluctuations in the turbulent boundary layer of aircraft, and as such the derivation of an accurate model to predict the power spectral density of these fluctuations remains an important ongoing research topic. Early models (such as those by Lowson and Robertson) were derived by simplifying the governing equations, the Reynolds-averaged Navier Stokes equations, and solving for fluctuating pressure. Most subsequent equations were derived either by applying statistical and mathematical techniques to simplify the Robertson and Lowson models or by making modifications to address apparent shortcomings. Overall, these models have had varying success—most are accurate near the Mach and Reynolds numbers they were designed for, but less accurate under other conditions. In response to this shortcoming, Dominique demonstrated that a novel technique (machine learning, specifically artificial neural networking) could produce a model that is accurate under most flight conditions. This paper extends this research further by applying a different machine learning technique (nonlinear least squares regression analysis) and dimensional analysis to produce a new model. The resulting equation proved accurate under its design conditions of low airspeed (approximately 11 m/s) and low turbulent Reynolds number (approximately 850,000). However, a larger dataset with more diverse flight conditions would be required to make the model more generally applicable.
Full article
(This article belongs to the Topic Advances in Underwater Acoustics and Aeroacoustics)
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Open AccessArticle
Identification and Analysis of Flight Delay Based on Process Relevance
by
Qingmiao Ding, Linyan Ma, Yanyu Cui, Bin Cheng and Xuan He
Aerospace 2024, 11(6), 445; https://doi.org/10.3390/aerospace11060445 - 31 May 2024
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Flight delay identification is an important way to coordinate the operation time of airport ground service providers and improve the efficiency of airport operations. By analyzing the flight turnaround operation process, considering the randomness and synchronization of the turnaround process, and using Colored
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Flight delay identification is an important way to coordinate the operation time of airport ground service providers and improve the efficiency of airport operations. By analyzing the flight turnaround operation process, considering the randomness and synchronization of the turnaround process, and using Colored Petri Nets and Python (4.0.1), we explore the correlation between various links in the flight turnaround process and the take-off delay at the next station. This paper is committed to improving the service performance of airports and airlines, dynamically predicting flight delays, and providing guidance for avoiding excessive time in the actual operation of bad combinations. The results show that there are six kinds of bad combinations in the departure slip-out link, which is the most likely to affect the transit time. The maximum lifting degree in the bad combination is 2.043, and the maximum average delay time in the bad combination is 22.5 min. When the combination of passenger boarding and departure slip-out time is too long, it has a great positive correlation with delay. When the other links are in a state of being able to pass the station on time, the departure time and baggage loading and unloading are the two links that most affect the flight delay value.
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Open AccessArticle
Negative Medium-Voltage Direct Current Discharges in Air under Simulated Sub-Atmospheric Pressures for All-Electric Aircraft
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Sai Pavan Kalakonda, Mohammad Hamidieh, Adil Bhojwani and Mona Ghassemi
Aerospace 2024, 11(6), 444; https://doi.org/10.3390/aerospace11060444 - 30 May 2024
Abstract
The increase in the global temperature due to greenhouse gas emissions is a major concern to the world. To achieve the goal of zero emissions by 2050 in the USA the practical realization of all-electric vehicles, particularly all-electric aircraft (AEA), is important. For
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The increase in the global temperature due to greenhouse gas emissions is a major concern to the world. To achieve the goal of zero emissions by 2050 in the USA the practical realization of all-electric vehicles, particularly all-electric aircraft (AEA), is important. For the design of electrical power systems (EPSs) in all-electric aircraft, a bipolar medium-voltage direct current (MVDC) system of ±5 kV is being investigated. However, several challenges manifest when using such voltages in a low-pressure environment. One of the main challenges is the partial discharge (PD) behavior of the insulation. It is important to study the PD behavior of the insulation by simulating the aviation environment in the lab. This work aimed to study the partial discharge behavior of air under a negative DC voltage in a needle-to-plane electrode geometry by simulating the aviation pressures in the lab. The partial discharge inception voltage (PDIV) and the breakdown voltage (BDV) show an obvious pressure-dependent variation. Regression analysis was performed to better understand the relationship between the PDIV and pressures. Plots were drawn for the average discharge current at each voltage step until breakdown. This paper’s findings can provide valuable insight into the design of EPS for an AEA. To the best of our knowledge, such a study has not been carried out to date.
Full article
(This article belongs to the Special Issue Electric Power Systems and Components for All-Electric Aircraft)
Open AccessArticle
Orbital Pursuit–Evasion–Defense Linear-Quadratic Differential Game
by
Zhen-Yu Li
Aerospace 2024, 11(6), 443; https://doi.org/10.3390/aerospace11060443 - 30 May 2024
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To find superior guidance strategies for preventing possible interception threats from space debris, out-of-control satellites, etc., this paper investigates an orbital pursuit–evasion–defense game problem with three players called the pursuer, the evader, and the defender, respectively. In this game, the pursuer aims to
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To find superior guidance strategies for preventing possible interception threats from space debris, out-of-control satellites, etc., this paper investigates an orbital pursuit–evasion–defense game problem with three players called the pursuer, the evader, and the defender, respectively. In this game, the pursuer aims to intercept the evader, while the evader tries to escape the pursuer. A defender accompanying the evader can protect the evader by actively intercepting the pursuer. For such a game, a linear-quadratic duration-adaptive (LQDA) strategy is first proposed as a basic strategy for the three players. Later, an advanced pursuit strategy is designed for the pursuer to evade the defender when they are chasing the evader. Meanwhile, a cooperative evasion–defense strategy is proposed for the evader and the defender to build their cooperation. Simulations determined that the proposed LQDA strategy has higher interception accuracy than the classic LQ strategy. Meanwhile, the proposed two-sided pursuit strategy can improve the interception performance of the pursuer against a non-cooperative defender. But if the evader and defender employ the proposed cooperation strategy, the pursuer’s interception will be much more difficult.
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Open AccessArticle
Activity Modeling and Characterization for Airport Bird Situation Awareness Using Avian Radar Datasets
by
Jia Liu, Qunyu Xu, Min Su and Weishi Chen
Aerospace 2024, 11(6), 442; https://doi.org/10.3390/aerospace11060442 - 30 May 2024
Abstract
Birds in airport airspaces are critical threats to aviation safety. Avian radar systems are effective for long-range bird monitoring and hazard warning, but their functionalities are confined to a short-term temporal scale. Spatial–temporal activity modeling and characterization for birds are not studied comprehensively
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Birds in airport airspaces are critical threats to aviation safety. Avian radar systems are effective for long-range bird monitoring and hazard warning, but their functionalities are confined to a short-term temporal scale. Spatial–temporal activity modeling and characterization for birds are not studied comprehensively from historical radar datasets. This paper proposes a radar data analysis framework to characterize bird activities as a long-term functionality complement. Spatial domain modeling initializes data mining by extracting reference spots for data filtering. Bird activities are quantified in the temporal domain. Activity degrees are utilized for periodicity extraction with the daily segment random permutation strategy. Categorical probabilities are calculated to interpret bird activity periodicity characters. Historical radar datasets collected from an avian radar system are adopted for validation. The extracted activity periodicity trends for diurnal birds present prominent consistency with artificial observation records. Migratory bird periodicity trends present a good match with ornithology understandings. A preliminary experiment is presented to indicate the possibility of predicting bird activity levels, especially for migratory birds.
Full article
(This article belongs to the Special Issue Advances in Air Traffic and Airspace Control and Management (2nd Edition))
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Open AccessArticle
Exploring the Psychological Well-Being of Flight Cadets through a Comprehensive Survey Analysis of Self-Awareness and Self-Acceptance
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Dan Miao, Xiaodong Cao, Bingxu Zhao, Yuan Shi and Yunze Shi
Aerospace 2024, 11(6), 441; https://doi.org/10.3390/aerospace11060441 - 30 May 2024
Abstract
A robust level of self-awareness and self-acceptance is crucial for flight cadets. In this study, a total of 106 flight cadets from various grades and flight training sites were assessed using the self-awareness and self-acceptance scale. The scales were optimized through item analysis,
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A robust level of self-awareness and self-acceptance is crucial for flight cadets. In this study, a total of 106 flight cadets from various grades and flight training sites were assessed using the self-awareness and self-acceptance scale. The scales were optimized through item analysis, reliability, and validity assessments. The finalized scales demonstrated an acceptable level of reliability and validity. Upon analyzing the collected data, it was observed that the overall self-awareness and -acceptance levels among the evaluated pilot students fell within the normal range. However, identifying positive symptoms directly proved challenging. The tested flight cadets exhibited moderate symptoms across each factor, with instances of severe symptoms in academic self-awareness. Notably, flight cadets trained abroad exhibited a lower level of self-awareness and -acceptance compared to those trained in China. But this phenomenon was not reflected in grade difference. Regression analysis revealed that physical and emotional self-awareness dimensions accounted for 62% of the variations in the psychological dimension, while passive self-acceptance explained 72% of the changes in active self-acceptance. Finally, in view of the issues found in the research, corresponding management measures and recommendations are presented to enhance the self-awareness and -acceptance levels of flight cadets.
Full article
(This article belongs to the Special Issue Aerospace Human–Machine and Environmental Control Engineering)
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Modeling and Analysis of the Flap Actuation System Considering the Nonlinear Factors of EMA, Joint Clearance and Flexibility
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Qi Wan, Chunyu Song, Yong Zhou, Ruiting Tong, Shangjun Ma and Geng Liu
Aerospace 2024, 11(6), 440; https://doi.org/10.3390/aerospace11060440 - 29 May 2024
Abstract
The performance of the flap actuation system directly affects the control effect and the flight quality of an aircraft. The electromechanical actuator (EMA) and the linkage mechanism are important components of the system. In order to achieve the goals of good transmission accuracy
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The performance of the flap actuation system directly affects the control effect and the flight quality of an aircraft. The electromechanical actuator (EMA) and the linkage mechanism are important components of the system. In order to achieve the goals of good transmission accuracy and dynamic response, the influence of nonlinear properties in the transmission chain including the EMA and linkage mechanism should be considered. A co-simulation model at the system-level of the flap actuation system was developed, which takes nonlinear factors of the EMA, the impact dynamics of the linkage mechanism with joint clearance and the rigid–flexible coupling characteristics into account. Moreover, the experiments with different command frequencies and loads were performed. The simulation and experimental results were compared to verify the effectiveness of the co-simulation model. Finally, the effects of nonlinear properties including the contact stiffness and clearance of a planetary roller screw mechanism, EMA anchorage stiffness, number of clearance joints, flexibility and load are discussed. This work can contribute to analyzing the performance of an electromechanical multibody system with nonlinear characteristics, which has crucial academic meaning and engineering application values for the development of systems with high speed, good reliability and long life.
Full article
(This article belongs to the Section Aeronautics)
Open AccessArticle
Instrument to Study Plume Surface Interactions (PSI) on the Lunar Surface: Science Motivation, Requirements, Instrument Overview, and Test Plans
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Ariana Bueno, Michael J. Krasowski, Norman Prokop, Lawrence C. Greer, Christina M. Adams and Nilton O. Rennó
Aerospace 2024, 11(6), 439; https://doi.org/10.3390/aerospace11060439 - 29 May 2024
Abstract
Safe landings are imperative to accomplish NASA’s Artemis goal to enable human exploration on the Moon, including sample collection missions. However, a process known as plume surface interaction (PSI) presents a significant hazard to lunar landings. PSI occurs when the engine exhaust of
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Safe landings are imperative to accomplish NASA’s Artemis goal to enable human exploration on the Moon, including sample collection missions. However, a process known as plume surface interaction (PSI) presents a significant hazard to lunar landings. PSI occurs when the engine exhaust of a lander interacts with the surface ejecting large amounts of regolith particles at high velocities that can interfere with the landing, disturb the surface, and damage hardware. To better understand PSI, the particle impact event (PIE) sensor is being developed to measure the kinetic energy and the flux of ejecta during landings, to quantify the potential damage, and to quantify the ejecta displaced. Multiple parameters were estimated to define the PIE instrument requirements. These estimates demonstrate that ejecta can travel at velocities of up to 800 m/s and impact the surrounding area with energies of up to 400 µJ. A significant amount of ejecta can be deposited several 10 s of meters away from the landing site, modifying the surface and causing dust-related challenges. The PIE sensor will be launched for the first time in an upcoming lunar lander. Then, PIE measurements will be used to improve PSI prediction capabilities and develop mitigation strategies to ensure safe landings.
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(This article belongs to the Special Issue Spacecraft Sample Collection)
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Open AccessArticle
Experimental Investigation of Lithium-Ion Batteries Thermal Runaway Propagation Consequences under Different Triggering Modes
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Juan Yang, Wenhao Liu, Haoyu Zhao and Qingsong Zhang
Aerospace 2024, 11(6), 438; https://doi.org/10.3390/aerospace11060438 - 29 May 2024
Abstract
In the stage of aircraft development and airworthiness verification, it is necessary to master the influence of lithium-ion battery (LIB) thermal runaway (TR) propagation. In this paper, the battery TR propagation behavior under different trigger positions and modes is studied experimentally, and the
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In the stage of aircraft development and airworthiness verification, it is necessary to master the influence of lithium-ion battery (LIB) thermal runaway (TR) propagation. In this paper, the battery TR propagation behavior under different trigger positions and modes is studied experimentally, and the calculation and comparison are carried out from the parameters of real-time temperature, voltage, propagation speed, total energy released, and solid ejecta. When the two adjacent cells at the top corner, side, and center of the module are overheated, TR occurs at about 1000 s for the triggered cells, while the whole-overheating trigger mode takes a longer time. The latter’s transmission speed is extremely fast, spreading 2.67 cells per second on average. The heat generated by the solid ejecta of the whole-overheating trigger mode is 82,437 J, which is more destructive. The voltage of the triggered cell fluctuates abnormally in a precursor manner when the internal active substances in the cell undergo a self-generated thermal reaction. This work can provide a reference for the safety and economical design of system installations and the correct setting of airworthiness verification Method of Compliance (MoC) experiments to verify whether the aircraft can bear and contain the adverse effects caused by LIB TR.
Full article
(This article belongs to the Special Issue Electric Power Systems and Components for All-Electric Aircraft)
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Open AccessArticle
Effects of Different Initial Conditions on Combustion Process of Ammonium Dinitramide-Based Energetic Propellant in Straight Nozzle
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Luyun Jiang, Chentao Mao, Jianhui Han, Haichao Cui, Baosheng Du, Yongzan Zheng, Jifei Ye and Yanji Hong
Aerospace 2024, 11(6), 437; https://doi.org/10.3390/aerospace11060437 - 28 May 2024
Abstract
As a new type of green propellant, ammonium dinitramide (ADN)-based energetic propellants have wide application value and development potential in the field of space propulsion. This paper delves into the intricate impact of varying initial temperatures, pressures, and propellant component ratios on critical
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As a new type of green propellant, ammonium dinitramide (ADN)-based energetic propellants have wide application value and development potential in the field of space propulsion. This paper delves into the intricate impact of varying initial temperatures, pressures, and propellant component ratios on critical parameters, including temperature, combustion rate, and heat release, in the straight nozzle of an ADN-based propellant. The findings indicate that an elevation in both initial temperature and ADN ratio expedites the thermal decomposition rate of ADN, thereby elevating the average temperature in the nozzle. However, the elevation in initial temperature has a negative effect on the overall rise amplitude of average temperature. Furthermore, the initial pressure setting is crucial in determining whether the oxidation reaction of the fuel CH3OH occurs in ADN propellants. When the initial pressure is greater than 10 atm, CH3OH is completely consumed, and the final average temperature is about 2650 K, which increases by 558.89% compared with that at 1 atm. Our work aims to provide theoretical guidance and practical optimization strategies for enhancing propellant performance and optimizing thruster structure design.
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(This article belongs to the Section Astronautics & Space Science)
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Open AccessArticle
A Simple Method for Identifying the Natural Frequency of a Micro Satellite with a Primary Structure Made of Aluminum Alloy
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Kei-ichi Okuyama, Keigo Yoshikawa and Chihiro Oue
Aerospace 2024, 11(6), 436; https://doi.org/10.3390/aerospace11060436 - 28 May 2024
Abstract
Micro satellites must survive severe mechanical conditions during their launch phase. Usually, the structural design of a micro satellite is performed using the internal stress analysis and the natural frequency analysis, which are based on a finite element method (FEM). The validity of
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Micro satellites must survive severe mechanical conditions during their launch phase. Usually, the structural design of a micro satellite is performed using the internal stress analysis and the natural frequency analysis, which are based on a finite element method (FEM). The validity of this structural design is evaluated through vibration tests. In an early stage of development, which has a FEM model of a satellite in the process of creation, presumption of the minimum natural frequency of a satellite may be difficult. In this study, a simple method for determining the longitudinal and lateral minimum natural frequencies of micro satellites during the ascent phase was clarified. The structure of the micro satellites used in this research is made of aluminum alloy, and they have a monocoque structure. The Young’s modulus and moment of inertia of area used to calculate the minimum natural frequencies were determined using the area ratio of the monocoque structure to the entire satellite. When the method proposed in this study is used, the calculated values agree with the vibration-tested values within 10%. In particular, in the case of W6U-type satellites, the two agree within a range of approximately 2% in the longitudinal direction and approximately 5% in the lateral direction. In the early stages of a satellite structure design when a FEM cannot be created, the proposed method will work effectively as the method of determining the minimum natural frequency. In order to simplify the process of micro satellites development, this paper describes a practical estimation method of the minimum natural frequency for micro satellites.
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(This article belongs to the Special Issue Deployable Space Structures and Mechanisms)
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Open AccessArticle
Reliability-Based Topology Optimization with a Proportional Topology for Reliability
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Noppawit Kumkam and Suwin Sleesongsom
Aerospace 2024, 11(6), 435; https://doi.org/10.3390/aerospace11060435 - 28 May 2024
Abstract
This research proposes an efficient technique for reliability-based topology optimization (RBTO), which deals with uncertainty and employs proportional topology optimization (PTO) to achieve the optimal reliability structure. The recent technique, called proportional topology optimization for reliability (PTOr), uses Latin hypercube sampling (LHS) for
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This research proposes an efficient technique for reliability-based topology optimization (RBTO), which deals with uncertainty and employs proportional topology optimization (PTO) to achieve the optimal reliability structure. The recent technique, called proportional topology optimization for reliability (PTOr), uses Latin hypercube sampling (LHS) for uncertainty quantification. The difficulty of the double-loop nested problem in uncertainty quantification (UQ) with LHS can be alleviated by the power of PTO, enabling RBTO to be performed easily. The rigorous advantage of PTOr is its ability to accomplish topology optimization (TO) without gradient information, making it faster than TO with evolutionary algorithms. Particularly, for reliability-based topology design, evolutionary techniques often fail to achieve satisfactory results compared to gradient-based techniques. Unlike recent PTOr advancement, which enhances the RBTO performance, this achievement was previously unattainable. Test problems, including an aircraft pylon, reveal its performances. Furthermore, the proposed efficient framework facilitates easy integration with other uncertainty quantification techniques, increasing its performance in uncertainty quantification. Lastly, this research provides computer programs for the newcomer studying cutting-edge knowledge in engineering design, including UQ, TO, and RBTO, in a simple manner.
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(This article belongs to the Special Issue Computing Methods for Aerospace Reliability Engineering)
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Open AccessArticle
Multiple-Bird-Strike Probability Model and Dynamic Response of Engine Fan Blades
by
Siqi Wang, Jinhui Li, Haidong Lin, Zhenhong Deng, Baoqiang Zhang and Huageng Luo
Aerospace 2024, 11(6), 434; https://doi.org/10.3390/aerospace11060434 - 28 May 2024
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Bird strikes pose one of the most significant threats to aviation safety, often leading to substantial loss of life and economic damage. Many bird strike incidents involve multiple birds. However, in previous bird strike studies, the problem of multiple bird strikes has often
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Bird strikes pose one of the most significant threats to aviation safety, often leading to substantial loss of life and economic damage. Many bird strike incidents involve multiple birds. However, in previous bird strike studies, the problem of multiple bird strikes has often been neglected. In this paper, the bird slicing process of a rotating engine fan is examined, and a probability model is introduced to assess the risk of multiple impacts on the fan blades. In addition, this paper utilized an implicit–explicit calculation method. The parameters of blade root stress, tip displacement, plastic deformation, and energy were selected to investigate the effects of the time interval and strike position of a bird strike on the dynamic response of and damage to the blades. The results indicated that the position of bird strikes has a more pronounced effect on blade damage compared to the time interval between impacts. Damage to a blade is most severe when the blade root is struck multiple times. Multiple bird strikes may not always lead to a significant increase in maximum blade tip displacement, and may even have a dampening effect.
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Open AccessArticle
Effects of Different Structural Film Cooling on Cooling Performance in a GO2/GH2 Subscale Thrust Chamber
by
Jixin Xiang, Yujie Jia, Zhiqiang Li and He Ren
Aerospace 2024, 11(6), 433; https://doi.org/10.3390/aerospace11060433 - 27 May 2024
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To investigate the wall cooling of the thrust chamber in an engine, two film-cooling structures, namely, a circular hole structure and a slot structure, were designed. Numerical simulations were performed to study the coupled flow and regenerative cooling heat transfer in thrust chambers
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To investigate the wall cooling of the thrust chamber in an engine, two film-cooling structures, namely, a circular hole structure and a slot structure, were designed. Numerical simulations were performed to study the coupled flow and regenerative cooling heat transfer in thrust chambers with different structures. The influences of parameters such as the film mass flow rate and film hole size on wall cooling were analyzed. Experiments were conducted in a thrust chamber to validate the accuracy of the numerical calculation method. The results indicate that the slot-structured film adheres better to the wall than the circular-hole-structured film, and the film closely adhering to the wall provides better insulation against hot gas, resulting in a reduction of approximately 6% in wall temperature. When the film hole size changes, the change in circumferential wall temperature in the upstream region of the slot-structured film is more pronounced. This paper aims to provide a reference for the design of the cooling structure at the head of the thrust chamber in engineering and suggests directions for optimization and improvement.
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Open AccessArticle
Cyclic Ablation Properties of C/SiC-ZrC Composites
by
Hailang Ge, Lu Zhang, Huajun Zhang, Fang Wang, Xiguang Gao and Yingdong Song
Aerospace 2024, 11(6), 432; https://doi.org/10.3390/aerospace11060432 - 27 May 2024
Abstract
To reveal the ablation performance of C/SiC-ZrC composites under different ablation modes, C/SiC-ZrC composites were prepared using chemical vapor deposition, precursor infiltration, and pyrolysis. Single ablation and cyclic ablation tests were conducted on the C/SiC-ZrC composites using an oxyacetylene flame, in order to
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To reveal the ablation performance of C/SiC-ZrC composites under different ablation modes, C/SiC-ZrC composites were prepared using chemical vapor deposition, precursor infiltration, and pyrolysis. Single ablation and cyclic ablation tests were conducted on the C/SiC-ZrC composites using an oxyacetylene flame, in order to obtain ablation parameters, as well as macroscopic and microscopic ablation morphology for the different ablation modes. The results show that the linear ablation rate and mass ablation rate of different ablation modes decrease with increasing time. The linear ablation rate and mass ablation rate of cyclic ablation are 12% and 24.2% lower than those of single ablation. Within the same ablation time, the C/SiC-ZrC composites subjected to cyclic ablation exhibit shallower and more evenly distributed pits, caused by high-temperature airflow ablation. The material surface has a white oxide layer composed of SiO2 and ZrO2, and the carbon fibers inside are wrapped by oxide particles, enhancing the ablation resistance of C/SiC-ZrC composites.
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(This article belongs to the Special Issue Current Trend of High Temperature and Pressure Materials in Hypersonic Vehicles)
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